Rumen Liquor pH, Osmolality and Volatile Fatty Acid Changes in Calves Fed Intensively on Barley with Hay Added

Abstract

SUMMARY Rumen liquor samples were removed from calves during their period of adaptation to a ration containing 87 · 5 per cent barley, 10 · 0 per cent protein and a mineral and vitamin supplement, together with 1 lb of hay for each calf every day. This rumen liquor was examined to determine alterations to pH, osmolality and volatile fatty acid (VFA) fractions present. The rumen liquor pH determined from the barley and hay fed calves was lower than their controls, but it was not as low as that recorded from similar experiments where hay was omitted from the diet. The presence of a biphasic rumen osmolality pattern during this period may at first reflect fluid movement from the rumen immediately the ration alteration commenced. The later peak may be a consequence of fermentation associated with the increasing quantity of food consumed. The volatile fatty acid concentrations and proportions reflect the cereal content of the ration. The correlation of rumen pH and VFA in a “fully adapted” calf may be the result of completed adaptations to the new diet. The influence on the rumen liquor environment of the addition of 1 lb of hay daily for each calf is discussed.