SONTHAYA MOONSIKEAW, THERDCHAI VEARASILP, CHOKE MIKLED
Chiang Mai University, Department of Animal Science, Thailand
The experiment was conducted to determine the effect of fumaric acid supplementation on pattern of rumen fermentation in dairy cows. Four crossbred Thai Native x Holstein Friesian cows with average body weight of 416 54kg fitted with rumen fistula were used in the experiment. The animals were divided into 2 groups of two animals each and used in a 2 x 2 crossover design. The cows were fed twice daily at 0600 and 1800 hours with 2kg each of rice straw and concentrate. Fumaric acid was supplemented at 2% level of feed intake (80 g) in the treatment group. Rumen liquor was taken at 0900 hours for 4 days and analysed for volatile fatty acids. Rumen pH was measured directly in the ventral sac of the rumen with a gel electrode at --1, 1, 2, 3, 4, 5 and 6 hours after morning feeding. Ammonia nitrogen concentration was analysed from the rumen liquor taken at --1, 1, 2, 3 and 5 hours after feeding. The concentrations of propionic acid, butyric acid and total volatile fatty acids of cows fed with fumaric acid were significantly higher than in cows not supplemented with fumaric acid (p < 0.05). The concentration of acetic acid in both treatments was not significantly different (p > 0.05). The cows fed with fumaric acid had less ammonia nitrogen in the rumen at --1 and 1 hour after feeding than the cows not supplemented with fumaric acid (p < 0.01). The rumen pH at --1, 1, 2, 3, 4, 5, and 6 hours after feeding in both treatments were not significantly different (p > 0.05).
Keywords: Ammonia-nitrogen, dairy cow, fumaric acid, rumen pH, volatile fatty acid