Effects of Leucaena leaf pellet on bacterial diversity and microbial protein synthesis in swamp buffalo fed on rice straw

The experiment was conducted to determine the effect of Leucaena leaf pellet (LLP) supplementation on feed intake, microbial protein synthesis and rumen microbial population and diversity in swamp buffalo fed on rice straw. Four swamp buffalo bulls were randomly assigned according to a 4×4 Latin square design to receive LLP at 0, 150, 300 and 450 g/h d/d. Untreated rice straw was fed ad libitum, while concentrate was fed at 5 g/kg BW. The results revealed that rice straw intake and total intake were significantly improved when level of LLP supplementation increased. Ruminal NH3-N concentration was significantly higher than in the control group. Population of fungal zoospores, amylolytic bacteria, proteolytic bacteria and cellulolytic bacteria were significantly increased (P<0.05) with increasing LLP supplementation while the population of rumen protozoa decreased. Supplementation of LLP increased the population of total bacteria, Ruminococcus albus, Fibrobacter succinogenes, and Ruminococcus flavefaciens, while population of methanogenic bacteria were decreased (P<0.05). The N balance and microbial nitrogen supply were remarkably improved when LLP supplementation level increased. Rumen methanogen diversity was not shifted as analyzed by PCR-DGGE technique, while rumen total bacterial diversity was similar by sampling time and treatments. Supplementation of LLP can improved rumen ecology, thus improved N-retention and microbial N supply.