304 CATTLE-BREEDING. 



weather has an immediate effect on the yield 

 of milk as it should be. The effect is usually 

 attributed to the broad, general principle that 

 food is first supplied to the support of life, and 

 as one of the incidents of this support of life, to 

 the supply of fuel to keep up the animal heat; 

 and in consequence when the demand for fuel 

 increases, the food which had been devoted to 

 the formation of milk is deflected to the fuel 

 supply. While this is true, it is, in addition, 

 apparently true that a sudden change to a cold, 

 wet clay, or a sudden exposure, produces a more 

 instantaneous and radical effect on the milk 

 supply than is explicable on this theory. The 

 cold seems to stop the secretion of milk to 

 a large extent, somewhat as a chill often 

 checks all the secretions of the organs, of the 

 body. Thus good authorities estimate the de- 

 crease of milk at once effected by exposure to 

 a severe change of weather to be from twenty- 

 five to forty per cent. This decrease seems, 

 moreover, not to be checked by a correspond- 

 ing and instantaneous increase of food; the 

 effect of the increased food not being felt for 

 some time after it is eaten owing to the com- 

 paratively slow process of assimilation. 



While in the case of young stock, and to a 

 minor degree also of old, one of the objects in 

 affording shelter is to protect against the danger 

 of illness and injury from frost bites and chills, 



