208 MANUAL OF FARM ANIMALS 



While no doubt some such formal standard as the Wolff- 

 Lehman or the Haecker should be followed in calculating the 

 amount of food required for milk production, yet it is well to 

 remember that there are many difficulties encountered in feeding 

 dairy cattle that standards cannot decide. Chief among these 

 are the digestibility of the food and the individuality of the ani- 

 mal. Our methods of arriving at the digestibility of foods are 

 crude, and foods vary widely in their digestibility, and either of 

 these difficulties may seriously interfere with such close figuring 

 as is recommended in the Haecker standards; that is to say, the 

 digestive values assigned the foods may easily be so erroneous as 

 to offset any saving that seemingly occurs from such calcula- 

 tion. 



The individuality of the cow is a factor which standards can- 

 not take into account. Cows vary widely in the amount of food 

 they will consume for the production of milk, some requiring 



twice as much food to produce 

 a given product as others. 

 Some hold that this variation 

 is due to the fact that the cow 

 will consume the feed, though 

 she does not need it, and that 

 by limiting her ration she can 

 often be made to produce at 

 a profit. That there is a vast 

 Fig. 72. — Holstein-Friesian Cow difference among individuals in 



"DicHTEE Calamity." Owned ,i j. r j j • j 



by John Arfman. the amount of food required 



for a given product must not 

 be lost sight of if one is to succeed in the dairy business. 



The age of the animal also has an influence on the amount of 

 food required for milk production. This subject has also been 

 investigated by Haecker. His experiments show that the heifer 

 requires considerably more nutrients for the production of a 

 given amount of fat than the mature cow. From these experi- 





