The Effect of Replacing Forage with Palm Oil Byproduct on Rumen Fermentation Products in vitro

This study was conducted to reveal the effects of substituting forage with a combination of palm oil byproducts (POB) on the digestibility, total concentration of volatile fatty acids (VFA), ammonia and methane gas production through an in vitro study. The experimental design followed a completely randomized design (CRD) 4 x 4 with four treatments and four replications. The treatments were T0 = 90% kumpai forage (Hymenachine amplexicaulis) + 10% rice bran, T1 = 60% kumpai forage + 30% POB + 10% rice bran, T2 = 30% kumpai forage + 60% POB + 10% rice bran and T3 = 90% POB + 10% rice bran. The results showed that the digestibility of DM, OM and CP in feed containing 60% POB was lower (P less than 0,05) compared to feed without POB. Whereas, there was no difference in digestibility between 60% and 90% POB in the ration. The difference in molar proportion of acetate and propionate was not significant (P greater than 0,05) among treatments. However, the molar proportion of butyrate, total VFA, ammonia and methane gas production were significantly (P less than 0.05) affected by treatments. The molar proportion of butyrate increased significantly (P less than 0.05) with increasing levels of POB in the ration. At 90% POB, the proportion of butyrate was significantly higher (P less than 0.05) than those at 0%, 30% and 60% POB levels, but there was no significant difference between 0% and 30% POB levels. The total VFA concentration at 60% POB was significantly lower (P less than 0.05) than in the control diet (0% POB). However, the differences in VFA concentration among 0%, 30% and 90% POB were not significant. The ammonia concentration was highest (P less than 0.05) at 90% POB compared to the other POB levels. Methane production was lowest at 60% POB, with no significant differences among the 0%, 30% and 90% POB levels.