Doctoral Degrees (Animal, Wildlife and Grassland Sciences)

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  • ItemOpen Access
    Sustainable wood harvesting principles with the aim to restore rangeland in the Thornbush Savanna of Namibia
    (University of the Free State, 2022) Boys, Jerome Marcelino; Smit, G.N.; Malan, P. J.
    The savannas of northern Namibia are prone to woody plant thickening, and land owners, therefore, attempt to restore rangelands through the removal of some or all of the woody plants with a view to reduce the negative competition interactions with the herbaceous layer, allowing an increase in the grazing capacity for livestock. The utilization of the bush resource made available through these bush control programs has led to the development of a lucrative bush value-chain industry which often leads to the over-exploitation of the resource for short-term financial gains. The effect of the most common harvesting practices such as non-selective and selective woody biomass harvesting was investigated over a three-year period in an area northwest of Otjiwarongo, described as the North-central plateau of Namibia and with vegetation classified as Thornbush Savanna. The dominant woody plant species were Senegalia mellifera and Vachellia reficiens. They are also the most sought-after species for charcoal production for their high wood yield potential, and for this reason they are also the species of interest in this study. The coppicing ability, survival, change in woody species composition, woody plant recruitment through coppice and/or sapling establishment, rate of biomass production, effect of annual total coppice defoliation on coppice regrowth survival of selected species, and growth rates and mortalities of woody plants were studied. The trail layout consisted of plots of 50 x 30 m (1 500m²) with at least two replications of each treatment. The non-selective (bush-roller and chainsaw) harvesting showed no significant differences (P>0.05) in coppice regrowth of Senegalia mellifera and Vachellia reficiens. However, although not significant (P>0.05), the chainsaw harvested plots had higher coppice rates when considering all other woody species whereas, bush-roller harvested plots had a higher sapling establishment as compared to the chainsaw harvested plots. Dichrostachys cinerea was the only species that had a highly significant (P=0.002) increase in sapling establishment. There was a change in dominance from high wood-potential (mostly S. mellifera, V. reficiens, Vachellia tortilis, V. hebeclada) to low wood-potential (mostly all Grewia species, D. cinerea, Catophractes alexandrii) species. The ETTE ha⁻¹ is projected to return to its original pre-harvest state in less than 12 years, whereas the wood biomass did not show any signs of returning to its original pre-harvest state. Annual total defoliation of coppice proved to be effective for the control of coppicing woody plants without the need for any chemical treatment (arboricide). There was a highly significant difference (P<0.01) in the rate of coppice between the two seasons (hot wet summer and cold dry winter) as treatments. Plants initially harvested in summer had a higher coppice and survival rate than plants harvested in winter. The summer harvested S. mellifera stumps coppiced more vigorously compared to V. reficiens. The winter harvested V. reficiens coppiced more vigorously compared to S. mellifera. There were highly significant differences (P<0.001) in coppice amongst the selectively versus non-selectively harvested plots. Plants harvested selectively, while retaining 4 500 ETTE ha⁻¹, had lower coppicing rates than those where the whole area was harvested non-selectively. The high ETTE ha⁻¹ before harvesting could not be matched three years after harvesting, whereas plants ha⁻¹ in the selectively thinned plots significantly (P<0.05) exceeded the original plant density (plants ha⁻¹) before initial harvesting within three years. Mature S. mellifera woody plants had a significantly higher (P<0.001) mortality rate in the bush-thickened control plots. The mortality of V. reficiens was not as high as that of S. mellifera. Regarding shoot growth, the growth in shoot length was more pronounced than that of shoot diameter. Vachellia reficiens had a significantly higher (P=0.001) growth rate in shoot length compared to S. mellifera. Allometric regression equations were also developed from harvested undamaged Senegalia mellifera and Vachellia reficiens plants for inclusion into the BECVOL-3 model. Highly significant relationships (P<0.01) were found between the spatial canopy volume and the dependent biomass variables predicted. There were negligible differences in percentage species composition of herbaceous plants amongst the different bush control treatment plots. Although surveys in all plots confirmed a state of bush thickening as per the general rule of thumb and thus the need for some form of bush thinning, the grass dry matter production did not improve, as generally assumed, with reduced woody plant competition. The herbaceous dry matter production showed a more pronounced positive response to increased rainfall rather than bush thinning during the study period. The first year of the study had a below-average annual rainfall and the rest of the years followed with above average annual rainfall.
  • ItemOpen Access
    The introduction of captive bred African lions (Panthera leo) to a private wildlife reserve in the Limpopo Province, South Africa
    (University of the Free State, 2021-11-15) Booyens, Paul Lodewyk; De Waal, H. O.
    The objective was to utilise an unique opportunity to monitor and explore the social and feeding behaviour, and the reproductive ability of captive bred, and reared African lions (Panthera leo) when reintroduced as a founder population on a large private wildlife reserve (hereafter, the Reserve). The study did not aim to justify the captive breeding of lions, but the potential value of such lions was assessed, when recently introduced to a free-roaming scenario, to augment the conservation status of this iconic African predator species. It was hypothesised that the reintroduction of such African lions in a free-roaming scenario would be deemed successful if the following five criteria were met: (i) The ability to form social groups in an extensive wild habitat; (ii) The ability to become self-sustaining with no interference or supplementation by management; (iii) The ability to reproduce by raising offspring to maturity/female sexual maturity and/or dispersal of males from natal prides; (iv) The ability to teach offspring to hunt effectively, interact socially, reproduce, and secure a healthy and viable F2- generation, characteristic of wild managed lions; and (v) Be regarded as suitable potential founders for reintroduction programmes where wild populations have disappeared or need to be augmented.The Reserve was established in the Limpopo Province, South Africa with a vision to include the Big Five of Africa. Therefore, five African lions, bred and reared in captive facilities, were introduced in 2017 to the Reserve. The five lions comprised an adult male (10 years old and previously used for breeding at a captive facility in the Free State Province, South Africa) and four large female cubs (two years old, sourced from a captive facility in the Limpopo Province, South Africa). In preparation for the envisaged introduction of lions, the adult male was moved from the Free State Province in November 2016 and joined with the four large female cubs in a 1-ha camp at their natal captive facility in the Limpopo Province. Four weeks after being joined, the five lions were relocated, and in December 2016 they were released in a boma (4-ha holding facility) on the Reserve to acclimatise. While the five lions were in the boma for a 6-week period, they were fed twice a week blue wildebeest (Connochaetes taurinus) or zebra (Equus quagga) carcasses. Without pre-release training, the five lions were released from the boma on 27 January 2017, when the gates of the boma were simply opened. The spatial utilisation of the Reserve by the lions were monitored with satellite GPS collars, fitted to a few selected individuals. The ultra-high frequency (UHF) capabilities of the satellite GPS collars also allowed for real-time locating of the lions. The information was used to determine their temporal and spatial utilisation, home range selection, possible group formations, birthing incidences, and successful hunting sites. The ArcGIS Desktop (V. 10.8.1) was used to analyse the data. In addition, visual observations of lions and detected kill sites were done from vehicles and electronically submitted via a WhatsApp group, whereafter it was chronologically logged for analysis. Social behaviour, prey killed, attempted hunts, and body condition of the lions were recorded via the WhatsApp group. Photographs and videos of the events were used to confirm activities. Timelines of temporal activities and incidences were created for the lions, showing important occurrences such as social interaction, mating, births of known litters and hunting. When appropriate, the timelines of different individuals were linked to provide better insight of the social interaction of the lions on the Reserve. When deemed necessary, excess lions were removed from the Reserve to comply with Provincial and National legislation and ensure ecological sustainability of the Reserve. Inbreeding of the lion population was prevented by vasectomising some males and by introducing an unrelated adult male to the Reserve in 2020. The lions showed varying degrees of social bonding and possible reasons for the grouping behaviour are provided. During the study, only two stable groups of more than two adult lions were recorded. The hunting success of the lions could not be accurately determined, because of large areas of dense vegetation and the few access roads, limiting the recovery of the remains of kills before being scattered by scavengers. Furthermore, the dense vegetation of some areas on the Reserve prevented the visual sighting of hunting attempts. Therefore, the hunting success of the lions was determined indirectly by the continuous evaluation of body conditions and the changes in the density of suitable prey species on the Reserve. Since the lions were released from the boma, they were self-sustaining. The cub survival rate was high and comparable to that on small wildlife reserves (<1 000 km2). Population growth was high, as was expected for a wild managed population. In the study, most cubs brought from hiding by their mothers, comprising 2, 3 or 4 cubs when first sighted, survived. Subsequently, some young lions dispersed from their natal prides, and became self-sustaining. Two of the lionesses born on the Reserve, namely F1-generation lions, later gave birth to their own litters, namely F2-generation lions. In conclusion, when introduced in a free-roaming scenario on the Reserve, the captive bred, and reared African lions, as well as their offspring (i) formed social groups, albeit it often a single lactating female with cubs; (ii) became self-sustaining by hunting successfully, with no interference or supplementation by management; (iii) reproduced and raised offspring to reach female sexual maturity and dispersal of sub-adult males from natal prides; (iv) taught their offspring to hunt effectively and interact socially, enabling reproduction of the species, thereby securing a healthy and viable F2-generation, characteristic of wild managed lions; and (v) suggested that similar lions may be considered as founders for reintroduction programmes, where wild populations have disappeared or need to be augmented in specific circumstances.
  • ItemOpen Access
    Relationship of corticoid, thyroid and metabolic profiles with fertility of beef females on sourveld and mixed sweetveld
    (University of the Free State, 2000-09) Erasmus, Johann Andre; Wilke, P. I.; Greyling, J. P. C.
