Abstract

Three, Holstein Friesian, non-lactation crossbred dairy cows were used to evaluate the effect of Eucalyptus (Camaldulensis) leaf meal powder (EUCAP) supplementation on feed intake, digestibility and rumen fermentation. The animals were randomly assigned according to a 3 × 3 Latin square design using three levels of EUCAP supplementation (0, 100 and 200 g/hd/d) and offered rice straw ad libitum, together with concentrate at 0.5% body weight. The results revealed that voluntary feed intake kg/hd/d) was significantly decreased when EUCAP was supplemented at 200 g/hd/d. Digestibility coefficient (%) of DM, OM, CP, NDF and ADF were similar among treatments. Ruminal temperature and pH were not affected by EUCAP supplementation. However, NH3-N and BUN concentrations were decreased when supplementation of EUCAP at 200 g/hd/d. Ruminal fungal zoospores were not significantly different among treatments, while protozoa, bacteria population by direct counts were significantly reduced with increasing supplementation levels of EUCAP. In addition, viable total bacteria, proteolytic bacteria and cellulolytic bacteria were decreased when EUCAP were supplemented at 100 and 200 g/hd/d while amylolytic bacteria was not different among treatments (P>0.05). Furthermore, total volatile fatty acid concentrations, proportion of acetate, acetate to propionate ratio were reduced with increasing level of supplementation, while, proportion of propionate increased. Methane production was reduced in supplemented treatments at 100 g/hd/d. Supplementation of EUCAP at 100 g/day for ruminants could be on alternative feed enhancer which reduces rumen methane gas production in cattle, while nutrient digestibilities were unchanged.

Key words: Eucalyptus, rumen fermentation, rice straw, rumen manipulation, cows.