Roughage/concentrate ratio on ruminal ammonia concentration, pH and volatile fatty acids in crossbred dairy cows

Abstract

The objective with this study was to evaluate the effects of concentrate levels in ruminal ammonia concentration, pH and volatile fatty acids (VFA). Twelve canulated cows, no lactating and no pregnant, were randomly distributed in blocks. Cows were fed Russel grass (Cynodon sp) hay ad libitum and concentrate in the proportions of 25%, 50% and 75% of dry matter. Two experimental periods, which 23 days for diet adaptation, and the 28th day for rumen fluid sampling (0, 2, 4, 6, 8, 10 and 12 hours). Ruminal N-NH3 concentration reduced by increasing the levels of concentrate in diets. Rumen pH reduced with sampling time and concentrate level. Total VFA concentration were not affected, but acetate:propionate ratio increased.