Masters Degrees (Animal, Wildlife and Grassland Sciences)
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Item 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.Item 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 availableItem 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, AntonieAfrikaans: 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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 (PItem 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.Item Open Access Food-related determinants of Kudu carrying capacity in a semi-arid savanna(University of the Free State, 2001-11) Van der Waal, Cornelis; Smit, G. N.English: A comparative study was conducted in order to investigate the relationship between forage availability and parameters of kudu populations thought to have a bearing on kudu carrying capacity in a semi-arid savanna. This involved eight game-fenced study units. The leaf production and standing crop of woody and forb species were determined. Woody species were classified according to rainfall season acceptance to browsers, the presence and absence of physical deterrents and foliage retention period into the dry season. Ungulate densities were determined during the late dry season of 1999 by helicopter census. The leaf dry mass production below a height of 2 m, the mean browsing height of kudu, ranged from 362 kg ha' to 695 kg ha' (mean = 516 kg ha') between study units. The forb standing crop (dry mass) ranged from 83 kg ha' to 376 kg ha' (mean = 214 kg ha') between study units. Large-scale kudu mortalities were reported in the dry season of 1998 in the study area. Below average rainfall received during the preceding rainfall season probably contributed to these mortalities, which were further aggravated by a prolonged cold spell experienced at the time. The lack of late dry season woody foliage was significantly related to mortalities. Relationships between kudu mortalities and kudu density or study unit size were insignificant. Kudu faecal nitrogen concentration was determined at regular time intervals during the dry season of 1999. This was preceded by a normal rainfall season. Kudu faecal nitrogen concentration declined during the dry season and reached a minimum during the dry hot season (August - October). Kudu faecal nitrogen concentration peaked during the month of November. Mortalities and poor physical condition of kudu populations were linked to low dry hot season kudu faecal nitrogen concentrations. Variation in kudu faecal nitrogen concentration was significantly explained by the availability of woody species' foliage, excluding the contribution of early deciduous species. It is hypothesised that kudu survival is largely dependent on the nutritional status of the animals. Animals with a low nutritional status are more susceptible to diseases and the effect of physical exposure during adverse weather. The nutritional status of kudu populations is apparently dependent on the availability of dry season foliage resources, which is again dependent on the preceding rainy season's rainfall. During droughts, forage resources available during the late dry season, the critical period, are important. During average rainfall years, kudu appear to be less dependent on critical resources, and the availability of dry season resources before the critical period is entered becomes increasingly important. Different strategies to optimise kudu production, given the variation in forage resources between years, are discussed. It is proposed that kudu carrying capacity in semi-arid savanna is based on the availability of forage resources during the dry season, taking into account the effect of rainfall on resource availability/quality.Item Open Access The effect of season and nutrition on the reproductive potential and sexual characteristics of Boer goat bucks(University of the Free State, 2001-12) Theron, Orion; Greyling, J. P. C.; Schwalbach, L. M. J.English: A study to evaluate the effect of season (ambient temperature, daylight length and relative humidity) and nutrition on the reproductive potential and sexual characteristics of young Boer goat bucks was carried out between June (winter) and November (spring), 2000. This study was carried out at the University of the Free State campus in Bloemfontein, South Africa. Twelve Boer goat bucks with a mean initial age of 12 months were used in this study. These bucks were divided into two similar experimental groups, with regard to body weight. A high nutritional plane diet was randomly allocated to one group (Group H) and a low nutritional plane diet was allocated to the other group (Group L). The total mixed diet based on Themeda triandra (Red grass) summer hay, supplemented with maize meal, molasses, HPK 40, HPK 60 and lucerne at two different nutritional levels (High and Low) was given ad lib to the two respective experimental groups. Prior to the observation period, all the bucks were subjected to a prescribed diet for adaptation, for a period of 4 weeks. Then 2 weeks prior to the observation period of this trial, each group received their respective treatment diets. During these 6 weeks, the experimental bucks were trained for semen collection with the aid of an artificial vagina. Apart from the different nutritional management, both groups were housed and managed under similar conditions. Semen samples from each buck were collected by means of an artificial vagina. Semen was collected twice weekly throughout the observation period (winter and spring). In order to have a more realistic and accurate measurement an average of the two measurements taken per week (i.e. semen volume, mass motility etc.) was used as a measurement for the respective week. The following semen parameters were evaluated: semen volume, semen colour, mass motility, sperm concentration, percentage live sperm and percentage