488 NUTRITION OF FARM ANIMALS 



On the whole it may be said that such experiments as are on 

 record agree with the deductions from physiological data and 

 indicate that the need for warm quarters for dairy cows has 

 been overemphasized, but are insufficient to establish the 

 limits within which stable temperature does not affect yield. 

 Much doubtless depends, as Spier points out, upon the previous 

 treatment of the cows. Warmly stabled animals carry a sum- 

 mer rather than a winter coat and a low temperature seems 

 likely to have more effect on such animals than on those grad- 

 ually accustomed to it as the weather grows colder. 



Where cows are kept in the stable most of the time the ques- 

 tion of temperature is of special interest in its relation to ventila- 

 tion. Practically, a cow stable must be warmed in most cases 

 simply by the heat derived from the animals themselves and 

 a high temperature can be obtained only by means of more or 

 less restricted ventilation. If low temperatures can be used, 

 more perfect ventilation, with its beneficial effects upon the 

 health and vigor of the animals, is possible. 



4. THE UTILIZATION OF FEED IN MILK PRODUCTION 

 The utilization of protein 



584. Meaning of utilization. The conception of the utiliza- 

 tion of protein in milk production as here considered is substan- 

 tially identical with that of its utilization in growth already 

 discussed (470). It is the ratio of the protein contained in 

 the milk to the least amount of feed protein which is required 

 to produce it under the most favorable conditions. 



585. Surplus protein katabolized. While it is evident that 

 milk production requires a liberal supply of protein in the ration, 

 the amount actually secreted in the milk is determined pri- 

 marily by the individuality of the animal, precisely as is the 

 storage of protein in the case of the growing animal. It is not 

 possible to increase at will the amount of protein secreted in 

 the form of milk by increasing the supply of protein in the feed. 

 While it appears to be true that the activity of the milk glands 

 can be stimulated somewhat by an abundant protein supply 

 (599) , it is nevertheless true that the animal produces an amount 

 of milk determined essentially by its capacity and any surplus 

 of protein over that necessary for this purpose is katabolized 