    English: During the 1981/82 season, first-calf Bonsmara cows on the sourveld (lower plane of natural pasture) supplemented with an NPN lick in winter (sourveld +N), and sourveld not supplemented with an NPN lick in winter (sourveld - N), had significantly lower mean blood (2.13; 2.12 and 2.30 mmol/l; P < 0.01), plasma (3.20; 3.10 and 3.38 mmol/l; P < 0.01) and red blood cell glucose (1.06; 0.98 and 1.09 mmol/l, P <0.05) concentrations, compared to the cows on mixed sweetveld (higher plane of natural pasture) supplemented with an NPN lick in the winter (sweetveld +N). Similar results were obtained with regard to total plasma protein, 66.0; 68.0 and 72.0 gil (P < 0.01), plasma albumin, 32.0; 32.0 and 34.0 gil (P < 0.01), and plasma globulin, 35.0; 36.0 and 38.0 gil (P <0.05) for the 3 treatments respectively. Plasma urea concentrations appeared to be a good indicator of protein status of first-calf cows on the 3 treatments, concentrations being 1.75; 1.35 and 3.75 mmol/l (P < 0.01) respectively.During the following year (1982/83), differences in energy and protein constituents were much smaller, and only plasma albumin and urea concentrations were indicative of the higher nutritive value of the mixed sweetveld. First-calf cows on the sourveld + N had significantly (P < 0.01) lower plasma cortisol concentrations than their counterparts on mixed sweetveld + N during the 1980 period (11.94 vs. 13.02 ng/ml respectively), and the 1981/82 period (8.78; 7.32 and 9.76 ng/ml for females in the 3 treatment groups respectively. During the subsequent year, virtually no differences in plasma cortisol levels were observed. No significant difference in plasma thyroxine concentrations was noted between experimental animals on the sourveld and mixed sweetveld during the 1980 period. During the following 2 seasons, plasma T4levels were significantly (P <0.001) elevated in the experimental animals on the mixed sweetveld (41.80; 40.80 and 48.1 0 ng/ml during 1981/82, and 39.10; 40.80 and 46.60 ng/ml during 1982/83 for females in the 3 treatment groups respectively. Pregnancy influenced the mentioned metabolites and hormones Bonsmara cows to varying degrees. Lactation suppressed blood and plasma glucose concentrations for 8 to 10weeks after parturition. The influence oflactation on total plasma protein, albumin and globulin concentrations was not significant, and variable. Plasma urea levels were considerably suppressed in lactating first-calf cows, compared to dry cows in the 3 treatment groups, viz. 1.28 vs. 1.96 (P < 0.05); 1.02 vs. 1.53 (P < 0.01) and 3.05 vs. 3.98 (P < 0.05) respectively. Little differences were noted during the subsequent year. The adrenal cortex and thyroid activity were suppressed by the effect of lactation in first-calf cows in all 3 treatment groups during the 1981/82 season. Cows having higher mean blood glucose concentrations after first parturition (8 weeks prior to mating) conceived at the next mating, compared to lower concentrations of infertile cows, viz. 2.49 vs. 1.93 mmolIl, and 2.20 vs. 2.07 mmol/l during the 1981/82 and 1982/83 seasons respectively. Similar results were obtained for plasma glucose (3.57 vs. 2.75, and 3.36 vs. 3.27 mmol/l respectively), plasma cortisol (8.2 vs. 4.0, and 8.3 vs. 5.3 ng/ml respectively) and plasma thyroxine (45.2 vs. 34.5, and 41.0 vs. 37.2 ng/ml respectively). Fertile cows were in a weight gaining phase from parturition to mating. Season of the year generally did not have a significant and consistent influence on blood and plasma metabolites. Energy, and some of the plasma protein metabolites, were significantly higher during the summer of 1981/82, than during the winter. During the following year (1982/83), results were generally reversed, with plasma albumin and urea levels being higher during the winter than summer seasons. Plasma cortisol concentrations were generally elevated during the summer season, compared to the winter season.
  • ItemOpen Access
    Genetic improvement of beef cattle in a tropical environment with special reference to the Gudali and Wakwa breeds in Cameroon
    (University of the Free State, 1999-11) Ebangi, Achenduh Lot; Erasmus, G. J.; Tawah, C. L.
    English:In an attempt to genetically Improve Gudali beef cattle JO Cameroon, two selection experiments were conducted between 1968 and 1988 at the Animal Production and Research Stations of Wakwa, Ngaoundere. The one experiment involved a two-breed synthetic beef breed, the Wakwa, obtained from inter se matings of the first filial generation of American Brahman (50%) x Gudali (50%) crosses. The other experiment involved recurrent selection of the indigenous purebred Gudali in an effort to enhance its beef production without any serious detrimental effects to its adaptational qualities.In order to assess the genetic progress of the two experiments, a study using mixed model methodology was carried out. The objectives were to quantify factors affecting growth traits, estimate (eo )variance components, predict genetic merit (breeding values) for direct and maternal performance and determine genetic progress by examining direct and maternal genetic trends for all animals. A total of 2886 records for birth weight (BWT), 2732 for average preweaning daily gain (ADG), 2899 for weaning weight (WWT), 2098 for yearling weight (YWT) and 1957 for eighteen months weight (EWT) of Gudali cattle were used in the study. Corresponding number of records for the Wakwa were 1793, 1656,1838, 1372and 1328. The results indicated that sire, sex, season (S), calf birth year (C), herd (H), HxSxC interaction, cowage group and ages at weaning (WAGE), yearling (YAGE) and eighteen months (EAGE), as well as covariates for weaning, yearling and eighteen month weights, were significant (p<0.05) sources of variation for these traits. Therefore, for reliablegenetic parameter estimations and evaluation of genetic merit of individual candidate animals for selection, these sources of variation should be taken into consideration. Hence the inclusion of these factors in the mixed model for the estimation of genetic parameters and prediction of breeding values.Estimates obtained for direct, maternal and total heritabilities were 0.37, 0.05 and 0.21 for BWT; 0.24, 0.17 and 0.07 for ADG; 0.27,0.19 and 0.11 for WWT; 0.51, 0.20 and 0.22 for YWT; and 0.18, 0.02 and 0.18 for EWT, respectively, in the Gudali. Corresponding estimates in the Wakwa were 0.55, 0.23 and 0.18 for BWT; 0.26, 0.07 and 0.12 for ADG; 0.28, 0.09 and 0.15 for WWT; 0.18, 0.00 and 0.17 for YWT and 0.14, 0.06 and 0.17 for EWT. Estimates for genetic correlations between direct and maternal effects were generally highly negative and ranged from -0.76 for ADG to -0.98 for YWT in the Wakwa and from -0.77 for WWT to - 0.88 for BWT in the Gudali. However, in both breeds the genetic correlation was nil for EWT. These estimates obtained are indicative that there are distinct possibilities of improving direct preweaning and/or postweaning growth in the both breeds through selection. However, a high selection intensity for direct performance may in the long run be detrimental to maternal performance as a result of the generally strong genetic antagonism between them. Although some estimates of genetic parameters for preweaning weight from one to seven months traits were not obtained for the Wakwa breed due to limited data, estimates obtained for the Gudali indicated that the highest, although moderate, estimate for maternal heritability (0.24) was for weight at two months of age. Therefore, an attempt to optimise direct and maternal performance in the Gudali through selection could be mosteffective at two months and at yearling, respectively. It is suggested that the apparent genetic antagonism generally found between direct and maternal ability be specifically investigated using more suitable data.An assessment of genetic progress indicated positive and significant (p
  • ItemOpen Access
    In vitro embryo production in cattle
    (University of the Free State, 2007-08) Rust, Johannes Matthias; Greyling, J. P. C.; Schwallbach, L. M. J.
    English: The objective of this study was the development of efficient in vitro embryo production (IVEP) technology for application on fertility-impaired beef and dairy cows. Fertility-impaired implying animals that could neither reproduce nor produce embryos through conventional MOET procedures due to old age, pregnancy, repeated MOET procedure treatments, certain abnormal uterine conditions and general failure to conceive and become pregnant following repeated inseminations or natural services, as well as due to physical injuries. The investigation concentrated on whether it was possible to produce embryos from a donor cow with this profile and additionally other aspects such as - the best logistical approach for IVEP when presented with a fertility-impaired donor cow - whether superovulation could be used as an enhancing tool when presented with a pregnant donor - and the affect of season on all aspects of IVEP from fertility-impaired donor cows. It was established that a period of OPU could enhance the production of higher numbers of embryos additional to eventual slaughter of the donor cow (10 more embryos on average per donor) and that the culturing of a small number of oocytes and embryos does not negatively affect the eventual IVEP result (10 % more embryos were produced from individual donors). result was a good indicator of how to plan the logistical approach when confronted with these types of donor cows and it also suits the practical situation faced when producing in vitro embryos from small numbers of oocytes collected from these donor cows. It was evident that additional superovulation does not enhance the IVEP potential of pregnant dairy cows (0.02 more embryos per donor per OPU session), unless more refined research is undertaken to optimize the actual superovulation protocols and oocyte recovery procedures. The additional cost implication of added hormonal treatment for superovulation may actually act as a deterrent for cattle stud breeders to embrace this technology. However, the mere fact that it was possible to produce embryos from pregnant dairy cows could be utilized as a useful tool for accelerated genetic improvement in the dairy and beef cattle industry in South Africa. It was established that season (recorded as ambient temperature and photoperiod) had a definite effect on all aspects of IVEP in fertility-impaired beef cattle cows, a trend that was evident from literature in some laboratory IVEP trials on slaughterhouse material and also in the normal reproduction pattern of beef cattle cows in the South African context. This trend manifested itself in the IVEP pattern of fertility-impaired cows. There was a definite decrease in IVEP during the period of late summer (5.4 %) and early autumn (0 %) with a definite delayed effect of high temperatures and possibly photoperiod evident. Alternatively, the optimum period for IVEP seemed to be during winter (between 11 % and 20 %) and spring (between 22 % and 26 %) which also indicated a possible temperature and photoperiod affect. This effect on oocyte quality and eventual embryo production results could also serve as an indicator for other management decisions regarding normal reproduction management in beef cattle as well as the planning of conventional superovulation and embryo transfer programmes. From the obtained results it was clear that IVEP is possible from fertility-impaired and pregnant donor cows. However, there are certain aspects that need to be focussed on to ensure that optimum results are obtained when applying IVEP on these animals. Optimum results are a prerequisite for this technology to be accepted by the South African cattle breeding industry. IVEP is still in a preliminary phase of application in the South African cattle industry and is not within the ability of all breeders. This will, however, become a powerful tool for use in accelerated genetic improvement programmes and will also ensure that superior genetic material from animals that would have been lost for breeding will continue to be utilized in the cattle breeding industry.
  • ItemOpen Access
    The utilization by domestic ruminants in Botswana of treatment diets containing cereal crop stovers treated with urea or urea and molasses
    (University of the Free State, 2007-03) Letso, Moagi; De Waal, H. O.
    English: The studies were aimed at examining the effects of treatment with urea or urea and molasses on the physical and chemical composition of stovers of sorghum, maize and millet and assessing the potential of these treated cereal crop stovers as additional feed for domestic ruminants in Botswana. The trials were carried out at Sebele, Botswana College of Agriculture (BCA), Botswana. Sebele is situated at 24º 33'S and 25º 57'E and is at an altitude of 994 m above sea level. Cereal crop stovers were ground in a hammer mill and treated with 10 g urea/kg stover (T1), 25 g urea/kg stover (T2) or 10 g urea + 10 g molasses/kg stover (T3) for 3 weeks. The experimental design for the treatment of the cereal crop stovers was a 3 x 4 completely randomized factorial design [3 cereal crop stovers and 3 treatment methods (T1, T2, T3) plus untreated]. Samples of cereal crop stovers untreated or treated with T1, T2 or T3 were obtained and analysed for dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and in vitro DM digestibility (IVDMD). The physical changes on the cereal crop stovers due to treatments were noted. Six steers, four of which were fitted with rumen cannulae, and six goats and six sheep were used in a crossover experiment to evaluate the utilisation of treatment diets containing stovers of sorghum, maize and millet treated with T1, T2 or T3. The animals were kept in individual pens and fed a basal diet of veld grass hay plus a commercially available feed, namely Pen-feed. Each animal had unrestricted access to water and a mineral lick and were adapted to the respective treatment diets for 14 days, followed by 7-day sampling periods The data collected included the feed intake and digestibility coefficients of DM, OM, CP, NDF and ADF. Data were also obtained on metabolisable energy (ME) intake, average daily gains and the pH and ammonia concentration of rumen fluid. Treatment with T1, T2 and T3 increased the CP, NDF, ADF, ADL and IVDMD of the cereal crop stovers. The mean CP (g/kg DM) of cereal crop stovers increased from 69.75 (untreated) to 99.94, 112.63, and 110.50 when treated with T1, T2 and T3 respectively. Significant improvements in the total intake of DM and CP by steers compared to the Control diet were observed when feeding cereal crop stovers treated with T2 and T3. The improvements in the intake and nutrient digestibility coefficients when providing some treatment diets containing the treated stovers are comparable to those obtained when offering lucerne hay which implies that these treatment diets may be suitable replacements for lucerne hay. However, the treatment diets did not significantly improve the average daily gain and metabolic body weights of the steers, goats and sheep. Therefore, treatment diets containing stovers of sorghum, maize or millet treated with T1, T2 or T3 used in the present study are recommended for maintenance rather than production purposes.
