Animal, Wildlife and Grassland Sciences

Permanent URI for this community

http://hdl.handle.net/11660/91

Browse

Now showing 1 - 20 of 105

Open Access
Korreksiefaktore by seleksie van Merinoskape
(University of the Free State, 1971-01) Kotzé, Francois de Klerk; Du Toit, J. J.
English: Investigation was conducted into the influence of the age of dam and twinning on body weight, greasy fleece weight and certain fleece characteristics on lambs up to the age of 10 months. The above-mentioned fleece characteristics included percentage clean yield, fibre diameter, staple length and crimps per inch (2.54 cm). The aim of this study was to establish correction factors for the selection of Merino lambs at an early age. 403 Merino lambs from three different flocks from the Southern Free State was used as experimental material. Because of the range in age between lambs at any stage after birth it was necessary to transform the body and greasy fleece weig.hts to a standard age. For this transformation the linear-and daycorrection methods were employed. The averages reached by the results of these two methods generally differed significantly from each other (P<0.05). In addition semi-logarithmic growth-curves for the different groups of lambs were drawn. The weights that were obtained on 60 and 120 days of age were compared with the average weights which were obtained from the above-mentioned two methods of transformation. From these results it was obvious that the daycorrection method had better results than the linear method if the right factor for the weight-gain per day was used. It was found that lambs of mature ewes on 60, 120, 190 and 303 days of age respectively weighed 1.1, 1.0, 0.8 and 0.9 kg heavier than lambs of young ewes, while twin lambs were 1.1 kg lighter than single lambs on 60 days of age. The differences in body weight between sexes on 60 and 120 days were non-significant. Statistically the differences between the two groups of lambs in greasy fleece weight, per cent clean yield, fibre diameter, staple length and crimps per inch (2.54 cm) were of no significance.
Open Access
Die doeltreffendheid van proteïen- en energiebenutting deur vleisvarke
(University of the Free State, 1972) Smith, Gerhardus Adam; Van der Westhuizen, A. A.
Abstract not available
Open 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.
Open 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.
Open Access
Die toevoer van beeste en die gehalte van karkasse uit 'n vleisproduksie oogpunt by die Bloemfonteinse slagpale
(University of the Free State, 1979-07) Theunissen, Rudolf Johannes; Smith, Antonie
Afrikaans: 1. Ondersoek is ingestel na die toevoer van slagdiere en die gehalte van die karkasse by die Bloemfonteinse slagpale. 2. Die doel van die studie was om ondersoek in te stel na die tipes diere wat geslag word en gehalte van die karkasse wat aan die verbruiker gebied word. 3. Verskeie gegewens is van elke karkas wat in die studie gebruik is, ingesamel en statisties ontleed. 4. Resultate het aangedui dat baie diere op 'n ongewisselde ouderdom geslag word en lae grade behaal. 5. Te veelosse word op h hoë ouderdom (agttand) geslag en waarvan die eetbaarheidseienskappe laag is. 6 'n Ongewenste verhouding van 2:1 tussen manlike en vroulike diere dui op swak bestuur op plase, met lae kalfpersentasies as een van die vernaamste probleme. 7. Karkasse wat hoë grade behaal het, was deurgaans beter daaraan toe sover dit eienSkappe wat op gevleisdheid betrekking het betref. 8. Resultate dui aan dat die graderingstelsel doeltreffend funksioneer en toegepas word. 7. Verwantskappe tussen eienskappe wat verkry is, dui aan dat karkasmassa die mees akkurate maatstaf is om karkassamestelling te evalueer. 10. Kneusings het h onbeduidende rol gespeel, maar dit is hoofsaaklik weens die kort afstande wat diere vervoer is. 11. Duidelike prysverskille kom tussen die verskillende grade voor veral binne verskillende ouderdomsgroepe. 12. Die Bloemfonteinse verbruiker word voorsien van 'n klein hoeveelheid karkasse, van goeie gehalte met goeie eetbaarheidseienskappe. 'n Oormaat karkasse van jong diere wat lae grade behaal en ouer diere wat hoê grade behaal, maar waarvan die eetbaarheidseienskappe reeds afneem maak die balans van die beesvleis wat voorsien word uit.
Open Access
Waterbalans studies in geselekteerde subhabitatte van 'n Burkea-Savanna
(University of the Free State, 1980-11) Moore, Arno; Opperman, D. P. J.; Van Rooyen, D. J.
English: During this project the field-water balances in four subhabitats of the Burkea savanna in Phase II of the Savanna Ecosystem Project at Nylsvley were studied.The project included a study of the water redistribution patterns in the soil, the determination of the changes in soil moisture storaqe over depth as well as the determination of evapotranspiration losses in the E. pallens, O. pulchra, G. flavescens and B. africana subhabitats. The water-use efficiencies in the E. pallens, O. pulchra and G. flavescens subhabitats in terms of mm Et (daily)/ unit leaf area for the species E. pallens association (grasses), O. pulchra and G. flavescens, and for the subhabitats as a whole, were calculated. Water is the basic driving force and limiting factor in the Burkea-savanna, anq a basic knowledge of the natural field-water balances is essential for further plantphysiological and other research aimed at the understanding of the natural plantphysiological processes in the Burkea savanna ecosystem. There is a high degree of root -integration in the Burkea savanna, and the three subhabitats E. pallens, O. pulchra and G. flavescens were hydrologically isolated by means of poly-ethylene strips in order to interpretate the hydrological processes on a subhabitat basis. The soil-water balance, based on changes in soil moisture storage, was used in calculating evapotranspiration losses. Soil-water content was, determined gravimetrically and by means of the neutron scattering technique. The neutron probe used in this study was calibrated in the field for Nylsvley conditions. Leaf area determination was necessary as a criterium against which the water-use in the isolated subhabitats could be evaluated. Different methods and techniques were used in determining the leaf area of grasses, 0.pulchra and G. flavescens. The results are given as soil-water redistribution curves, daily evapotranspiration losses (mm) and water-use efficiency in terms of daily Et (mm)/unit leaf area. The redistribution curves show that water-uptake occurs mainly in the top 60 cm of the soil profile in the E. pallens and O. pulchra subhabitats. Deeper in the soil profiles water was available for uptake even throughout the dry months. In the G. flavescens and B. africana subhabitats water-uptake took place throughout the soil profile and no water was available during the dry months. Redistribution of water in the soil profile was rapid and a shower of + 50 mm redistributed within + 12 hours to a depth of 90 cm. No statistical meaningful differences in evapotranspiration losses were fOund· between the four subhabitats. There were, however, some tendencies and it seemed that the evapotranspiration losses were the highest from G. flavescens subhabitats, followed by B. africana subhabitats, E. pallens subhabitats and finally O. pulchra subhabitats. This was found for periods from four to seven days after a shower. As far as water-use efficiency is concerned, no statistical meaningful difference was found. It appeared, however, that G. flavescens used the most water per unit leaf area. Highly statistical meaningful differences were found between water-losses from sites with a transpiring grass cover; sites with a non-transpiring (dead)_grass cover; and sites with no grass cover (bare). Unfavourable weather-conditions resulted in smaller differences than could be expected under conditions of desication.