abnormal sperm. Other sexual characteristics (serum testosterone concentration, scrotal circumference, testes volume, scrotal skin thickness and libido) as well as rectal temperature and body weight was recorded every second week concurrently with semen collection. The environmental factors (ambient temperature, daylight length and relative humidity) were recorded daily. From this study it can be concluded that the semen and sexual characteristics of young Boer goat bucks observed during this trial, were markedly influenced by the week (season) in which semen was collected, although no clear seasonal trend was observed. In general the animals on the higher nutritional plane diet tended to record higher serum testosterone levels and superior semen and testicular characteristics compared to those from the group maintained on a lower plane of nutrition. These differences however were only significant at certain times of the observation period. It can be also concluded that the Boer goat buck maintains its libido and satisfactory potential fertility (testicular characteristics and semen quality) during the winter (outside the natural breeding season). The effect of season and nutrition on the fertility of Boer goat bucks would have been better evaluated, had this study been carried out for all 4 seasons of the year and the nutritional differences been more extreme.Item Open Access The effect of different milk pricing schemes on a selection index for South African Holstein cattle(University of the Free State, 2002-11) Tesfa, Kal'ab Negash; Van Wyk, J. B.; Neser, F. W. C.English: A total of 150673 first lactation records of South African Holstein lactating cows were used to estimate the genetic parameters of milk (MY), butterfat (BFY), and protein (PRY) yields, and butterfat (BFP) and protein (PRP) percentages. The data comprising 113 056 dams and 1 429 sires, distributed over 1 205 herds, were collected over a period of 21 years, 1980 to 2000. The study was aimed at the following aspects: to determine the non - genetic factors influencing milk traits for use in the model for a subsequent genetic analysis; to estimate the variance-covariance components and heritabilities of all traits. Finally, to calculate the weighting factors for a selection index and predict the expected response to selection when using different milk pricing systems. Five fixed effects were defined, viz: milking frequency, age at calving, herd, month of calving and year of calving. Analysis of variance indicated that all effects were highly significant (p < 0.0001) explaining on average 64.60%, 62.96%, 64.36%, 15.66% and 23.86% of the total variation for MY, BFY, PRY, BFP and PRP, respectively. Considering the R2 and RMSE as an option, month of calving for all traits, milking frequency for BFP and PRP, and age at calving for PRP showed a minor contribution to the variation and were, thus, excluded from the model for the subsequent analysis. Heritability estimates varied from medium for BFY and PRY to high for MY, BFP and PRP. This indicates that faster genetic progress will be possible through selection of MY, BFP and PRP. The highly positive genetic correlation among yield traits indicates selection for milk yield will result in a favourable response with butterfat and protein yield. However, it will lead to an unfavourable response to selection for the percentage traits. This is due to a negative genetic correlation between milk yield with percentage traits. Using the Desire program, weighting factors and expected response per generation for milk, butterfat and protein yield were calculated under three milk buyers (A, B and C) pricing systems. The standard deviations of alternative breeding objectives and selection indices were also calculated. The weighting factors for milk, butterfat and protein yields were 0.16, 2.41 and 3.24 for milk buyer A, 0.04, 3.43 and 5.70 for milk buyer Band 0.03, 3.48 and 4.37 for milk buyer C, respectively. While the expected response for the corresponding traits, when the intensity of selection equals one, were +546kg, + 16.6kg and + 15.6kg for MY, BFY, PRY respectively. in the ease of milk buyer A, +509kg, +17.1kg and +15.7kg for milk buyer B and +504kg, + I7.3kg and + I5.5kg for milk buyer C. The correlations of indices of B and C with respect to index A were 0.97 and 0.84, respectively. This indicates that the loss of efficiency when selection index Band C were used is 3 % and 16 %, respectively. Rankings of Holstein cows under the three milkpricing systems were different and this indicates that depending on the choice of their breeding goals South African Holstein breeders should follow different selection programs.Item Open Access The genetic basis of gestation length in Bonsmara cattle(University of the Free State, 2002-11) Van Graan, Arno C.; Neser, F. W. C.; Van der Westhuizen, J.; Theron, H. E.English: The purpose of this study was to investigate the genetic and phenotypic parameters for gestation length and birth weight in Bonsmara cattle in South Africa. The genetic and phenotypic parameters were determined when the traits were firstly treated as traits of the calf and secondly as traits of the dam. A total of 26962 gestation length and birth weight records were used for this investigation. The data was collected from 1989 to 2000. The phenotypic correlation between gestation length and birth weight was moderate and positive (0.22). The sources of non - genetic variation for gestation length and birth weight were sex, herd x year x season (HYS) and age of dam (linear and quadratic). When the traits were treated as traits of the calf all the sources of non-genetic variance were highly significant (P<0.001). Age of dam quadratic was not significant for birth weight when the trait was treated as a trait of the dam. The traits were analysed through univariate and bivariate