Optimum level of ammonia in the rumen liquor of cattle fed tropical pasture hay.

Abstract

Fermentation of Heteropogon contortus in nylon bags in the rumen of steers was studied during stepwise infusion of urea and sulphate that increased dietary N from 4 to 15 g/kg organic matter (OM) and rumen ammonia from <2 to 140 mg N/l. Maximum fermentation was observed at ammonia levels of about 45 mg N/l. However feed intake rose at all levels of N infusion and despite a decline in in VIVO OM digestibility at the higher levels of infusion, digestible OM intake also rose throughout the experiment. (