No abstract available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

With the worldwide increase in consumption of poultry meat in recent years, the production of hatchable eggs from broiler breeding stock has become a critically important component of the poultry industry. Surprisingly, a perusal of the literature pertaining to broiler breeder nutrition leads to the conclusion that research nutritionists have neglected these birds. It has been assumed in many cases that the research on laying hens is applicable to broiler breeders. However, fundamental differences are apparent between the two strains that should be investigated more comprehensively if the potential of broiler breeder hens is to be achieved. Commercial laying hens have been selected predominantly for increased egg production whereas broilers have been selected for early rapid growth rate. By selecting for improved growth rate, both food consumption and mature weight of these birds has increased (Reddy, 1996), but because of the negative genetic correlation between body weight and egg production (Robinson et al, 1993) reproductive performance has not been improved. Broiler breeder hens differ from commercial laying hens, by their non-normal frequency distribution of egg outputs, their considerable lipid reserves, and by the fact that many do not lay in closed cycle. The practice of restricting feed intake during both the rearing and laying periods has become a standard management procedure in commercial broiler breeder operations and this differs from the manner in which commercial hens are fed. This raises important issues regarding the requirements of these birds for energy, amino acids and other essential nutrients, as the birds do not have the opportunity of meeting their nutrient requirements by adjusting food intake upwards when one or more of these nutrients is deficient in the feed. It is the duty of the nutritionist to provide the correct daily allowance of each nutrient in order to achieve maximum egg output by the flock, but given the variation between hens within a flock, such decisions need to be made on both biological and economic grounds. Improved strains are continually being produced by breeder companies, which exhibit better growth, feed efficiency and productivity. The way in which broiler breeder hens were fed in the past might not be the most effective way to feed the latest strains. Getting the right amount of feed with the right nutrient levels at the right time is the most important part of feeding broiler breeders, and to succeed their daily nutrient requirements need to be known. Information concerning the nutritional requirements of broiler breeder hens is limited in comparison to other types of domesticated poultry. However, enough information is available concerning energy and amino acid nutrition of this type of poultry to enable one to develop models useful for constructing accurate feeding programmes. The most appropriate way of estimating the nutrient requirement of broiler breeder hens during the laying period, or of optimising a feeding strategy, is by the use of simulation models. Emmans and Fisher (1986) suggested that a better approach to the problem of describing requirements and of expressing them quantitatively can be achieved by considering: firstly, the bird’s characteristics, secondly by defining resource scales carefully and thirdly by considering the quantities of each resource needed per unit of function. This approach has a greater chance of success than attempting to measure requirements by direct experimentation. Energy and amino acids are required for growth of tissues, egg production, maintaining normal body temperature, vital life functions and activity. For development of feeding programmes, we are most concerned with the three primary components, maintenance, growth and egg output. There are a number of factors that impact on the total nutrient requirement of the breeder. The maintenance component is affected by body size, environmental temperature, level of activity (housed in floor pens vs. cages) and possibly breed. Regarding the growth component, in the case of broiler breeders during lay the composition of growth needs to be addressed: whether this is only lipid gain or also includes protein gain. Lastly, the egg component is influenced by egg mass and hen age. In order to calculate energy and amino acid requirements, one must have knowledge of the requirements per unit of body protein weight, growth rate and egg mass. By continually monitoring the environmental conditions in the broiler breeder house, as well as body weight, egg weight and egg number, it is possible to estimate the state of the hens at any time and hence the optimum nutrient concentrations that should be fed the next day of the laying period by using the Breeder Model presented in this thesis. Optimising the feeding of broiler breeders during the laying period is made difficult because of the many interacting factors influencing their performance All the hens are not the same, they are not housed in the same environments, and the costs of feeding and the revenue derived from the sale of the product differs from one locality to another. The solution to this problem lies in the use of simulation models to describe the causal relationship between inputs and the predicted responses. This thesis explored new concepts and components for a simulation model to predict the nutrient requirement and performance of broiler breeders after sexual maturity. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