Open Access
Die invloed van die frekwensie van kragvoervoeding op die benutting van melkbeesrantsoene
(University of the Free State, 1989-01) Matthee, Stephanus Willem; Van der Merwe, H. J.; Engels, E. A. N.
Afrikaans: In die geval van hoë produserende melkbeeste word groot hoeveelhede kragvoer, by twee geleenthede per dag aan melkkoeie verskaf. Hierdie praktyk mag moontlik met 'n lae rumen-pH na kragvoervoeding, verskuiwings in die rumenmikrobepopulasies, veranderings in eindprodukte van vertering en swakker rantsoenbenutting gepaard gaan. Na aanleiding hiervan is ondersoek ingestel na die invloed van frekwente kragvoervoeding op rantsoenverteerbaarheid, rumenparameters, voerinname, liggaamsveranderings en produksieparameters. Twaalf volwasse Frieskoeie is in twee produksiegroepe (HP-hoë produksie en LP-laer produksie) gestratifiseer. Volgens melkproduksie is kragvoer in twee-, vier- of agt porsies per 24-uur verskaf. Bykomstig is grof gemaalde (25 mm) lusernhooi ad lib. aan proefdiere verskaf. Hierdie prosedure is gedurende vroeë, mid- en laatlaktasie in 'n gebalanseerde omskakelingsproefontwerp uitgevoer. Binne elke laktasiestadium is drie verterings- en innamestudies uitgevoer, waartydens rumenparameters by gefistuleerde koeie (die helfte van die proefkoeie in elke produksiegroep) ook bestudeer is. In teenstelling met LP-koeie het frekwente kragvoervoeding met 'n nie-betekenisvolle (P ≤ 0,05) verhoging in die skynbare verteerbaarheid van droë- en organiese materiaal, ruproteïen en veral vesel by HP-koeie (23,9 kg melk/dag) gepaard gaan. Hierdie geringe verhogings het ten spyte van laer kragvoerkonsentrasie en geringe hoër DM-inname tydens die verteringsproewe voorgekom. Frekwente kragvoervoeding het geen statisties betekenisvolle effek op die gemiddelde daaglikse rumen-pH, variasie in pH oor 24-uur periodes, minimum pH-waardes, tydsduur van pH verlagings, ammoniakkonsentrasie, totale en individuele vetsuurkonsentrasie en asyn- tot propioonsuurverhouding in die rumen uitgeoefen nie. Neigings tot In laer gemiddelde rumen pH (by HP-diere - waarskynlik weens hoër voerinnames) en meer konstante rumen-pH het met frekwente kragvoervoeding voorgekom. Alle proefkoeie het, veral gedurende vroeë- en midlaktasie (30,98 tot 57,40% kragvoerrantsoene) laer rumen pH's getoon. Eweneens het frekwente kragvoervoeding slegs geneig om 'n laer gemiddelde daaglikse ammoniakkonsentrasie te veroorsaak. Tendense soos 'n meer konstante rumenammoniakkonsentrasie en laer ammoniakpieke na kragvoervoeding is in sommige gevalle met frekwente kragvoervoeding gevind. Beide asyn- en propioonsuurproduksie het oor die algemeen 'n geringe styging met frekwente kragvoervoeding getoon. In sommige gevalle is ook nie-betekenisvolle kleiner variasie in totale en individuele vlugtige vetsure en As: Ps-verhouding rondom die daaglikse gemiddeld vanweë frekwente kragvoervoeding waargeneem. In ooreenstemming met verteerbaarheid en rumenparameters het frekwente kragvoervoeding geen statistiese betekenisvolle (P ≤ 0,05) voordeel ten opsigte van die inname van voer- en verteerbare voedingstofinname gelewer nie. 'n Neiging tot verhoogde ruvoerinname, deurdat fisiese en metaboliese innamebeperkings moontlik in In mate opgehef is, het veral by die frekwent gevoerde HP-diere (30 tot 57% kragvoer) voorgekom. 'n Soortgelyke neiging tot verhoogde inname van voedingsbestanddele (DM, OM, RP en NDF) en verteerbare voedingstowwe is by die frekwent gevoerde diere waargeneem. Geen statisties betekenisvolle (p ≤ 0,05) verskille in liggaamsmassaveranderings, melkproduksie en -samestelling (bottervet, proteïen en laktose) het voorgekom nie. Frekwente kragvoervoeding het slegs met 'n geringe verhoging in melkproduksie by die HP-diere gepaard gegaan. Relatief lae bottervetkonsentrasies, waarskynlik weens algemene hoë voerinnames en lae rumen-pH's, het gedurende vroeë- en midlaktasie voorgekom. Verder het frekwent gevoerde diere in die huidige studie geen voordeel bo konvensioneel gevoerde diere in die doeltreffendheid van voer- en ME-benutting vir melkproduksie getoon nie. Samevattend blyk dit volgens die resultate van die huidige ondersoek dat frekwente kragvoervoeding by melkbeeste, inname, rumenomgewing , vcedingstofbenutting en melkproduksie en kwaliteit nie noemenswaardig beïnvloed nie. Hierdie bevindinge geld egter slegs vir die kragvoerpeile (maksimum 57%) wat in die huidige studie toegepas is.
