Masters Degrees (Animal and Poultry Science)

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Adaptation and behaviour of finishing pigs to Vachellia tortilis leaf meal inclusion.
(2017) Thabethe, Fortune.; Chimonyo, Michael.
The broad objective of the study was to determine the adaptation and behaviour of pigs fed on incremental levels of Vachellia tortilis leaf meal based diets. Forty-eight clinically healthy male pigs Large White × Landrace with a mean (± SD) body weight of 63.8 ± 3.28 kg were randomly assigned to individual pens in a completely randomized design. Eight pigs were fed on diets that contained 0, 30, 60, 90, 120 and 150 g/kg DM of V. tortilis leaf meal. Pigs were fed ad libitum and had free access to clean water throughout the experiment. Average daily feed intake (ADFI), average daily gain (ADG) and gain: feed ratio (G: F) were determined weekly. The adaptation period was calculated at the end of the experiment for each individual pig. Coefficient of variation (CV) of feed intake across V. tortilis leaf meal diets was calculated. Number of visits to the feeder were calculated. The time spent eating, drinking, standing, lying down, sniffing, biting objects and licking objects were observed using six closed circuit television cameras (CCTV) once a week for three days. There was a quadratic decrease (P < 0.001) in ADFI, while ADG increased linearly (P < 0.001) with incremental level of V. tortilis leaf meal. Incremental level of V. tortilis leaf meal increased G: F ratio quadratically (P < 0.001). A linear increase in adaptation period of pigs was observed (P < 0.05) with increasing inclusion level of V. tortilis leaf meal. The variation of feed intake, expressed as a coefficient of variation, increased linearly (P < 0.05) with increasing inclusion level of V. tortilis leaf meal. Increasing inclusion levels of V. tortilis leaf meal linearly iii decreased time spent eating, lying down and the number of visit to the feeder (P < 0.05). Time spent standing and biting objects increased linearly with increasing inclusion level of V. tortilis leaf meal (P < 0.05). There was no relationship (P > 0.05) between V. tortilis leaf meal inclusion and time spent drinking, sniffing and licking of objects. It can be concluded that pigs require a long time to adapt to Vachellia diets. Increasing levels of V. tortilis leaf meal also alters time spent on behavioural patterns of pigs.
Attempts to improve the yield of bovine blastocysts by incorporating insulin, selenium and transferrin in the In Vitro system.
(1996) Bowles, Chloe Melissa.; Lishman, Arthur William.
To produce an embryo via in vitro maturation, in vitro fertilization and in vitro culture methods it is vital to obtain consistent results and at the same time a large number of bias to cysts from the immature oocytes collected, especially when only a small pool of these oocytes are available. The aim of the present investigation was to improve maturation rates, fertilization rates and blastocyst production rates by adding insulin (10 µg/ml), selenium (10 ng/ml) or transferrin (10 µg/ml) to the media. These were added individually or in different combinations and a complete randomised block design was set up to account for block and day effects. It was hypothesised that each treatment would improve maturation and fertilization rates and blastocyst production rates. It was found that of the treatments added to the maturation medium, Selenium at 10 ng/ml improved maturation percentages (80.4% vs 61.8%) and also increased fertilization percentages (68.0% vs 58.4%) and the number of bias to cysts produced (24.6% vs 11.5%). None of the treatments had a beneficial effect on fertilization rates or on blastocyst production rates when added to the fertilization medium. The treatments added to the culture medium showed that Transferrin at 10 µg/ml or Transferrin in combination with Insulin and Selenium increased the percentage of bias to cysts produced by in vitro culture methods (35.3% and 31.5% vs 18.7%). The addition of Transferrin also increased the percentage of bias to cysts that hatched (21.9% vs 14.2%) showing an improvement in the viability of the blastocysts produced. It is recommended that the maturation medium should include Selenium at 10 ng/ml. The fertilization process should have none of the investigated substances added to it and the culture medium should include Transferrin at 10 µg/ml. This combination should optimize the number of viable blastocysts that are produced in a bovine in vitro system.
Biological and economic response of laying hens to dietary lysine and energy contents during peak and late production periods.
(2001) Netshipale, Justice A.; Slippers, S. C.; Gous, Robert Mervyn.
The effect of dietary energy and amino acid contents during the peak of production of laying hens has been well investigated, but little is known about the late production period. In most of the previous studies the focus has been on improving the performance of laying hens with little, if any, consideration of the costs of achieving the maximum performance. The aim of the present study was, (i) to investigate the effect of dietary lysine and energy contents on the performance of laying hens (ii) to find out whether young (30-40 weeks) and old hens (60-70 weeks) perform the same at given dietary lysine and energy contents, and (iii) to determine the differences in income and costs generated by young and old laying hens. It was hypothesised that young laying hens will perform better and yield more income at given dietary lysine and energy contents than old hens. Two experiments were conducted, during peak (30-40 weeks) and late production period (60-70 weeks) with 240 Lohmann Brown laying hens. For the first experiment, four basal diets, which were a combination of two lysine and two energy levels, were supplied by a commercial feed company. These basal diets were blended with one another in different proportions to produce 15 experimental diets, resulting in five lysine and three energy levels. In the second experiment a feed formulating program (WINFEED) was used to formulate four basal diets with lysine and energy levels that were intended to be close to those used in experiment 1. Due to a blending error, diets with three lysine and five energy levels were produced. This error made it impossible to compare the results of the early and late production period, as originally intended. During both experiments, each bird was allocated between 1.4 and 2 kg feed at the start of each week, when feed was weighed. Egg numbers were recorded daily, at the same time each day, and mean egg weight was recorded by weighing eggs on three consecutive days during each week. It was found that the dietary lysine contents used in both experiments were sufficient to support maximum egg production and that resulted in no statistically significant differences (p>0.05) between treatments being observed in egg production traits (rate of lay, egg weight and egg output). A significant effect of dietary energy content was observed on feed intake, which confirmed that dietary energy content had a significant but indirect effect on egg production, through its effect on the amount of dietary lysine consumed. Older birds were found to be producing 21 g less egg material per day than younger hens, at a given (comparable) dietary lysine and energy content. This result confirmed that older hens require more nutrients to produce a given quantity of egg material. Since the performance of old hens was lower at a given dietary lysine and energy content, the profit generated was also lower. Younger hens generated numerically higher returns than the predicted returns for older hens, at any given combination of dietary lysine and energy tested. However, it was not possible to verify the results statistically, because the expected responses used for older hens were predicted from the results of young hens. In both ages (over the range of dietary lysine and energy contents used) highest returns were realised with the combination of lowest dietary energy and all lysine contents. The effect of a change in egg price was felt more with hens producing heavier egg at both ages, with young hens being more affected than the old hens. The results from these experiments give some indication on trends of returns for hens of both ages, although the economic optimum combinations of dietary energy and lysine could not be predicted (because of the dietary lysine and energy contents used, that were all sufficient to support maximum egg production).
The biological and economic responses of growing pigs to nutrient density.
(1999) Nelson, Lyska Michelle.; Gous, Robert Mervyn.; Ferguson, Neil Stuart.
No abstract available.
Biological control of the common house fly Musca domestica L. in horse stables, using Bacillus thuringiensis serovar israelensis and Beauveria bassiana.
