MILK PRODUCTION 43! 



renewal in the natural way, sometimes to the duration of 

 two or three years, but in such instances the yields become 

 so small after a time as to prove unprofitable. 



It is also important that the milk yields shall be well 

 sustained during the normal season for milk-giving, by 

 feeding liberal supplies of suitable food. Should declension 

 in milk yields result at a period unnecessarily soon, from 

 want of food suitable and sufficient in quantity, and should 

 the attempt be made to advance the milk, yields subsequently 

 by giving proper food, it will be only partially successful. 

 The yield may be increased but not to what it would have 

 been under proper management. The increase possible 

 would be proportionate to the extent of the declension in 

 the milk yields, and to the duration of the period covered 

 by such declension. 



During the period of highest milk yields, the cow and 

 a.so other females generally lose more or less in flesh. The 

 loss in body weight is proportionate to the relative milk 

 yields, but it may be affected to some extent by other in- 

 fluences such as inheritance and the nature of the food. As 

 the milk yields decline, the lost weight is gradually re- 

 stored under normal conditions, until it reaches the former 

 level. 



Age and milk production. Milk producing capacity 

 in cows may be divided into three periods, as follows : ( I ) 

 The period which leads up to maximum yields; (2) the 

 period of maximum yields; and (3) the period of declen- 

 sion which follows. These vary in individual animals and 

 to some extent in breeds. A good cow properly managed 

 should be profitable in the dairy for nine or ten years. This 

 period, however, is longer than the average dairy cow is 

 retained in the average herd. Assuming that the cow 

 produces profitably for, say nine years, the three periods 

 above referred to will cover three years each. The discus- 

 sion that follows is based on the assumption that cows 

 come into milk when two years old, which is usually the 

 case with dairy cows. 