Open Access
Weidingkapasiteitstudies op veld in die Noord-Kaap
(University of the Free State, 1990-11) Venter, Izak Stephanus; Van Rensburg, W. L. J.; Vorster, L. F.
No abstract available.
Open Access
The use of different anabolic agents in gilts
(University of the Free State, 1995-07) Dias, Geraldo Paulino; Greyling, J. P. C.; Kotzé, W. F.
24 Crossbred gilts (Large White x Landrace) purchased as weaners were randomly allocated to four treatment groups (n = 6) and submitted for an observation period of three phases: Phase I, in which the animals were treated with anabolic agents (nandrolone, clenbuterol, zeranol); Phase 2, could be seen as the anabolic agent clearance period; and Phase 3, in which certain carcass characteristics and meat quality parameters were measured. The trial was aimed to compare the effect of the different anabolic agents zeranol (implants of 36 mg/pig, every three weeks, for 9 weeks), clenbuterol (daily oral dose of 0.5 mg/pig, for 9 weeks) and nandrolone (intramuscularly injected, 50 rng/pig, every ,3 weeks, for a period of 9 weeks), on growth rate parameters, carcass and meat characteristics, visceral organ growth and blood concentrations of urea, glucose, creatinine, oestradiol and the hematocrit. The gilts were individually housed and fed a pig growth diet (16% crude protein) ad libitum, with free access to water. Body weight of all animals were recorded every 48 hours to monitor the average daily gain (ADG) and the growth rate up to the target liveweight of 85 kg. Weekly feed intake was monitored and the feed conversion rate (FCR) determined for the individual animals and the mean of the groups. Backfat thickness (P2) and eye muscle diameter were measured weekly with the aid of a sonar apparatus in all animals, to monitor the deposition of fat and lean muscle. Blood was sampled weekly from 4 specific animals per group for the determination of hematocrit, blood urea, blood glucose, blood creatinine and blood oestradiol concentrations. The clearance rate of the anabolic agents was monitored in the urine sampled every second day from all anabolic agent treated animals following cessation of treatment. At slaughter (85 kg liveweight), several carcass measurements were done. Visceral organ weights were noted and meat quality parameters (water loss, cutting resistance, pH) were determined. Zeranol treatment revealed an improved growth rate (ADG of 727 g/d and 147.3 days to attainment of 85 kg) compared to the control and the other treatment groups. None of the three anabolic agents improved the FCR significantly, although the control showed the lowest mean value (2.76 kg feed/kg liveweight gain). A tenclency for an increase in this parameter was observed over time, in all the groups, the highest mean value being encountered in the group treated with zeranol (3.32 kg feed/kg liveweight gain). Overall average daily feed intake was significantly (P<0.05) greatest in the zeranol treated animals (2.03 kg/cl). Backfat thickness (P2) deposition assessed through ultrasonic measurements, showed no significant differences between the treatments and the control. The diameter of the eye muscle, weekly monitored by the same method, from the P2 site, showed significant (P<0.05) differences - the control having the highest value (4.43 mm/week). The clearance rate of the anabolic agents was faster in clenbuterol treated animals than in the zeranol group, while for nandrolone group this could not be. assessed, because its metabolites in swine are still unknown. Zeranol treated animals had a significantly (P<0.05) improved cold carcass weight and dressing percentage (68.8 kg and 79.8% respectively). Mean values for backfat thickness were generally high in carcasses from zeranol treated animals (PI = 13.5 mm; Pi = 14.8 mm; P3 = 16.6 mm) which leaner carcasses were obtained in the clenbuterol group (PI = 6.7 m; P2 = 7.4 mm; P3 = 8.6 mm). The eye muscle area (physically measured) was significantly (P<0.05) higher in the nandrolone group (34.3 cm2) compared to the Zeranol group (30.6 cm2), but not statistically different from the control and the nandrolone group. Zeranol, clenbuterol and nandrolone treatments did not significantly alter carcass conformation indicators. However, carcass weight was recorded to be positively (P< 0.05) correlated to ham circumference (r = 0.52); chest depth (r = 0.64) and chest diameter (r = 0.56). With the exception of cutting resistance values, in which the zeranol treatment group produced more tender meat (3.74 kg shear force) than the control and the other two treatments, the rest of meat quality parameters measured (muscle pH; cooking loss of water holding capacity) were not affected by the treatment with anabolic agents. No significant differences in the weights of digesta, digestive tract and the visceral organs (liver, kidneys, lungs, heart and spleen) were found following anabolic agent treatment. Suppressed ovary growth (0.6 g of weight) and over-growth of the reproductive tract (134 g uterus weight) and increased size of the vulvas were observed following zeranol implantation of gilts. The reproductive organs from clenbuterol and nandrolone groups were functional and apparently unaffected. The determination of blood urea, blood glucose, blood creatinine and blood oestradiol levels using specific kits to assess the concentrations of the metabolites and hormones generally did not result in definite trends of increases or decreases over time. These determinations could thus not be accurately used as possible indicators of the metabolic status following the use of zeranol, clenbuterol and nandrolone in gilts. It was concluded that the use of clenbuterol and nandrolone in gilts yielded no improvements in the growth parameters. In gilts treated with zeranol, overall growth rate was higher. Ultrasonic measurements of backfat thickness and eye muscle diameter proved to be an inaccurate and unreliable predictor of fat thickness or leanness of the carcass. A longer withdrawal period is necessary after an implantation of pigs with zeranol compared to the rapid clearance realised after an oral dose of clenbuterol. The faster growth rate obtained following the use of zeranol implants is counteracted by higher feed costs of lean meat production and the yield of poorer ratio of lean-to-fat content in the carcass when compared to the clenbuterol and nandrolone treatments. The growth of the digestive tract, liver, heart, kidneys, spleen and lungs were not affected by anabolic agent treatment, and thus the anabolic effect of zeranol concerning growth characteristics is not through an increased gastrointestinal capacity. The assessment of growth performance and feed utilisation efficiency through blood levels of glucose and urea appear to be time consuming and not always practical. Further investigations regarding blood biochemistry, ideal doses of the anabolic agents, their metabolism and clearance rate in swine, as well as the margin of consumer's safety, is still of crucial importance for the future legal and safe use of anabolic agents in the pig industry. From the results obtained, it would seem that the use of these anabolic agents for the respective treatment periods and doses in gilts are not justified.