The Nguni sheep of Zululand, South Africa, are called the Zulu sheep. They are a source of food and cash for the rural farmers of KwaZulu-Natal. There is insufficient information available about the characteristics of this breed and accordingly the breed is classified as “insecure”. Documentation of characteristics of a breed is important for its utilisation, improvement or conservation. This study was undertaken to document (i) the utilization of the Zulu sheep, (ii) some morphological characteristics, (iii) establishing a cost effective body measurement recording means and (iv) the intra- and inter-population genetic variation of the breed using random amplified polymorphic DNA markers. A survey was conducted to investigate the socio-economic and cultural values of the farmers attached to livestock including the Zulu sheep. A total of 76 rural farmers were interviewed in the areas of the Mhlathuze district in northern KwaZulu-Natal. Constraints and the indigenous knowledge of the farmers on livestock production were also recorded. The results confirmed that the Zulu sheep in the rural areas are indeed used as a source of protein and cash when necessary. Farmers reported that the Zulu sheep are tolerant to ticks and able to withstand the hot and humid conditions of northern KwaZulu-Natal. Goats and cattle as well as the Zulu sheep are also used for payment of dues in the tribal courts. Even so, Zulu sheep are not used for any cultural purposes. The system of management is fairly extensive. Some farmers apply indigenous knowledge as part of management practices. For instance, they use indigenous plants as nutrient supplements and for increasing the reproduction rate of these animals. Lack of modern animal husbandry skills was declared by the farmers as one of the main challenges. A perception among the farmers was that the Government could assist in addressing this challenge. Three populations of Zulu sheep reared extensively in three localities were used for the morphometric and genetic studies. The areas were the community of KwaMthethwa (Enqutshini), University of Zululand (UNIZULU) and Makhathini Research Station. Makhathini and KwaMthethwa are 260 and 40 km, respectively, away from UNIZULU. The morphometric study was undertaken to determine the extent of phenotypic diversity between Zulu sheep populations using six morphological characteristics. Effects of some factors (location, age, sex and season) on some of these traits were estimated. Results showed that the size of the body measurements, wither height (WH), heart girth (HG), live weight (LW) and scrotal circumference (SC) were significantly different between the populations. Variation in these body measurements was influenced significantly by the location, season, the sex and the age of sheep. Mature ewes weighed up to 32 kg whereas the rams weighed up to 38 kg. The differences in LW, HG and WH between the seasons were small. The SC increased with the age of the ram up to 28 cm for mature rams. Other traits observed were the colour and the ear length of Zulu sheep. Ear size ranged from ear buds to the most common large ears (9 to 14 cm). The dominating colours observed were brown and a combination of brown and white. Live weight prediction equations were estimated employing HG, WH and SC data. The LW prediction equations showed that the regression of HG and WH produce the best estimate equations of LW; however the HG alone also showed reliable LW estimates. Scrotal circumference was more precise for estimating the LW of younger rams below 22 months of age (R2 = 0.64 – 0.78). Fifty-two Zulu sheep from the three locations were used to assess the genetic variation within the Zulu sheep breed. A total of 2744 RAPD bands were generated ranging from 0.2 to 2 kb; ~46% of these bands were polymorphic. The genetic diversity was the lowest (5.17%) within the UNIZULU population, 8.62% within the KwaMthethwa population and highest (11.04%) within the Makhathini population. The genetic diversity between all populations was estimated at 21.91 %. Phenotypic diversity was relatively similar for the UNIZULU and Makhathini populations (41.25% and 45.63%, respectively). The phenotypic diversity between the three populations was 48.26%. Genetic and phenotypic diversity was lower for Makhathini and UNIZULU populations than for the KwaMthethwa population. It was concluded that the Zulu sheep is a smaller sized breed compared to the other South African indigenous sheep breeds like the Dorper which has been reported to have some similar