  • ItemOpen Access
    Studies on the behavioural and genetic aspects of ewe rearing ability and lamb survival in South African sheep flocks
    (University of the Free State, 2002-11) Cloete, S. W. P.; Erasmus, G. J.; Van Wyk, J. B.; Schoeman, S. J.
    English: The dissertation is based on a number of separate trials conducted since 1989. The central theme is ewe rearing ability and lamb survival, and the study includes 15 papers prepared over an 11-year period from 1992 to 2002. These papers are all linked by their emphasis on sheep production as influenced by lambing and neonatal behaviour and its interface with breeding and management. The papers demonstrate the various phases the study went through, and how it eventually transpired into an account of genetic change in lamb output achievable through rigorous selection. The individual papers already contain abstracts. This summary is intended to provide readers with a broad overview of the most important outcomes of the study. The study was organised in three parts, as follows: Part 1:Background Initially, two papers provided the background for the investigations into lamb survival and ewe rearing ability. The first paper dealt with the average reproductive performance of sheep in the Southern Cape, and with levels of reproductive wastage in a number of flocks. It demonstrated that approximately one in four breeding ewes did not care for at least one lamb at lamb marking. Losses were more or less evenly distributed between barrenness and rearing failure. It was impossible to identify managerial practices conclusively associated with a good reproductive performance. Evidence was provided that an improvement in the reproduction of the current flock can be achieved by a simple method of selection that can be practiced by commercial farmers with minimal record keeping. The second paper considered rearing ability in four experimental flocks of the Merino, SA Mutton Merino and Dormer breeds. A minority of ewes was shown to contribute markedly to the observed levels of rearing failure. Animals classified as being "good" or "poor" mothers on their lamb rearing history were shown to differ in one or more pelvic dimensions in two Merino flocks and the SA Mutton Merino flocks. Ewes classified as "good" had larger dimensions. Rearing ability was also demonstrated to be repeatable in the Tygerhoek Merino flock, where sufficient data were available. Part 2: The dynamics of behaviour in lambing flocks This part of the dissertation included four papers. The first paper detailed aspects of parturition and separation from one or more lamb in Dormer and SA Mutton Merino ewes. Length of parturition was found to be dependent on breed, with Dormer ewes having shorter parturitions than SA Mutton Merinos. They also were less likely to be assisted and Dormer lambs were less likely to die during or shortly after parturition. Across years, length of parturition was also repeatable in ewes. Early movement (within two hours) of ewes from the lambing site and high concentrations of lambed ewes in the same paddock were found to result in higher levels of separation from one or more lambs, resulting in lamb mortality. The second paper detailed neonatal progress in lambs and related it to birth weight and lamb survival. Survival was affected by neonatal progress as well as by live weight gain from birth to 3 days in lambs. No breed differences were found for the interval from birth to standing or from standing to apparently suckling in Dormer and SA Mutton Merino lambs. It was, however, found that the traits were moderately heritable, using paternal halfsib methods on a relatively small data set. The mechanisms of difficult births were subsequently investigated in Dormer and SA Mutton Merino ewes, since the two breeds were markedly different in this respect. The etiology of difficult births in the breeds was found to differ vastly. Dystocia and feto-pelvic disproportions commonly led to prolonged parturitions and assistance in SA Mutton Merinos. Uterine inertia were more likely to be observed in Dormers. The ability of factors associated with birth difficulties (pelvic dimensions, litter size and weight, ewe live weight and conformation) to predict length of parturition within breeds was, however, limited. In the final paper of this part of the dissertation, it was possible to partition the genetic variances for behaviour traits observed during lambing in Dormer and SA Mutton Merino ewes. Maternal additive variance ratios for length of parturition were moderate and significant in both breeds. Neonatal progress (time intervals from birth to standing and from standing to apparently suckling) was lowly heritable in both breeds. The interval from standing to suckling was also influenced by the maternal permanent environmental variance in SA Mutton Merinos. Direct and maternal breeding values for behavioural traits differed significantly between lambs that survived and those that died in most cases. This result suggested a genetic association of lamb mortality with lambing and neonatal behaviour. Part 3: Responses to selection for ewe multiple rearing ability This part of the dissertation was based on observed responses in two Merino lines that were divergently selected for ewe multiple rearing ability since 1986. The line selected in an upward direction for multiple rearing ability is referred to as the High (H) line. The line selected downwards is referred to as the Low (L) line. This part of the study consists of nine papers. In the first paper, separation of ewes from one or more lambs was studied in the Merino lines referred to above. Ewes in the H line were more likely to be separated from one or more lambs because of interference, and they tended to be more interested in other parturient ewes. Ewes in the L line tended to be more likely to desert their lamb(s). Ewes that left their birth sites within two hours of birth were more likely to be separated from one or more offspring. The ability of ewes and lambs from the Hand L lines to recognize each other were investigated next. Ewes in the H line were able to find their lambs sooner after the lamb being tethered 20 m away, compared to their L line contemporaries. They were also able to establish contact with all litter members in multiples sooner after finding a tethered lamb. Lambs in the H line tended to be more likely to bleat and tug on the tethering rope when tethered. They also followed their dams more closely when chased away with their dams at three days of age. The paper allowed the estimation of preliminary genetic parameters for mutual recognition of one another by ewes and lambs, although it was not the primary objective. Significant maternal genetic variances were found for most of the traits. The following paper demonstrated a better lamb survival in H line lambs, despite a higher multiple birth rate. Line differences were reported, mostly involving behavioural adaptations conducive to lamb survival in the H line. Ewes in the H line generally experienced shorter births, and H line lambs were less likely to succumb during or soon after parturition. Ewes in the H line showed better cooperation with the first suckling attempts of their lambs, and H line lambs apparently suckled sooner after standing than L line contemporaries. This line difference remained after correction for the better cooperation of H line ewes. A marked advantage in terms of weight of lamb weaned per breeding ewe in the H line was demonstrated for the five years of this study, when compared to the L line. It was found that a substantial proportion of births will not be supervised if the supervision of Merino ewes in South Africa was confined to daylight hours in intensive systems. A larger than expected frequency of very short intervals between subsequent onsets of parturition was observed. If the contention that births would trigger each other could be substantiated, it could be of benefit to quantify the mechanism involved. Knowledge of this would facilitate the synchronisation of natural births in pasture lambing flocks, where it is impractical to alter the distribution of births by nutrition. Relatively few line differences were found in this paper. The distribution of birth sites within paddocks could not be related to selection line. Ewes in the H line ewes were more likely to groom their lambs shortly after birth, while L line ewes commenced grazing sooner after birth. These behavioural adaptations in the H line would generally facilitate lamb survival. Behavioural data from the H and L lines were recorded over a lO-year period and subjected to a genetic analysis. The line differences obtained earlier could be confirmed in this study. Genetic parameters estimated from the data indicated that behaviour traits in lambs and ewes were lowly to moderately heritable. In lambs, a significant heritability estimate was derived for the interval from birth to standing. Maternal heritability estimates were significant for length of parturition and for the interval from birth to standing. Maternal permanent environmental variances were significant for maternal cooperation and the interval from standing to apparently suckling. When behavioural traits were assessed in ewes, length of parturition, maternal behaviour score and the period that ewes remained on or near the birth site were found to be moderately heritable. Genetic divergence was found for the H line compared to the L line. The derived genetic trends indicated changes conducive to lamb survival in the H line. Direct additive, maternal additive and maternal permanent environmental variance ratios were subsequently derived for lamb birth weight, birth coat score and lamb weaning weight. Birth coat score was highly heritable and not influenced maternally. Genetic and phenotypic trends indicated divergence between the H and L lines for weaning weight over the period of assessment. Genetic divergence was particularly strong in the case of direct breeding values for weaning weight. Birth weight and birth coat score were independent of selection line. Genetic parameters were estimated for annual reproduction traits, ewe greasy fleece weight and ewe body weight at joining, using a repeatability model. Heritability estimates for reproduction traits were low, consistently below 10 % of the overall phenotypic variance. Ewe permanent environmental variances were higher, between 7 and 12 %. Genetic correlations of reproduction traits with ewe joining weight were favourable and very high in the case of weight of lamb weaned per ewe. Corresponding genetic correlations with ewe greasy fleece weight were low and variable. Ewe permanent environmental correlations of reproduction traits with ewe joining weight and greasy fleece weight were unfavourable and high in some instances. Phenotypic trends indicated divergence in the expected direction between the Hand L lines in the reproduction traits considered. These tendencies were confirmed by genetic trends based on averaged predicted breeding values within birth years. The results confirmed that genetic progress at a rate of 1-2 % per year was attainable in reproduction traits, despite low additive variance ratios. Genetic parameters were estimated for hogget wool and live weight traits, as well as for testis measurements. Adequate genetic variation for exploitation in a well-structured breeding program was estimated in all traits. Genetic trends indicated change towards heavier and plainer sheep in the H line, while L line contemporaries became smaller and more developed. Genetic trends for testis circumference suggested divergence in the expected direction between lines. This result was, however, associated with the genetic change in live weight, since no line difference was found in testis circumference corrected for live weight. Genetic trends for clean fleece weight and fibre diameter indicated no divergence between lines. Age influences on reproduction, wool traits and live weight were assessed in H and L line ewes subjected to at least 10 years of divergent selection. Genetic parameters derived from this data set were generally consistent with previous estimates, despite the usage of a much smaller data set. The Hand L lines differed markedly for reproduction, but no differences in the shape of age trends were found between lines. Compared to average L line performance, the superiority of H line ewes amounted to 56 % in the case of weight of lamb weaned per ewe. Ewes in the H line were heavier than L line contemporaries at two-tooth age, but the line difference disappeared at later ages. Wool production of L line ewes were heavier than those of their H line contemporaries, particularly in the middle age groups (3 to 6 years), where the highest fleece weights are expected. Fibre diameter increased with ewe age, with no apparent line difference. It was contended that the stress of increased reproduction resulted in the different age trends for the respective selection lines for live weight and greasy fleece weight. In the final instance, this dissertation provides a framework for the genetic improvement of lamb output in pasture-fed sheep by selection for reproductivity. Unwanted correlated genetic changes were minimal, although the stress associated with an increased reproduction impaired live weight and wool traits in mature animals to an extent. The interface between behaviour, lamb survival and ewe rearing ability were clarified for a number of South African sheep breeds, leading to a better understanding of the dynamics involved. These results contributed to the formulation of adapted husbandry and breeding practices, in the context of overall flock productivity. Results pertaining to behaviour appeared to be fairly robust across studies involving different resource populations, and should be appropriate for extension to the broader industry.
  • ItemOpen Access
    The influence of feeding various roughage: concentrate ratios on milk production of Friesland cows
    (University of the Free State, 1974-12) Neitz, Martin Heinrich; Smith, A.
