FKKDING WORK ANIMALS AND GROWING ANIMALS 



457 



animals. A calf two to three weeks old has been known to re- 

 tain 73 per cent, of the proteids consumed. As the animal grows 

 older, the percentage of the food retained in the body decreases. 

 The proportion of food eaten to live weight also decreases; thus, 

 a larger proportion of the food must be used for maintenance. 



The following experiments of Weiske 1 were begun with lambs 

 four months old, and carried out in 7 periods of i^ months each. 

 The nutritive ratio was 1 : 4.6 at first and later, when about 15 

 months old, was i : 6.3. 



PER 50 KILOGRAMS LIVE WEIGHT. 



The quantity of food per 50 kg. weight consumed, decreases 

 with the age of the animal, and the gain in weight decreases much 

 more rapidly. Thus, the food eaten in the 8th period is 7/11 of 

 that in the first, while the gain is only ^. 



The increase in weight of young animals is largely flesh, body 

 organs, and bones. They thus require considerable protein. 

 Young animals also require more mineral matter than older ones, 

 to build up the bones. Lime and phosphoric acid especially are 

 required. The preceding table shows the decreased retention of 

 lime with age of the animal. 



The following data compiled by Henry from the results of a 

 number of feeding experiments with pigs at various Experiment 

 Stations, shows the increase in the quantity of food required for 

 a pound of gain as the animal grows older : 

 1 Landw. Jahrbucher, 1880, p. 205. 

 30 



