144 Testing Milk and Its Products. 



feeding experiments conducted under a great variety of 

 conditions and in many countries. Cows that are fairly 

 well fed will almost invariably give more milk when 

 their rations are increased, but the milk will remain of 

 about the same quality after the first few days are passed 

 as before this time, provided the cows are in good health 

 and under normal conditions. Any change in the feed 

 of cows will usually bring about an immediate change in 

 the fat content of the milk, as a rule increasing it to some 

 extent, but in the course of a few days, when the cows 

 have become accustomed to their new feed, the fat con- 

 tent of the milk will again return to its normal amount. 

 171. The records of the cows included in the feeding 

 experiment at the Illinois station, to which reference has 

 been made on p. 133, furnish illustrations as to the effect 

 of heavy feeding on the quality of milk. The feed, as 

 well as the milk of the cows, was weighed each day of 

 the experiment. During the month of December each 

 cow was fed a daily ration consisting of 10 Ibs. of tim- 

 othy hay, 20 Ibs. of corn silage and 2 Ibs. of oil meal; 

 the table on p. 134 shows that cow No. 3 produced on 

 this feed an average of 12.1 Ibs. of milk, testing 3.8 per 

 cent, of fat. In January the grain feed was gradually 

 increased until the ration consisted of 12 Ibs. of timothy 

 hay, 8 Ibs. of corn and cob meal, 4 Ibs. of wheat bran and 

 4 Ibs. of oil meal. All the cows gained in milk on this 

 feed; cow No. 3 thus gave an average of 4 Ibs. more 

 milk per day in January than in December, but the aver- 

 age test of her milk was 3. 7 per cent., or one- tenth of one 

 per cent, lower than during the preceding month. The 

 heavy grain feeding was continued through February 