Open Access
The effects of breed and housing system on the production and reproduction of weaner piglets in an outdoor pig unit
(University of the Free State, 1995-08) Visser, Daniël Pieter; Erasmus, G. J.; Botha, T.
Outdoor pigfarming is a concept which (within the 20th century) had its origin (revival) in the early 1950s in England. Today approximately 15% of all breeding sows in England are kept out of doors while in South Africa probably less than 0,3% of sows (recorded), are kept out of doors. The rationale for outdoor pig farming was motivated from four angles of incidence: firstly an economic viewpoint, secondly the animal's adaptability to the environment, thirdly an ethological viewpoint and finally the new political dispensation - specifically the prospective small-farmer. The ultimate aim of this study was to identify the most suitable genotype and farrowing house of outdoor pigfarming based on the reproduction information of the sow's litters. The effect of genotype was significant (P = 0.0695) only for the trait litter size at birth, implying no significant poorer performance from the other genotypes in terms of relative reproductive efficiency. The three linear models, obtained by ANOV A procedures using SAS, which were specified for the reproductive traits litter size at birth, mortality and weaning mass, could explain very little of the variation for the three traits and Rl values of 0,05, 0,086 and 0,45 were calculated for the three traits respectively. However, the effect of parity was highly significant (P = 0.0001) for all three traits. The effect of house was non-significant (P = 0.3314) for number of piglets born alive, but significant for mortality (P = 0.0548) and highly significant for weaning mass (P = 0.0056). The inferiority of farrowing house 5 was undoubtedly revealed in this study. The importance of sufficient clean and fresh straw which will not only stimulate the sow's natural nesting activities, but will also form a buffer and heating mechanism for the young piglets, was clearly shown, given the significant (P = 0.0548) effect of house on mortality rate, and the highly significant (P = 0.0056) effect of house on weaning mass. In retrospect the reproduction performance of the outdoor breeding sow is measured against the norms applicable to the modern sow, however, the outdoor sow has to reproduce while competing with all the elements of nature (Falconer's paradox). The effect of parity was highly significant (P = 0.0001) for all three traits. This study, especially Tables 4,4; 4.8 and 4.11, showed that three distinctive (significant) phases could be identified during a sow's reproductive lifetime (Figures 4.1; 4.3 and 4.4). The commencing phase (Ist and 2nd litter) where number of piglets born alive, mortality and weaning masses are at its lowest. The optimising phase (3rd to 5th litter) when numbers of piglets born alive, and weaning mass reach their optimum while mortality rate reaches the intermediate stage. The diminishing phase (from the 6th litter onwards) where the number of piglets born alive are less than the optimising phase and more than the commencing phase, and mortality rate reaches its peak and weaning mass declines significantly.
Open Access
The genus Cheiracanthium (Araneae: Clubionidae) in southern Africa
(University of the Free State, 1995-11) Lotz, Leon Nico; Van der Merwe Louw, S.; Dippenaar-Schoeman, A. S.
English: The southern African representatives of Cheiracanthium C.L. Koch, 1839 are revised after examining 617 adult specimens. Eight species of Cheiracanthium are recognized from this region, four are new (C. dippenaarae, C. minshullae, C. presleyensis and C. slziluvanensis) and four are redescribed (C. africanum Lessert, 1921, C. furculatum Karsch, 1879, C. imbel/e Caporiacco, 1947 and C. vansoni Lawrence, 1936). Eleven species are synonymized (C. franganilloi Caporiacco, 1949 and C. nigropalpatum Schmidt & Jacque, 1983 = C. africanum Lessert, 1921; C. kiwunum Strand, 1915, C. mohasicum Strand, 1915, C. hoggi Lessert, 1921, C. natalense Lessert, 1923, C. castum Lawrence, 1927, C. lawrencei Roewer, 1951, C. melanostomel/um Roewer 1951 and C. melanostomellum caboverdense Schmidt & Piepho, 1994 = C. furculatum Karsch, 1879; C. nairobii Caporiacco, 1949 = C. imbel/e Caporiacco, 1947). The male of C. vansoni Lawrence, 1936 is described for the first time. Cheiracanthium hottentotum Strand, 1907 is considered a nomen dubium. The study resulted in the recognition of a new genus, Clzeiramiona, and this resulted in the transfer of six species (C. clavigerum Simon, 1897, C. filipes Simon, 1898, C. simplicitarse Simon, 1910, C. lzewitti Lessert, 1921, C. silvicolum Lawrence, 1938 and C. akermani Lawrence, 1942) to the new genus. keys are provided to the clubionid genera known from the Afrotropical Region as well as the Cheiracanthium species known from southern Africa. Distributional and habitat data are given for the eight Cheiracanthium species recorded from southern Africa. Medical and agricultural importance as well as relationships are also discused.
Open Access
Ondersoek na linieêre klassifikasie in die Suid-Afrikaanse Jerseyras
(University of the Free State, 1999-05) Van Niekerk, Daniel Jacobus; Neser, F. W. C.; Erasmus, G. J.
