COMPOSITION OF MILK AND CREAM 5 t 



usually present. When cows are constantly in heat (nymphomania, 

 •"bullers") the milk yield is diminished and the composition may 

 lie altered. Abortion, while lowering the amount of milk, does 

 not influence the composition — unless the cow is otherwise sick. 



The milk-yielding capacity of cows generally increases up to 

 the eighth year of age, and then decreases. With the decrease of 

 yield there appears to be often a decrease in fat and total solids in 

 the milk. It was thought at one time that the spaying of cows 

 would prove of advantage in sustaining the yield and improving the 

 richness of their milk, but it has not been found so in practice, 

 ■except in those animals which are constantly in heat owing to 

 disease. 



The dehorning of cattle is said to improve the yield of milk, 

 but there can be no conceivable reason for this other than in the 

 freedom from fighting and wounds which this practice accomplishes. 



The composition of milk is of great importance in that the 

 value of milk depends upon the amount of fat it contains, other 

 things being equal. 



It has now become the custom for creameries in most' parts of 

 the country to pay a sum for milk proportionate to the amount of 

 butter-fat it contains as estimated by the use of the Babcock machine 

 at certain stated intervals. First-class, pure or " certified " milks 

 now sold for an advanced price in cities should contain a high 

 average of fat, unless sold exclusively for infants' use. Such milk 

 often averages five per cent. Then again it is for the farmer's ad- 

 vantage, if he is to produce a high quality of milk, that he know the 

 composition of the milk of all his individual cows so that the poorer 

 ones may be weeded out. This may be accomplished by the use of 

 a Babcock machine on the farm (see p. 193). 



Colostrum (common name beastings, etc).- — Colostrum is the 

 milk secreted immediately after calving and differs very markedly 

 in composition from ordinary milk. Colostrum is of a slightly 

 yellowish or brownish color and has a peculiar smell, a slimy con- 



