CALORIFIC VALUE OF FOODS 197 



even under carefully controlled experimental conditions. 

 Where a large portion of the food consists of hay, large 

 variations in digestion must be expected. Kellner found, 

 for example, in meadow hay, that the digestibility varied 

 from 46 to 79 per cent. The digestibility varies roughly 

 with the fibre, and the relative food values can be obtained 

 by the formula, 2\ X oil per cent. -f- albuminoids per cent. 

 4- carbohydrates per cent. J fibre per cent. Kellner 's 

 tables, however, are the best available method. 



The most efficient animals for converting cattle food into 

 human food are undoubtedly those producing milk. The 

 daily ration for a fattening beast is very similar to that for 

 a cow giving about two gallons of milk a day. In a week a 

 fattening beast would give perhaps about n Ibs. of beef, as 

 against 140 Ibs. of milk from a cow. As the food value of 

 the beef is about double that of the milk, weight for weight, 

 the advantage of milk is seen to be enormous. Even if the 

 milk is converted into cheese, about 14 Ibs. of cheese would 

 be obtained, and again, cheese is more than double the feeding 

 value of beef, weight for weight, so that under any circum- 

 stances the cow is far more efficient than the bullock for 

 converting cattle food into human food. Of course, the 

 amount of labour involved with dairy stock is greater than 

 that of fattening stock. The next most efficient animal to 

 the cow is probably the pig, and sheep are generally rather 

 better than the ox for the utilization of food material, 

 though mixed grazing is best. On the general average, 

 the sheep get lower quality food, and give a better return. 

 If, however, cattle were slaughtered early, for the production 

 of much more veal and less beef, economy would be effected 

 in this way ; but, on the other hand, the earlier slaughtered 

 animals will need to be fed with an average higher quality 

 food, and an average greater expenditure of labour. Poultry 

 are not economical converters of low-grade food into human 

 food. It is only if they are fed to a large extent on such 

 things as clover meal and fish meal that they can be considered 

 as producing human food economically. Tables 25 and 26 

 give the data necessary to convert calories into human 