English: A total of 36000 records that were obtained from INTERGIS were used in this study to determine genetic parameters for the South African Jersey breed. After editing 9447 records qualified for the analysis. The data set consisted of animals with official first lactation records and linearly scored during their first lactation. The individual animal record contained the following information: identification number, sire, dam, birth date, owner, classification date, classifier, 13 linear type-traits (wither height, strength, dairy form, rump angle, thurl width, rear legs, hoof inclination, fore-udder attachment, rear-udder height, rear-udder width, udder cleft, udder depth and teat placement), final udder class, final class, age at first calving, milk-, butterfat- and protein production, butterfat percentage, protein percentage as well as length of lactation. A variance analysis on 9447 records was conducted by means of the SAS OLM (1988) procedures. The following effects were tested: herd, year of birth, year and season of calving, classifier, classification year, classification month, region, age at first calving and stage of lactation. Effects that were significant at the 1% level were included in the model. Nine models were specified and the resulting heritability estimates were obtained by DFREML procedures (Not all the non-genetical effects were significant for all the traits). Bivariate REML-procedures were done to determine the genetic parameters for the South African Jersey breed. The heritability estimates obtained varied between 0.05 for hoof inclination to 0.32 for wither height. The heritability estimates are in agreement with results reported in the literature. The genetic and phenotypic correlations obtained between the 13 linear type-traits and the three production traits (milk, butterfat, protein) are in agreement with results reported in the literature. The highest positive genetic correlation was found between rear udder height and rear udder width (0.99). The highest positive genetic correlation with protein production was found with rear udder width (0.83). The highest negative correlation was found between rear legs side view and hoof inclination (-0.96). These results could be used to the benefit of the breed, for example in determining estimates breeding values for linear type traits.
Open Access
Milk production of South African boer and indigenous feral goats under intensive and extensive feeding systems
(University of the Free State, 1999-11) Mmbengwa, Victor Mbulaheni; Greyling, J. P. C.; Du Toit, J. E. J.
English: The primary aim of this study was to investigate the milk production potential (quantity and quality) of Indigenous feral and Boer goat does under intensive and extensive nutritional regimes. The study was carried out at two different locations to accommodate the nutritional regimes. The extensive group was maintained at the Paradys experimental farm of the Department of Animal Science (Faculty of Agriculture), which is situated 20 km south of Bloemfontein. Whilst the intensive group was maintained on campus, at the Faculty of Agriculture, Bloemfontein. The animals used were 36 multiparous goat does, out of which 18 were Boer and 18 were Indigenous feral goats. Half (n = 9) of the Boer goats and half (n = 9) of the Indigenous goats were each randomly allocated to an extensive and intensive group. The intensively fed group received a complete diet. Each doe was given 2 kg/d and daily feed intake was recorded. In the extensive group, does were maintained on natural pastures with no feed supplementation. All does were milked twice a week. During each milking does were subjected to two milking periods. The first milking was done to empty the udder, and no records of milk production were taken. The second milking was undertaken two hours after the first milking, and the milk output from each teat was recorded and milk samples collected. The percentage milk fat, solids non-fat, lactose and protein in the samples were determined. Blood samples were taken once a week, to determine the serum progesterone concentrations, as an indicator of oestrous activity. All animals (does and kids) were weighed weekly to determine live weight changes during the post partum lactation period. Weekly teat measurements were also done. The Boer goat does produced more milk than Indigenous goats (P<0.05). The intensively fed Boer goat does produced their maximum quantity of milk (3.7 ± 1.4 I/day) during Week 4, compared to the extensive group that peaked (1.1 ± 0.7 I/day) at Week 8. Similarly, the. intensively fed Indigenous goats had their highest milk yield (1.9 ± 70 I/day) during Week 5, compared to the extensive group (1.1 ± 7.1 I/day) at Week 11. The intensively managed does had a maximum milk fat yield (8.79 ± 2.58% and 8.86 ± 3.68%) in Weeks 1 and 8 for Boer and Indigenous does, respectively. This maximum yield (not significantly different) was achieved in Weeks 1 and 5 for the same respective breeds in the extensive group. A correlation coefficient (r) of 0.073 between milk production and milk fat content was observed. Boer goats showed a trend of producing a higher milk lactose content throughout the trial. Boer goats fed intensively yielded maximum (5.6 ± 1.6%) and minimum (3.8 ± 0.7%) milk protein contents in Weeks 1 and 7, respectively, while for the extensive group these values were attained during Weeks 11 (7.2 ± 4.9%) and 6 (3.6 ± 0.5%), respectively. A correlation coefficient of 0.125 was recorded between milk protein content and the daily milk yield. The Boer goats in the extensive group produced the highest mean daily SNF content (10.7 ± 5.1%). The larger Boer goats had a significant (P<0.05) higher feed intake. The correlation coefficient between feed intake and milk production was 0.7 for the Boer goat and r = 0.4 for the Indigenous goat. The mean body weight was 45.0 ± 8.7 kg vs 32.3 ± 6.1 kg for Boer and Indigenous goats under the intensive feeding regime, and 42.3 ± 8.0 kg vs 29.3 ± 4.5 kg for those under an extensive feeding regime. Considerable variation in teat lengths was recorded. Peak serum progesterone concentration was recorded during Week 7 for the Boer goats (intensive group) and Week 12 for the Indigenous goats (intensive group). Ovarian activity (progesterone levels) remained low in the extensive groups throughout the observation period. Milk yield was significantly related to the nutritional status and the breed of the goat. The Boer goat produced more milk than the Indigenous goat. It is, thus, suggested that it can be used for milk production in the rural areas of South Africa. This may improve the nutrient intake of the rural communities.
Open 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
Open Access
Evaluation of cryopreservation methods for in vitro produced bovine embryos
(University of the Free State, 1999-11) Nedambale, Tshimangadzo Lucky; Greyling, J. P. C.; Rust, J. M.