(2013) Martins, Cheralyn.; Chimonyo, Michael.; Laing, Mark Delmege.
House flies (Musca domestica L.) are common pests affecting horses and their owners. Control of house flies in stable yards is currently based on the use of pesticides. However, the development of resistance by these flies to most pesticide groups has motivated horse owners to seek alternative methods of fly control. An entomopathogenic fungus, Beauveria bassiana (Bb) and an entomopathogenic bacterium, Bacillus thuringiensis var. israelensis (Bti) are two biological agents known to have activity against house flies. The broad objective of this study was to evaluate the effect of these two biological control agents on house flies in an equine environment. Using a structured questionnaire, presented in Chapter 2, thirty horse owners in KwaZulu-Natal were asked about the nuisance value of house flies, their current control measures, the potential market for biocontrol agents against house flies, and each owner’s perception of biocontrol methods. The horse owners were using three methods of house fly control namely, physical, chemical and biological. Most horse owners (97%) wanted access to effective biocontrol agents for control of house flies. Most horse owners (80%) stabled their horses at night, some or all of the time. The resultant manure piles in the stable yard were considered to be the primary cause of house fly problems. About 64% of the horse owners were dissatisfied with the currently available methods of controlling house flies in this situation. Chapter 3 covers two observational trials in which varying doses of Bacillus thuringiensis var. israelensis (Bti) were fed to horses, in order to identify a baseline dosage to give to horses in order to adequately control house fly populations growing in horse manure. The bacterium Bti, grown on wheat bran, was fed to six miniature horses at doses of 0, 0.125, 0.25, 0.5, 0.75, and 1.0 g per meal in Trial 3a, and at 0, 0.5, 1, 2, 4 and 8 g per meal in Trial 3b. Faeces were collected three times a week for 11 weeks and placed in incubation trays to allow the number of emerging adult house flies and closed pupae to be counted. In Trial 3a, there was a significant reduction in the number of closed pupae with an increase in Bti in the feed. The regression equation suggests that there will be 3.1 times as many closed pupae in the faeces when horses are fed 1 g of Bti in their feed, than when horses are fed no Bti. This dosage is the minimum baseline dosage for future trials. v Using manure from horses dosed in Trials 3a and 3b, the survival of the bacterium through the gut of horses was evaluated using a standard isolation technique. The growth of Bt colonies on the manure after the Bt isolation technique showed that some of the bacterial cells survived transition through the digestive tract of the horse. This study was qualitative in nature and did not attempt to quantify the level of Bti spore survival. These two observations suggest that Bacillus thuringiensis var. israelensis has the potential to be used as a biocontrol agent, applied via horse feed, for the control of house flies in stable yards. Future clinical trials, with appropriate replication, should be conducted using 1 g Bti/meal as the lowest test dosage. The objective of Chapter 4 was to determine whether spraying Bti or Bb on to horse manure is effective in the control of house flies. Over a six week period, two spraying trials were conducted in which increasing doses of Bb and Bti were sprayed on to 500 g samples of horse manure. Counts of house fly pupae and adults were taken. The doses of Bb and Bti tested were 0, 1, 2, 4 g in Trial 4a, and 0, 4, 8 and 12 g in Trial 4b. The research reported in Chapter 4 was characterized by the unexpectedly high levels of biological variation in egg, larvae and pupae numbers that were found in samples of horse manure, taken from the same skip two days apart. The statistical design of the two trials conducted was inadequate to cope with the high level of variation about treatment means for fly and larval counts. However, despite the lack of significant differences between treatment means, there is observational evidence that suggests that both Bb and Bti do have an effect on house fly survival. A simplified statistical model, which compared the number of hatched house flies on untreated manure, with the number on manure treated with any level of Bb (1 to 4 g /250 ml water), found a significant reduction in the number of hatched flies on treated manure. There was no significant corresponding reduction in the number of closed pupae, which suggests that Bb acts primarily before the larva pupates. The optimal dose of Bb and Bti to be sprayed on to manure could not be determined because of the high variation about treatment means. It is suggested that, in future trials similar dosages for Bb could be tested, but that higher dosages of Bti (starting at 2 g/250 ml water) should be used. Trial periods should be extended and replication increased dramatically to reduce variation about treatment means. Transformation of data before analysis may also be necessary to equalize variation about treatment means.
Bone quality and incidence of urolithiasis in male broiler breeders fed a male or female ration.
(2024) Dube, Sithembisiwe.; Tyler, Nicola Claire.
Separate sex feeding is highly practiced in breeder farms as it gives a more targeted approach to nutrition, aligning the dietary requirements with the specific needs of male and female birds. Some breeder farmers give the female ration to male breeders as it saves having two feed silos per house and eliminates the chances of females receiving the wrong feed. However, the drawback is that the female ration contains high crude protein (CP), calcium (Ca), and phosphorous (P), which is more than recommended for male requirements. A total of 40 male broiler breeders fed a male-specific ration (MM), and 40 male broiler breeders fed a female ration (MF) at depletion were acquired from KwaZulu-Natal farms. Kidney weight (KW) and kidney lesion score (KLS) from euthanised male broiler breeders were examined as an indication of urolithiasis. Tibia bone weight (BW), bone thickness(BT), bone breaking strength (BBS), tibia ash% (TA%), organic matter (OM%) and Ca/P% were quantified to assess the effects of excess CP, Ca and P on bone quality. Data collected were subjected to a two-sample t-test at a 95% confidence interval using GenStat statistical analysis software, and principal component analysis (PCA) was performed using XLSTAT. The biplots from the PCA were used to predict correlation among the variables. The study results showed that the kidney weights of MF were significantly larger compared to MM (P<0.001). Kidney lesion scores were observed in 50% MF and were significantly higher than in MM (P<0.001). Significant differences in BW, BBS, TA%, and OM% were found between MM and MF. Bone thickness, and bone Ca%, P% and Ca/P% were not significantly different among the two groups. The findings suggested that high CP, Ca and P in female feed given to male broiler breeders can negatively affect kidney and bone quality. The results indicated a significant correlation between dietary composition, bone strength and the incidence of urolithiasis. The study concluded that the nutritional composition designed for female broiler breeders may not be entirely suitable for the physiological needs of male breeders, contributing to an increased susceptibility to urolithiasis. Also, high Ca can interfere with the absorption or retention of Ca and other minerals like P, resulting in low bone quality.
Breast meat yield in broilers affected by lighting and dietary energy levels in starter and finisher phases.
(2015) Smith, Giles Elliott.; Ciacciariello, Mariana.; Tyler, Nicola Claire.
