Evaluation of Forages in the Laboratory. II. Simplified Artificial Rumen Procedure for Obtaining Repeatable Estimates of Forage Nutritive Value

Abstract

The usual artificial rumen procedure has been simplified and adapted to give repeatable estimates of forage nutritive value. A 1-g sample of the ground forage was fermented in a 125-ml Erlenmeyer flask containing 30 ml of McDougall's artificial sheep saliva adjusted to pH 6.7 and 25 ml of strained rumen fluid obtained from a fistulated cow fed and managed in a standardized manner. Immediately after the addition of all contents the flask was flushed with CO2, capped with a Bunsen valve, and incubated at 39 C for 24 hr. The per cent forage cellulose digested in this manner was significantly correlated with TDN, DDM, DE (calories per gram), and the digestion coefficient of energy determined in conventional animal digestibility trials. The artificial rumen method and prediction equation given in this paper yielded DE estimates on 19 forages which, when compared with the animal DE values, showed a coefficient of variation of 5.2%. The inclusion of a standard forage in each trial allowed adjustments to be made so that cellulose digestion obtained on two different days had a coefficient of variation of only 1.59%. It was found that the crude protein and digestible protein content of hays are highly correlated (r = 0.999) and that the latter could be estimated from the former with a resultant standard error of 0.25 and coefficient of variation of 2.26%. © 1962, American Dairy Science Association. All rights reserved.