July 9,1917 Rate of Passage of Food Residues through Steers 6i 



rapid passage of the crude fiber through the animal. While Table V 

 indicates no change in the digestion of nitrogen arid fat, it should be 

 pointed out that the actual digestion of these nutrients was probably 

 increased by the more rapid movement through the animal. This in- 

 crease was probably counterbalanced by the metabolic nitrogen and fat 

 residues accompanying the greater flow of digestive juices when the pas- 

 sage of the food residue was more rapid. 



DISCUSSION OF RESULTS 



The differences attending the accurate measurement of the time 

 required for the passage of food residues has retarded studies along this 

 line although the question is one of considerable importance. In the 

 work reported here only the last method can be considered as offering 

 direct results, although the two other methods were of value. From 

 the standpoint of the specific problem the weakness of the first method 

 is in that it still remains to be proved definitely that the rate of passage 

 of feed residue through the steer can be measured by the moisture 

 content of the feces. Our work has shown that, if a high moisture 

 content of the feces is indicative of rapid passage, then the apparent 

 digestion is more complete probably for all the nutrients with the more 

 rapid passage and less complete with the slower movement. Unfor- 

 tunately the method of study shows only the relationship and not the 

 extent of the variation in digestion associated v/ith a high moisture 

 content. These results are in accord, however, with cattle-feeding 

 practice, in that cattle are not considered as doing best or making the 

 most of their food unless the feces has a certain semiliquid consistency 

 and has a strong odor of bile. Practical feeders have long realized the 

 advantage of feeding some slightly laxative feeds at all times if the best 

 results are to be secured from the feeding. 



In making a closer examination of Table I and the results given there 

 it is interesting and probably of significance to note that the variation, 

 or contradictory results obtained (indicated in the table by the omission 

 of the positive or negative sign), occurred with those rations that might 

 be considered as abnormal. One of these rations contained 31 per cent 

 of cornstarch and 69 per cent of silage, while the other contained 47.3 

 per cent of starch. 



In the case of tiie second method, which proved impractical for the 

 main object sought, the experiments showed that some solid particles 

 of the feed might remain in the steer as long as 60 days, or even longer. 

 The slaughter tests made later showed that hard particles of feed and 

 foreign substances were especially prone to become delayed in transit 

 either in the reticulum, in the fourth, or true, stomach, or in the first few 

 ventral folds of the duodenum. The coarse feeds and roughages retard 

 the rate of passage of feed residues, a point proved conclusively by the 

 slaughter tests. 