The increased demand in poultry products has prompted researchers to investigate opportunities and methods which may streamline the production of valuable commodities. Two experiments were conducted in this study. Both experiments were conducted to determine whether breast meat yield (BMY) would be enhanced in broilers reared under short daylengths of 8 and 16 h if higher levels of dietary metabolisable energy (ME) were fed. In each experiment, 1000 as hatched broilers were reared in four light tight rooms, each room divided into two pens which were populated with 125 chicks in each. Within each room two levels of dietary ME were fed resulting in a 2 × 2 factorial experimental design with the main effects being daylength and dietary ME. The first experiment focused on the starter phase of 1 to 10 d. The dietary treatments consisted of a control starter ration formulated to represent the nutrient levels of a standard commercial ration and a treatment ration which was similar to the control ration however contained 15% higher ME. Live weight and performance parameters of body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured at 7 and 10 d. At 10d, three birds from each pen were randomly selected and slaughtered for body part analysis. Lighting and dietary treatment had no effect on live weight, BWG, FI and FCR at 7 or 10d. Body part analysis showed that BMY, thigh yield and drumstick yield were unaffected by lighting and dietary ME as main effects. A significant interaction between dietary ME and daylength occurred where BMY and thigh yield were reduced when broilers were fed a 15% higher ME diet and reared on 8 h daylengths. The second experiment focused on the finisher phase of 25 to 35d. Lighting treatments remained the same as the first experiment but dietary treatments differed slightly as the treatment diet contained only 10% higher ME than the control diet which was formulated to the nutrient levels of a standard broiler finisher. At 35 d performance parameters of live weight, BWG, FI and FCR were measured. It was observed that live weight and FI were reduced in broilers fed a diet containing 10% higher ME from 25 to 35d. At 35d, body part analysis from 3 broilers slaughtered from each pen revealed no significant differences in BMY, thigh yield and drumstick yield from dietary ME and daylength. Breast meat yield in broilers within the starter and finisher phase was not improved on short daylengths of 8 and 16 h through the addition of dietary ME in higher levels than that conventionally used.
Breed susceptibility to enterotoxigenic and enteroaggragative Escherichia coli strains in South African pigs.
(2013) Chaora, Nyaradzo Stella.; Chimonyo, Michael.; Dzomba, Edgar Farai.
Escherichia coli diarrhoea is the most important source of mortality in piglets. The most frequently isolated strain in enterotoxigenic E. coli diarrhoea is F4ab/ac. Recent studies in South Africa reported non-fimbrial strains such as PAA and EAST-1 to be prevalent. The objective of the study was to determine whether there are breed differences among pigs with respect to E. coli adhesion phenotypes and correlate them to polymorphisms at selected candidate genes in the South African population. A total of 225 pigs aged 3-12 weeks of the imported (Large White, Landrace and Duroc), local and crossbreds, were sampled from the Eastern Cape and Limpopo provinces of South Africa and genotyped for PCR-RFLP polymorphisms at four candidate genes associated with E. coli F4ab/ac resistance/susceptibility. These genes were Mucin 4 (MUC4), Mucin 13, (MUC13), Mucin 20 (MUC20) and Transferrin Receptor (TFRC). The TFRC and MUC13 genes were less polymorphic, the C allele was close to fixation and the homozygous CC genotype was the most frequent in all three pig populations. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for the TFRC locus. The g.8227G>C polymorphism in MUC4 segregated in all three breeds and the marker was moderately polymorphic. There was a significant difference (P <0.05) in genotypic distribution amongst breeds for MUC4.The g.191C>T polymorphism in MUC20 segregated in the local and crossbred pigs and was close to fixation in the imported pigs. There was a significant difference (P <0.05) in allelic and genotypic distribution amongst breeds for MUC20, which was moderately polymorphic. There was a reduction in heterozygosity in both the TFRC and MUC13 loci, although MUC4 and MUC20 genes had higher heterozygosity levels. The MUC4 gene had a negative FIS value, indicating outbreeding at this locus. The MUC20, MUC13 and TFRC genes had a positive FIS value, indicating inbreeding at these loci. Overall, the studied population was outbred. Imported pigs in TFRC and MUC20 deviated from Hardy-Weinberg equilibrium (HWE). All breeds were in HWE at the MUC4 and MUC13 genes. There was no linkage disequilibrium observed amongst the analysed loci. iv A total of 109 piglets of three breeds (Large White, indigenous and crossbred) aged 3-5 weeks, were investigated for the susceptibility to E. coli F4, PAA strains and EAST-1 toxin. Adhesion tests were conducted on pig intestinal cells, which were viewed under a phase contrast microscope. Three phenotypes were identified as, adhesive, weakly adhesive and non-adhesive. There was a significant association (P <0.05) between breed and level of adherence of the F4 and PAA strains. Highest frequencies of adhesion phenotypes were observed in the indigenous pigs for both F4 and PAA E. coli strains. Large White pigs had the lowest frequency of non-adhesion in F4 and PAA E. coli strains. The F4 strain had a higher (P <0.05) level of adherence compared to PAA and EAST-1 in Large White pigs. Age of pigs had a significant effect on the level of E. coli adherence in indigenous and crossbred pigs (P <0.05). Adhesion of F4 and EAST-1 was higher in weaned indigenous and crossbred pigs, respectively, than in suckling piglets. There was no significant difference between F4 adhesion and the genotypes at all four candidate genes genotypes. The study showed that both imported and local pig populations carry receptors and are susceptible to F4, PAA and EAST-1 E. coli infections. Indigenous pigs were less susceptible than Large White to E. coli infection. Although polymorphic and segregating in the populations, the MUC4 g.8227G>C and MUC20 g.191C>T mutations were not associated with the adhesion phenotypes and cannot be used in the selection of susceptible animals.
The calcium requirement of commercial layer pullets in the pre-laying period.
(2003) Themeli, Lufuluvhi Reginald.; Gous, Robert Mervyn.
Specifications for the amount of calcium to be included in feeds for pullets and laying hens vary considerably in the scientific literature. Much of this variation is due to the fact that genetic selection has changed the growth rate, age at sexual maturity and potential egg production of laying hens over the years, and these changes will continue in the future. Husbandry techniques have also changed, so that pullets are now sometimes encouraged to start producing eggs at an earlier age with the use of appropriate lighting programmes. The supply of calcium to pullets in the pre-laying period depends critically on the age at which the pullets reach maturity and start to lay eggs, as pullets should be given an opportunity to deposit calcium in their medullary bone just before laying commences. The difficulty is knowing how much calcium should be included in the feed before sexual maturity, and for how long before this event a higher calcium content should be included, in order to minimise problems associated with mineral deficiencies and excesses during the laying period. The aim of the present study was to determine whether, by offering pullets a choice of two feeds varying in calcium content, the choice they made in the period leading up to sexual maturity could be used to determine the amount of calcium that should be fed to them during this period. Two experiments were conducted with Hyline pullets: in the first, 384 pullets were used, starting at 14 weeks of age, and in the second, 144 birds were used, starting at 10 weeks of age. In both experiments, equal numbers of Hyline Brown and Hyline Silver pullets were used. The first experiment consisted of four dietary treatments: Two basal diets were formulated to contain high (30 g calcium/kg) and low (8 g calcium/kg) calcium contents, with all other nutrients being the same. These two basal diets were fed alone and as a 1:1 blend to produce an intermediate calcium diet (19 g calcium/kg). The fourth treatment consisted of the low calcium basal and limestone grit as a choice diet. At 18 weeks of age six pullets from each treatment were killed for analysis of tibia breaking strength and 144 of these pullets (72 Silver and 72 Brown) were selected randomly and kept on the same treatment as before, but individually so that age at sexual maturity could be determined. There was no significant difference observed in age at sexual maturity or mortality, but pullets that were on the low calcium feed consumed significantly more feed and consequently, attained higher body weight gain than the other treatments. The opposite occurred for pullets that were on the high calcium diet. There was no significant effect of dietary calcium content on tibia breaking strength at 17 weeks. For the second experiment, pullets (n = 144) were reared on a lighting regime of 8L:16D to 10, 14 or 18 weeks, at which ages the photoperiod was increased to 14 hours. This had the effect of altering the age at sexual maturity, so that the effects of age and attainment of sexual maturity could be separated when determining the choice made by pullets in the amount of calcium consumed in the pre-laying period. In all cases, pullets increased their intake of calcium approximately two weeks before attaining sexual maturity, this increase being independent of the age of the pullets at the time. The study revealed that commercial laying-type pullets increase their intake of calcium, when given the opportunity to do so, approximately two weeks prior to the onset of lay. Where they do not have a choice between two sources of calcium this increased requirement for calcium causes pullets on low calcium feeds to increase their intake of feed and consequently simultaneously increase the intake of all nutrients other than calcium, resulting in an increased body weight. Where birds are fed a high calcium feed only, food intake does not increase to the same extent during this period, but the increase observed is likely to be to satisfy the increased demand for nutrients other than calcium in this pre-laying period. On the basis of the choices made by pullets in this study, these birds should be reared on low calcium feeds until two weeks before the onset of lay, at which stage the calcium should be increased to enable the pullets to deposit calcium in their medullary bone in preparation for the increased demand for calcium in the laying period.