analyses. Five basic models were used for the univariate analysis. The five models took the direct genetic, maternal genetic, and/or permanent maternal environmental genetic effects into account. The appropriate random effects were also included in, or excluded from the models. The model that fitted the data best was then used for a bivariate analysis. The direct heritability through the bivariate analysis was 0.38 for gestation length and 0.23 for birth weight. Maternal heritability was lower, 0.09 for gestation length and 0.11 for birth weight. The direct genetic correlation (0.40) and the maternal genetic correlation (0.57) between gestation length and birth weight were positive. In the above results the traits were treated as traits of the calf. The direct heritabilities for gestation length and birth weight, when the traits were treated as traits of the dam, were 0.15 and 0.16 respectively through bivariate analysis. The maternal heritabilities for gestation length and birth weight were very low to negligible (0.02 and 0.003). The direct genetic correlation (0.41) between gestation length and birth weight was positive, but the maternal genetic correlation (-0.83) was negative. Estimated breeding values (EBVs) for gestation length and birth weight were calculated for each animal in the data. The genetic trends for gestation length and birth weight were also determined. The trend for gestation length showed that there was a correlated response for shorter gestation length through the possible direct selection for lower birth weight. The trend for birth weight showed that there was selection for lower birth weight.Item Open Access Intake and digestibility studies with captive African lions (Panthera leo), leopards (Panthera pardus) and cheetahs ( Acinonyx jubatus)(University of the Free State, 2002-11) Borstlap, Dirk Gerber; De Waal, H.O.; Schwalbach, L. M. L.English: The long-term goal of this study of the quantitative nutrition of large African predators was to develop non-invasive techniques for the accurate determination of food intake and apparent nutrient digestibility by free-ranging predators. The specific objectives of this study were to: • develop non-invasive techniques to determine the apparent digestibility of fresh, nonprocessed food by three species of large African predators. • determine the apparent dry matter (DM) digestibility of typical carnivorous diets in terms of DM, crude protein (CP), minerals, fat and gross energy (GE). • obtain information on the digestive capabilities and the water retention in three species of large African predators. • lay the basis for developing a technique to determine the food intake on a nutrient basis by free-ranging large African predators. This study was conducted in the Bloemfontein Zoological Gardens (Bloemfontein Zoo) with paired captive male and female African lions (Panthera leo), leopards (Panthera pardus) and cheetahs (Acinonyx jubatus). Although the study was done with captive animals the techniques were developed in such a manner that its principles would be applicable in the uncontrolled environment of free-ranging predators. The study consisted complete intake and digestibility trials conducted and repeated three times respectively 'on a male and a female of each of the three predator species. The trial diets consisted of portions' of the limbs from either adult donkeys (Equus asinus) or a horse (Equus cabal/us). The trial carcass portions used consisted of two symmetrical and identical portions or cuts that were divided in different sections, e.g. the two front limbs or the two hind limbs originating from the same carcass. One carcass portion was fed to a specific predator as the trial diet and the mirror image carcass portion was retained for nutrient analysis in the laboratory. The trail diets were marked using maize seeds (Zea mays) as external marker to assist in the faecal identification and facilitate collection. After feeding a ration, total faecal and food refusal collections were made. The intake and apparent digestibility of the fresh food, DM and nutrients were determined using standard laboratory techniques. The results of the intake and digestibility trials with the African lion, the leopard and the cheetah have shown that these carnivores are well adapted for the ingestion and digestion of meat. Mean DM intakes ranged from 0.970 kg for a female leopard to 4.493 kg for a male lion. The mean apparent DM digestibility ranged from 0.854 to 0.957. Nutrients such as CP, lipid and GE had very high apparent digestibility coefficients by the predators ranging from 0.919 to 0.977 for CP, 0.983 to 0.995 for lipid and 0.918 to 0.967 for GE respectively. The apparent digestibility of minerals (ash) was lower ranging from 0.310 to 0.853. From this analysis the conclusion could be made that there is no statistical difference between the lions, leopards and cheetahs in this study in terms of the apparent digestibility of fresh food, dry matter (DM), crude protein (CP), lipids, minerals and gross energy (GE). This study also confirmed that large African predators obtain a considerable amount of water from their diets. The use of apparent digestibility coefficients for fresh food and DM can be a very useful method to estimate the actual food intake (on a fresh or DM basis) of carnivores. If the information is available and the techniques described are applied judiciously, it might be possible to estimate the food and nutrient intake of large African predators. Evaluation of the nutritional status of large African predators during the different physiological stages of their lives in a non-invasive manner will thus be possible. It will also provide scientific support to devise adequate, sustainable and holistic management practices to preserve both the large African carnivores and the environment that supports their existence.