Ruminal volatile fatty acid production rate and yield of lactating dairy cow fed total mixed rations differing in forage combination

摘要

Introduction The importance of the volatile fatty acid (VFA) as an energy source forruminants and their influence on protein depositionhas led to the development of various methods to estimate rate and yield of VFA production in the rumen.Isotope dilution techniques to measure VFA productionin vivo were developed in the mid 1950s and early1960s.Limitations onisotopic usage andadvances in anaerobic fermentation procedures have increased interest in an in vitrotechnique (Olsen and Mathiesen,1996).Due to limited supply of good quality of grass hay,high ratio of forage to concentrate in total mixed ration has been extensively accepted in dairy cows especially in small-and middle-scale dairy farm in China.Following an in vitro technique as described by Corley et al.(2004),the objective of the present study attempt to determine VFA production rate and yield of dairy cow fed total mixed rationsdiffering in foragecombination in vitro techniques.