    1. In a single-lactation 240-day continuous trail, 64 lactating dairy animals were used to study input-output response to complete rations. Nine first-calf heifers and seven cows were allotted by the procedure of balancing to each of the four experimental treatments. Ration treatments were: 80% lucern: 20% concentrate (ration A), 60% lucern: 40% concentrate (ration B), 40% lucern: 60% concentrate (ration C) and 20% lucern: 80% concentrate (ration D). The crude fibre percentages of rations A, B, C and D were 23,16; 19.34; 16,11 and 12.01, respectively. These rations were pelleted and fed ad lib. in addition to 9 kg of maize silage daily. A digestibility trial with four additional lactating dairy animals was carried out simultaneously. 2. With decreasing proportions of lucern, digestibility of the dry matter increased from 55,55 to 65,33 per cent (P<0,05). Increasing the proportion of concentrates in the ration led to an increased concentration of metabolizable energy (P<0,05). The digestible protein in the rations varied very slightly (P>0,05). 3. Changes in body mass of cows and first-calf heifers due to ration treatment were non-significant (P>0,05). Age was the most important factor influencing body mass variations of experimental animals; differences between cows and first-calf heifers being highly significant (P<0,01) in favour of the cows. The individual mean body mass gain of the first-calf heifers during their first lactation was 80,4 kg compared to 9,9 kg of the cows in their second and later lactations. 4. There were non-significant (P>0,05) differences, due to ration treatment, in the daily amount of actual milk, 4% fat corrected milk and solids corrected milk produced by cows. Although first-calf heifers on ration D produced 19,3 to 27,0 percent more actual milk, 14,0 to 23,0 per cent more 4% fat corrected milk and 16,3 to 22,9 per cent more solids corrected milk than heifers on either the A, B or C rations, these differences were non-significant. 5. Cows on ration A, B and C produced more (P<0,05) milk, 4% fat corrected milk and solids corrected milk, during each stage of lactation, than the first-calf heifers. Cows fed ration D showed a significantly (P<0,05) higher production than heifers, during the third to fifth month of lactation and a non-significant difference during the sixth to tenth month. 6. Small non-significant (P>0,05) differences occurred in the mean solids-no-fat content of milk. Solids-not-fat content of milk produced by cows ranged from 8,69 to 9,02 per cent and from 8,90 to 9,16 per cent in the case of first-calf heifers. The milk produced by first-calf heifers had a significantly higher (P<0,01) solids-not-fat content than cows during all stages of lactation, irrespective of ration treatment. 7. Milk fat was non-significantly affected by ration treatment. Decreasing lucern content in the ration was accompanied by a decrease in the fat percentage of milk produced by cows (0,3) and by heifers (0,29). 8. The dry matter and gross energy consumption by cows tended to decrease as the dry matter digestibility of the ration increased, differences being non-significant. Similarly as the metabolizable energy concentration increased (increasing with a decreasing proportion of lucern) the voluntary intake by cows tended to decrease. Metabolizable energy intake between ration treatments was very constant and was related to the mean daily yield of the cows. The intake of dry matter and gross energy by first-calf heifers remained more or less the same for all rations (P>0,05). However, as the dry matter digestibility of the ration increased the metabolizable energy consumption by heifers tended to increase, differences being non-significant. 9. Cows consumed significantly (P<0,01) more dry matter, gross energy and metabolizable energy during certain stages of lactation than first-calf heifers, irrespective of ration treatment. In the case of cows the efficiency of metabolizable energy utilization for milk production increased as the lucern portion in the ration increased, differences non-significant. A very similar tendency was noticed with the first-calf heifers. Irrespective of ration treatment cows produced milk more efficiently (P<0,05) during the third and fourth month of lactation than during the later months. The effect of stage of lactation on efficiency of use of metabolizable energy for milk production by heifers was less pronounced than that obtained with cows, but the differences were non-significant. 10. Irrespective of treatment the cows produced milk more efficiently (P<0,01) durng the third and fourth month of lactation than the first-calf heifers. During the fifth, sixth and seventh month of lactation efficiency of milk production by cows and heifers was very similar. During the eighth and ninth month of lactation heifers were more efficient than the cows. 11. In terms of marketing fresh milk the profit margins over cost of feed was 5,6; 6,0; 6,1 and 6,2 c per litre when cows were fed rations A, B, C and D respectively. The profit margins for first-calf heifers were 4,8; 4,7; 4,8 and 6,0 c per litre for the same rations. Reproduction of cows and first-calf heifers was non-significantly affected by ration treatment. 12. None of the experimental rations caused bloat-, digestive- or general stiffness problems. Seventeen cases of mastitis occurred during the course of three years and seven months. 13. In four switchback trials with 16 lactating dairy animals the pelleted experimental rations were compared with otherwise identical non-pelleted rations (lucern portion being chaffed in 2,5 cm lengths). The method of preparing the rations by either pelleting or non-pelleting did not appreciably influence the dry matter consumption (g DM/W kg 0,75), daily amounts of actual milk produced, solids corrected milk and composition of milk. However, animals receiving ration D in a non-pelleted form, produced significantly (P<0,05) more solids corrected milk and total solids in milk than animals fed the corresponding pelleted ration.
  • ItemOpen Access
    FarmRec: 'n geïntegreerde ekstensiewe veeboerdery rekordhoudingstelsel
    (University of the Free State, 2003-04) Theron, Johannes Frederick; Smit, G. N.
    English: Extensive farmers in South Africa do not generally keep records of their farming activities, and if they do, it only entails financial record keeping for the Receiver of Revenue. Resources for farm record keeping, especially with regard to grazing and animals, are scarce, and the systems that do exist are elementary. Those farmers who do keep records make use of various approaches, ranging from manual and paper-based systems and computer spreadsheets, to specialist software for certain aspects oftheir farming activities. The FarmRec record-keeping system was developed to provide for a wide range of livestock farming activities. With the development of this record-keeping system, existing shortcomings and problems were addressed, taking into consideration all aspects to be included and contained in a record-keeping system in order to provide a purposeful, comprehensive and user-friendly product. Various information categories are integrated in this system, thereby negating the need for several different types of record-keeping systems. The main purpose of record keeping is to gather information from one's own data. The need for specific information makes it necessary for records to be kept of certain resource data. The relation between resources and the information obtained from them is comprehensively discussed. This relation also indicates the flow of data and information between resources. The FarmRec system was designed and developed around these relations. The waterfall and evolutionary development processes were used to develop and test the system, and to make corrections and improvements to the system. By means of this system, records are kept of information relating to paddocks, land, grazing, animal numbers and animal management actions, as well as of animal and plant product quality and quantity, income and cost information, infrastructure, and financial and rainfall information pertaining to the farming unit. The information to be provided for the different record-keeping facets is discussed. Attention is also given to the integration of information. The information is made available in the form of reports. The extent to which these reports are available is determined by the degree to which the user entered the data of the different facets into the computer. This system makes a large number of reports available to the user. The type of report is determined by the grouping of the selected data. The user himself/herself determines the selection criteria, which consist of the reporting period or date, subunit, groupings and sorting order, as well as level of detail in the report. The system was provided to users and then evaluated to gain an indication of the ease with which the functions and reports in the system can be used. From the evaluation it can be deduced that the FarmRec system is user friendly and easy to use. The system offers many more functions and reports than needed or used by any individual user, but the diversity of users means that different combinations of functions and reports are needed. The level of use by users also varies considerably. With the exception of a few isolated reporting functions, respondents indicated that the functions in the system are easy to use and of much value. The FarmRec system succeeds in addressing a wide range of record-keeping facets. The users indicated that the magnitude and integration are more than sufficient. The system resulted in an improvement in the keeping of grazing records - an aspect that otherwise went unrecorded. Record keeping in respect of grazing was made possible for the user by means of simple notes on animal movement. The total record keeping of the users furthermore improved from their original record-keeping systems. The improvement in record keeping occurred without the users having to spend more time on record keeping. This is regarded as a very positive reaction, as many users indicated that the time available for record keeping is extremely limited.
  • ItemOpen Access
    Crude protein and mineral status of forages grown on Pellic Vertisol of Ginchi, Central Highlands of Ethiopia
    (University of the Free State, 2002-11) S/gebreal, Lemma Gizachew; Smit, G. N.
    The study was conducted at Ginchi, which is situated in the western Shoa zone of the central Ethiopian highlands. The main aim of the study was to assess the crude protein (CP) and mineral status of feeds produced in the Vertisol area of Ginchi by relating them to pasture management, seasonal and/or soil factors. Aspects of the farming systems that relate to feed resource management, utilization, constraints and opportunities were also investigated. The N and mineral element status of the soil and the feeds were evaluated during the dry and wet seasons of 2001 by analysing samples collected from adjacent 18 year round grazed grassland (YRG) plots, 12 seasonally stock excluded grassland (SSE) plots, 10 tef (Eragrostis tef) and 9 grass pea (Lathyrus sativus) plots, and noug (Guizotia abyssinica) seedcake samples obtained from oil extracting plants. The results of the farming systems study demonstrated a strong inter-dependence between crop and livestock subsystems. Livestock rely on crops for their diets as much as the latter do on livestock for traction power and manure. Stored feed supplies are preferentially fed to working oxen, milking cows and animals intended for sale. The period extending from the late dry season (March-May) up until the mid wet season (July) appeared to be the time when feed shortages were most critical. Smallholders try to cope with the problem through efficient use of SSE, grassland, crop residues and crop weeds. Occasionally they also provide domestic herbivores with locally produced supplemental feeds, common salt, mineral rich soil or mineral water. Soil samples were analysed for particle size class, pH, organic matter (OM), cation exchange capacity (CEC), N, P, Ca, Mg, K, Na, Fe, Mn, Cu and Zn. Most of these soil parameters differ markedly (P<0.05) between the different land use systems. Parameters such as OM and total N in particular were very high in grassland soil in comparison to soil under cropping systems (P<0.01). The results also revealed a substantial across site variation of these soil parameters. For native pastures, the type of pasture management had a considerable influence on floristic composition, herbage CP and mineral concentration. Compared to the YRG grassland the SSE grassland contained a higher proportion of herbaceous species with superior CP and mineral concentrations. The CP and mineral contents of YRG grassland exhibited marked changes with the advance of the season (P
  • ItemOpen Access
    Rangeland evaluation and perceptions of the pastoralists in the Borana zone of southern Ethiopia
    (University of the Free State, 2003-03) Bayene, Solomon Tefera; Snyman, H. A.; Smit, G. N.
