Six tropical feedstuffs were analyzed for proximate composition, Van Soest components, mineral contents and amino acid composition. The crude protein contents (dry basis) of cassava tuber meal, sesame oil meal, coconut oil meal, rubber seed meal, cassava leaf meal and sweet potato leaf meal were 2.9, 35.2, 21.8, 12.0, 20.2 and 10.4%, respectively. The corresponding values for acid detergent fiber were 5.0, 23.5, 29.4, 39.1, 35.0 and 46.4%, respectively. Cassava tuber meal contained 88.4% nitrogen-free extract, but was poor in minerals and amino acids. Sesame oil meal had a silica content of 12.2% possibly indicating adulteration with sand; it was rich in all the minerals, especially Ca (2.32%), Mg (.56%), P (1.04%) and Fe (.32%). Coconut oil meal contained high amounts of Na (852 ppm) and K (1.83%), whereas the Zn (249 ppm) and Mn (252 ppm) were higher in cassava leaf meal. With the possible exception of sesame oil meal, the sulphur amino acids are likely to be the most limiting when these feedstuffs are fed to livestock. True metabolizable energy (TME) values of cassava tuber meal, cassava leaf meal and sesame oil meal were determined using 24 adult Single Comb White Leghorn roosters. After 24 hours of fasting, six roosters were force-fed 25 g of each of these feedstuffs. Six roosters were fasted for another 48-hour period and served as negative controls. Excreta were collected for two consecutive 24-hour periods. Length of collection period had no effect on the TME of cassava tuber meal and sesame oil meal, indicating that a 24-hour collection period was adequate for these feedstuffs. A collection period of 48 hours or longer was, however, required for roosters force-fed cassava leaf meal. The mean TME values (dry basis) of cassava tuber meal, cassava leaf meal and sesame oil meal were determined to be 3.76 ± .06, 1.99 ± .28 and 2.42 ± .09 kcal/g, respectively. Three digestion trials, each involving 12 crossbred gilts averaging 35.2 kg body weight, were conducted to determine the effects of crude fiber and Virginiamycin on digesta rate of passate (RP) and nutritional parameters. Two levels (3.2 and 7.3%) of crude fiber and two levels (0 and 11 ppm) of Virginiamycin were used in a 2 x 2 factorial arrangement of treatments. All diets were isonitrogenous and isocaloric. RP was determined by noting the time required for a change in feces color following the addition of 0.5% chromic oxide to the diet. The high fiber diet had a faster (P<.001) RP and this was associated with depressions (P<.001) in the digestibility of dry matter (DM), energy (E), cell content, cell wall (CW), acid detergent fiber (ADF), hemicellulose, cellulose, lignin and ash. Virginiamycin supplementation slowed (P<.01) the RP of both low and high fiber diets, but improved (P<.10) the DM, E and CW digestibility of the high fiber diet only. Non-significant improvements (P<.15) in the digestibility of ADF and cellulose were also observed when Virginiamycin was supplemented to the high fiber diet. Fiber increased (P<.05) fecal nitrogen, whereas Virginiamycin supplementation decreased (P<.05) fecal nitrogen. Results suggest that Virginiamycin supplementation improved the energy utilization in a high fiber diet, but had little effect on a low fiber diet. A study was conducted, concurrent to the first total collection digestion trial, to evaluate the applicability of chromic oxide indicator method to estimate the digestibility of nutrients. Digestion coefficients derived from the indicator method were in close agreement with those determined by the conventional total collection method for the low fiber diet, but underestimate the values for the high fiber diet. / Master of Science

