MILK PRODUCTION 469 



Cals. per pound. This is greater than the energy content of 

 the dry matter gained by very young animals, but less than 

 that computed in later stages of growth. In a general way, 

 then, it may be said that milk solids correspond in proportion 

 of protein and in energy value per pound to the gains made by 

 growing animals when in the neighborhood of three months old. 



557. Rate of production of milk solids. A beef calf three 

 months old may be assumed to make a growth of approximately 

 1.5 pounds per day, containing perhaps three-fourths of a pound 

 of dry matter with an energy content of about 2200 Cals. 

 The very moderate yield of 15 pounds of average milk per 

 day would contain about 1.92 pounds of total solids equiva- 

 lent to 5030 Cals. of energy. In other words, considerably 

 more than twice as great a production would be effected by the 

 relatively small bulk of the secreting cells in the udder as by 

 the whole body of the calf. When it is further considered 

 that the product of the dairy cow is all edible, her great 

 economic value as a producer of human food becomes ob- 

 vious. On this point Jordan says : l " A cow yielding 6000 

 pounds of average milk per year is not regarded as an 

 unusual animal. This means, however, the annual produc- 

 tion of not less than 780 pounds of milk-solids, an amount 

 at least double the dry matter in the body of a cow weighing 

 900 pounds. When we consider that this manufacture of new 

 material is carried on not only during a single year, but through 

 the entire adult life of the animal, we begin to realize how ex- 

 tensive are the demands upon the food supply. Still more 

 striking is the case of high-grade cows yielding annually over 

 half a ton of milk solids, and when we remember the perform- 

 ance of Clothilde, whose 26,000 pounds of milk produced in 

 a year certainly contained more than 2500 pounds of solid 

 matter, we must regard the cow as possessing wonderful powers 

 of transmutation. Her capacity for the rapid and economical 

 production of human food of the highest quality is not equaled 

 by any other animal." 



558. Factors of milk production. Milk production differs 

 from meat production in one very essential particular. In the 

 latter, broadly speaking, an increase in the whole body of the 

 animal is what is sought, and while the product may vary in 



1 The Feeding of Animals, 1908, p. 308. 



