The purpose of this investigation was to provide direct experimental evidence for or against the suggestion that amino acids and B vitamins are among the nutrients absorbed from the rumen of the ruminant. The investigation was subdivided into two parts: (1) six ruminal fistula experiments and (2) nine blood-sampling experiments. The goat (Capra) was the experimental animal. In the ruminal fistula experiments, solutions of amino acids, B vitamins, and usually propionic acid were added to an empty rumen for 120 or 150 minutes. Propionic acid, a substance known to be absorbed from the rumen, was included in most of the solutions to provide a positive control for ruminal absorption. In addition, in all but the first two experiments, polyethylene glycol was added to the solutions in order to provide a marker substance for differential water movement into or out of the rumen. Controls for the experiments included the taking of a sample from the solution in the rumen at zero time and incubating the sample for the duration of the experiment in a water-bath held at 37°C. The ruminal and control solutions were sampled at periodic intervals during the experiment. The results demonstrated not only marked decreases in the concentrations of propionic acid in the ruminal solutions but also, in most cases, marked decreases in the concentrations of the amino acids and the B vitamins assayed: tryptophan, methionine, tyrosine, glycine, lysine, riboflavin, nicotinic acid, and pantothenic acid. In contrast, the concentrations of these constituents in the control solutions usually demonstrated either no decrease or a small increase. In the first three blood-sampling experiments, the concentrations of amino acids and nicotinic acid in the plasma draining the rumen were compared with the concentrations in the peripheral plasma. The results demonstrated that seldom were the concentrations of an amino acid or nicotinic acid higher in the plasma draining the rumen than in the peripheral plasma. The results did suggest, however, that there had been slight increases in the plasma concentrations of the amino acids with time. Accordingly, the next six blood-sampling experiments were designed to determine if time-related increases in the blood concentration of alpha amino nitrogen occurred after the addition of amino acids to the rumen. Blood samples were removed periodically from anesthetized goats, both before and after the addition of a solution of amino acids to an empty rumen. The results demonstrated time-related increases in the blood concentrations of alpha amino nitrogen. These results and those obtained for the ruminal fistula experiments are interpreted as supporting the suggestion that amino acids and B vitamins are absorbed from the rumen. In the General Discussion, a preliminary attempt is made to answer three questions: 1) What is the manner of the passage of amino acids and B vitamins across the ruminal epithelium? 2) Does this passage of amino acids and B vitamins occur under normal feeding conditions? 3) How does this passage of amino acids and B vitamins across the ruminal epithelium fit into the scheme pictured for the metabolism and final fate of these compounds in the ruminal contents? As a part of the attempt to answer the first question, literature reviews are presented on the manner of absorption of amino acids and B vitamins in the small intestine, kidney, placenta, and other tissues. Then, after a literature review on the manner of absorption of substances other than amino acids and B vitamins from the rumen, the data of the present investigation are examined for evidence as to the manner of absorption of amino acids and B vitamins from the rumen. The examination led to the following statement: the movement of amino acids across the ruminal wall of the goat is determined by a summation of the effects of chemical, electrical, and possibly metabolic potentials. Unfortunately, other than to suggest that the process of simple diffusion is involved, the nature of the data for the B vitamins was not such as to yield much information on their manner of absorption. In the attempt to answer the second question, the fulfillment or non-fulfillment of the following conditions is considered: (1) the demonstration of the presence of amino acids and B vitamins in the rumen, (2) the demonstration of the relation of the concentrations of individual amino acids and B vitamins in the ruminal liquor to their concentrations in the blood plasma, and (3) the demonstration of the absorption of individual amino acids and B vitamins from an ingesta-filled rumen. Although fulfillment of the third condition was not obtained, fulfillment of the first two conditions was obtained and led to the statement that a strong possibility exists that the absorption of amino acids and B vitamins occurs from the rumen under normal feeding conditions. In the attempt to answer the third question, a number of factors are discussed in turn: (1) the environmental conditions of the rumen, (2) the influence of the diet on the composition of the population of microorganisms in the rumen, (3) the physical and chemical nature of the dietary constituents, (4) the relative stability of amino acids and B vitamins in the ruminal ingesta, and (5) the physiological state of the animal. Evidence is presented to demonstrate that each of these factors probably exerts an important influence on the content of amino acids and B vitamins in the rumen. It is suggested that, when the interaction of the many factors is such as to produce higher