The purpose of this study was to evaluate the feed value of Leucaena leucocephala (Lam) De Wit, as a renewable protein supplement for low-quality forages. Eight trials were conducted at the University of Pretoria experimental farm in Hatfield and the Agricultural Research Council experimental farm in Roodeplaat. The overall results showed that Leucaena leucocephala is a suitable protein supplement for low-quality forages. The chemical composition showed that Leucaena leucocephala forage has adequate potential nutrients. The rate of nitrogen degradation in the shoot was much slower and to a lesser extent than in mature pods with seeds, while the dry matter in the shoot degraded faster and to a greater extent than in the pods. In comparison with other forages (Lucerne, Eragrostis and Veld grass), Leucaena forage experienced a time lag of 6 hours before nitrogen could start degrading unlike the other three forages which did not have time lags. However, the dry matter in Leucaena forage did not experience any time lag, which gave Leucaena forage the best performance among the four forages. Lucerne on the other hand, had more readily available RDP, while Leucaena had more UDP. The effect of supplementing low-quality forages with varying levels of Leucaena forage was that the combinations between Leucaena and Veld grass gave better performance than the combinations between Leucaena and Eragrostis grass. Crude protein is the limiting factor in the performance of low-quality forages. Therefore, the supplementation of low-quality forage with Leucaena resulted in higher feed intake, digestibility and passage. The addition of Browse PlusTM increased the daily feed intake, the production of rumen ammonia and volatile fatty acids significantly. However, it did not have a significant effect on the rumen environment and the proportions of volatile fatty acids. The incubation and colour detector methods for the detection of Synergistes jonesii bacteria in the rumens of sheep were found to be simple, reliable and fast. It was confirmed that Synergistes jonesii bacteria can persist for more than four months in the rumens of sheep through autumn and winter drought without Leucaena forage in the diet. It was also shown that seasons have an influence on the level of mimosine in Leucaena forage. Hence, it was recommended that the forage has to be utilised fresh in summer when the level of mimosine is lower to minimise the risk of toxicity. / Agriculture, Animal Health and Human Ecology / D. Phil. (Environmental Science)

Includes bibliographical references (leaves 196-220) Studies the growth, body composition, feed intake of grazing animals, the use of anabolic agents, fatty acid composition of ruminants fats; and, the effect of saturated fat on human health.

Includes bibliographies. / xix, [252] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This research addresses probe fed classical rectangular microstrip antenna elements and arrays, that are fabricated on substrate materials with various thicknesses and relative permittivities. Formulae are developed for calculating the patch dimensions, the resonant input resistance, the resonant frequency, the bandwidth and the radiation patterns of elements, as well as the mutual coupling coefficients of arrays. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1996

The purpose of this study was to evaluate the feed value of Leucaena leucocephala (Lam) De Wit, as a renewable protein supplement for low-quality forages. Eight trials were conducted at the University of Pretoria experimental farm in Hatfield and the Agricultural Research Council experimental farm in Roodeplaat. The overall results showed that Leucaena leucocephala is a suitable protein supplement for low-quality forages. The chemical composition showed that Leucaena leucocephala forage has adequate potential nutrients. The rate of nitrogen degradation in the shoot was much slower and to a lesser extent than in mature pods with seeds, while the dry matter in the shoot degraded faster and to a greater extent than in the pods. In comparison with other forages (Lucerne, Eragrostis and Veld grass), Leucaena forage experienced a time lag of 6 hours before nitrogen could start degrading unlike the other three forages which did not have time lags. However, the dry matter in Leucaena forage did not experience any time lag, which gave Leucaena forage the best performance among the four forages. Lucerne on the other hand, had more readily available RDP, while Leucaena had more UDP. The effect of supplementing low-quality forages with varying levels of Leucaena forage was that the combinations between Leucaena and Veld grass gave better performance than the combinations between Leucaena and Eragrostis grass. Crude protein is the limiting factor in the performance of low-quality forages. Therefore, the supplementation of low-quality forage with Leucaena resulted in higher feed intake, digestibility and passage. The addition of Browse PlusTM increased the daily feed intake, the production of rumen ammonia and volatile fatty acids significantly. However, it did not have a significant effect on the rumen environment and the proportions of volatile fatty acids. The incubation and colour detector methods for the detection of Synergistes jonesii bacteria in the rumens of sheep were found to be simple, reliable and fast. It was confirmed that Synergistes jonesii bacteria can persist for more than four months in the rumens of sheep through autumn and winter drought without Leucaena forage in the diet. It was also shown that seasons have an influence on the level of mimosine in Leucaena forage. Hence, it was recommended that the forage has to be utilised fresh in summer when the level of mimosine is lower to minimise the risk of toxicity. / Agriculture, Animal Health and Human Ecology / D. Phil. (Environmental Science)

Graduation date: 1993

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.