    The study was conducted in the Borana rangeland of southern Ethiopia. In the last few decades the Borana rangelands have been degraded while the pastoralists adhered to the traditional grazing strategies. The main aims with this study were to investigate the soil characteristics as well as aboveground plant communities and to assess the condition of the rangeland. In addition, the pastoralists' perceptions and cattle-rangeland management practices were evaluated. The botanical composition of the grass layer, woody vegetation structure, soil and the rangeland condition were studied in four communal grazing areas (Did Yabello, Did Harra, Dubuluk and Melbana), three land use systems (communal land, government ranch and traditional grazing reserve) and along distance gradients from water source. Species composition and basal cover of the grass layer was estimated using frequency of occurrence of plant species. Woody plant data were standardized to tree equivalent ha-l (l TE = 1 tree, 1.5 m high). Rangeland condition was assessed based on ecological condition index, weighted palatability composition of the grass layer, the structure of woody plants and soil compaction. Soil seed bank was studied under three land use systems and along a distance gradient from water source. Survey on cattle-rangeland management practice and pastoral perceptions was conducted on 40 individual households and 118 elders (7 per group). Survey results of the pastoral households and elders indicated that the average household in the study area was 7 members. The percentages of male and female children who attended schools were 26 % and 9 % respectively. Livestock holding per household was estimated to be 14 cattle, 10 goats, 6 sheep and 2 camels. Cultivation is widespread in the study area. Major constraints in livestock production were in order of importance: drought, feed shortage, water scarcity, animal diseases, predators and communal land tenure. According to the pastoralists, contributing factors to rangeland degradation were in descending order: recurrent drought, human and livestock pressure, expansion of cultivation, ban on fire and development of water ponds. A total of 49 grass species were identified in this study. The communal land had higher and lower percentages (P<0.05) of annual and perennial grasses, respectively, than the government ranch and the traditional grazing reserve. There were no marked differences (P>0.05) among the four communal grazing sites and the three different distances from water concerning both annuals and perennials. The occurrence of Chrysopogon aucheri was higher (P<0.05) on the government ranch (23 %) and traditional grazing reserve (27 %) than on the communal land (14 %). The frequency of C. aucheri did not vary between the communal grazing sites (average = 14 %) and along distance gradient from water (average = 12 %). Leptothrium senegalensis and Chloris myriostachya did not vary (P<0.05) between the land use systems (average = 4 % and 1 %, respectively) and along the distance gradient from water (average = 2 % for both species). The frequency of Sporobulus nervosus was highest (P<0.05) in the communal land (13 %), whereas the occurrence of S. pyramidalis did not differ markedly (average = 32 %) between the land use systems (P>0.05). Both species did not show prominent variations along the distance gradient from water (average = S. nervosus-14 % and S. pyramidalis-36 %). Grass basal cover was fairly low and similar in the land use systems, communal grazing sites and distance gradients from water. A total of 54 woody plants were identified. Total density of woody plants was higher (P<0.001) on the communal land (l 083 TE ha-I) or the government ranch (l 188 TE hal) than on the traditional grazing reserve site. Within the communal grazing sites, the densities at Did Yabello (l 318 TE ha"), Did Harra (l 088 TE ha") and Melbana (1 178 TE ha") were higher (P<0.05) than on the fourth site, Dubuluk. Results from the distance gradient from water revealed that differences were not significant (P>0.05) between the near, middle and far sites (average = 1 150 TE ha-I). Overall figure showed the advancement of woody encroachment in the semi-arid Borana rangelands. The most important invaders were Commiphora africana, Grewia tembensis, Acacia drepanolobium and A. brevispica. Soil chemical analysis revealed low nutrient contents, which did not vary significantly (P>0.05) in all the study areas. Similarly, differences in pH, soil texture, soil bulk density and soil compaction were not significant. Assessment of rangeland condition indicated that both ecological condition index (ECI) and weighted palatability composition (WPC) were highest on the government ranch (711 and 55 %, respectively). Along the distance gradient from water, differences in rangeland condition (P>0.05) were not significant (average: ECI = 533 and WPC = 29 %). Within the communal grazing sites, Dubuluk and Melbana had relatively higher ECI and WPC values (average: 602 and 36 %, respectively) than the other two sites (average = 520 and 25 %, respectively). The soil seed bank study revealed that a total of 44 plant species were identified. Of these, 25 % were grasses and 75 % were non-grass plant species. As for the land use systems, seedling and floristic density of the graminoids were higher (P<0.05) on the traditional grazing reserve (798 seedling m-2 and 361 plants m-2, respectively) than on the communal land and the government ranch. Along the distance gradient from water, the differences were not significant (P>0.05). Similarity between grass flora of seed bank and above ground plant community was low. It can be concluded in this study that the deteriorating conditions of the Borana rangelands were revealed by changes in the structure and composition of the grass layer, woody vegetation, soil fertility and by the status of the soil seed bank. Bush encroachment is the critical problem. Therefore, workable control programs need to be devised immediately. It is also vital to develop a clear policy at national level on the use and management of the communal rangeland resource.
  • ItemOpen Access
    Rangeland evaluation in relation to pastoralists perceptions in the middle Awash valley of Ethiopia
    (University of the Free State, 2003-01) Gedda, Abule Ebro; Snyman, H. A.; Smit, G. N.
    Pastoralism is the most dominant land use form in the arid rangelands of Sub- Saharan Africa in which Ethiopia is not an exception. However, in Ethiopia and elsewhere, rangeland-based life-styles are in difficulty with the rangeland environment under threat because of both external and internal constraints. The spatial variability of the annual rainfall in these areas also has an affect on the pastoralists livelihood. Accordingly, four studies were undertaken in two neighbouring districts occupied by pastoralists of different ethnic groups living in the middle Awash valley of Ethiopia with the objective of evaluating the condition of the rangelands, which was related to the perception of the pastoralists in order to come up with possible recommendations to minimize further degradation. The pastoralists perceptions of the rangeland resource were studied through group discussions and by using a structured questionnaire where each household was taken as a unit of analysis (90 households from Oromo living in Kereyu-Fantale district and 55 households from Mar living in Awash-Fantale district). The data was analysed using Statistical Package for the Social Sciences (SPSS). The result showed that the average family size per household was about 6.74, with nearly 80% of the people without any kind of education. The main source of income for both pastoral groups was from the sale of animals. The second source of income to the Oromo and Afar pastoralists was from the sale of crops and milk and milk by-products, respectively. Both pastoral groups reported that woody species like Cryptostegia grandiflora, Capparis fascicularis, Erythrina abyssinica and Flueggea virosa) and herbaceous species like Tribulus terrestris, Tephrosia subtriflora and Cynodo are sources of poisons which affect their livestock production. Ninety seven and 3% of the Oromo respondents use Cymbopogon commutatus and Chrysopogon plumulosus for house roofing respectively, while 38.1%, 23.0%, 10.6% and 28.3% of the Afar pastoralists use C. commutatus, C. exacavatus, Enterpogon and Sporobolus ioclados, respectively for a similar purpose. Seventy six percent of the Oromo and 77 % of the Afar respondents do not harvest grasses from the rangelands and the primary use of woody plants in both pastoral groups was for livestock feeding. It was indicated that the grazing lands were bush encroached notably with Acacia senegal, A. nubica and Prosopis juliflora (Awash-Fantale district only) and the condition of the rangeland to be in poor condition. None of the Afars and only 12% of the Oromo pastoralists had private grazing lands. The majority of the respondents chose to continue with communal type of ownership in the grazing lands and a shortage of water was a critical constraint to the Oromo pastoralists. There is a critical shortage of livestock feed during the dry season and the first measure taken to solve feed shortage is migration. Unfortunately, 90% of the Oromo and 60% of the Afar respondents replied that migration is a bad practise. The Afar pastoralists (cattle = 20; sheep = 12; goats = 26; Camels = 15) had a higher number of livestock owned per household than the Oromo pastoralis (cattle = 10; sheep = 8; Goats = Il; Camels = 5). Rangeland condition in terms of grass, browse and soil parameter was studied at Il sites in Awash- Fantale district and 10 sites iri Kereyu -Fantale district using techniques and/or methods mostly developed in South Africa. Grazing and browsing capacities were also calculated for each of the rangeland sites. The most dominant grass species-in the study districts was Chrysopogon plumulosus followed by different species of Sporobolus. The percentage bare ground as estimated by the point method varied from 0.33 to 10.79 with a mean value of 5.27. The basal cover in both districts was low, averaging 3.35%. The DM yield of the grass ranged between 168.52 kg ha" to 832 kg ha-I. The grazing capacity varied from as low as 54.14 ha LSU-I to as high as 7.06 ha LSUI. The results of the evapotranspiration tree equivalent (ETTE ha") showed that the study districts were bush encroached with A. senegal, A. nubica and P. juliflora. In both districts, the browse production (total leaf DM) ranged from as low as 194 kg ha" to 3 311 kg ha-I, with most of the leaf dry mass found above the height of 1.5 m. In both districts, the highest browsing capacity (ha BU-I) was contributed by A. senegal and A. nubica. The condition of the communal grazing lands was also assessed m relation to benchmark sites. Basal cover and the DM yield of grasses was higher in the benchmark sites (basal cover= 5.3% and DM yield of grasses = 985.7 kg ha") than the sample sites (basal cover = 3.3% and DM yield of grasses = 447.2 kg ha"), which indicated that given proper management, there is ample room to improve the grazing capacity of the rangelands. With the objective of studying the effects of tree species' on grass species composition, yield and some soil parameters under different grazing gradients (light, medium and heavy) in two sub-habitats (under canopy and open grassland), two tree species (Acacia tortilis and Balanites aegyptica) were identified. The data was analysed using DECORANA and SAS (Statistical Analysis System). The results showed that the grass species found at the heavily grazed sites were mostly annuals and less desirable species. The major difference between the medium and lightly grazed site in grass species composition was the presence of Panicum maximum under the canopy of trees in lightly grazed condition. The DM yield of grass improved substantially as the grazing intensity decreased (heavy = 31l. 9 kg ha", medium = 1 607 kg ha-I and light = 2 737.5 kg ha"). At the medium and lightly grazed sites, the DM yield of grass was higher (P<0.001) under tree canopies than the corresponding open grasslands. Soil nutrient status increased as the grazing pressure decreased from heavy to light grazing. Electrical conductance, percentage nitrogen and organic carbon increased (P<0.01) under tree canopies compared to the corresponding open grasslands whereas they decreased with an increase in the depth. of soil. In conclusion, all studies with different objectives and arguments clearly indicate that the condition of the rangelands IS poor, requiring careful and participatory interventions. Future studies need to distinguish between climate and man-made droughts although droughts are a normal phenomenon in these drier areas. Rangelands in poor condition increase the intensity and frequency of climatic droughts.
  • ItemOpen Access
    Genetic factors affecting milk production, growth and reproduction traits in Bos indicus x Bos taurus crosses in Ethiopia
    (University of the Free State, 2002-11) Mulugeta, Sendros Demeke; Schoeman, S. J.; Neser, F. W. C.
