DIGESTIBILITY OF FEEDING STUFFS 65 



Even swine are able to digest considerable amounts of vegetable 

 fiber. Direct experiments have shown that the digestion coefficients 

 for fiber obtained with this class of animals are as follows : In the 

 case of wheat bran, 39 per cent ; wheat shorts, 37 per cent ; barley, 

 49 per cent; corn, 39 per cent; corn and cob meal, 39 per cent; 

 cracked wheat, 60 per cent; pea meal, 78 per cent; green oats and 

 vetch, 49 per cent. These figures, in most cases, compare favorably 

 with the average digestibility coefficients for the respective feeds 

 obtained with steers or sheep. 



Breeds. — Different breeds of the same class of farm animals do 

 not appear to differ appreciably in their digestive capacity, nor do 

 individual animals of the same breed differ in this respect, so long 

 as the animals compared are in good health and have good teeth. 

 Very young as well as old animals are handicapped in eating whole 

 dry grains, on account of their inability to chew their feed well, and 

 it should be fed wet or ground to such animals. Differences in the 

 digestibility of feeds have sometimes been found in the case of 

 individual animals, but there does not seem to be any regularity in 

 the variations observed, and these are, therefore, likely to be acci- 

 dental and due to errors of experimentation. 



Age. — Age does not seem to affect the digestive capacity of 

 animals whose digestive apparatus is fully developed, nor does 

 a fair amount of work influence the digestion, provided that this is 

 done at a moderate rate, like ordinary work of horses, mules, and 

 oxen. Work done at a rapid pace, on the other hand, is likely to 

 diminish the digestibility of the rations fed. 



The various conditions bearing on the chemical composition of 

 plants which have already been discussed are also of importance in 

 so far as they affect the digestibility of plants. Among other factors 

 that might be supposed to influence the digestibility of feeding 

 stuffs, besides those already mentioned, are the following: 



Quantity of Feed. — The quantity of feed does not appear to 

 appreciably affect its digestibility. It should be said, however, that 

 the testimony on this point is somewhat conflicting. The results of 

 early experiments by Wolff and others, indicating a similar digesti- 

 bility of small and large rations, have not been corroborated by more 

 recent work. It seems reasonable to suppose that the digestive fluids 

 will vary to a certain extent, both in composition and amounts, with 

 the character of the rations fed, in case of herbivora, as found to be 

 the case with carnivora in the brilliant investigations by the Eussian 

 physiologist Pavlov. 4 There issome evidence with herbivora. which 



-"'Work of the Digestive Glands," London, 1910; see also Amer. jr. 

 Physiol., 37, p. 50. 

 5 



