24 DAIRY FARMING 



selecting and retaining calves from only the best milkers, 

 at the same time culling out those cows whose records 

 have not been satisfactory. This work cannot be done to 

 best advantage unless records are kept of the quantity 

 and quality of .milk from each cow for a whole lactation 

 period, as discussed in chapter IX. 



Buying Cows. Where all of the cows in the founda- 

 tion stock are grades, none of the calves, of course, can 

 be registered. It is desirable, therefore, to add to the 

 herd from time to time, as means permit, some good 

 pure-bred cows of the same blood as the bulls that have 

 been used. This has the advantage of enabling the owner 

 to dispose of his calves to better advantage. 



The purchase of cows, however, is always attended with 

 the danger of introducing contagious diseases into the 

 herd, ' especially tuberculosis and contagious abortion. 

 For this reason the purchasing of cows should be carried 

 on in a limited way only. It is, of course, always in order 

 to buy cows when the object is to add to the herd pure- 

 bred individuals of exceptional dairy merit. But the 

 practice of buying cows should never be carried to the 

 point of making it the principal means of replenishing the 

 herd, especially since the latter can be accomplished 

 much more satisfactorily by raising the calves from the 

 best cows. 