Capacitation of Nguni semen for in vitro fertilization of bovine oocytes.
(1995) Durrans, Lesley Jane.; Lishman, Arthur William.
In vitro maturation, fertilization and culture is a technique which is increasingly utilised in the animal science industry for embryo production. However, optimal conditions for in vitro maturation, fertilization and culture have not been clearly defined and much research is being done to improve this situation. If these techniques are to be valuable in the production of large numbers of animals in short periods, they must be efficient and reliable. The first part of this investigation aimed to produce comparable rates of fertilization from each of 5 Nguni bulls tested in an in vitro fertilization trial. It was hypothesised that each bull would respond favourably to one or more of the treatments tested. A complete randomised block design was set up to account for block and day effects. A total of 2422 cumulus-oocyte complexes were matured and fertilized with swim-up separated frozen-thawed Nguni semen incubated for 1 min in Ca-ionophore A23187 (0.1, 0.2 or 0.4 µM) or for 15 min in heparin (0.05, 10 or 25 µg/ml). Controls for parthenogenesis and capacitation or acrosome reaction in the fertilization medium were included. Presumptive zygotes were transferred to CR1aa medium and supplemented with 10% and S% FCS on days 4 and 7 post-insemination, respectively. Bull performance was assessed using four criteria: embryo cleavage, a score based on a cleavage index (Score 1; minimum -1, maximum 6) and one which gave greater weight to morulae and blastocysts (Score 2; minimum -1, maximum 10) and blastocyst production. Day effects were highly significant (P<0.001). Parthenogenetic activation of 31.6% of oocytes occurred. Depending on the bull used, cleavage rates (%±s.e.m.) varied from 29.S±2.2 to 40.6±2.6, Score 1 from 0.30±0.07 to 0.6S±0.07, Score 2 from 0.30±0.07 to 0.72±0.08 and % blastocysts from 0.6±0.6 to 4.8± 1.1. Treatment did not significantly affect performance and there were no bull x treatment interactions. However, bull differences in performance were observed. The IVF system employed was not stable and did not produce repeatable results. It was concluded that treatment concentrations tested may have been too low or, alternatively, that treatment effects were being masked by a factor influencing the IVF system more strongly than the treatments tested. In the second part of this investigation, laboratory tests to determine semen quality were examined. It was hypothesised that semen quality would correlate with performance determined during the in vitro trial and, thus, provide predictors for bull fertility in vitro. A dual staining procedure which detects live/dead or acrosome reacted/not acrosome reacted sperm was also utilised to determine whether bull x treatment interactions may have existed in the in vitro trial but were obscured by other factors influencing the IVF system. Sperm motility and abnormal morphology were assessed using light microscopy on whole frozen-thawed semen samples. Statistical analysis could not be done because of lack of replication. Percentages of immotile sperm were high (60.16% to 78.51%), with considerable variation in progressive motility (13.90% to 34.35%) between bulls. A large variation in numbers of morphologically normal sperm was observed between bulls (66% to 90%), with major deformities (9% to 19%) accounting for most of the abnormalities. High negative correlations with performance (as defined in the in vitro trial) were found between % normal sperm and % proximal droplets (r=-0.66 to -0.88). Percentage of minor abnormalities, distal droplets and coiled tails correlated positively with fertility (r=0.67 to 0.91). Motility did not correlate highly with any of the criteria used to assess bull performance. Correlations of semen quality to performance were contradictory to expected results and this may have been due to swim-up separation of sperm for the in vitro trial which was not carried out for semen quality assessment. At present, these semen quality tests do not allow prediction of bull fertility in vitro. Assessment of sperm stained for evaluation of live/dead and acrosome reacted/not acrosome reacted was a lengthy procedure. Again, statistical analysis was not possible due to the lack of replication. High percentages of sperm were characterised as dead (52.4% to 100%). Bulls did respond differently to the various treatments, as determined by the proportion of acrosome reacted sperm and live acrosome reacted sperm. Thus, bull x treatment interactions were apparent, suggesting that the IVF system was more strongly influenced by other factor(s) which reduced sensitivity to the treatments tested. In summary, more research is needed to stabilise the IVF system if production of large numbers of embryos is to become economically viable.
Characterisation of determinants of predation of goats in communal production systems.
(2016) Durawo, Charity.; Chimonyo, Michael.
Predation is challenge in communal goat production systems. The broad objective of the study was to explore determinants of goat predation in communal production systems. A survey was conducted in 195 households in flat and mountainous terrains of Bergville local municipality in KwaZulu-Natal, using pre-tested semi-structured questionnaires to determine the effect of genotype and topography on the incidence of predation of goats. An average of eight goats was reported per household. Diseases and thefts, followed by predation were ranked as the major causes of goat losses in both areas. Jackals (Canis aureus L.), caracal (Felis caracal), wild dogs (Lycaon pictus) and leopards (Panthera pardus) were the common predators during the hot wet season. There were no leopards and caracal in the hot dry season in the flat environments. Farmers reported no leopards in the flat terrains in the cool dry season. Farmers owning non-descript goat genotypes were five times more likely to experience predation problems than farmers owning the indigenous Nguni goats. Farmers staying in mountainous environs were 2.3 times more likely to experience predation challenges than farmers in the flat land. Kids were the major class of goat targeted by predators. Predation largely occurred in the veld and drinking areas. The major finding from the survey was that the Nguni goat genotype is less likely to be lost to predators. Assessing goat vigilance behaviour in predation risk areas is important in understanding determinants of goat predation. The second objective of the study was to assess the vigilance of free grazing Nguni goats in different flock sizes and ages in flat and mountainous terrains. Vigilance behaviour was categorized into antipredator or social vigilance and further distinguished into vigilance with or without chewing. Goats spent more time (P< 0.05) in antipredator vigilance than social vigilance. In the flat terrains, does in large flocks spent 2.5 times more time in antipredator vigilance with chewing than does in small flocks. A similar pattern was observed in the mountainous environments. For large flocks, does in flat terrain spent 1.9 times more time in antipredator vigilance with chewing than does in mountainous areas. For large flocks, kids in flat terrain spent 2.7times more time than in mountainous areas in antipredator vigilance with chewing. In the flat terrain, does in large flocks spent five times more time in antipredator vigilance without chewing than does in small flock sizes. In mountainous areas, does in large flocks spent twice more than the time spent by does in small flock sizes. In flat terrain, kids in large flocks spent seven times more time in antipredator vigilance without chewing than kids in small flocks. In large flocks in the flat terrain, kids spent more time in antipredator vigilance with chewing than does (P< 0.05). Age of goats had no effect on the vigilance behaviour. It was concluded that, in flat environments, goats exhibit more antipredator vigilance than those in mountainous areas. Goats in larger flocks spent more time in antipredator chewing vigilance behaviour.