characteristics to the Nguni sheep. The results confirmed that the Zulu breed has the capacity to survive without dipping and supplements during the dry season. This adaptation is of value to the communities of KwaZulu-Natal. Such characteristics warrant conserving the breed to prevent genetic erosion. The phenotypic and genetic diversity between the three populations of Zulu sheep may indicate that there is an opportunity of genetic exploitation by selecting animals based on phenotypic as well as genetic characteristics. In order to promote the conservation and sustainable use of the Zulu sheep, it was recommended that an open nucleus breeding scheme from lower-tier flocks (of the farmers) for pure breeding to nucleus flocks (in Government ranches) could be appropriate. The scheme would also address the challenges of animal husbandry as well as contribute to the improvement of the livelihood of the farmers. Farmers could use a tape measure to estimate the LW of sheep when they cannot afford scales. The morphological characteristics and the genetic diversity data generated from this study could be combined into a single data base for this sheep breed. More extensive studies, using the same or some additional phenotypic characters such as reproductive performance, need to be done. Genetic characteristics of Zulu sheep using microsatellites and mitochondrial DNA should be done to complement the present study. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Kikuyu pasture was fertilized at low and high levels of nitrogen (N), namely 50 and 200 kg N/ha, after mowing and clearing the plots, to induce low and high levels of N in the herbage. The subsequent growth was harvested at 20-, 30- and 40-d re-growth. These treatments were conducted in spring, summer and autumn. Treatments included level of N, stage of re-growth and season as variables in digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in pens equipped with Calan gates. Nitrogen fertilization level had no impact on herbage dry matter digestibility (DMD). Stage of re-growth influenced digestibility in the spring and summer, the highest values recorded in the 30-d treatment. However, in the autumn, the 20-d re-growth recorded the greatest digestibility. Digestibility declined as the season progressed. Digestibility was not correlated to any of the chemical fractions measured in the herbage, including in vitro DM digestibility (IVDMD). Voluntary feed intake (VFI) followed a similar trend to digestibility, with peak values recorded for the 30-d treatment in the spring and summer, while the 20-d material induced the greatest intake in the autumn. Nitrogen fertilization had a negative impact on VFI over all seasons. Similarly to digestibility, VFI was not correlated to any of the chemical fractions measured, but was correlated to digestibility and moisture concentration of the herbage. Nitrogen degradability was determined using the in situ bag technique. Differences (p<0.05) were recorded for the quickly degradable N (a) and potentially degradable N (b) fractions within season, but not for the degradation rate of the slowly degraded fraction (c) per hour. The effective degradability (dg) was not influenced by N fertilization level in the spring, while N fertilization increased the dg values in the summer and autumn. Stage of re-growth exerted a positive effect (P<0.05) on the dg values. Rumen pH, rumen ammonia and blood urea nitrogen (BUN) levels were measured in rumen fistulated sheep. Rumen pH increased also with increasing level of N fertilization and declined with advancing stage of herbage re-growth in the autumn. Rumen ammonia increased with time of sampling post feeding to 4 hrs and then tended to decline by 6 hrs. Nitrogen fertilization level influenced rumen ammonia levels (p<0.05), with the low N level producing the lowest rumen ammonia levels. Rumen ammonia levels were highest at 20-d re-growth stage in summer and at the 40-d re-growth stage in autumn. DM concentration of the herbage had an inverse relationship with rumen ammonia. BUN levels were increased by high N fertilization and were positively correlated to rumen ammonia levels. Five years of digestibility data (82 digestion trials) and three years of intake trials (38 trials) data was pooled. These data, chemical composition of the herbage and the daily maximum temperatures, rainfall and evaporation recorded at and prior to the digestion and intake trials at Cedara were analysed using multiple regression techniques. Rainfall and temperature in the period of cutting and fertilization had a negative effect on digestibility, irrespective of the stage of re-growth at harvesting, 20, 30 or 40 days later, and a combination of the two proved significant, accounting for the most variance in DDM. Temperature depressed DMD by 11.4 g/kg DM per degree rise in temperature (Degrees C). Temperatures recorded during the cutting and fertilization phase were highly negatively correlated to VFI, irrespective of stage of re-growth. The DM concentration of the herbage as fed accounting for 32% of the variance in DMD, the NPN content of the herbage accounting for only 12.2% of the variance and the ash concentration of the herbage accounting for 15.9% of the variance in digestibility. Non-protein nitrogen was negatively correlated to VFI. Both DMD and VFI were highly negatively influenced by the moisture concentration of the herbage. Overall, the results of these trials demonstrated that environmental factors such as rainfall and temperature had a far greater impact on the digestibility of kikuyu herbage than the chemical composition, which had a minimal effect. Nitrogen fertilization did not influence herbage digestibility overall, but exerted a highly negative impact on voluntary intake. / Thesis (Ph.D.