ARTICLE 70 FEED & ADDITIVE MAGAZINE August 2024 Management of the rumen in cattle and sheep is crucial for achieving the required growth rates with multiple studies linking good rumen development to higher average daily liveweight gains. The focus in terms of management should therefore not only be on protecting rumen integrity during periods of elevated stress such as during weaning, but also on maintaining it throughout the fattening period. This is key if livestock are to grow at planned rates to reach target slaughter weights. Recently, Caitlyn De Vos, Ruminant Development Manager at Vitam International, worked with her team on a trial looking at the rumen of fattening lambs in a feedlot system, she explains the findings. The health and performance of sheep, like dairy cows and beef cattle, heavily depends on the rumen's ability to facilitate digestion and absorption, as well as provide a barrier against the transmission of pathogens and toxins. Rumen microbes break down dietary polysaccharides into volatile fatty acids (VFAs); most importantly propionate, acetate, and butyrate. Between 50 and 85% of VFAs produced in the rumen are absorbed in that chamber of the stomach (Aschenbach et al., 2011) and this process relies on having well developed rumen papillae to maximize the surface area. The absorption of VFAs impacts lamb growth because they are responsible for up to 75% of metabolizable energy in ruminants (Bergman, 1990). This means that having well developed rumen papillae is essential for lambs to have sufficient energy to fatten as well as grow in frame and stay healthy. However, there is a fine line to tread between providing a diet that generates sufficient VFAs for growth and maintaining rumen wall integrity. VFAs are weak acids which means that they dissociate in the rumen and release a proton. This decreases the ruminal pH and results in ruminal acidosis which damages the ruminal epithelium and impacts the rumen microbes, ultimately reducing feed intakes and so reducing the potential for VFA- and so energy- production (Penner, 2014). Small ruminants and lambs are more sensitive to stress, which is why the acidosis risk is high in feedlot lambs due to a combination of environmental and dietary risk factors. Fattening lambs are typically fed with high fiber and dam milk, until they are moved to finishing feedlot pens, where they will receive a high starch, low- fiber diet. The stresses of weaning, transport PROTECTING THE RUMEN IN FEEDLOT SYSTEMS Caitlyn de Vos Ruminant Development Manager Vitam International
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