Effect of inclusion of different levels of Leucaena silage on rumen microbial population and microbial protein synthesis in dairy steers fed on rice straw

Effect of inclusion of different levels of <i>Leucaena</i> silage on rumen microbial population and microbial protein synthesis in dairy steers fed on rice straw

Animal Bioscience, April 2016

27165024

Thien Truong Giang Nguyen, Metha Wanapat, Kampanat Phesatcha, Sungchhang Kang

Leucaena leucocephala (Leucaena) is lifelong tropical legume that can be directly grazed or harvested and offered to ruminat as hay, silage or fresh. However, Leucaena contain phenolic compounds, which are considered anti-nutritional factor as it may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects of Leucaena silage (LS) feeding levels on rumen microbial population, N-balance and microbial protein synthesis in dairy steers. Four, rumen fistulated dairy steers with initial weight of 167 ± 12 kg were randomly assigned to receive dietary treatments according to a 4 x 4 Latin square design. Treatments were as followings: T1 = untreated rice straw (RS; Control), T2 = 70% RS + 30% LS, T3 = 40% RS + 60% LS, and T4 = 100% LS. Dairy steers were fed rice straw and LS ad libitum and supplemented with concentrate at 0.2% of BW/day. Results revealed that rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers received 60% of LS (P<0.05) whereas amylolytic bacteria population was not affected by treatments (P>0.05). Protozoal population was linearly decreased with increasing level of LS (P<0.05). Moreover, N-balance and microbial protein synthesis were enhanced by LS feeding (P<0.05) and were the highest in 60% LS group. Based on this study, it could be concluded that replacement of rice straw with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.