Effects of nipple or bucket feeding of milk-substitute on rumen by-pass and on rate of passage in calves.

I . Effects of feeding liquid milk-substitute to young calves either by nipple-pail or open-bucket o n the rumen by-pass and on the rate of passage were studied. z. Sixteen Holstein calves, aged I week initially, were used in three experiments in which calves were slaughtered after they were given liquids (milk-substituteand water) containingchromic oxide and SrCI, .6H,O as a tracer either by the nippleor bucket-feeding method, and the distribution of tracers to the rumen, abomasum and the lower alimentary tracts was examined. 3. When the liquid milk-substitute containing tracers was given by the nippleor bucket-feeding method to calves having been trained to the corresponding procedures for the preceding I week, most of the tracers was directed into the omasum and abomasum. There seemed no difference in the functioning of oesophageal groove closure between the two feeding procedures. Even when the liquid milk-substitute containing tracers was given by the nipple-or bucket-feeding method to calves which had been accustomed to different procedures for the preceding week, the majority of tracers were found in the abomasum immediately after administration, though a slightly greater proportion of the tracers entered the reticulo-rumen. 4. Continuing bucket feeding of liquid milk-substitute effected an efficient closure of the oesophageal groove at least up to 16 weeks of age. After calves were accustomed to consume liquid milk-substitute from the bucket from I to 4 weeks of age, drinking warm water from the bucket also caused efficient closure at least up to 16 weeks of age. 5 . When tracers were administered with warm water, Cr,O, and strontium, especially the latter, transferred much more rapidly to the lower gut than when they were administered with liquid milk-substitute, probably reflecting the curd formation of the milk-substitute in the abomasum. When liquid milk-substitute with tracers was fed by the bucket-feeding method, Sr transferred more rapidly to the lower gut than when the milk-substitute was fed by the nipple-feeding method, indicating that the feeding procedure of liquid milk-substitute has an apparent effect on the rate of passage.