Effect of Varying Alfalfa:Barley Ratios on Energy Intake and Volatile Fatty Acid Production by Sheep

Five completely pelleted rations consisting of the following alfalfa:barley ratios—100:0, 85:15, 70:30, 55:45, 40:60, were fed to 10 ewes in rotation in a Latin-square design. As the level of barley increased, there was an almost linear increase in digestibility of energy accompanied by a similar decrease in Relative Intake. As a result, a constant digestible energy intake was maintained with all rations containing barley. Alterations in rumen fermentation due to increasing increments of barley was indicated by decreases in the molar proportion of acetic acid accompanied by marked increases in butyric acid. In a concurrent study, 0, 180, or 360 gm. of barley were fed daily after the consumption of which an ad libitum allowance of alfalfa hay pellets was given. In this instance, digestibility of energy also increased as Relative Intake decreased, with each addition of barley to the ration. A possible explanation of the results is given which was based on the changes in rumen microbial fermentation due to the addition of concentrates.