title: Effect of inclusion of different levels ofLeucaenasilage on rumen microbial population and microbial protein synthesis in dairy steers fed on rice straw.
abstract: OBJECTIVE
  Leucaena leucocephala(Leucaena) is a perennial tropical legume that can be directly grazed or harvested and offered to ruminants as hay, silage, or fresh. However,Leucaenacontain phenolic compounds, which are considered anti-nutritional factors as these may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects ofLeucaenasilage (LS) feeding levels on rumen microbial populations, N-balance and microbial protein synthesis in dairy steers.
  
  
  METHODS
  Four, rumen fistulated dairy steers with initial weight of 167±12 kg were randomly assigned to receive dietary treatments according to a 4×4 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 LSad libitumand supplemented with concentrate at 0.2% of body weight/d.
  
  
  RESULTS
  Results revealed that the rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers that received 60% of LS (p<0.05), whereas the 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.
  
  
  CONCLUSIONS
  Based on this study, it could be concluded that replacement of RS with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.
authors.affiliation: Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Thien Truong Giang
authors.initials: TT
authors.lastname: Nguyen
authors.affiliation: Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Metha
authors.initials: M
authors.lastname: Wanapat
authors.affiliation: Tropical Feed Resources Research and Development Center (TROFREC), Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Kampanat
authors.initials: K
authors.lastname: Phesatcha
authors.affiliation: Agricultural Unit, Department of Education, National Institute of Education, Phnom Penh 12410, Cambodia.
authors.forename: Sungchhang
authors.initials: S
authors.lastname: Kang
keywords: Dairy Steers; Leucaena Silage; Microbial Population; Microbial Protein Synthesis; Rice Straw