    English: Five separate studies were conducted to investigate the genetic factors affecting growth, milk production and reproduction traits in Bos indicus x Bos taurus crosses in Ethiopia. The first three studies were based on early growth data collected from the purebred Boran (Bo), Barca (Ba), Horror (Ho) (Bos indicus) and their crosses with the Friesian (F), Jersey (1) and Simmental (S) breeds (Bos taurus). Early growth data were for calves that were representing three purebred Bos indicus and 38 crossbred genotypes and were separated from their dams one day after birth and fed milk from a bucket. The fourth and fifth studies were based on milk and reproduction data collected from cows of two purebreds (Boran and Friesian) and eight crossbred (crosses of Friesian and Jersey with Boran) genotypes. In the first study, five genetic models were evaluated for goodness of fit and estimation of crossbreeding parameters. These models were: 1) Dominance model, 2) Dickerson's model (recombination loss), 3) Additive x dominance interaction model, 4) Dominance x dominance interaction model and 5) Kinghom's model (x). Models 2 to 5 are epistatic models that included all effects in model one plus one type of epistatic interaction based on a two-locus gene model. The models were evaluated using data for birth, weaning, yearling weights and preweaning average daily gain. All five models tested provided high levels of fit, with adjusted R2 values averaging 93% over traits. All the epistatic models fit the data significantly (P<0.05) better than the dominance model for all the traits. Among the epistatic models, Dickerson's model (Model 2) gave significantly (P<0.05) higher R2 values compared to the other epistatic models. Crossbreeding parameters estimated from this model has relatively lower sampling correlations and correspondingly lower standard errors. This model could, therefore, be considered as the most appropriate one for parameter estimation and prediction of performances of untested genotypes for future crossbreeding decisions for the breeds involved in this study. In the second study, breed difference, heterosis and recombination loss were estimated for birth weight (BWT), weaning weight (WWT), preweaning average daily gain (ADG) and yearling weight (YWT), fitting an animal model. Differences between genotypes were significant (P<0.01) for all traits. Genetic group means adjusted for environmental effects ranged from 20 to 30 kg for BWT, 88 to 114kg for WWT, 122 to 157kg for YWT and 358 to 492g for preweaning average daily gain (ADG). The breed additive effect of the F as a deviation from the Bo was significant (P<0.01) and positive for all traits. Relative to the Bo mean, the additional breed additive contribution of the F breed on BWT, WWT, ADG and YWT was 39.3, 16.5, 9.3 and 10.3%, respectively. On the other hand, the breed additive effects of the Ho and J breeds were significantly (P<0.01) negative for all traits. The heterotic effects were significantly negative (P<0.01) for BWT for all F and S crosses, but positive (P<0.01) for all other traits for all types of crosses. The average heterosis estimated within the F, J and S breeds were: -2.1±0.6, 0.2±0.6 (P>0.05) and -2.3±0.6 kg for BWT, 8.8±2.1, 11.8±2.3 and 13.7±2.4 kg for WWT, 60.4±11.3, 64.8±12.3 and 90.6±12.7 g for ADG and 19.8±2.6, 19.5±2.8 and 20.8±2.9kg for YWT, respectively. The recombination effects were significant (P<0.01) for the majority of crosses for all traits. The estimates for the recombination loss were negative for all traits, except for BWT. The average recombination effects estimated within the F, J and S breeds were: 2.6±0.8, 2.9±0.9 and 2.4±1.0 kg for BWT, -13.6±3.2, -4.2±3.4 (P>0.05) and -16.0±4.0 kg for WWT, -88.0±17.1, -39.4±18.4 and -102.2±21.3 g for ADG and -14.4±4.0, -0.1±4.4 (P>0.05) and -17.5±4.9 kg for YWT, respectively. In the third study, variance components and direct and maternal heritabilities were estimated for weight at birth, weaning and yearling and preweaning average daily gain. Data were analysed using six alternative animal models (direct and including or excluding maternal effects). The direct heritability estimates from the "best" model for each trait were: 0.14±0.03 for birth weight, 0.08±0.03 for weaning weight, 0.06±0.02 for preweaning average daily gain and 0.13±0.03 for yearling weight. The direct maternal heritability estimates were small, but significantly different from zero for only birth weight (0.07±0.02), weaning weight (0.04±0.02) and preweaning average daily gain (0.04±0.02). Direct genetic correlations between birth weight and the other three traits were: 0.66±0.08, 0.55±0.19 and 0.50±0.12 with weaning weight, preweaning average daily gain and yearling weight, respectively. The genetic correlation between weaning weight, preweaning average daily gain and yearling weight was high and ranged from 0.82±0.11 to 0.97±0.O1. Small, but non-zero maternal heritabilities estimated for weaning and preweaning average daily gain for artificially reared calves in this study should be interpreted cautiously because of potential bias from unaccounted breed additive and non-additive effects of the dam. Results of this study also showed that estimates of variance components and genetic parameters suitable for general use can be obtained from mixed purebred and crossbred data after appropriately accounting for breed additive and non-additive effects. In the fourth study, breed additive and non-additive effects plus heritabilities and repeatabilities for milk yield per lactation (LMY), milk yield per day (DMY), lactation length (LL), annual milk yield (AMY), annual milk yield per metabolic body weight (AMYBW) and cow weight at calving (BW) were estimated. In addition, genetic, phenotypic and permanent environmental correlations were estimated between AMY and LL, AMY and BW and LL and BW. Data for each trait were analysed, using two equivalent repeatability animal models: first, fitting genotype as a fixed group effect and in the second model substituting genotype with breed additive, heterotic and recombination effects as fixed covariates. Among the genotypes the Bo had the lowest and the F the highest performance for all traits. The least-squares means for the Bo breed were 529±65 kg for LMY, 2.8±0.1 kg for DMY, 193±6 d for LL, 514±61 kg for AMY, 7.8±0.7 for AMYBW and 304±3 kg for BW. Both F and J breed additive effects, measured as a deviation from the Bo breed were significant (P<0.01) for all traits, except for BW of the J. The F and J additive contributions were 2774±89 and 1473±362 kg for LMY, 7.1±0.2 and 4.8±0.8 kg for DMY, 146±8 and 81±7 d for LL, 2345±71 and 1238±319 kg for AMY, 20.6±0.9 and 18.9±4.3 kg for AMYBWand 140±4 and -21±22 kg (P>0.5) for BW, respectively. The heterotic contributions to the crossbred performance were also positive and significant (P<0.01) for all traits, except for BW in the F x Bo crosses. The Fl heterosis expressed as a deviation from the mid-parent values were 22 and 66 % for LMY, 11 and 20% for DMY, 29 and 29% for LL, 21 and 64 % for AMY, 42% (P>0.05) and 42 % for AMYBW and 2% (P>0.5) and 11% for BW for the F x Bo and J x Bo crosses, respectively. The recombination effect estimated for the F x Bo crosses was negative and significant for LMY (-526±192 kg, P<0.01), DMY (- 3.0±0.4 kg, P<0.01)AMY (-349±174, P<0.05) and BW (-68±11 kg, P<0.001). For the J x Bo crosses the recombination loss was only significant and negative for DMY (-2.2±0.7 kg, P<0.05) and BW (-33±17, P<0.05). The direct heritabilities (h2) and repeatabilities (r2) estimated for each trait after correcting for the fixed environmental and breed additive and non-additive effects were 0.24±0.04 and 0.39±0.02 for LMY, 0.19±0.03 and 0.30±0.02 for DMY, 0.13±0.03 and 0.19±0.02 for LL, 0.23±0.04 and 0.37±0.02 for AMY, 0.17±0.05 and 0.39±0.02 for AMYBW and 0.10±0.03 and 0.34±0.02 for BW, respectively. The estimated genetic correlations between AMY and LL, AMY and BW, LL and BW were 0.71±0.08, 0.17±0.18 and 0.23±0.20, respectively. In the fifth study, estimates of breed additive differences, heterosis and recombination loss, as well as heritabilities were obtained for age at first calving (AFC), calving interval (Cl), days open (DO) and number of services per conception (SPC). The genetic parameters were estimated using a repeatability animal model for Cl, DO and SPC and a unitrait animal model for AFC. The overall least-squares means estimated were: 38.3±0.26 months, 435±4 days, 145±10 days and 1.58±0.03 (number) for AFC, Cl, DO and SPC, respectively. The breed additive effects of F and J were only significant (P<0.01) for AFC. Relative to the Bo, both the F and the J additive contributions for AFC were -5.4±0.5 and -5.5±1.9 months, respectively. Crossing the F and J breeds with the Bo breed also resulted in significant heterosis (P<0.05) ranging from I0ta 21% in all traits. The estimated recombination loss was only significant for AFC (2.8±1.0 months) for the F x Bo crosses. Heritability estimates were high for AFC (0.44±0.05) and low for Cl (0.08±0.03), DO (0.04±0.03) and SPC (0.08±0.02). The corresponding estimates for the repeatability (r2 ) were 0.14±0.02 and 0.14±.0.02 for Cl and DO, respectively. The repeatability estimate for SPC was zero.
  • ItemOpen Access
    Wool sheep production systems for the Western Highveld of South Africa
    (University of the Free State, 2000-05) Van Vuuren, Barend Gerhardus Jansen; Van der Merwe, H. J.; Cilliers, J. W.
    English: The aim of this study was to evaluate the biological and economical feasibility of wool sheep farming in the Western Highveld of South Africa. The performance of young sheep utilizing Digitaria eriantha Steud. (Smuts finger grass) both during the winter and summer periods, fertilised at rates of 60 kg N + 10 kg P/ha vs. 120 kg N + 20 kg P/ha, was investigated. Rainfall, both in terms of quantity and distribution, was the most critical factor during both the summer and winter seasons. During the winter period, the quantity rather than the quality, of the foggage was the limiting factor. The results of this study, with the below normal rainfall recorded, showed that stocking rates of two, four and six sheep/ha for a six month period are sufficient for the maintenance requirements of wooled sheep. During these dry seasons a fertilization rate higher than 60 kg N + 10 kg P/ha had no beneficial effect as far as mass gain/ha is concerned. The results obtained during the summer period were also very disappointing, mainly due to a lack of available pasture. Rotational grazing, instead of continuous grazing, should probably rather be applied during the summer period. The biological and economical feasibility of three various wintering strategies (silage, foggage/crop residues and veld) of Merino ewes and their progeny, for both an autumn and a spring lambing season, were also evaluated. This study indicated that the utilisation of Smuts finger grass foggage and crop residues during winter, realised the best results for animals of both lambing seasons. However, the biological and economical availability of the various feed sources would ultimately be the deciding factor on the most appropriate system. Although the animals of the intensive treatment (silage) had the best performance (mainly in terms of body mass and mass gain), the animals of the foggage/ crop residue treatment showed compensatory growth during the summer period. This resulted in little or no differences in the body mass of these two treatments at the end of the summer period. In the case of ewes utilising winter veld, their compensatory growth was insufficient for a total recovery in body mass. Ewes wintered on maize silage as the sole roughage source returned the highest body masses and body mass gains. However, this advantage was not transferred to the performance of their progeny and the quality and quantity of the wool produced. The conclusion was made that natural protein supplementation should be provided additional to the silage, especially for woolled sheep. Cost of the silage will also exert a great influence on the financial viability of this enterprise, as this proved to be the highest feed cost. Maize crop residues proved to be an invaluable, high energy feed source that becomes available at a crucial time in the fodder flow for woolled sheep. This product also has little or no other commercial value. Despite the lower clean wool percentage, animals of this treatment still realised the highest clean wool mass (kg). The greater fiber diameter was also not so severe as to cause a reduction in price. The poor performance of the ewes on winter veld was disappointing. In the long term, this does not appear to be a viable option. Where available, an alternative nutritional strategy should be applied. This extensive treatment can also be seen as a 'Iow cost approach' with reduced inputs and, consequently, a reduced income. Ewes lambing during spring required less supplementation. This was mainly due to the fact that they utilised crop residues during late pregnancy and they raised their lambs during spring. For both the lambing seasons the utilisation of foggage/crop residue realised the highest and the animals of the silage treatment the lowest gross margin for all the parameters tested (gross margin per small stock unit and per ewe), the only exception being the gross margin/ha, which was higher for the intensive treatment than that of the extensive treatment during the spring lambing season. The cost of intensification should, however, be kept in mind. The results of this investigation clearly indicated the biological and economical advantages of utilising foggage/maize crop residues during the winter months.
  • ItemOpen Access
    Produksiepotensiaal van verskillende eerstekruising Afrikanerbeeste
    (University of the Free State, 1977-11) Mentz, Andreas Hercules; Smith, A.