English: The objective of this study was to evaluate four cryopreservation techniques for in vitro produced bovine embryos, and to select the best method for practical application. The cryopreservation methods investigated were three vitrification methods and a slow freezing method. This study was done at the ARC-Animal Improvernent Institute in conjunction with the University of the Orange Free State (Department of Animal Science). Embryos were obtained by the IVM, IVF and IVC of bovine follicular oocytes. A total of 136 early blastocysts, blastocysts and expanded blastocysts were randomly assigned to four different treatment groups. In the conventional slow freezing method, the IVP bovine embryos were first held in ViGro™Holdingplus medium before being transferred to 1.5M ViGro™EG Freezeplus medium (TMT 4). In this technique, the IVP embryos were loaded into 0.25ml straws. The straws containing the embryos were immediately placed into a programmable freezer (CL-863 cryo-chamber) at -6°C. Straws were seeded after a 5 minutes equilibration period. Embryos were initially cooled from -6 "C to -30°C at a rate of 0.3 °C/min. Thereafter, from -30°C to -33°C the rate was changed to 0.1 °C/min. After the target temperature was reached, straws were immediately transferred to liquid nitrogen. Vitrification of IVP bovine embryos was performed according to the following procedures: Embryos were initially placed in 10% EO in ViGro™Holdingplus medium for 5 minutes (Equilibration I), thereafter in 40% EO + 0.3M trehalose in ViOro ™Holdingplus medium for 5 minutes (Equilibration 11), both at room temperature. Embryos were then transferred to vitrification solutions, containing 40% EO (TMT 1); 40% EG + 0.3M trehalose (TMT 2); 40% EG + 0.3M trehalose + 20% PVP (TMT 3) in ViGro TM Holdingplus. Embryos were then loaded into 0.25ml straws, and plunged directly into liquid nitrogen (LN2). The straws were vertically stored in liquid nitrogen (- 196°C) until thawing and evaluation took place. Thawing of embryos within the straws was carried out in a water bath (32 DC). Each straw was placed in a water bath for 30 seconds. The straws were dried, cut and the contents transferred to ViGro ™Holdingplus medium. Recovered embryos were washed twice in fresh ViGro™I-Ioldingplus, and embryos were morphological examined for their viability under a stereo microscope. The viable embryos were cultured in IVC media. Embryo survival was recorded immediately after thawing, 24 hours and 48 hours post-thawing by monitoring the re-expansion of the blastocoel and expansion of the blastocyst. Statistically, there was a significant (P<0.05) difference in survival rate between embryos frozen in TMT 3 (77%), compared to those frozen in TMT 2 (41%), immediately after thawing. There was no significant difference in embryo survival rate for the other treatment groups. At 24 hours post-thawing, there was a significant (P<0.05) difference in survival rate between embryos frozen in TMT 3 (60%), compared to those frozen in TMT 1 (26%). There was also a significant (P<0.05) higher survival rate for embryos frozen in TMT 3 (60%), compared to those frozen in TMT 2 (21%). At 48 hours post-thawing, however, there was no significant difference in survival rate for embryos frozen in all the treatment groups. TMT 3 had the highest survival rates of embryos (37%). The generalized linear model (Bonferroni multiple comparison test) was used to test and predict the embryo survival rate between the treatment groups. The predicted (theoretical) embryo survival rate correlated highly and significantly (P<0.05) higher with the survival rate of embryos frozen in TMT 3. Embryos Frozen in TMT 3 were also predicted to be more likely to survive, compared to the other treatment groups. The results clearly indicate the beneficiary effect of this vitrification method (TMT 3). Vitrification is simple and more cost effective, compared to the slow freezing method (TMT 4), which is time consuming and expensive. Although there was no significant difference 48 hours ostthawing, TMT 3 could be recommended as the method for cryopreservation of IVP bovine embryos. The addition of 0.3M trehalose with 40% EO in the ViGro™Holdingplus medium decreased the survival rates of the IVP bovine embryos. Embryos frozen and thawed in 40% EO in ViGro™Holdingplus had higher survival rates, compared to those frozen/thawed in TMT 2, from immediately after thawing, to 48 hours post-thawing. Perhaps the addition of trehalose in the solution (ViGro™Holdingplus), already containing non-permeating agent (sucrose), increased the concentration of non-permeating agent in the freezing solution. High concentrations of non-permeating agent may be detrimental or toxic to the embryos. The presence of 20% PVP with 0.3M trehalose and 40% EO dramatically increased the survival rate of IVP bovine embryos. The PVP plays some kind of protective role during the freezing and thawing processes. Although the mechanism of protection is not clear, it may be that it prevents water from entering the cells during vitrification and thawing, which in turn prevents intracellular ice formation. Intracellular ice formation is lethal to embryos during thawing. It can be concluded that the combination of 40 % EO + 0.3M trehalose + 20% pyp (TMT 3), used as a vitrification solution, be recommended as suitable method for cryopreservation of IVP bovine embryos. It gave the highest embryo survival rate from immediately after thawing to 48 hours post-thawing. The advantage of this vitrification technique is that it is simple, quick and inexpensive. Additional research is needed to develop an effective cryopreservation method that will reduce the sensitivity problem of in vitro produced embryos. In vitro produced embryos contain lipids that cause them to be more sensitive to freezing, compared to those produced in vivo. The ability of vitrified in vitro produced bovine embryos still needs to be evaluated for their development in utero, in controlled embryo transfer programs.
Open Access
The value of recording body measurements in beef cattle
(University of the Free State, 2000-02) Maiwashe, Azwihangwisi Norman; Theron, H. E.; Van Wyk, J. B.
