38 SCIENCE AND PRACTICE OF DAIRYING. 



The space in the udder, which is occupied by the milk before 

 milking, consists of four milk cisterns, and of a richly-branched net- 

 work of canals and vessels leading up from them, the finest ends and 

 dilations of which form the gland-basket. When, after milking, 

 the udder begins to fill again, the milk formed must distend the 

 canals and vessels, where it is held by capillary attraction, and where 

 the forward movement of the fatty globules is retarded through 

 congestion and friction, before it reaches the milk receptacle. This 

 explains why it is that, under ordinary circumstances, the percent- 

 age composition of fat and of solids in milk steadily increases from 

 the beginning to the end of the process of milking, and its specific 

 gravity decreases; and why the milk which comes last is always 

 richer in fat. The increase of solids is sometimes as great, some- 

 times less, and sometimes somewhat greater than that of the fat; so 

 that we may well say it is practically influenced by the increase in 

 fat only. This phenomenon becomes more noticeable the longer the 

 time which intervenes between two consecutive milkings is. As a 

 rule, it may be said to take place no longer when the interval 

 between the milkings is less than four hours. 



If a similar period intervene between the two milkings in the case of 

 cows milked twice a day, and the conditions influencing the health of the 

 cows are approximately similar, it may be said that between the morning 

 and evening milk, so far as quality and quantity are concerned, there is no 

 difference. If, on the other hand, the intervening periods between the 

 times of milking are unequal, it may be almost always noted that the milk 

 obtained after the longer interval is greater in quantity, but contains less 

 solids; and after the shorter interval is less in amount, but contains a 

 larger amount of solids. 



After it had been discovered, as the result of experiments with a few 

 cows, and with shorter intervening periods, that milking three or four 

 times a day gave more milk, and milk richer in fat occasionally with as 

 much as 20 per cent of an increase in amount, and as much as 25 per cent 

 increase of fat, than is obtained with two milkings, it was recommended 

 that cows should be milked regularly three times a day. The author will not 

 contend that, as a rule, milking three times a day, under otherwise similar 

 conditions, does not give a larger yield than milking twice a day; but he 

 is convinced, from numerous observations, that the amount of such increase 

 is largely exaggerated. In no case can it be expected in introducing the 

 two-times-a-day milking, instead of the three-times-a-day milking, or vice 

 versa, into large herds, that an increase or decrease in yield, similar to 