concentrations of amino acids and B vitamins in the rumen, the proportions of amino acids and B vitamins that pass from the rumen by absorption through its wall will be an important pathway for these nutrients. To conclude the General Discussion, the possible nutritional implications of the absorption of amino acids and B vitamins from the rumen are considered. One suggestion made is that a general absorption of nutrients from the rumen would permit the simultaneous arrival at the liver, or elsewhere in the body, of volatile fatty acids, amino acids, B vitamins, and inorganic ions. This should promote more efficient utilization of each of the nutrients. Another suggestion made is that ruminal absorption of amino acids and B vitamins places the host ruminant in a better competitive position relative to its contained microbial population in the competition for nutrients. Finally, a suggestion is made that the action of the ruminal wall in absorbing amino acids helps to explain the results that have been obtained for certain nitrogen retention experiments in ruminants. / Science, Faculty of / Zoology, Department of / Graduate

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A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Resource Conservation Biology. Johannesburg, 29 May 2017. / An understanding of animal foraging behaviour is key to proper management strategies that ensure the survival and species persistence within nature reserves. Here the foraging behaviour of ruminant (hartebeest and wildebeest) and non-ruminant (zebra) grazers were observed and compared between two areas with distinctively different vegetation structure, the natural vegetation (NL) and previously cultivated land (PCL), in Telperion and Ezemvelo Nature Reserves (TENR). Natural vegetation was dominated by tall grass of low greenness with patches of short to very short grass, while the PCL was dominated by areas of very short to short grass (grazing lawns) with patches of medium to tall grass. Step rate (SR) and foraging time spent per feeding station (FTFS) were used as indices of foraging behaviour. I also measured the characteristics of the grass sward (grass height and greenness) grazed on by the three species. Both ruminants had high SR and low FTFS. Despite having similar SR and FTFS, ruminants grazed on grass of different height. Hartebeest preferred tall grass with low greenness content (0-10%), while wildebeest preferred short to very short grass and were significantly selective of areas with relative high greenness (11-50%) on PCL, more so than any other species. Compared to ruminant grazers the non-ruminant (zebra) had low SR and high FTFS and like hartebeest they grazed on medium to tall grass of very low greenness content (0 10%). This study did not reveal any difference in feeding behaviour within species between the two study sites. The finding of this study confirms that ruminant and non-ruminant species have different foraging behaviour, and habitat heterogeneity is necessary for the reserve to support different grazing species. Key words: digestive physiology, feeding station, step rate, wildebeest, hartebeest, zebra / GR2018

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A series of investigations were undertaken in vitro and in vivo to investigate the nutritive value of cottonseed (WCS), the rumen microbial degradation of oilseeds and legume seeds, and the effects of gossypol on the rumen microbial (bacterial, protozoal and fungal) fermentation, and on the growth of animal cells in culture. An HPLC (High Performance Liquid Chromatography) method for the analysis of gossypol in WCS and in rumen liquor of sheep fed with WCS was also studied. Six oilseeds namely WCS (Gossypium sp.), mustard seed (Brassica sp.) (cv. Albatross), linseed (Linum sp.) (cv. Antares) and three cultivars of rape seeds (Brassica spp.) (cv. Bienvenu, cv. Libravo and cv. Samourai) were incubated with rumen contents in consecutive batch culture (CBC) and examined for their microbial dry matter (DM) degradation. For comparison, another selection of legume seeds namely narbon seed (Vicia narbonensis), mungbean seed (Phaseolus aureus) (cv. Satin), two cultivars of cowpeas (Vigna unguiculata) (cv. Banjo and cv. Caloona), and lablab seed (Lablab purpureus) (cv. Highworth) were also examined for their DM degradation. The oilseeds tended to show lower DM losses, gas production and volatile fatty acids (VFA) concentration than the legume seeds. It is uncertain whether the presence of fat, fractions within fibre such as xylose and lignin, and/or antinutrients such as gossypol in WCS and glucosinolates in rape seeds might contribute to the low fermentation. Although legume seeds are known to contain many antinutrients such as tannins, lectins, protease inhibitors and cyanogenic glycosides, they appeared more readily fermentable than the oilseeds. The overall results suggest that gossypol would affect the numbers of rumen protozoa and fungi, but gossypol was not the only factor and probably not even a major factor influencing the nutritive value of whole cottonseed. In particular much more detailed analysis on the plant cell wall structures such as the proportions of different sugars, and the amounts of lignin-carbohydrate complexes present would need to be performed to determine whether such factors might limit the degradability and fermentability of whole cottonseed. There is also possibility that antinutrients other than gossypol such as pigments tannins and flavanoids may also affect the rumen ecosystem.