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Protein has been identified as a major reason that people purchase a horse feed, with anecdotal explanations offered for the poor prediction of response of horses to their rations, particularly in the sport horse market. The current research identifies through hierarchical cluster analysis that the myriad of riding feeds offered on the South African market fall into only four simple categories on the basis of wet chemistry. Feeds were subjected to the in vitro gas production technique (IVGPT) described by Pell and Schofield (1993), using equine faecal inoculum. Gas profiles, corrected for control fermentation profiles in the absence of substrate, were fitted to the model described by Campos et al. (2004) to derive GP kinetics. Gas production kinetics, and information in respect of pH, degradation efficiency, lag time and apparent and true digestibilities were obtained. The feeds were tested for glycaemic response in miniature horses using the hexokinase method with deproteinization using an auto analyser (Roche Diagnostics). Blood glucose parameters of feeds (mean, peak, slope and time to peak and area under the curve) in each group were compared by analysis of variance and regression with covariates. In vivo analysis of rates of passage and digestibility using using post-prandial percentages of acid insoluble marker collection was used to study the gastrointestinal process, to indicate foregut and hindgut compartmental flow. The need to balance nitrogen levels with a proportional supply of fermentable carbohydrate contradicts widely used protein intakes in the horse. In vitro fermentation was used in an analysis of nutrient synchrony, to identify optimal fermentative capacity for utilization of horse feeds. The characteristics of horse feeds were related to requirement and were composited in an analysis of the representation of horse feeds that would best reflect optimal utilization in the horse, to produce a method of feed characterisation that would lead to the optimal prediction of response of horses to feeds offered to South African horses. / Thesis (Ph.D.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The growing demand for meat worldwide by the increasing human population (6.8 billion) calls for an increase in livestock production as well as attention to environmental sustainability. Production increases are critical especially in Africa with the highest annual population growth rate (2.5%), where most communities rely on livestock for protein supply. Attempts by intensive livestock farming to optimize production are limited by fibrous quality feeds (roughages) and their unavailability in both developed and developing countries. The overall objective of this study was to scan both domestic and wild herbivores in search for microbial ecosystems with superior fibrolytic potential that can be used as feed additives. It was hypothesized that microbes from wild herbivore can improve fibrous feed breakdown in domesticated ruminants. Experiment 1 evaluated the use of fresh or in vitro cultured faecal inoculum (FF) from two Jersey cows as a potential substitute for rumen fluid (RF). Cultured FF was a better substitute for fresh RF as demonstrated by percentage differences in exocellulase activity (0.4%) and true degradability (TD) (7%), compared to the differences observed between fresh RF and FF for exocellulase activity (33%) and TD (14%). It was applied in subsequent experimentation because it was cost effective (no surgery and reduced sample collection time). The second experiment compared the fibrolytic competence of cultured faecal inocula from three hindgut fermenters (miniature horse (mH), horse (H) and Zebra (ZB)) in summer and winter grazing in their natural environment. Both cellulase enzyme assays (exocellulase, endocellulase and hemicellulase) and in vitro maize stover digestibility study ranked the herbivores according to their fibrolytic competence as ZB > H > mH. The effect of cultured faecal inocula from H, ZB and wildebeest (WB) and its combined systems (N1=H+WB, N2=H+ZB, N3=WB+ZB and N4=H+WB+ZB) on the fermentation of maize stover were also evaluated in vitro. Both enzyme assays and MS degradability studies showed that the combined systems were higher (P<0.01) in fibrolytic activities compared to the