English: Body size and shape are objectively described using body measurements in beef cattle. How these measures of size and shape relate to the functioning of the individual is of paramount importance to livestock producers. Changes in these parameters that lead to inefficient animals are never welcomed by farmers. Therefore, constant checks on the relationships between body measurements and performance traits are vital in selection programs. To estimate heritabilities and genetic correlations among body measurements and growth traits, data of 7 266 performance records of Bonsmara bull calves participating in on-farm growth tests (Phase D) were used. The data set was extracted from the Integrated Registration and Genetic Information System (INTERGIS) of South Africa. The data covered a 25-year period i.e. from 1972 - 1996. Data were recorded from 45 herds, with 439 sires and 5 180 dams involved. Traits analyzed were scrotal circumference (SC), body length (BL), shoulder height (SH), birth weight (BW), weaning weight (WW), final weight (FW) and average daily gain (ADG) from weaning to final test date. Multivariate REML methodology was used to estimate (co)variances and genetic components for different traits. In cases where there were more than one value for an estimate, the values were pooled, weighting each estimate by the inverse of its sampling variance. Different models were, however, fitted for each trait. The permanent environmental effect was found to be important for most of the post-weaning traits, but it could, however, not be considered in the multivariate runs. This was due to computational limitations imposed by the data set. A simple model considering only direct animal effect and random error was fitted for all post-weaning traits. Heritability estimates for body measurements ranged from medium for body length (0.27±0.05) to high for shoulder height (0.42±0.05) and scrotal circumference (0.46±0.06). Corresponding estimates for performance traits were: direct (0.31±0.05) and maternal birth weight (0.10±0.03), direct (0.29±0.05) and maternal weaning weight (0.04±0.02), average daily gain (0.19±0.04) and final weight (0.30±0.05). Generally, body measurements were favourably and positively correlated with performance traits (0.03 to 0.83). However, scrotal circumference was found to be genetically weakly correlated to maternal birth weight (-0.22±0.15) and average daily gain (0.1O±O.13). A close to zero genetic correlation was found between average daily gain and maternal weaning weight (0.03±0.17). These results suggest that selection for fast growing bulls may not influence maternal performance at weaning. Considering the favourable genetic correlations between body measurements and performance traits, it could be inferred that selection for body measurements is compatible with that of performance traits. However, a further study should be conducted to evaluate which of those traits considered in this study are of economic importance so that an appropriate selection index can be developed.
Open 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.
Open 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.
Open Access
Synchronisation of oestrus in indigenous goats: the use of different progestagen treatments
(University of the Free State, 2000-11) Motlomelo, Khoboso Christina; Greyling, J. P. C.; Schwalbach, L. M. J.
English: A study aimed at comparing the efficiency of different progestagen treatments used for oestrous synchronization in indigenous South African goats was carried out between February (autumn) and September (spring), 2000. The study was carried out at Paradys experimental farm, of the University of the Orange Free State situated approximately 20km south of Bloemfontein, in the Free State province. Forty-eight indigenous feral does and 42 Boer does were used in this experiment, during the normal breeding season. The two breeds were randomly allocated and distributed between the three progestagen synchronizing treatment groups of 30 does per group. The treatment groups were medroxyprogesterone acetate (MAP), fluorogestone acetate (FGA) and controlled internal drug release dispenser (CIDR) groups. These three main progestagen treatment groups were further subdivided into six flush feeding groups of 15 does each, namely A1 (MAP X flush feeding); A2 (MAP X control); B1 (FGA X flush feeding); B2 (FGA X control); C1 (CIDR X flush feeding) and C2 (CIDR X control). Three groups (A1, B1 and C1) were flush fed with crushed maize for 3 weeks prior to breeding. Progestagen treatment was administered for 16 days. All does were injected with 300lU PMSG im at the time of progestagen withdrawal. Oestrus was detected with the aid of vasectomized bucks at 8 hour intervals for a period of 96 hours following progestagen treatment. Blood samples were collected at 4 day intervals during synchronization and at 8 hour intervals after progestagen treatment removal, as well as at days 14 and 21 following AI. Six weeks prior to kidding, pregnant does were divided into two groups, one supplemented with whole maize grain, while another one acted as a control group, irrespective of flush feeding and progestagen treatment prior to pregnancy. The parameters measured, included body weight, oestrous response, onset of oestrus, duration of oestrus, conception rate, gestation length, total litter weight, litter size, kid birth weight, sex of kids and mortality rates of kids. Body weight of the does was not affected by progestagen treatment, flush feeding or pregnancy supplementation. Higher body weights at breeding were associated with a higher conception rate. Weight gain or loss prior to breeding had no effect on conception rate and litter size. Prior to synchronization, only 17.8% of the experimental does were observed to be cyclic. Following oestrous synchronization, the overall oestrous response recorded was 96.6%. Oestrous response for three progestagen treatments was 93.1%, 96.7% and 100.0% for MAP, FGA and ClDR, respectively. Progestagen treatment had a significant (P<0.01) effect on the time to onset of oestrus following cessation of progestagen treatment, with ClDR treated does exhibiting oestrus earlier (27.2±4.5h), compared to the FGA (30.9±4.6h) and MAP (32.2±7.1h) treated does. There was no significant difference on the duration of induced oestrous period between the three progestagen treatment groups (FGA: 32.0±13.7h; MAP: 32.6±13.8h and ClDR: 35.2±13.7h). The mean serum progesterone concentration in CIDR treated does was significantly (P<0.05) higher from day of device insertion until cessation of treatment, when compared to the MAP and FGA treated does. No significant difference in serum progesterone concentrations was observed between MAP and FGA treated does throughout the observation period. At the onset of oestrus, the mean serum progesterone concentrations were 0.3±0.2ng/ml, 0.2±0.5ng/ml and 0.4±0.1ng/ml for MAP, FGA and CIDR, respectively. The difference was non-significant. At 21 days following AI, pregnant does had significantly (P<0.01) higher serum progesterone concentrations (17.3±0.9ng/ml), than the non-pregnant does (3.6±5.4ng/ml). The overall conception rate for all groups was 52.2%. The conception rates for the CIDR, MAP and FGA groups were 46.7%,51.7% and 60.0%, respectively. The differences were non-significant. The mean gestation length for all groups was 149.1±4.1 days. Gestation length was not affected by progestagen treatment, flush feeding or late pregnancy supplementation. Does bearing quadruplets had a significantly (P<0.05) shorter gestation length (142.7±2.8 days), when compared to does bearing singles, twins and triplets (150.0±2.8 days, 148.8±4.3 days and 150.0±4.1 days, respectively). The total litter weight for single births was significantly (P
Open Access
The influence of tree thinning and subhabitat differentiation on the reproductive dynamics of acacia mellifera subsp. detinens
(University of the Free State, 2001-11) Hagos, Mesghena Ghilay; Smit, G. N.