Feeding of animal has become increasingly a big challenge for smallholder farmers in the dry season in most of Sahelian countries. Sheep has an important role in social and economical activity of smallholder farmers. Millet stover (MS) and groundnut haulms (GH) are the main crop residues used. Among concentrates, millet bran (MB) and wheat bran (WB) are mostly used by smallholder farmers in feeding animals. However, these crop residues and concentrates are used inadequately. MS is a poor quality roughage diet, legume residues such as GH and brans are rich in nutritive value. The general objective of this study was to develop a feeding technology transferable to smallholder farmers by supplementing MS with GH, MB and WB to increase the growth performance of sheep during the dry season. The first study evaluated the effect of chopping millet stover (Pennisetum glaucum L. R. Br.) in sheep feeding and the degradability in sacco of feeds. Two Holstein cows were used to determine the degradability in sacco of feeds. The potential dry matter degradability (g/kg) were 846, 809, 730, 410, 550 and 370 for millet bran (MB), wheat bran (WB), groundnut haulms (GH), millet stover, leaves plus sheath and stems of MS respectively. The potential nitrogen degradability (g/kg) of MB, WB and GH were 865, 908 and 817 respectively. The nitrogen content was 7.4, 15.1, 22.0 and 26.2 g/kg for MS, GH, millet bran and wheat bran respectively. The effects of chopping millet stover (MS) on dry matter intake in Oudah bicolor sheep were studied in Maradi, Niger. Four treatments were T0 (unchopped MS), T1 (MS chopped, 50 cm), T2 (MS chopped, 25 cm) and T3 (MS chopped, 10 cm). A randomized block design was applied on 36 sheep, implying 9 sheep per treatment (T0, T1, T2 and T3). The treatment T2 or 25 cm chopping size gave the best MS intake of 560 g/day. The second study evaluated the effects of supplementing millet stover (MS) with groundnut haulms (GH), millet bran (MB) and wheat bran (WB). These supplements can improve the feed value of MS and promote live weight gain of sheep in the dry season. The purpose of this study was to develop a feeding technology transferable to smallholder farmers by supplementing MS. The study was conducted in two successive phases. The phase 1 of 66 days, evaluated the effect of GH, MB and WB supplementations on MS intake and growth performance of sheep, the phase 2 of 14 days, assessed the effect of GH, MB and WB supplementations on intake and digestibility of MS. Six treatments were constituted, namely, 1, 2, 3, 4, 5 and 6 formed by four levels of GH (0, 200, 400, 600g) and two others (600g GH + 100g MB) and (600g GH + 75 g WB) respectively. A randomized block design was applied on 36 Oudah bicolor sheep, implying 6 male lambs per treatment (1, 2, 3, 4, 5 and 6). The GH supplementation levels had a linear effect (P<0.001) on dry matter intake (DMI) of MS, cell wall and nitrogen. Millet stover intake (MSI) decreased significantly with increasing level of GH. However the total dry matter intake (TDMI) significantly increased with GH levels. MB increased (P<0.05) both TDMI, TOMI and nitrogen intake (NI), (P<0.001). WB increased MSI (P<0.05), TDMI and TOMI (P<0.01), NI (P<0.001) and cell wall intakes. GH supplementation had both a linear and quadratic effect on DM digestibility of MS, cell wall and nitrogen digestibility. GH had a linear and significant effect (P<0.001) on live weight gain (LWG) and efficiency. The maximum average daily gain (80.5 g/day) was obtained with treatment 6 followed by the treatment 5 (68 g/day). The animals of treatment 1 received MS stover alone and lost their weight (-19.13 g/day). It is concluded that groundnut haulms, millet bran and wheat bran had good nutritive value whereas millet stover had low nutritive value. The 25 cm chopping size was the one to propose to smallholder farmers. The supplementation of MS as the basal diet with GH and brans enhanced sheep production through improvements in digestibility and intakes of TDM, TOM, cell wall and nitrogen. Key words: Millet stover; groundnut haulms; millet bran; wheat bran, chopping; intake; degradability; growth performance; Oudah bicolor sheep. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.