individual systems. The microbial ecosystems were ranked as N1 > N2 > N4 > H > ZB > WB >N3; and N3 > N1 > N4 > WB > N2 > ZB >H by their exocellulase activity and degradability parameters, repetitively. The diversity of microbial ecosystems was confirmed by numerous active carboxymethyl cellulase bands present on a carboxymethy cellulose zymograms in experiment 4. The combined microbial ecosystems contain more active and variable bands of cellulases than in the individual microbial ecosystems. Systems N3 and N1 were considered as the best inocula for rumen transinoculation studies. Experiment 5 assessed the in vivo effect of direct-fed microbials from N1 and N3 on MS degradation, ruminal fermentation characteristics and cellulase enzyme profile in sheep. Feed dry matter intake increased (P<0.03) in N1 but tended to increase when inoculated with N3. The treatments, N1 and N3 increased (P<0.05) rumen exocellulase (9.4 and 33.2%, respectively) and endocellulase (82.1 and 47.1%, respectively) specific activities but not hemicellulase activity. Maize stover degradability parameters for N3 (TD, degradability of the insoluble fraction of MS, effective degradability, total SCFA and propionate) measured after 96 h of incubation tended (P>0.05) to be numerically different (1.1, 5.4, 7.1 and 7.9%, respectively). Increase in propionate for N3 was accompanied by higher total SCFA and lower CH4. A decrease in CH4 and no difference in CO2 allow both systems to be environmentally friendly since they have been associated with global warming. These studies showed that direct-fed microbials from N1 and N3 inocula have the potential of improving the utilization of maize stover feeds in ruminants, particularly in view of its simplicity and availability which allows it to be implemented at a relatively lower cost compared to other specific strains or microbial cultures. However, more research is required to identify, purify and classify the superior fibrolytic microbes in the most active ecosystems. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Diet selection and its variation due to difference in forages nutritive value are central processes in plant-herbivore interactions. An incorporating of these parameters may allow predicting diet selection patterns which are a basic underpin for sustainable vegetation management and profitable animal production. To achieve these issues many studies were done two of which were run to study the browse-browser interactions in a sub-humid subtropical savannah, a herd of goats was used as a model browser in natural pasture. Other studies evaluated the nutritive value of five plant species which were the most selected by goats. The objectives of this study were to (i) determine the seasonal patterns of diet selection of goats on woody species and their nutritive value and (ii) to predict the diet selection. The secondary objectivrs were to (i) investigate how plant characteristics such as plant morphology (spinescence, and broad vs. fine leaves), phenology (evergreen vs. deciduous species) and plant chemistry (nitrogen, neutral detergent fibre, acid detergent fibre, acid detergent lignin, condensed tannin, cellulose and hemicellulose) are relate to the diet selection patterns and to (ii) evaluate the nutritive value of the most plant species selected by goats during the different seasons. Two experiments were conducted at Owen Sitole College of Agriculture, KwaZulu-Natal, to determine diet selection of goats grazing/browsing in Zululand Thornveld. The first experiment was done in the early wet season (November 2007) and late wet season (March/April 2008) while the second experiment was conducted in the dry season (June/July 2008), early wet season (November/December 2008) and late wet season (February/March 2009). The relative abundance of browse species in the veld was determined and used to estimate the selection index. In the first part, diet selection was estimated using (i) direct observation of animals (account bouts) by observing every one minute two goats while they were foraging with others for 3 hours in the morning and 1.5 hours in the afternoon on alternate days for a total of six days and (ii) an indirect plant-based method by observing at regular intervals 40 marked branches on ten plants of each browse species every two days for a total of six days. The browse species observed were: Gymnosporia senegalensis, Acacia nilotica, Acacia karroo (Acacia natalitia), Scutia myrtina and Dichrostachys cinerea. In both seasons, the three most selected species according to the plant-based observations were S. myrtina, A. karroo and D. cinerea. Consistently, A. nilotica experienced moderate defoliation and G. senegalensis the least. However, on the basis of the selection index, the species followed the order: A. nilotica > D. cinerea > A. karroo > S. myrtina > G. senegalensis in the early wet season and A. nilotica > S. myrtina > D. cinerea > A. karroo > G. senegalensis in the late wet season. Both methods did not rank species in the same order. The selection index was