COMPARATIVE NUTRITIVE VALUE OF FOODS 159 



supply us with the relative values of fat, albu- 

 minoids, and carbohydrates for the production of 

 increase in the ox, but the value of digestible fibre is 

 not given. We have, hov^^ever, the values for the 

 production o^ increase actually obtained when meadow 

 hay, oat straw of good quality, and wheat straw were 

 added to a rather meagre diet for the purpose of fatten- 

 ing. If we take the digestible fat, albuminoids, and 

 carbohydrates of the meadow hay, and give to each 

 the average calorific value found for it in Kellner's 

 production experiments, we find that the sum of these 

 values is almost identical with the calorific value 

 actually obtained when the hay was used as food. A 

 similar calculation in the case of the oat straw shows 

 also a near agreement with the value actually obtained 

 by experiment. With wheat straw the case is dif- 

 ferent ; the calculated value is here much above that 

 found on actual trial. With the exception, therefore, 

 of straw of this character, the simple omission of the 

 digested fibre from the calculation appears to give 

 results nearly agreeing with the truth. We must 

 remember, however, that this is only the case so long 

 as we are dealing with ruminant animals ; in the case 

 of the horse, as Zuntz has shown, giving no value to 

 the fibre does not suffice to obtain an accurate expres- 

 sion of the value of a labour ration. 



In the following table we give the calculated values 

 of ordinary cattle foods both for maintenance and pro- 

 duction purposes. To obtain the maintenance value 

 in terms of starchy we refer to the amounts of digestible 

 constituents contained in 1,000 lbs. of the food (pp. 155, 

 156), and make the following simple calculation: — 



Albuminoids x 1-25 + Amides x 0-6 + Fat x 2-3 + Carbo- 

 hydrates + Fibre. 



