92 SCIENTIFIC FEEDING OF ANIMALS 



experiment with ruminants has shown that ioo kg. 

 fairly good meadow hay forms 8 kg. body fat when 

 added to the maintenance ration. In a similar 

 experiment where starch was fed instead of meadow 

 hay it was found that the weight of fat gained was 

 exactly equal to quarter of the weight of starch 

 given. If the 8 kg. fat obtained from the hay be 

 multiplied by 4, the quantity of starch which 

 would have the same effect as 100 kg. of the hay is 

 obtained, that is, 32. This figure 32 is then the 

 starch equivalent of the meadow hay. This does not 

 in any way mean that the meadow hay contained 

 32% starch, but expresses the food value of the 

 hay compared to the starch. When, therefore, it 

 is seen in Table I of the Appendix that winter 

 cereal straw has a starch equivalent of 11-5, summer 

 cereal straw 18-8, potatoes 19, rye bran 46-9, 

 barley 72, and flax seed 119-2, the meaning will be 

 clear. How far these figures are applicable in the pro- 

 duction of energy or milk, or how they apply to horses 

 and pigs, will be discussed later. The method of esti- 

 mating the starch equivalents or values of different 

 feeding-stuffs will also be treated later in the intro- 

 duction to the Tables for the calculation of rations. 



In digestion, in the formation of flesh, and, as 

 will be subsequently seen, in the production of milk, 

 the digestible protein plays a very important part, so 

 the mere giving of the starch equivalent will not 

 suffice to fully express the nutritive value of a food- 