negatively (P<0.05) correlated to neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). In the second part, observations were taken on feeding time of two goats, randomly selected per day for 7-8 days. Observations were made during active foraging periods for 2 hrs in the morning and 1.5 hrs in the afternoon. The duration of each feeding bout and the species of woody plant from which bites were cropped at each feeding station were recorded. Season and plant species affected diet selection and preference. The five main species selected (utilized) by goats in decreasing order were S. myrtina, A. nilotica, D. cinerea, Acacia natalitia and Chromolaena odorata. Scutia myrtina was the most preferred (highest utilisation relative to availability) in the dry season while D. cinerea comprised the greatest proportion in the early and late wet seasons. Scutia myrtina was most preferred in the dry and early wet seasons while A. nilotica was most preferred in the late wet season. Spinescent species were generally selected more than non-spinescent species in all seasons, while fine-leaf and deciduous species were selected more than broad-leaf and evergreen ones in the wet seasons. However, preference for broad-leaf and evergreen species increased in the early wet season. Although plant chemistry varied across seasons, it did not explain the preference of goats for various plant species in this study. Instead, effects of chemistry were species- specific. The nutritive value of the five main species selected by goats was evaluated by chemical composition, in vitro gas production, in vitro degradability and in sacco degradability. Two experiments were conducted for the in vitro studies, the first experiment was to test the effect of season and species, while the second experiment tested the biological effect of tannins using polyethylene glycol 4000 (PEG). The PEG treatment was applied to samples of the early and late wet seasons only. The parameters were maximum gas production (GP), degradation rate (C), lag time (lt), maximum rate of GP at the point of inflection (μ), half time to the maximum gas volume(T1/2), gas produced from fermentation of soluble and slowly degradable fractions (A and B, respectively), their degradation rates (c1 and c2, respectively), apparent (ApDeg) and true degradability (TrDeg), microbial yield (MY), partitioning factor (PF), degradation efficiency factor (DEF) and short chain fatty acids (SCFA). There were wide variations among seasons and species in crude protein (CP), NDF, ADF and condensed tannins. Season and species affected kinetics of gas production, GP, TrDeg, MY, PF and SCFA. Chromolaena odorata had the highest CP (185.8-226.4 g kgˉ¹), GP (87.3-104.1 ml gˉ¹ DM), gas produce from soluble (47.6-50.9 ml gˉ¹ DM) and insoluble (39.8-50.9 ml gˉ¹ DM) fractions during the three seasons compared to other browse species. The TrDeg ranged from 634 to 856 g kgˉ¹ DM. The total SCFA varied between seasons and among species. The addition of PEG decreased TrDeg and PF, and increased GP and total SCFA. The GP, its degradation rate (C) and gas from the soluble fraction were positively correlated to CP without and with PEG. Gas from the soluble fraction was negatively correlated to NDF, ADL and CT; and GP to CT without PEG. In the in sacco study, the parameters of dry matter (DM) and nitrogen (N) degradability were soluble (a) and slowly (b) degradable degradability, the degradation rate (c), potential degradable (PD), effective degradability (ED) and lag time (lt). Season affected PD of DM degradability and ED of both DM and CP. Browse species and its interaction with season affected all parameters except b fraction of CP and interaction did not affected PD of CP. Chromolaena odorata had the highest estimated parameters of degradation during the three seasons compared to other browse species. Based on PD and ED, the plant species followed this decreasing order: C. odorata, A. nilotica, A. natalitia, S. myrtina and D. cinerea. All parameters were positively correlated to CP except the a and b fractions of DM and CP, respectively, and lt of both DM and CP. All parameters were negatively correlated to NDF, ADF and ADL except the b fraction and rate of degradation. Condensed tannins (CT) were negatively correlated with all parameters except the b fraction and PD of DM and CP, and lt of DM degradation. Cellulose was negatively correlated with a of DM and lt of CP degradation. The broad objective of this study was to assess whether plant characteristics, in sacco degradability, in vitro gas production, digestibility or chemical composition (NDF, ADF, ADL, CT and CP) could predict the selection of browse species. The parameters were selection index, plant characteristics (spinescence, or leaves phenology), chemical composition, in vitro gas production, in vitro degradability and in sacco degradability parameters. Most of these parameters were poor for predicting selection by goats of browse species. Spinescence (spn), leaves phenology (phen), NDF, CP and CT accounted for 86% of the variation