Relationships between End Products of Rumen Fermentation and Utilization of Metabolizable Energy for Milk Production

Abstract

Three rations in which the proportion of estimated net energy (ENE) derived from hay or a concentrate mixture of corn meal and soybean meal was varied from 50% hay-50% concentrate (Ration A) to 75% hay-25% concentrate (Ration B) or 100% hay (Ration C) were fed to six, mature, lactating Holstein cows. The end products of rumen fermentation (total methane production and molar proportions of volatile fatty acids in the rumen) were studied in relation to lactation efficiency. Indirect calorimetry was used to measure the efficiency of utilization of metabolizable energy (ME).