17 



represented by the line f/ to r is the amount required to main- 

 tain the animal's body, which is the same quantity as in the 

 first case; however, the cut of one-fourth in the ration will be 

 seen to come entirely on that available for milk production and 

 reduces that amount one-half. 



Suppose that the ration of such a cow will be still further 

 reduced to one-half of the full ration, or that required for 

 maintenance alone, as represented by the third line. In this 

 case the cutting down of the ration one-half would remove all 

 available feed for milk production. However, the animal would 

 not cease producing milk at once. This is a point of great 

 importance in feeding cows, and a lack of such knowledge leads 

 to serious errors in feeding. The milk-producing function is so 

 strong that the cow will continue to produce milk for some 

 time, even when the feed is insufficient, utilizing the reserve 

 material which has been accumulated in the body in the past. 

 This always happens in the case of a heavy-milking cow during 

 the first few weeks after the birth of a calf. At this time it is 

 not generally possible, and not desirable on account of the 

 condition of the animal, to feed her heavily enough to supply 

 the nutrients necessary to produce the milk. Even if the feed 

 were offered, the appetite is not usually strong enough to cause 

 the necessary amount of feed to be taken to prevent loss in 

 weight. As a rule, all heavy-milking cows decline in weight 

 for the first two or three weeks, and occasionally for ten weeks, 

 after calving, which means that the nutrients used for milk 

 production have been in excess of the feed supplied for that 

 purpose. The same thing happens in the case of a cow that is 

 not fed a sufficient ration for the amount of milk she is pro- 

 ducing. She may continue to produce considerable milk for a 

 while by drawing on the reserve material of the body, but as 

 soon as this is exhausted, the production of milk must come 

 down to the amount available for this purpose, above the 

 ration of maintenance. When the feed is in excess, the cow 

 begins to store reserve material on her body. If the amount of 

 milk produced by a cow varied directly with the feed, and she 

 did not store up nutrients at one time and draw on reserve 

 materials at another, it would simplify the problem of feeding 

 very much and result in more economical feeding at all times. 



