Proceedings of Seventeenth jN^ormal Institute 223 



A COMPARISON OF DIGESTIBLE CO-EFFICIENTS FOR CATTLE, SWINE 



AND POULTRY AS SUGGESTIVE OF A MORE ACCURATE BASIS 



ON WHICH TO COMPUTE POULTRY RATIONS 



A. B. Dann 



An attempt made two years ago to tabulate and compare the 

 rations recommended by the various experiment stations brought 

 out rather forcibly the fact that we have no uniform basis on 

 which to compute the nutritive ratio and the total nutriment of 

 our poultry rations. It was with the hope that there might be 

 some one basis which we could adopt for the sake of uniformity, 

 if for nothing more, that the present study was made. It re- 

 presents an attempt to incorporate in one paper all the data on 

 digestibility by poultry that could be found, and to compare this 

 data with similar factors for other animals, in the hope of finding 

 a more accurate basis for study of the nutrients in poultry feed- 

 ing. 



Due to the difficulty of obtaining coefiicients of digestion of 

 feeds by poultry, which has resulted in the very meager data now 

 available, we have come to freely use the coefficients for other 

 animals, and, in some cases, the total composition of feeds 

 direct, without considering digestibility at all. To quote from a 

 fairly recent bulletin : " With the present experiments, the nu- 

 tritive ratio has been considered as the ratio of the protein to 

 the sum of the fat multiplied by 2.3, and the nitrogen-free-ex- 

 tract matter. That is, the digestibility has not been taken into 

 consideration, and the fiber has not been included in these calcu- 

 lations." If I am correctly informed, the station computes the 

 nutritive ratio in all instances from the total composition of the 

 grain, disregarding digestibilty entirely. 



Most of the stations, however, lacking data for poultry, are 

 using digestible coefficients for cattle. This has been spoken 

 of as the best wo have, and on these grounds has been used rather 

 widely, although there . is a feeling that the figures for swine 

 would be more accurate. But here again we are little better off 

 than with poultry, for the amount of data available on digesti- 

 bility by swine is scarcely as voluminous as that for poultry. In 

 an attempt to justify the use of digestible coefficients by cattle, 



