FOOD REQUIREMENTS 375 



Haecker's standard for dairy cows allows for maintenance 

 for a 1000 lbs. cow 0*7 lbs. of protein, 7-0 lbs. of carbo- 

 hydrates, and -1 lb. of fat. The additional food requirement 

 for the production of the milk varies with the composition 

 of the milk, which is judged by its fat content. 



6. Work. — The efficiency of the horse and its capacity 

 for mechanical work have been considered (p. 252). (a) The 

 energy of the food must cover the maintenance requirement 

 (p. 371). If the efficiency be taken as 38i per cent., the 

 food must in addition supply 3^ times the energy expended 

 in mechanical work. It is estimated that a horse of 

 1000 lbs. weight, working a full day of eight hours^ will do 

 work equivalent to between 4000 and 5000 Calories. The 

 food therefore should contain between 12,000 and 15,000 

 Calories, in addition to the maintenance requirement. 



(6) The protein metabolism is little atfected by work, so 

 long as a sufficient supply of carbohydrates and fats are 

 available as a source of energy (p. 262). There is therefore 

 no need for any marked increase of the protein above the 

 maintenance requirement. 



The food requirement for a working horse, doing a full 

 eight-hour day's work, should yield about 1 to 2 lbs. protein and 

 80,000 Calories, i.e. nearly double the maintenance require- 

 ment. 



3. Feeding Standards, 



Various feeding standards have been proposed as guides 

 to feeders. In these, the food required for different animals 

 and for different kinds of production are usually stated in 

 lbs. for an animal of a fixed weight — 1000 lbs. live weight 

 for large animals. The ration for anv individual animal can 

 be calculated according to its weight (p. 265). 



Three standards which are commonly used may be briefly 