    English: In the development of crossbreeding systems in beef production under South African conditions, more information on the combination ability of various types of exotic beef breeds with the indigenous Africander is of primary importance. For this reason four breeds of bulls namely Brahman, Charolais, Hereford and Simmentaler were used on purebred Africander cows in this study. These breeds represented a Zebu type, large frame lean meat type, small frame fat meat type and a large frame dual purpose type of cattle respectively. Simultaneously purebred Africanders were produced as controls. The progeny of the five bull breeds (838 in total) were evaluated in respect of duration of gestation, birth and weaning mass. Postweaning growth and development of steers as slaughter animals were studied under two production systems while the female progeny were evaluated as breeding animals. Special attention was given to the occurrence of interactiombetween sire breed and production system as well as sire breed and production function. It is apparent that the choice of a breed/type of bull for the production of Africander F1-calves is of utmost importance due to the effect thereof on birth mass. and dystocia. As a result of the extreme size of the Charolais-Africander calves at birth and the extent of dystocia, the production of this cross seemed not to be of any merit. Furthermore, although this combination of breeds performed very well in a semi-intensive production system, it was found that the female progeny lack in mothering ability and cannot be recommended as replacements in herds. The crosses of Brahman, Hereford and Simmentaler bulls, however, proved to be of excellent potential for exploitation under specific conditions. The Brahman progeny has a dual purpose production potential in an extensive production situation as a store animal as well as a replacement heifer. Likewise the Simmentaler cross has a multi-purpose production function in terms of replacement heifer and slaughter animal. For the latter purpose it became apparent that this cross is equally efficient as a fodder animal or store, keeping in mind that it only becomes marketable at an advanced mass especially under extensive grazing conditions. Hereford crosses proved to be extremely suitable as Slaughter animals, regardless of the production system, although it performed especially well under intensive management.
  • ItemOpen Access
    The demography and population status of lions (Panthera leo) in the Mana Pools National Park, Zimbabwe
    (University of the Free State, 2008-11) Monks, Norman John; De Waal, H. O.
    English: Demographics of the lion population in the Mana Pools National Park were studied between 2001 and 2007. No detailed work had previously been carried out on this subject in the park. Demographic data was obtained from six prides, with two prides (Chitake and Jesse) being on the Zambezi Valley floor at the base of the Zambezi Escarpment in the south, and four prides on the Zambezi floodplain in the north. The Zambezi floodplain in the Mana Pools National Park is 95.5 km² in extent and in area comprises 11.2% of the park. Approximately 46% of the adult lion population occurs on the floodplain where approximately 63% of the lion prey base in the park is found. Not all prides could be studied at the same intensity, however, demographic data was obtained for all six prides. The Nyamepi pride on the floodplain was the most intensely studied. A population estimate of 67 adult and sub-adult lions was made for the Mana Pools National Park. Overall density throughout the park was 3.05 lions/100 km². Density ranged from 0.65/100 km² in the escarpment which held 0.3% of the prey species taken by lions to 12.7/100 km² on the floodplain. There were 1.8 adult males to 3.3 adult females and all prides were attended by a male. Mean group size (adults and sub-adults) was 7.8 (range 5-11). The adult and sub-adult age class made up 70.7% of the population and large and small cubs made up 29.3% of the population. Cub survival to one year of age was 66.7%. Females produced their first litter between 43-53 months of age and cohorts of cubs were produced on average every 38.5 months. Pride males had an average tenure with the pride of 33.25 months and sub-adult males dispersed from the pride between 36-57 months with a mean of 39.8 months. Home ranges varied on the floodplain from 28.1 km² to 278 km² and from 50.2 km² to 379.3 km² on the valley floor. The floodplain Nyamepi pride males had a home range two and a half times that of the females. Only the Valley floor lions had differences in dry and wet season home range size (dry season 57.7 km² and wet season 379.3 km²). Demographic variables, when compared to other lion populations in similar habitat in protected areas in Africa, did not differ and the Mana Pools National Park lion population appears to be normal. The Mana Pools National Park is surrounded in the west and east by Safari areas (administered by ZPWLMA) and has no man-made or natural barriers between them. No work was carried out on lions in the surrounding Safari areas but it was found that males frequently made excursions into the Safari areas (one collared male was shot in Chewore Safari area 80 km from the darting site in Mana Pools). Lions also frequently crossed the Zambezi River into the Lower Zambezi National Park, Zambia. It is presumed that there is a two-way movement between the Mana Pools National Park and Safari areas and the Park and the Lower Zambezi National Park, but could not be confirmed in this study. The spotted hyaena population in the Mana Pools National Park was found to be in the low-medium category when compared to other populations in protected areas in Africa (Purchase, 1999). All data accrued during the present study showed that this population do not pose a threat to lion conservation in and around the Mana Pools National Park.
  • ItemOpen Access
    Alternative management systems to increase beef production under extensive conditions
    (University of the Free State, 2016-06) Grobler, Susanna Maria; Scholtz, M. M.; Greyling, J. P. C.; Neser, F. W. C.
    South Africa is still a net importer of beef. Therefore, by increasing off take in the beef sector, South Africa can move towards self-sufficiency. With fertility being regarded as one of the main components influencing total beef herd efficiency, it is essential that the quoted calving percentage of 62% in the commercial beef sector of South Africa must be improved. If the long calving seasons can be shortened and the calving percentage increased, more and heavier calves with a more uniform age can be weaned. Cows that calve early also have a better chance of conceiving in the next breeding season and are generally seen as the more fertile animals Development, production and quality of replacement heifers is a crucial component in the extensive beef production system. In general, beef heifers are managed to calve for the first time at three years of age, but in some cases mating of heifers at one year of age have been advocated. All extensive beef production systems in South Africa are dependent on natural veld and it is well documented that veld condition have a huge influence on a number of beef production parameters. Studies conducted on natural veld have concentrated mainly on aspects that affect herd efficiency, including calving percentage, pre-weaning growth and supplementation of cows and calves. However, none of the studies focused on the reproduction performance of beef cattle mated naturally after synchronization, heifer age at breeding and effect of grazing system on veld condition. The aim of the study was to evaluate: the effect of estrous synchronization followed by natural mating on the calving percentage and calving distribution of multiparous beef cows and heifers; effect of breeding heifers at either 14 months or 26 months of age and the evaluation of a high utilized grazing system and controlled selective grazing on veld condition and animal performance. The effects of climate on cow-calf production characteristics over time was also evaluated. The study was conducted from 2009 to 2015 at the Roodeplaat experimental farm (REF) of the ARC-Animal Production Institute (25°34’11.27’’S; 28°22’05.36’’E) on 900 ha of natural rangeland described as Sourish Mixed Bushveld. The experimental herd (n=92) was divided in four sub-herds consisting of 23 cows each at the beginning of the project in 2009. It was ensured that the four sub-herds were as uniform as possible at the beginning of the project e.g. age, weight, previous number of calves. Within each sub-herd, 50% of the cows and heifers were synchronized prior to the commencement of the breeding season. Two sub-herds were subjected to high utilized grazing and two sub-herds were subjected to controlled selective grazing. The two grazing systems were related to the use of 30% or 60% of the available grass dry matter. Half the heifers were mated at 14 months and the other half at 26 months. Results from this study indicated that calving percentage and body condition score did not differ significantly (P=0.54) between cows that was either synchronized or not synchronized followed by natural mating. However, estrous synchronization prior to natural mating did influence the average days to conception with synchronized cows calving earlier, except for 2012 in the calving season. Over the six-year project period 15% more cows from the synchronized group conceived within 293 days after the onset of the breeding season. Calves from the synchronized cows weaned on average 5kg heavier than the cows that were not synchronized although this difference was not significant. Conception rates of heifers mated at 26 months were significantly (P<0.05) higher than heifers mated at 14 months of age. It would seem that it may be more viable to breed Bonsmara heifers in an extensive production system in the Sourish Mixed Bushveld region at 26 months of age for the first time. Synchronization of 14 month old heifers did not improve conception rate over 14 month old heifers bred naturally. However, the calving percentage of synchronized heifers bred at 26 months was 6% higher than the non-synchronized heifers. Almost no veld condition change was recorded except for veld condition scores for both controlled selective grazing and high utilization grazing. In addition, the results indicate a tendency that high utilization grazing improved veld condition score and grass species composition over that of controlled selective grazing, but the duration of the study is too short to make a definite conclusion on the effect of grazing strategy on veld condition. It was also shown that grazing strategy did not have a significant influence on cow weight and calf growth over the six-year period, indicating that both grazing strategies are sustainable in the Sourish Mixed Bushveld if carrying capacity is adhered to. With the significant differences between years (P ≤ 0.05) for calving percentage, cow weight at calving, cow weight at weaning, calf birth weight, calf weaning weight and body condition score over the six-year observation period, the effect of seasonal temperature, relative humidity and rainfall is elucidated. Forward stepwise regression procedures were performed to determine what climatic data were involved in cow and calf weight at birth and weaning as well as calving percentage. In spite of the high standard errors (which were probably due to the small sample size), maximum relative humidity one month prior to the start of the breeding season, made a major contribution to explain calving percentage and minimum temperature within the last month of the 3 month breeding season, had a low negative correlation with calving percentage. It can be speculated that high humidity in the study region (Sourish Mixed Bushveld) is an indication of warm and wet conditions, negatively impacting cow and bull comfort, leading to lower conception rates. The negative correlation between minimum temperature within the last month of the breeding season and calving percentage may indicate that the cows were unable to cool down at night during the warmer summer months of the year, leading to lower conception rates and resorptions. The researcher acknowledge that the available herd size may be a limitation and that a bigger herd or sub-herds’ size combined with bigger land size could benefit the project outcome, possibly resulting in more significant differences and/or enhanced interpretation of results.
  • ItemOpen Access
    Comparison of genetic and immunological responses to tick infestation between three breeds of sheep in South Africa
    (University of the Free State, 2016) Thutwa, Ketshephaone; Van Wyk, J. B.; Cloete, S. W. P.; Dzama, K.
