Browsing by Author "Gerber, Natalie Dawn."
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Item The effect of feed type and diet quality on kinetics of digestion : the degradation properties of certain protein supplements, and the effect of concentrate supplementation and basal roughage quality on eating behaviour and particle passage from the rumen of sheep.(2002) Gerber, Natalie Dawn.; Nsahlai, Ignatius Verla.The unique anatomical structure of the ruminant animals' digestive tract allows them to convert forages containing high levels of fibre into the valuable products of meat, milk and wool. At the same time, an interdependent relationship between the host animal and the rumen microbial population has evolved and a minimum requirement for dietary fibre by the ruminant was established. Where roughage intakes are high, intake is limited by rumen capacity and the rate of clearance of previously ingested material from the rumen. When animals are fed particularly poor quality roughage diets, high in fibre, as in sub-Saharan Africa, the problem of limited rumen capacity is compounded. The rate of passage of ingested material through the digestive tract will also influence the ability of the host animal to extract nutrients, whilst the degradation that a feed undergoes in the rumen will have a direct effect on the availability of nutrients to the host animal and, conversely, the availability of nutrients to the rumen microbes themselves. In sub-Saharan Africa, where readily available forage tends to be high in fibre and low in soluble nutrients (such as nitrogen) and readily digestible carbohydrates, the potential exists for the development of supplementation strategies that will enhance rumen microbial fermentation and microbial protein synthesis. This study comprised three separate, although interrelated investigations into aspects of rumen clearance and degradation parameters of eight nitrogen supplements. The supplements investigated were canola, copra, cottonseed oilcake, defatted maize germ, luceme meal, lupin seed meal, soya oilcake and sunflower oilcake. The first part of this study investigated the disappearance of dry matter (DM) and nitrogen from eight plant protein sources contained within nitrogen-free polyester bags incubated in the rumen of three fistulated Jersey cows. In addition, the protein sources were force-fed to adult cockerels to obtain an estimate of the intestinal digestion of the available protein by the host animal. The intercept values and time lags for DM degradation were highly significant (P