The study was conducted in an area described as "Kalahari Thomveld" in the vicinity of the towns of Bray and Pomfret in the North-West Province, where Acacia mel/itera subsp. detinens is the dominant woody species. The soils of the area are deep sand to loamy soils described as Kalahari sand with an extremely low organic matter and mineral element content. The study area consisted six 0.5 ha plots (50 m x 100 m), where the trees were thinned during November 1989 to different densities, ranging from a totally cleared plot (0%) to plots thinned to the equivalent of 10%, 20%, 30%, and 50% of the tree density of a control plot (100%) of about 2 000 tree equivalents (TE) ha-l. The plots were located adjacently on a homogeneous area of 3.0 ha. Treatments were allocated randomly to the plots and not in numerical order. A permanent transect of 20 m x 100 m was established in the center of each plot for phenological observations and harvesting of seeds. The remainders of the experimental plots were used for soil sample collection and to determine seed distribution within the defined subhabitats. The spatial canopies of all rooted live A. mel/itera trees encountered in the fixed transects (5 m x 100 m), located in the middle of each of the experimental plots, were measured and the number of Evapotranspiration Tree Equivalents (ETTE) ha-l calculated, using the BECVOLmodel. Estimates of the browsing capacities were also made from the leaf dry matter estimates. For the study of the phenology, seed harvesting and leaf biomass estimates of individual trees, fifty (50) A. mel/itera trees (10 sample trees/plot) were randomly selected. Only one phenological observation was done at the onset of flowering (August 2000) and all the pods and seed from the marked trees were harvested during late November 2000. Tree thinning brought about ear1yflowering of A. mel/itera in the lower tree density plots, possibly as a result of reduced inter-tree competition. However, the mean seed production over the tree density gradient did not follow a specific trend, and differences were observed between the seed production of individual trees. Significant correlations between ETTE ha" and leaf dry mass (kg ha") and total seed production ha" were established. Although the correlation coefficients were low, there are indications that seed production of individual trees increase with an increase in ETTE tree-land leaf dry mass tree". For the determination of seed mass and seed dimensions ripe A. mellifera seeds were randomly selected from each sample tree (n = 10 and 50, respectively) after which they were weighed and measured. Seeds harvested from the high tree density plot were longer, wider and thicker than those from the lower tree density plots. The average seed dry mass production tree-1 showed no distinct pattern and was not correlated with the tree density, but the total seed dry mass ha-l increased in relation to an increase in tree density. Leaf biomass of the A. mellifera trees per unit area, expressed as ETTE ha" and leaf dry mass ha", was highly correlated with the seed dry mass ha-l . There is no carry over of A. mellifera seed from one season to another and thus no persisting seed bank exists. The percentage of viable fresh A. mellifera seeds was observed to decrease with the increase of the time and exposure to high temperature and moisture fluctuations. For the study of seed distribution within defined subhabitats (stem base area, under canopy spread and open area), six A. mellifera trees in each tree density plot were randomly selected. Small rectangular plastic containers were inserted. in the three subhabitats of all marked trees (in two opposing directions). In all subhabitats a larger number of seeds were blown toward the prevailing wind direction. The number of seeds accumulated in the open subhabitats in both wind directions was also higher in comparison to the canopied subhabitats. A very low, non-significant correlation was observed between ETTE ha-l and seed distribution along the tree density gradient of the three subhabitats. For the assessment of germination potential, 50 normal and 20 bruchid beetle infested seeds were randomly selected from each plot. Germination tests were conducted at the facilities of the Department of Agronomy, UFS, and root and coleoptile lengths and growth rates were also measured. Thinning of A. mellifera trees had no effect on the germination potential of the seeds from the various tree density plots and an extremely high germination potential of the fresh A. mellifera seeds were found. Though some damage was caused, bruchid beetle infested seeds exhibited a low but fast germination rate, possibly due to faster imbibition of moisture. No marked difference in root length and root growth rates were observed between seeds of the various plots. However, seeds harvested from the lower tree density plots developed a higher coleoptile length with a faster coleoptile growth rate than the control (100%) plot. Soil from the canopied and uncanopied subhabitats were analyzed for soil nutrient status in order to evaluate seedling growth. Soils excavated from the canopied subhabitats were more acidic and displayed higher concentrations of P, total Nand organic matter than the uncanopied (open) subhabitat. However, no marked differences in exchangeable cautions were demonstrated between the subhabitats, except Ca that displayed higher concentrations in the canopied subhabitat. No allelopathic effect that inhibits the growth of seedlings was found to be present in soil from the canopied subhabitats of A. mellifera. Marked differences in growth parameters of the seedlings grown in the soils from around the stem base area in comparison to the other two subhabitats were observed. The relatively higher soil nutrient status observed in soils of this subhabitats is considered responsible for this increased growth. In general, A. mellifera seedlings grown in the soil from the lower tree density plots exhibited higher growth rates than those from the control (100%) plot. A denser root system, as reflected by higher total root lengths and root dry mass, was observed in seedlings grown in soil from the low tree density plot and declined linearly in soils collected along the tree density gradient. In general, the subhabitat differentiation had a more pronounced effect on seedling growth than soil differences associated with the tree density gradient.