Choice feeding as a method of meeting the changing protein requirements of broilers during their growing period.
(2005) Abdella, Mohamed Salih.; Gous, Robert Mervyn.
Broiler production is an important animal production enterprise with potential to make high returns. Increasing feed efficiency and early body weight gain has always been a top priority in the broiler industry. The general objective of broiler nutrition is to maximise production performance and profitability . Nutrition is of major importance in raising chicken, and feed is a major input in poultry production systems, accounting for over 60% of total production costs in commercial poultry sector Renkema (1992). The cost of feed is therefore often a constraint especially in developing countries. For instance, Onyenokwe (1994) observed that high cost of feed ingredients in many African countries has caused many poultry farmers to abandon the industry. The continued rise in feed prices is due to competition for some of the ingredients with human e.g. sorghum, wheat and maize. Broiler farmers are therefore forced to use combinations of feed ingredients of low cost to obtain savings and avoid any further loss of profits. It is therefore important to give special attention to feed and feeding since the rate of feed consumption increases rapidly with advancing age of the birds and good nutrition is reflected in the bird's performance and its products. The profitability of a broiler enterprise depends on the efficient conversion of feed to meat. Broilers have the ability to convert the feeds into meat with a high efficiency. For instance Morris and Njuru (1990) reported that broilers have much higher daily rates of protein deposition than layer chicken strains. This implies that fast-growing strains would require greater daily protein intakes than slow-growing ones. In the past, the major criteria for assessing the performance of broilers has been growth rate and feed conversion ratio (FeR). Diet specifications and feeding programmes have been aimed at maximising these two parameters whereby overall flock performance is calculated based on the total weight of chicken produced from total feed deliveries. With the new developments in understanding of nutritional factors affecting broiler growth and carcass composition, it is now possible to apply sophisticated and yet efficient approaches to feeding broilers.
The constraining effect of feed bulk on the voluntary feed intake of laying hens.
(2004) Moore, Martina Louise.; Gous, Robert Mervyn.
1. Two experiments were designed to determine a suitable method of measuring and predicting feed bulk, such that this could be used to predict when the feed intake of a laying hen would be constrained by feed bulk. 2. In the first trial the diluents used were cellulose, plasterer's sand, sunflower husks, sawdust and vermiculite. These were included at 100, 250 and 500 g/kg into a commercial layer feed which was used as the basal feed. The trial was divided into three phases of 21 days each. After each phase, either the diluent fed was changed, or the inclusion level of the diluent was changed. 3. It was observed that as the water-holding capacity (WHC) of the feed increased, the feed intake decreased. The scaled feed intake (SFI) of the hens was fitted to the reciprocal of the WHC to give the relationship; SFI (g/kg body weight) = 313.6 (±8.9) x 1/WHC. This regression was the best fit and represents the maximum amount of feed that the laying hen can consume when the constraint measured is the reciprocal of WHC. 4. Trial 2 identifies the physical characteristics of the feed that best describe the bulkiness of the feed, and also determined the extent, and the rate at which, the laying hen can adapt to feeds that are high in bulk. The five diluents that were used were wheat bran, river sand, potter's clay, unexpanded polystyrene and sawdust, and the inclusion rates were 50, 100 and 150 g/kg. The hens were fed the feeds for six weeks. The equation from Trial 1 was fitted to the data from Trial 2 and few treatments were found to be constraining. 5. The constraining feeds from both trials and Williams (1993) were combined to obtain a more accurate assessment of the relationship between the SFI and the reciprocal of WHC. This relationship was represented by the equation; SFI (g/kg body weight) = 301.4 (±8.9) x 1/WHC. 6. The prediction of the effect of feed bulk on the voluntary feed intake of the hen is an important aspect for accurately predicting the feed intakes of the hen and formulating a "perfect" diet. The variation in constrained intakes was not accurately predicted by the WHC of the feed, although this measure of bulkiness was considerably better than any of the other measures applied.
Constraints on smallholder dairying in Swaziland : Manzini Region & surrounding areas.
(2005) Malima, Boyce Thabo.; Nsahlai, Ignatius Verla.
Summary: Swaziland has long had a disparity between the supply and demand of milk. Even at present milk production continues to be less than the market demand. The quantitative contribution of smallholder dairy farmers to local milk production remains unknown because of poor record keeping. This study was aimed at attaining a clear understanding of the dynamics of smallholder dairying in Swaziland, including the identification and understanding of the constraints faced by farmers in dairying, with the hope of devising workable solutions to them. A sample of 118 smallholder dairy farms were covered in this study, with a total herd of 306 lactating cows, comprising mainly of Jerseys and Holstein Friesians, with some cross breeds. There were no significant differences in mean milk yield/cow with respect to farmer gender (P > 0.05) and Agro-ecological zone location (P > 0.05) of the farms. Milking frequency had a significant effect on milk yield, since cattle milked once a day had lower (P < 0.05) milk yields than those milked twice a day. The cattle had extensively long calving intervals i.e. 448 ± 166 days, ranging from 292 to 1082 days. Low milk yield and poor reproductive performance of cattle were found to be mainly due to poor nutrition, breeding practices and stock quality. These are primarily a result of insufficient farmer training and inadequate technical assistance, scarce availability of quality stock, lack of investment resources and market support that includes favourable milk prices for farmers to make money. This performance of the Swazi smallholder dairy herd was then evaluated by comparing it to the performance of a larger, well-managed herd of known pedigree. Lactation records from 252 Jersey cows and 108 Holstein Friesian cows were obtained from Cedara Agricultural Research Institute, covering the periods; July, 2002 to July, 2004 and November, 2002 to April, 2004, respectively. Cows were grouped by parity and calving season and the gamma function proposed by Wood (Y = An(b) e(-cn)) was used to fit standard lactation curves on group data. The curve parameters A and b increased with parity, while that of c and s (persistency of lactation at peak) decreased, producing standard lactation curves save for the Holstein Friesian summer calvers, which produced atypical curves. The R(2) values (goodness of fit) increased with parity. Animal parity and calving season were found to influence the peak and shape of the lactation curves and their parameter estimates. The performance of the Swazi smallholder herd showed a mean deviation of the observed daily milk yield of the Holstein Friesian breed from the expected yield to be - 3.47 (SD 6.052) kg and that of the Jersey breed was - 16.92 (SD 5.473) kg. The mean proportional deviation of observed milk yield from the expected yield for the Holstein Friesian breed was - 0.3 (SD 0.37) and that of the Jersey breed to be - 0.6 (SD 0.19). The proportional milk yield deviation of the Holstein Friesian breed can be explained using the equation Y = O.1322(SE = 0.1293) x - 2.3581 (SE = 0.20639), where x = expected milk yield and Y is the proportional deviation of the observed milk yield deviation from the expected milk yield. With respect to the smallholder Jersey breed, no relationship was found that could explain the proportional milk yield deviation. The smallholder herd was shown to be underperforming, considering the potential for higher milk yields of the two breeds. In the quest to gain a greater understanding of the dynamics of smallholder dairying, the sample of 118 farmers was further analysed using multivariate statistics to categorise them based on their herd sizes, herd structures, management and success perceptions in dairying. The analysis produced three clusters (categories): cluster 1 had the largest herd sizes and poor milk production efficiency; cluster 2 had intermediate herd sizes, the highest number of farmers and more efficient milk production per cow. This cluster, however, had the highest proportion of calf mortalities. Cluster 3 had the smallest herd size, the lowest calf to cow ratio and the second highest calf mortality. Record keeping across all clusters was very poor and the average milk yield per cow was generally low. Most of the farmers do not appreciate the importance of annual calving of their cows as an integral part of the success of their dairy projects and winter feed supplementation is very poor across all the clusters. There remains a great need for the enlightenment of the farmers on the importance of good nutrition, breeding, calf rearing and record keeping in successful dairying.
