484 NUTRITION OF FARM ANIMALS 



So far as mere maintenance of body temperature goes, then, 

 no reason appears why a cow might not be subjected to com- 

 paratively low temperatures without causing any increased 

 katabolism for the sake of heat production solely. That the 

 same factors of size and weight, humidity of air, and the amount 

 and character of ration as in the case of the steer enter into the 

 question is obvious. 



580. Shelter, etc. The question of shelter does not differ 

 in principle with the cow and with the steer. The influence of 

 precipitation, wind, insolation and temperature of drinking 

 water are the same qualitatively on the cow as on the steer and 

 the same reasons which render shelter desirable in the one ca^e 

 apply in the other. 



581. Modifying factors. The foregoing facts, however, are 

 scarcely sufficient to justify the conclusion that a dairy cow 

 may be treated in this respect like a beef steer. In making a 

 quantitative application of these facts in practice, certain 

 modifying factors require consideration. 



Relative body surface. Even the most casual comparison 

 of the dairy cow with the beef steer is sufficient to show that 

 they differ materially in form and to raise the supposition that 

 the ratio of body surface to weight may vary considerably in 

 the two types. The writer is not aware of any measurements 

 of body surface of cows but one can hardly avoid the impression 

 that the spare angular form of the typical dairy cow exposes 

 relatively more surface than the compact, rounded form of the 

 beef animal. 



Condition. Outdoor winter feeding of cattle is practiced 

 largely with fattening animals and it is with them that most 

 experiments have been conducted. With such an animal a 

 considerable covering of fat is usually acquired before the onset 

 of extreme cold weather, while the typical dairy cow devotes her 

 feed to milk production and carries very little body fat. There 

 are no definite data as to the protective value of a fat covering 

 but doubtless it is a poor conductor of heat and it would seem 

 that it might have considerable influence in reducing radiation. 



Skin and hair. The skin of the dairy cow is reputed to be 

 thinner than that of the steer and may therefore be a better 

 radiator of heat. The coat of hair of the cow, too, is apt to be 

 shorter and lighter than that of the steer, whether as a result 



