Effect of Graded Levels of Fishmeal or Urea Supplementation on Rumen Environment and Ruminal Feed Degradation in Bali Cows

Abstract

An experiment to study the effects of supplementation of graded levels of urea or fishmeal on rumen environment and ruminal feed degradation in Bali cows fed low quality tropical grass hay (crude protein, CP = 3.53%) was conducted according to a 5 × 5 Latin square experimental design with five animals and five periods. In each period lasting for 3 weeks, five non-pregnant Bali cows were given ad libitum access to grass hay (G) or supplemented daily with two level of urea, i.e. 38 g (U38) and 74 g (U74), or two levels of fishmeal, i.e. 156 g (FM156) and 312 g (FM312). Supplementation of both urea and fishmeal reduced significantly (P < 0.01) the average rumen pH from 6.89 in G to 6.74 in FM156. Rumen ammonia concentration increased linearly (P < 0.01) with increasing levels of supplementation and the increase was more pronounced with urea than with fishmeal supplementation. Rumen ammonia concentration was significantly higher (P < 0.01) in urea than fishmeal supplemented cows at both levels of supplementation. Ruminal total as well as individual VFAs (Acetate, Butyrate and Propionate) concentrations were not affected by the increasing level of supplementation of both urea and fishmeal. Supplementation improved significantly (P < 0.05) in sacco rumen degradation of DM but not protein. Ruminal DM effective degradability was increased significantly with increasing level of fishmeal supplementation but not with increasing level of urea supplementation. Supplementation of increasing level of both urea and fishmeal improved rumen environment and feed degradability in Bali cows maintained on low quality tropical grass hay with fishmeal was proven to be the better supplement over urea.