Contribution of village chickens to the resource-poor households.
(2014) Gwala, Mlungisi Petros.; Chimonyo, Michael.; Nsahlai, Ignatius Verla.
Village chickens are reared by almost every rural household in low-income, food-deficit regions of the world, but their contribution to food security at both, household and national levels is not well understood. The study was conducted to determine distributions patterns of village chicken meat within resource-poor households. A total of 242 households participated in the survey. There was a strong association between village chicken and other livestock ownership (P < 0.001), large chicken flock owners reared other livestock species. Village chickens were kept mainly for home consumption. Adult members of the households ate more village chicken meat than broiler meat as compared to the youth (P < 0.05). Village chickens were mainly slaughtered during periods of transitory food shortages. Logistic regression identified gender of the head of household, income, religion and gender of the decision-maker as significant determinants to influence the consumption of preferred of village chicken meat cuts by adult males and females (P < 0.05). Children consumed less preferred portions (heads, necks and feet). Income received in the household, flock size and ownership of other livestock were significant determinants of households attaining adequate food throughout the year. It was important to assess factors that limit the consumption of village chicken meat to children. There was a relationship between number of children and consumption of intestines in the households (χ2 = 9.05; P < 0.05). Increasing number of children in the households increased chances of consuming intestines. Gender of the head of household, household size and age restriction practice were significant predictors for an adult male to preferred meat cuts (P < 0.05). Village chicken flock size and season were significant predictors for an adult female to consume neck and thighs. Household size was a major predictor for head and liver consumption by male children (P < 0.05). Household size was a significant predictor for a female child to consume meat from the head, feet and wing (P < 0.05). The number of village chickens slaughtered varied with seasons. As the household size increased, children, especially female children were likely to suffer from nutritional insecurity. Households did not fully utilise village chickens to optimise household protein intake among household members. Village chicken contribution to resource-poor households is not yet optimised to alleviate poverty in resource-poor households. The factors that affect meat consumption by household members should be considered for future programmes aimed to improve the contribution of village chickens.
Dairy constraint analysis in Eritrea, with special emphasis on Asmara and surrounding dairy farms.
(2003) Weldeselasie, Alemseged Moges.; Nsahlai, Ignatius Verla.
The overall objective of the study reported in this thesis was to assess the existing situation of the dairy sub-sector in Eritrea with special emphasis on the Asmara and surrounding dairy farms. The specific objective was analyse historical data and carry out a survey to identify the constraints of the dairy sub-sector in Eritrea. Historically, commercial dairy farming in Eritrea was started by Italian settlers during the 19th century when Eritrea was under Italian colonization. The growing demand for milk and milk products, especially in the urban centres stimulated the development of dairy farms by Italian settlers who owned large areas of fertile land mainly in the highlands, in which they established modern dairy farms using high merit dairy breeds such as the Holstein-Friesian. The introduction of artificial insemination (AI) in 1938 by the Italians for research purpose at the Veterinary Institute also contributed to dairy development. Based on the efficiency of A.I. services over time, four phases of development were identified. During 1972-1976 good achievement per inseminator and high effective inseminations were recorded. In 1978 -1980 the achievements declined but with increased number of calves and high effective inseminations as compared to phase one. From 1982-1989 the activity increased with effective inseminations ranging from 48-75.3%. During 1992-2000 effective inseminations ranged from as high as 58.8% to as low as 31.3%. Effective inseminations increased with the increased number of A.I. technicians. The highest achievements were recorded during the years 1993, 1998 and 1999. A survey was conducted on urban and peri-urban dairy farmers located in and around Asmara. Thirty dairy farmers were randomly selected and interviewed. Data on herd composition and breed, feed type and source, type of mating, dairy housing, health, farmers' status, milk production and marketing, problems and constraints faced by dairy farmers were collected. Interviewed farmers were characterised based on location, herd size, health service, and farmers' status. Dairy farmers varied in their access to forage. High proportions of peri-urban farmers have access to cultivated forage while high proportions of urban farmers have access to purchased forage. Usage of cultivated and purchased forage were related to location (p<0.05). Natural, AI and combined systems of mating were used by 86.7%,3.3% and 10% of farmers, respectively. Both urban and peri-urban farmers used the in-door system of housing. Foot and mouth disease (FMD), lumpy skin disease, nutritional disorders, mastitis, abortion, tuberculosis and digital problems were the most prevalent diseases. Dairying was considered by a majority (73%) of farmers as a primary means of income but by 27% as a part time means of earning an additional income. A large amount (67%) of milk produced was marketed through the formal channel while the rest (23%) was sold directly to consumers. Secondary data were collected from different institutions and libraries such as MoA, ASMDFCA and Asmara Pavoni social centre, through personal contacts with various individuals. A data set of 563 dairy farmers that included infonnation on farm identification number, location, breed, herd structure (cows, calves, heifers, bulls), milk yield/farm/day and milk yield /cow/day was subjected to cluster analysis. The main objective of clustering was to classify farmers according to their characteristic features. Three clusters, namely clusters 1, 2 and 3, were identified and had, respectively 47.04%, 45.06% and 7.91% urban (n=253) and 37.13%, 61.56% and 1.3% peri-urban (n=307) farmers. Clusters 1, 2, and 3, had 10±0.6, 5±0.5, 23±1.82 cows, and produced 49.7±3.45kg, 24.3±3.02kg and 117±10.73 kg of milk/farm/day, respectively. A group survey was conducted to identify the major constraints impeding dairy production. Pairwise ranking of the identified problems was done using a matrix. The constraints subjected to pairwise ranking were: feed shortage, lack of co-ordination, lack of skilled manpower, disease and shortage of veterinary drugs, lack of extension package, shortage of land, lack of milk cooling and transport facilities, lack of know-how and inconsistent AI service. Shortage of land, feed shortage and lack of co-ordination were identified as the major constraints facing dairy farmers. Dairy herd constraint analysis was also done on Elabered estate dairy. It is the only dairy farm that keeps dairy records. Data on lactation number, breed, last calving date, A.I. date and due date, body weight and height, milk yield per cow, condition score, number of AI's and pregnancy status of cows, were analysed using "Gwion dairy analysis programme by dairy man". Mean milk yield, condition score and average live body weight of the herd were 11.6±2 kg/day, 2±0.56 and 497.63±89 kg, respectively. Days in milk of first calvers and older cows fell between the ranges of 41-327 and 201-245 days, respectively. First and second calvers were below target average mature body weights. Mean age by stage of lactation of cows was 3.3±1.8 and mean age at first calving of the herd was between the range of 39-43 months. Mean calving interval (Cl), calving interval spread index, voluntary waiting period, average services per pregnant cows (SPC) and maximum services per conception were 435 ±88days, 55, 52days, 1.8±1.1 and 7, respectively. Poor heifer growth and poor fertility status were major constraints identified. The suspected causes were poor data management, poor heat detection and poor nutrition. Generally, the dairy sub-sector in Eritrea comprises urban and peri-urban dairy farms of different sizes operating in and around urban centres. The sustainability of the systems will be determined by their location towards the centre. With the expansion of towns and residential areas some dairies may discontinue. Social, environmental and economical aspects should be given due consideration for sustainable dairy production systems. Therefore, identifying the target group should help to intervene and solve constraints.