La peste des petits ruminants est une maladie infectieuse animale très contagieuse. Largement répandue en Afrique, au Moyen Orient, et en Asie, elle fait des ravages dans les élevages ovins et caprins. Les petits ruminants représentent une ressource nutritionnelle et économique essentielle dans les pays en développement, notamment pour les communautés rurales les plus pauvres. En Afrique sub-saharienne, l'impact de la maladie est d'autant plus élevé que les mouvements des animaux sont compliqués à contrôler (transhumance, commerce illégal, zones de conflits, etc.) et les contrôles sanitaires difficiles à organiser. Une coalition internationale a décidé de prendre en main le contrôle de cette maladie ravageuse en élaborant avec l'OIE et la FAO une stratégie mondiale de contrôle progressif et d'éradication de la maladie.La stratégie est basée sur la vaccination de masse mais les protocoles de vaccination ont principalement été élaborés sur des bases empiriques. Après une campagne de vaccination, la dynamique démographique entraînant le renouvellement du cheptel, la proportion d'individus immunisés au sein de la population (taux d'immunité) est amenée à diminuer au cours du temps (entrées d'animaux non vaccinés, e.g. les naissances, et sorties d'animaux vaccinés, e.g. les ventes). La décroissance du taux d'immunité permet d'évaluer l'efficacité de la vaccination à moyen terme. Si le taux d'immunité est assez élevé, le virus n'a plus d'hôte pour se propager. Le renouvellement du cheptel est délicat à estimer et varie d'un système d'élevage à l'autre. Ce manuscrit présente une méthode d'optimisation des protocoles de vaccination pour obtenir la meilleure couverture immunitaire possible.Un modèle dynamique de prédiction du taux d'immunité dans des élevages de petits ruminants d'Afrique sub-saharienne au cours d'un programme de vaccination pluri-annuel a été développé en utilisant la théorie des modèles démographiques matriciels. Cet outil a été utilisé pour évaluer différents protocoles proposés pour les zones sahéliennes arides / semi-arides et les zones sub-humides / humides. Les paramètres des modèles ont été estimés à partir des données disponibles et d'une revue exhaustive de la littérature.Des indicateurs synthétiques de l'efficacité des protocoles ont été calculés (persistance du niveau protecteur, taux d'immunité moyen, etc.), puis comparés.L'étude a confirmé la pertinence des protocoles proposés par l'OIE et la FAO, apportant des précisions pour les divers scénarios. Les couvertures vaccinales atteintes doivent être très élevées (>80%) pour permettre la protection d'un troupeau pendant toute la durée du programme. En zone sahélienne, les troupeaux doivent être vaccinés au plus tôt après la saison des pluies pour optimiser la portée de la vaccination. L'étude révèle aussi que le pic d'exploitation des mâles, dû à la Tabaski, et la situation épidémiologique initiale du troupeau influent peu sur la dynamique du taux d'immunité.L'outil développé au cours de cette thèse peut être utilisé pour toute maladie infectieuse pour laquelle on dispose d'un vaccin efficace à long terme et toute population domestique dont on connaît la dynamique. Il pourrait cependant être amélioré par l'intégration de la dynamique de la maladie et de la répartition spatiale des élevages sous forme de méta-communauté. / Peste des petits ruminants is a highly contagious animal disease. Widespread in Africa, the Middle East and Asia, it has a devastating effect on small ruminants. Small ruminants are essential to sustainable livelihood in developping countries, especially in rural communities. In western Africa, the disease incidence is higher because of the difficulty to control animals movements (transhumance, illegal trade, conflicted areas, etc.) and to settle adapted sanitary actions.A global strategy for the progressive control and the eradication of the disease has been developed by the OIE and FAO. It is based on mass vaccination, with vaccination protocols defined on empirical basis.After a vaccination campaign, the population dynamics is responsible for herd renewal, the proportion of protected individuals (post-vaccinal immunity rate) in the population is decreasing over time (entries of non-vaccinated animals and exits of vaccinated ones). The immunity rate decrease allows to assess to the efficiency of employed vaccination strategies in term of immunity coverage. From a given threshold, the immunity rate can stop the viral transmission. The population renewal has to be estimated carrefully because it varies from one farming system to another. The work described in this manuscript provides an optimization tool of vaccination strategy, supporting decision markers in the formulation of vaccination protocole achiving the best possible immunization coverage in a given socio-economical context.Using the demographic matrix model theory, we developed a seasonal model predicting the immunity rate dynamics in traditional small ruminants livestock of Western African during a vaccination program. We used this model to evaluate different vaccination protocols proposed for Sahelian arid and semi-arid areas, and Soudano-guinean sub-humid and humid areas. Model parameters were estimated from the available data and an exhaustive review of literature.Synthesising indicators of the protocoles efficiency were computed (length of protective immunity, average immunity rate, etc.) and compared.The work described in the manuscript broadly confirmed the protocols proposed by the OIE and FAO. Additionally, this work provides details for the various scenarios. Very high vaccination coverage (>80%) should be reached to protect the population during the whole program. In the Sahelian zone, herds should be vaccinated at the earliest possible from September to optimize the scope of vaccination. We also show that the males offtake increase due to Tabaski and the initial epidemiological situation poorly influences the immunity rate dynamics.Our tool is generic. I can be applied to any infectious disease which has a vaccine providing a lifelong immunity and for which the population dynamics is known. Nevertheless, it could be improved by implementing spatial analysis and disease dynamics.