Rumination in sheep. III. Experimentally induced variations on the circadian pattern of rumination

Abstract

The circadian (24-hr) pattern of rumination of caged sheep was found to be affected: (a) by the administration of a roughage ration per fistulam; (b) by the emptying of the rumen and the subsequent return of the rumen contents; (c) by the emptying of the rumen and the replacement of the contents by a buffer solution plus roughage. The period during which no rumination occurred following feeding was progressively shortened when increasing proportions of a ration of oaten chaff and lucerne chaff were administered per fistulam. The effect was much reduced when high protein sheep cubes were added to the chaff ration. The removal of the rumen contents after voluntary feeding and then their immediate return to the rumen tended to cause an early commencement of rumination. When the rumen contents were 'pasteurized' before return, however, rumination did not occur for an extended period afterwards. When the rumen contents were replaced with buffer solutions plus roughage, variable rumination responses occurred. In one instance apparently uninhibited rumination resulted.