in selection index (y) = -5.91 - 0.01CT - 0.002NDF + 0.02CP + 6.18spn + 2.43phen; (R2=0.86; n=20; RMSE=0.406; P<0.001; for phen, 1 = evergreen, 0 = deciduous; for spn, 1 = spinescent, 0 = spineless). It was concluded that in vitro gas production, in vitro degradability and in sacco degradability were poor predictors of selection index of browse species used by goats. Spinescence, leaf phenology, condensed tannins, CP and NDF were predictors of diet selection index and suggested that these plant species have potential to be used as feed supplements. Chromolaena odorata has the highest potential as feed protein source in goats. The addition of PEG (tannin binding agent) emphasizes that the inhibitory effect of tannins on rumen microbes was great in tannin-rich feeds. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

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. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Holstein calves were photographed and measured over a period of 84 days to determine the feasibility of Image Analysis as a measurement tool. It was determined that the disparity between actual measurements and image analysis measurements decreased as the bone length increased, and that image analysis could be used to monitor growth successfully in large ungulates, using the length of certain bone. Image analysis was then used to evaluate growth in Holstein calves on two weaning programs (weaned early at six weeks of age and weaned later at eight weeks of age). Calves were weighed and photographed over a period of 224 days to determine the effects of weaning on skeletal symmetry. Weaning time did have an affect on the skeletal symmetry of the calves, with calves weaned earlier found to be more asymmetrical. The extent to which skeletal symmetry is affected by a stress is determined by the nature and duration of the stress. The growth and development of Thoroughbred foals was recorded and photographed for a period of 300 days and the relative asymmetry for bilateral traits was assessed. Thoroughbred foal growth correlated to statistics reported over the last twenty eight years. Asymmetry can be detected in growing foals using image analysis. Weaning stress produced some asymmetry that the foals were able to recover from. One can use highly correlated body weight and height measurements to produce a tool stud managers can used to monitor growth. In young training Thoroughbreds (between 18 and 24 months of age), no significant asymmetry was found in the forelimbs but the hind legs displayed asymmetry, which has interesting implications for training and for performance criteria in the racehorse. Tools can be produced to monitor the growth and development of Thoroughbred foals destined to race, which can improve their management and the duration of their racing careers. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The objective of the study was to evaluate the effect of an exogenous multi-blend enzyme ( -glucanase and xylanase) on the performance of the broiler chickens and laying hens fed diets based on wheat and barley. Experiments were conducted on a flock of broilers and two flocks of laying hens. In both cases feed and water were provided ad libitum. The enzyme effect of enzyme addition on the broiler performance involved 2080 day-old male and female chicks in 48 pens, allocated one of four dietary treatments (0, 50, 100 or 200g/ton enzyme supplementation), to 35 days of age. On day 35, ten birds from each treatment were sacrificed for the analysis of the digestive organs weight (gizzards and livers). The trial was divided into two phases: a starter (1 to 21 d) and grower (22 to 35 d). Feed consumption was measured weekly and birds were also weighed weekly. The investigation of enzyme effect in laying hen diets involved 896 birds for each specific period. Each replicate consisted of four cages (four birds per cage) with a common feeder; 16 hens/pen of 56 pens. Eggs were weighed three times a week, feed consumption weekly and birds every weeks. The addition of a multi-blend enzyme significantly improve body weight, body weight gain, food intake, and feed conversion ratio for both sexes (P<0.05) in broiler chickens. There was a significant improvement in egg production in laying hens (P<0.05). Egg weight and egg mass were not significantly improved. Wheat and barley have cell wall components (arabinoxylans and -glucans respectively) which have a negative effect on the nutritive value of these feeds and therefore performance in poultry fed diets based on these ingredients. Addition of an exogenous multi-blend enzyme( -glucanase and xylanase) could help reduce these effects and improve performance and digestibility values in poultry. The null hypothesis was there will be no difference between supplemented and un-supplemented diets based on wheat and barley in performance of poultry. The results of this study suggest that the inclusion of 50 g/ton enzyme helps improve poultry performance, especially in young birds. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.