Efficiency of protein utilization by grazing ruminants and possibility for improvement
2019
Stojanović, Bojan (https://orcid.org/0000-0001-5057-1790) | Grubić, Goran (https://orcid.org/0000-0003-2673-9471) | Đorđević, Nenad | Božičković, Aleksa Đ. (https://orcid.org/0000-0002-8671-4906) | Simić, Aleksandar (https://orcid.org/0000-0002-7605-3796) | Davidović, Vesna M. (https://orcid.org/0000-0003-0764-3183) | Ivetić, Aleksandra
Pasture has a high ruminal crude protein (CP) degradability (>70%) that results in poor utilization of pasture protein (22 to 25%) which is far from the theoretical maximum efficiency of 40 to 45%. Increased ruminal ammonia absorption not only represent the N waste and an environmental problem but also may impair animal performance. A better utilization of protein from fresh herbage is possible by matching the supply of rumen degradable protein and carbohydrates. Replacing a part of the N-rich pasture by some other forage (corn silage, low N hay) or concentrates with a low protein content and a low ratio of degraded protein and degraded carbohydrates may decrease N losses and increase the efficiency of ration protein utilization. The optimal ratio of N to fermented organic matter in rumen is around 25 g/kg. Grazing a pasture with a high water soluble carbohydrates content may provide a higher energy supply at the rumen. Addition of fibrolytic enzymes in diets for pastured ruminants through the supplemented dry feeds could increase dry matter digestibility and improve the nitrogen use efficiency. The increase of tannin content in diets for grazing ruminants may reduce the ruminal protein degradability and increase nitrogen efficiency use. Optimal grassland management and supplement feeding of grazing ruminants may markedly increase the efficiency of utilization of protein from pasture.
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