Degradation parameters and modelling of degradation rate in the rumen of cattle fed non-supplemented roughages.
(2015) Katamzi, Masande.; Nsahlai, Ignatius Verla.
Feeding of animal has become increasingly a big challenge in livestock production systems as it is the most costly input. Ruminants are very important to mankind because they can convert fibre-rich vegetation into high quality protein sources for human consumption. The objective of this study was to determine roughage intake in ruminants using data. The study was conducted using two fistulated jersey cows and data from several literature records with feed properties, diet properties and in sacco degradation parameters. An in sacco degradation study was conducted at Ukulinga Research farm. Ten different roughages were used, namely; (MS) maize stover (Zea Mays), maize leaves (ML), (WS) wheat straw (Tritium sativa), (KK) kikuyu (Pennisetum clandenstinum), (EC) weeping love grass (Erograstis curvula), (ECC) weeping love grass at bloom stage (Erograstis curvula), veld grass hays (VGHA, VGHD, VGHC & VGHP) from Airport at Pietermaritzburg, Dundee, Camperdown and Ukulinga Research Farm, respectively. All collected data for both experimental and from the literature were used to determine correlations and build regression models based on degradation parameters, diet and incubated feed properties. Also, intake and total digestibility were predicted based on degradation rate and particle passage rate. In the study to determine degradation properties of roughages and their interaction with three different rumen environments, roughages in rumen environments supplemented with lucerne had increased (P<0.0001) insoluble but potential degradable fraction (b), potential degradability (PD) and effective degradability (ED) of dry matter. Rate of degradation (c), the potential and effective degradability differed (P<0.0001) amongst roughages in three different rumen environments but the DM solubility (a) did not. The outcome of the study to establish a regression model for degradation rate of roughages in non-supplemented diets produced six regression models & there were strong correlations (P<0.0001) between degradation parameters, diet properties and feed properties. In the study to use a model to simulate intake and digestibility, results showed small chances of predicting intake pertaining relationships in all observations with values of coefficient of determination (R2) ranging from 10% to 24%, suggesting that some factor may not have been fully appreciated. The best coefficient of determination (R2) for the digestibility relationship were 82% and 44% for two studies out of four meaning that there are possible chances that digestibility can be predicted. Significant variations of in sacco degradability parameters were reported among roughages incubated in different rumen environments. Therefore, these results may be linked with other studies and be used to find a relationship between degradation rates of low quality roughages. In conclusion, the inclusion of variables like retention time and other factors that significantly affects intake in addition to diet and incubated feed properties, may improve simulation of intake and total digestibility of non- supplemented low quality roughages.
Developing an energy evaluation protocol for horse feeds in South Africa.
(2004) Lindsay, Elaine.; Young, Marion Belinda.
The purpose of this study was to find the most accurate and reliable method available in South Africa to evaluate equine diets on an energy basis. Currently South African horse owners purchase food according to the crude protein content of the diet, not knowing the energy density of the diet, which they are feeding their animals. Energy is one of the most important measures of an animal feed, as the energy density determines how much of a diet needs to be fed to meet an animal's requirement. The level of feed intake determines the concentrations of all other nutrients in the diet, therefore one cannot formulate a diet correctly without knowledge of its energy content. Through domestication, there has been an increased demand for horses to perform under circumstances that require energy greater than that provided by its natural diet of grass alone. This has therefore lead to the inclusion of cereal grains and their by-products. These large grain meals can overwhelm the digestive capacity of the horse thus leading to various types ofdigestive disorders such as colic. Therefore by the development of an energy evaluation system, one could provide the horse with the correct amount of energy from the appropriate source without compromising its digestive system. Predicting digestibility of a diet is the basic step for energy evaluation of horse feeds. Currently horse diets in South Africa are formulated using ruminant total digestible nutrient (TDN) data. As large horses are difficult to work with in digestibility trials, a preliminary experiment was designed to see how accurate it would be to use miniature horses as predictors of digestible energy for large horses. By comparing the digestibility data with that of overseas predictive equations, where large horses were used, the results were found to be highly comparable. As it was established that miniature horses were a perfect pilot animal for digestibility studies on large horses, the next step was to determine the rate of passage in miniature horses so as to determine if the length of the collection period, in a digestibility trial, proposed by overseas researchers for large horses, was enough time to clear the digestive system in a miniature horse of the diet under investigation. An experiment was carried out using Celite® as an insoluble marker to determine rates of passage via the acid insoluble ash method. A mean retention time of 66.64 hours was obtained, therefore assuring that a collection period of 5 days, as recommended by overseas researchers, was sufficient time to clear the miniature horse's digestive system of the test diet. Following the preliminary trial, a digestibility experiment was designed to investigate the accuracy of using ruminant data to formulate equine diets as well as using rabbits as a possible pilot animal in horse digestibility trials. The trial involved five miniature horses, four male sheep and ten rabbits. Four commercial horse diets were investigated. From these results it was found that rabbits proved difficult too work with and did not favour the experimental conditions and therefore gave digestibility results very different to that of the equine. Ruminants proved accurate predictors of the digestibility of the fibre components for horses but not for the other digestible nutrients. Significant differences were found between the diets given only to the horses and diets that should have provided a higher digestible energy did not. This accentuates the need for the development of an energy evaluation protocol, so that equine diets can be formulated more precisely and thereby ensure that the energy requirements of the horse are met. In vivo digestibility results were compared to the same feeds incubated in vitro and significant differences (P<0.05) were found between the results obtained by the two methods. A possible reason for this could be the method employed for removing supernatant between the two stages of the Tilley and Terry (1963) method, leading to an overestimation of digestibility for feeds containing hay and incubated in vitro. No significant differences (P>0.05) were found between digestibilities, rates and maximum gas production between the sources of inoculum used. Significant differences (P<0.05) were found between digestibilities obtained by incubating concentrates alone or in an 80:20 ratio with hay. Further investigation is needed here as it was felt that the supernatant removal method contributed significantly to inaccurate in vitro results. This experimental work centres on discovering and developing the best method available to the South African feed industry for predicting digestible energy contents of horse feed, so as to improve defined performance within an equine discipline and reduce nutritionally-induced disorders.
