722 Starch Equivalents of Feeding Stuffs, [dec, 



these matters to the notice of those who are necessarily in- 

 terested in them will be made in this article. 



Digestibility Coefficients of Foods. — When dealing with 

 individual feeding stuffs it will first of all be a matter of 

 general agreement that in the chemical analysis we have 

 merely a statement of the amount of protein (albuminoids), 

 fat, carbohydrates, &c, present in the particular sample 

 which has been analysed. Often the analysis is limited to a 

 statement of the percentages of protein and oil as required 

 by the Fertilisers and Feeding Stuffs Act. It is generally 

 well known that a chemical analysis is not an absolute 

 measure of the worth of a feeding stuff. That part 

 only of a food or ration which is actually digested by 

 the animal can be of use to it, either for maintaining the 

 body in a condition of equilibrium, whereby the neces- 

 sary losses are made good, or for productive purposes, i.e., 

 for the formation of body tissue (flesh and fat), for the pro- 

 duction of milk, or as a source of energy for the performance 

 of work. Those foods which are rich in protein and oil or 

 in soluble carbohydrates have a high digestibility coefficient ; 

 that is to say, the amounts of nutrients (protein, oil, carbo- 

 hydrates, &c), which are proved to be present by means of 

 the chemical analysis are digestible to a large extent. If, for 

 example, a linseed cake had an analysis showing 40 per cent, 

 of crude protein, and 10 per cent, of oil, much the greater 

 part of these nutrients would be digestible. Taking the 

 average digestibility coefficients for the protein and oil in 

 linseed cake to be 90 per cent., as it would be. in the case 

 of a good sample, we see that the animal would actually 

 digest 36 per cent, of protein and 9 per cent, of oil. Equally 

 high digestibility coefficients would be found in the case of 

 most oil cakes, and in peas, beans, gluten meal, and feeding j 

 stuffs of animal origin, like meat or fish meal, milk, &c. In a j 

 similar way the soluble carbohydrates in such foods as 

 mangolds, swedes, turnips, peas, beans, wheat, and maize 

 have a high percentage digestibility, even up to 90 — 95 per 

 cent. 



We are forced therefore in estimating the value of any j 

 feeding stuff to consider only the digestible nutrients which 

 it contains, and not simply the chemical analysis. Thanks 



