Observations on the Development of Ruminal Lesions in Calves Fed on Barley

Summary Investigations have been made of some of the changes occurring in the calf rumen during the transition from conventional feeding to a diet containing 90% barley. During the first 7 weeks of barley feeding, there was a rise in the concentration of total volatile fatty acids in the rumen contents, with a rise in the propionic and butyric acid fractions and a fall in the acetic acid fraction. The pH of the rumen contents fell, but no increase was found in the amount of lactic acid in the rumen. A characteristic clumping of ruminal papillae developed after the change to barley feeding, and the rumen wall became thickened and increasingly rigid. The floors of the anterior dorsal sacs of the rumens from slaughtered calves showed, histologically, that the lesions of acanthosis, hyperkeratosis and parakeratosis had developed within 4 weeks of the change in diet. Many hairs were present in the interpapillary spaces of the rumen wall, and there were numerous lesions due to the penetration of the tissues both by animal and by vegetable hairs. Inflammation due to this cause appeared to be an important factor in the pathogenesis of rumenitis in calves fed on barley, and the thickening of the rumen wall was appreciably reduced when the ingestion of calf hair was prevented.