Development of a protocol for the molecular serotyping of the African horse sickness virus.
(2009) Groenink, Shaun Reinder.; Young, Marion Belinda.; Watson, Gregory M. F.
African horse sickness (AHS) is a viral disease with high mortality rates, vectored by the Culicoides midge and affecting members of the Equidae family. AHS is endemic to South Africa, and, as a result, affects export and international competitiveness in equine trade, and impacts significantly on the South African racehorse and performance horse industries. AHS also has devastating consequences for rural and subsistence equine ownership. The protocol developed in this dissertation has the potential to serotype and confirm the AHS virus within a few hours at significantly less cost than current methods. It will ease the financial and time constraints of studying an outbreak in real time and has the potential to solve many of the unknown factors surrounding AHS, particularly and most importantly, the role that each serotype plays in outbreaks and the form of the disease contracted by horses.
Diet selection and foraging efficiency of Nguni goats in the bushveld of Gauteng, South Africa.
(2012) Werekeh, Fomum Sylvester.; Scogings, Peter Frank.; Nsahlai, Ignatius Verla.
Diet selection and foraging efficiency are primary driving behavioural processes in mammalian herbivore plant interaction. They determine the quality of production and also impact on vegetation, necessitating managerial inputs that will sustain productivity and conserve or improve on its plant species composition. In view of a better understanding of browse/browser interaction in subtropical arid savannah, Nguni goats were adopted as our model browser considering their socioeconomic importance to local, regional and global economy. The primary objective of this research was to determine the seasonal and plant species trend of diet selection indexed by intake and foraging efficiency indexed by intake rate. The secondary objective was to investigate how plant morphological variables such as spinescence, shoot morphology such as long shoots as opposed to short shoots, and broad as against fine leaves, phenological variables such as evergreen versus deciduous species, and plant chemical components including: crude protein, neutral detergent fibre (NDF), acid detergent fibre (ADF), hemicellulose, cellulose, acid detergent lignin and condensed tannins relate and possibly explain the observed patterns. Six browse plants, Acacia nilotica, Acacia robusta, Ehretia rigida, Euclea crispa, Rhus lancea and Ziziphus mucronata were used in the first experiment to determine short term intake during the dry and rainy seasons. In the second experiment, 10 browse plants: Acacia nilotica, Acacia robusta, Combretum epiculatum, Dicrostachys cinerea, Ehretia rigida, Euclea crispa, Gymnosporia buxifolia, Rhus lancea and Ziziphus mucronata were used to determine short term intake rate in the dry, early rainy and late rainy seasons. Diet selection was significantly affected by species (F5,60= 31.87 ; p< 0.05) and the interaction between seasons and species (F,60= 2.52; p= 0.039). Intake was not significantly higher in the rainy relative to the dry season, 3.94 ± 0.42a gDM compared to 3.57 ± 0.42a gDM. Rhus lancea and A. robusta were the most preferred species in both seasons, while Z. mucronata was more preferred in the dry season than E. crispa but in the rainy season it was the opposite. Dichrostachys cinerea and A. nilotica were the least preferred in both seasons, but with improved intake of D. cinerea in the rainy season, whereas that of A. nilotica declined significantly. Intake of plant species with long shoots, which were also broad leafed, was significantly higher than that of old short shoot species (t= -3.99; df= 65.80; p= 0.0002). Similarly, intake of evergreen species was significantly higher than that of deciduous species (t= 5.22; df= 34.02; p< 0.0001). Cellulose in the rainy season positively correlated with intake (r= 0.85; n= 6; p= 0.031), bite number cropped (r= 0.98; n= 6; p= 0.001) and browsing time (r= 0.93; n= 6; p= 0.007). In the dry season there was no correlation of any plant chemical components with intake except cellulose that correlated with the intake variable of bite size (r= 0.87; n= 6; p= 0.023). The following regression equation was generated from the correlation to model intake: Intake= 0.68 + BS (3.07), (R2= 0.71; p< 0.05), where BS= bite size. Intake rate varied amongst species (p< 0.05), as well as seasons (p< 0.05). Instantaneous intake rate in the dry season were highest for A. caffra and G. buxifolia, followed by C. apiculatum, R. lancea, E. crispa, A. robusta and Z. mucronata. The bottom tier comprised of E. rigida, D. cinerea and A. nilotica. At the onset of the rainy season, A. robusta, A. caffra and R. lancea had the highest instantaneous intake rate, followed by C. apiculatum, E. crispa and Z. mucronata. The lowest instantaneous intake rates were derived from D. cinerea, E. rigida, G. buxifolia and A. nilotica. At late rainy season, A. robusta, A. caffra, C. apiculatum, E. crispa and R. lancea yielded the highest intake rate, followed by D. cinerea, G. buxifolia and Z. mucronata in the middle tier, and the least were derived from E. rigida and A. nilotica. Acacia caffra, A. robusta, R. lancea, C. apiculatum and E. crispa featured amongst species with the higest intake rate in all three seasons, whereas G. buxifolia from which one of the highest intake rates was derived in the dry season declined to amongst those with the least in both early and late rainy seasons. Ehretia rigida, D. cinerae and A. nilotica were consistent in all three seasons as the least efficiently foraged Browses with long shoots were more efficiently foraged upon than those with short shoots (t= -3.2; df= 284.64; p< 0.002). Evergreen plant species yielded higher instantaneous intake rate relative to deciduous species (t= 2.02; df= 278.01; p< 0.044). Intake rate of spinescent relative to spineless species was not significantly different but more bites were cropped from spinescent relative to spineless species (t= 2.80; df= 256.77; p= 0.006). Bite sizes were smaller for spinescent relative to spineless species (t= -3.30; df= 227.4; p= 0.001). There were significant positive correlations of cellulose with intake rate (r= 0.7; n= 10; p= 0.023), and with condensed tannins (r= 0.7; n= 10; p= 0.022) in the dry season. Additionally, cellulose also had a positive correlation with bite size in the same season (r= 0.7; n= 10; p= 0.016). At early rainy season, there was no correlation of intake with any of the plant chemical components, whereas, NDF (r= 0.6; n= 10; p= 0.044), hemicellulose (r= 0.8; n= 10; p= 0.012) and condensed tannins (r= 0.7; n= 10; p= 0.032) all correlated positively with browsing time at early rainy season. The following regression equations were derived to model intake rate and some intake rate related variables: (1) intake rate= 0.433 + BSDM (0.081), R2= 0.68, p< 0.05 and BSDM= bite size dry matter; (2) Bite rate= 0.503 –BSDM (0.147), R2= 0.597, p< 0.05 and BSDM= bite size dry matter; (3) Bite size dry matter= 1.713 – BR (4.210), R2= 0.597 ,p< 0.05 and BR= bite rate, and (4) Intake dry matter= 3.804 + BSDM (0.865), R2= 0.607, p< 0.05 and BSDM= bite size dry matter. Diet selection and foraging efficiency were both influenced more by shoot and leaf morphology than by spinescence. Plant chemistry on the other hand had diverse and inconsistent effect on diet selection and foraging efficiency trends. The results therefore have important and far reaching implications for Nguni goat and goat production as a whole in the bush veld of Gauteng and related ecological zones.

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