THE NUTRIENTS AND DIGESTION 325 



animals this difference is noted with all food constituents 

 except fat.' 



There appears to be small probability that the frequency 

 of feeding affects digestibility appreciably. 



Nutrients from Vegetable and Animal Sources. — ^As will be 

 seen by reference to the table of digestion coefficients for 

 poultry, protein in all cases, and fat in most cases, is more 

 digestible when supplied from animal sources than from 

 vegetable sources. These coefBcients are borne out by 

 practical experience and by feeding experiments generally. 

 With particular reference to protein Hartwell and Kirk- 

 patrick^ found that beef scraps and milk albumin showed 

 a marked superiority over cottonseed meal, linseed meal, 

 and gluten feed as a source of protein for growing winter 

 chickens, where the same amount of protein was added to 

 the same basal ration in each case, and an abundance of ash 

 supplied. 



W. P. Wheeler^ found that the best general results for 

 ducklings were had when 60 per cent, of the pfotein came 

 from' animal sources diu-ing the first four weeks. 



He found further that with ten lots of chicks, six lots of 

 immature pullets, two lots of young hens, and two lots of 

 old hens, fed contrasted rations which were as nearly alike 

 as possible, except that all the protein was of vegetable 

 origin in one case and 40 to 50 per cent, of animal origin in 

 the other, with every two, lots contrasted, the results were 

 markedly more satisfactory where the animal food was the 

 source of protein. 



The chicks having the animal food ration consumed 12 

 to 34 per cent, more food and made 22 to 100 per cent, faster 

 gains. The ducklings having the animal-food ration gave 

 satisfactory results, while over half of those restricted to 

 protein of vegetable origin died by the end of four weeks 

 (see Figs. 173 and 174). Most of the rest were saved by 

 adding meat meal to the ration. * 



' Kellner, The Scientific Feeding of Animals. 



2 Rhode Island Bulletin No. 45. 



' New York Experiment Station, Twenty-sixth Annual Report 