    𝑬𝒏𝒈𝒍𝒊𝒔𝒉 The study investigated genetic parameters and immunological responses to tick infestation in three South African sheep breeds (Namaqua Afrikaner [NA], Dorper and SA Mutton Merino [SAMM]). The study aimed to estimate genetic and crossbreeding parameters for tick count (TC) and weaning weight (WW), to examine the histology of tick attachment and control sites, to select reference genes for normalizing gene expression data in this study, to compare cytokines gene expression at tick attachment and control sites and finally to compare cutaneous hypersensitivity reactions to unfed larvae extracts (ULE) of Rhipicephalus evertsi evertsi between NA, Dorper and SAMM sheep. Genetic parameters for WW and TC were estimated using data of lambs maintained on the Nortier Research Farm from 2010 to 2015. Firstly, data of purebred commercial Dorper and SAMM lambs were combined with data of their reciprocal crosses to assess breed effects and the possible effect of non-additive genetic variation on WW and TC. In the second analysis, data of purebred commercial Dorper lambs were combined with data of the unimproved, indigenous NA and the NA x Dorper cross. In Analysis 1 the coefficient of variations (CV) were 24%, 95% and 50% for WW, untransformed total TC and square root transformed total TC, respectively. Genotype affected WW but not TC. A heterosis estimate of approximately 4% was derived for WW. A single-trait h² estimate for TC was 0.11±0.09. A model analysing across-genotype h² yielded a slightly lower h² estimate of 0.08 ± 0.07. In Analysis 2 the CV were 27% and 55% for WW and square root transformed total TC, respectively. WW and TC were affected by genotype. WW exhibited heterosis amounting to 8.5% while the corresponding value for TC amounted to -23%. The single-trait h² estimate for TC was 0.06±0.05. A model analysing across-genotype h² yielded a substantially higher h² estimate of 0.27±0.07. These results suggest that genetic variation in TC was primarily associated with differences among genetic groups while differences between individual animals within genetic groups were not as important. Heterosis estimates for WW were variable between two analyses, but within ranges reported in the literature. This study established significant variation in TC between sheep genotypes when the indigenous NA breed formed part of the analysis. The NA x Dorper cross resembled the improved Dorper breed for WW but the unimproved, resistant NA for TC and exhibited worthwhile levels of heterosis for both traits. Indigenous ovine genetic resources may be instrumental in providing genetic material for adaptive traits in environments susceptible to high levels of tick infestation. Further research is required to elucidate the role that adapted indigenous ovine genetic resources may play in an integrated tick management strategy under conditions characterised by high levels of tick challenge. A histological study was conducted to assess histological features at tick attachment and control sites in pure breeds. Skin biopsies were examined using routine histological techniques for immunological cell infiltration and skin reactions. Marked variation in immunological responses to tick attachment within and between sheep breeds was observed. There were differences between the attachment and control sites in most of the skin changes (defects) except for four skin defects in the NA. However, all breeds had similar frequencies of skin defects at tick attachment sites. Tick attachment sites were more likely to be infiltrated by cells within as well as across breeds. The NA and SAMM breeds tended to demonstrate greater cellular infiltrations of specific leukocytes at tick attachment sites compared to Dorpers. Basophils, mast cells and eosinophils were increasingly recruited at tick attachment site in NA ewes compared to the Dorper and, occasionally, the SAMM breeds. These results suggest the importance of these cells in sheep resistance to tick infestation. Tick genera influenced the recruitment of neutrophils to tick attachment sites. Tick gender, sampling site as well as tick engorgement level did not affect the number of immunological cells. Further studies should be done with one tick species at a time to better comprehend the species-specific impact of tick attachment to animals belonging to divergent sheep breeds. Five genes (18S, GAPDH, YWHAZ, B2M and SDHA) were tested for their stability. SDHA, YWHAZ and B2M were the most suitable reference genes recommended by geNorm analysis for normalizing gene expression data in sheep skin. These findings will assist in normalizing data in gene expression studies at tick attachment and control sites of the NA, Dorper and SAMM breeds. This study suggested that no reference gene is stably expressed in different experimental conditions. The expression of IL-1β, IL-8, CCL2 and CCL26 was quantified in real-time qPCR. IL-1β and IL-8 were more highly expressed at tick attachment than at control sites. NA ewes expressed IL-1β more at tick attachment sites than Dorpers. The NA breed was also more likely to upregulate the expression of the CCL2, CCL26 and IL-8 genes at tick attachment sites compared to control sites than the other breeds. This indicates that IL-1 β, CCL26 and IL-8 may play a part in resistance or susceptibility of sheep to tick infestation. The differences in expression of the two chemokines between the resistant NA and more susceptible SAMM and Dorper imply that the NA breed could be able to overcome the anti-chemokine activity of tick saliva. ULE of R. evertsi evertsi induced hypersensitivity reactions in all the breeds. The indigenous NA displayed stronger reactions, immediate and delayed, than the commercial breeds. The results suggest that cell-mediated immune responses are invoked to fight against tick infestation in the NA. The hypersensitivity reaction may be used as a phenotypic marker to select animals or breeds that are more resistant to tick infestation. It is well-known that challenge-based research for promoting resistance to pathogens is under scrutiny from an ethical and welfare perspective. The methods employed here could be refined to enable routine evaluation of valuable animals without resorting to more invasive strategies, such as allowing adequate natural challenge to accrue over time in selection candidates. Overall, the component studies reported in the thesis increased the present understanding of ovine tick-host interactions and factors contibuting to breed differences in tick loads. ___________________________________________________________________
  • ItemOpen Access
    Water use and production potential of Karoo shrubs
    (University of the Free State, 2015-06) Malan, Paul Johannes; Snyman, H. A.
    English: Variation in, and changing of climatological patterns, especially rainfall, as well as grazing intensity and frequency has the biggest influence on rangeland productivity and sustainable animal production in the Nama-karoo Biome. This study was conducted to quantify whole-plant productivity, nutritive value and morphological adaptations of Karoo shrubs to defoliation along a soil-water deficit gradient. Two Karoo shrubs, Nenax microphylla and Pentzia incana were investigated. The watering treatments included the following: 0 - 25% depletion (non-stressed), 25 – 50% depletion (mildly stressed), 50 – 75% depletion (moderately stressed) and 75 – 100% depletion (severely stressed) of field capacity. The defoliation treatments were defoliation intensity to a height of 50 mm, 125 mm and 200 mm; and defoliation frequencies of three-monthly, six-monthly and twelve-monthly which was also used as the control. Water availability proved to be the single most important factor influencing both above- and belowground rangeland productivity. Defoliation intensity had the lowest impact on productivity, while the impact of defoliation frequency was markedly higher on both above- and belowground phytomass production. The root:shoot ratio increased with increased water deficit as a means to improve the water absorption of the shrubs. Determination of water-use efficiency (WUE) included both above- and belowground phytomass, while it excluded evaporation which gave a more accurate estimation of WUE. This is of the few studies where root growth is also included in calculating WUE. The expression of WUE in terms of transpiration as was done in this study, is more sensitive for describing ecosystem functioning than evapotranspiration, as was done in most studies in the past. In general, the WUE of the shrubs increased when exposed to water stress and higher grazing pressure. The more frequent and intensely the plants were defoliated, the higher the nutritive value of the produced edible phytomass. The quantity of this produced phytomass was, however, very low. The increased CP (N-content) of the water stressed plants could have contributed to the increased WUE. Strong evidence of compensatory growth and WUE were recorded for both species. This compensatory ability especially enabled the shrubs to display increased recovery after defoliation when water is not limited. Water stress had no marked influence on the reproductive ability of the investigated shrubs. It was, however, proved that both defoliation frequency and intensity had a bigger influence on seed production and germination percentage, than water stress. Pentzia incana has a high density of reflective trichomes that provides protection against heat and solar radiation. It also has a high stomatal density which allows increased photosynthetic rates when growth conditions are favourable. The stomata of N. microphylla occur only on the abaxial (lower) side of the leaf which protects it from direct sunlight and heat. It also has a very high stomatal density which could contribute to its ability of compensatory growth when adequate water is available. Furthermore, the leaves have a shiny appearance which enables them to reflect solar radiation to reduce leaf temperatures. This study highlighted the complexity of the effect of external influences, like rainfall and grazing (defoliation) on the functioning of the rangeland ecosystem in the arid and semi-arid Nama-karoo Biome. Although the land user does not have control over plant water availability, control over defoliation is possible. Defoliation therefore should be the most important key aspect in sustainable ecosystem utilization.
  • ItemOpen Access
    Phenotypic and genetic characterization of indigenous chicken populations in Northwest Ethiopia
    (University of the Free State, 2007-05) Mogesse, Halima Hassen; Neser, F. W. C.; De Kock, André; Van Marle-Köster, Este
    English: This study was carried out to generate information on village based indigenous chicken utilization, management practices, opportunities and challenges, to identify, characterize and describe the phenotypic variation of indigenous chicken populations. The study was also aimed to provide preliminary data on the genetic variation of indigenous chicken populations using microsatellite markers and to compare and evaluate the growth, egg production, reproductive performances, as well as the rate of survival of indigenous chickens under intensive and extensive management levels. Surveys using both purposive and random sampling methods were carried out in four zones of Northwest Ethiopia to describe the village-based poultry production systems and constraints in order to design future improvement and conservation strategies. The result of this study showed that the majority of the respondents were female (74.16 %). This indicated that most of the time the women, whether in male-headed or female-headed households are responsible for chicken rearing, while the men are responsible for crop cultivation and other off-farm activities. About 99% of the respondents gave supplementary feeds to their chickens. Night shelter was provided by almost all farmers in a part of the kitchen (1.36 %) or in the main house (39.07 %), in handwoven baskets (7.29 %), in bamboo cages (1.51 %) or in a separate shed purpose-made for chickens (50.77 %). The major causes of death of chickens during the study were seasonal outbreaks of Newcastle disease (locally known as “fengele”) and predation. It is important to collect and conserve local poultry breeds before they are fully replaced by the so-called improved exotic chicken breeds. As most of the poultry production is managed by women, focusing on training and education of women will aid not only the improvement of poultry production but also family management, family planning and the overall living standards of the family and the community. In the phenotypic characterization, a total of three hundred chickens were characterized under field conditions for qualitative and quantitative traits following standard chicken descriptors. Seven distinct indigenous chicken populations from four administrative zones were identified. Large phenotypic variability among chicken populations was observed for plumage colour. About 25.49 %, 22.30 %, and 16.40 % of the chickens have white, grayish and red plumage colours, respectively. The rest showed a considerable heterogeneity regarding plumage colours, like black, multicoloured, black with white tips, reddish brown and white with red stripes. The following characteristics were also displayed: plain heads (51.18 %), yellow shanks (64.42 %), and pea comb (50.72 %). About 97.52 % of the chickens did not have feathers on their legs. Variations were also observed in quantitative characteristics such as shank length, egg size and body weight and other reproductive traits exhibited in an intensive management system. In the genetic analysis, indigenous chicken populations representing seven different areas of Northwest Ethiopia were studied using microsatellite markers to determine genetic diversity and relatedness. Three South African chicken lines and two commercial chicken (RIR and WLH) breeds were included for control. A high genetic diversity was observed overall loci and populations with a heterozygosity value of 0.76. The largest heterozygosity (0.93) across all markers was observed in the Mecha chicken population, while the smallest heterozygosity across all loci (0.66) was observed in the White Leghorn breed. A higher genetic distance (lower genetic similarity) between the RIR commercial chicken breed and the Ethiopian indigenous chicken populations were observed compared to RIR and South African fowls. This indicates that the Ethiopian indigenous chicken populations have still not been highly diluted by the RIR commercial chicken breed either through the extension program or through the regional poultry breeding and multiplication institutes. The present result indicated that the clustering of the chicken populations is in accordance with their geographical origin and market places. Microsatellite markers used in this study were found suitable for the measurement of the genetic variation in Ethiopian chicken populations. These results can therefore serve as an initial step to plan the characterization and conservation of indigenous chickens in the Amhara region, Ethiopia. A study on the performance of indigenous chicken populations in terms of growth, carcass yield, egg production and egg quality was evaluated under intensive management conditions compared with the RIR commercial breed. Significant differences were observed among the indigenous chicken genotypes of Northwest Ethiopia for body weight, feed intake, FCR, mortality percentage at different phases of growth, indicating the phenotypic variations of the different chicken ecotypes. The Mecha chickens had the highest growth rate, followed by Guangua and Melo- Hamusit chickens, indicating that these lines are good for meat production. Analysis of carcass characteristics has shown that most of the male and female finisher grower chickens have a higher dressing percentage than the commercial RIR chicken breed managed under intensive management. Furthermore, data on age at point of lay (days) indicated that indigenous chickens reached the first egg production stage from 144 to 168 days, while the RIR breed started producing eggs at 150 days. In general, the current result indicates that the performance of the indigenous chickens is comparable with the RIR breed under intensive management systems. This indicates that there is a chance for better performance if proper selection and breeding plan are designed for indigenous chickens.