DEVELOPMENTAL PROCESSES OF RETICULORUMEN MOTILITY IN CALVES

Abstract

The present investigation was carried out to make clear the developmental processof reticulo-rumen motility and the effects of feed components, especially dry matter, andvolatile fatty acids in the rumen on the development of reticulo-rumen motility incalves. In it, changes in intrareticulo-ruminal pressure were recorded from rumen-fistulated Holstein calves receiving several substances. Rumen contractions were ob-served in intact calves by auscultation, palpation, and ocular inspection on the surfaceof the left paralumbar fossa.The results obtained are summarized as follows.l) Five grades of reticulo-rumen motility were distinguished in the developmentalprocess of this motility in calves; that is, (I) contraction was recorded neither from thereticulum nor from the rumen, (II) reticulum contractions were only recorctea, (III)reticulum contractions and A-type rumen contractions were observed, (IV) A-type andB-type contractions were recorded, with B-type rumen contractions rarely observed, and(V) A-type and active B-type rumen contractions were recorded at the same rate as inthe adult.2) In calves allowed to have whole milk, hay, and grain ad libitum, B-type contrac-Lions at the adult level (Grade V) were recorded at 3 to 10 weeks of age. In each of the calves, the developmental degree of these contractions was related to the dry matteu-intake and the volatile fatty acid concentration in the rumen.3) In calves given whole milk alone, no stable rumen contraction was obserxzed(Grade II) during the whole period of the experiment, 4) In calves given whole milk orally and plastic sponge intraruminally, the develop-ment of reticulo-rumen motility reached Grade IV at 7, $9 weeks of age.5) In calves given whole milk orally and volatile fatty acid solution (pH 6) intra-ruminally, the development of reticulo-rumen motility reached Grade IVsV at 10 weeksof age.6) In calves given a volatile fatty acid solution and plastic sponge intraruminally inaddition to whole milk provided orally, the development of reticulo-rumen motilityreached Grade V at 3 to 5 weeks of age.7) By means of auscultation, palpation, and visual inspection on the surface of theleft paralumbar fossa, B-type contractions at the adult level were observed at 5 to 6weeks of age in calves under normal feeding. It was a general tendency that the greaterdry matter intake, the earlier appeared B-type contractions at the adult level.8) From the results mentioned above, it can be considered that the development ofreticulo-rumen motility is concerned not only with the amount of dry matter intake butalso with the volatile fatty acid concentration in the rumen. Consequently, it may beestimated that the development of reticulo-rumen motility is closely related to the de-velopment of fermentative activity in the rumen in calves.9) Ruminaion was already observed even when no cyclic reticulo-rumen contractioncould be noticed. It was also recorded in calves fed milk alone or milk plus volatile fattyacid solution. In the earliest stage of rumination, regurgitation with no diphasic con-traction of the reticulum was often observed.