SCIENTIFIC SWINE FEEDING 239 



that he will return to his former basis and be able to lay up any 

 of his salary at all. The same thing apparently takes place in 

 the protein metabolism of the pig. 



The pig being accustomed to metaboHze for maintenance 

 and waste 0.7 pound of protein a day will, for a time, when the 

 supply is reduced, use more for these purposes than is received, 

 consequently will reduce its store of protein tissue in the body. 

 However, after being fed a reduced ration for some time, the 

 factor of waste will gradually be reduced, the pig again reach- 

 ing a point of nitrogen equilibrium. This may be continued, 

 but under normal conditions it will never be possible to bring 

 the pig back to a point where it will be able to use for making 

 protein tissue as much of the protein of its food as it was able 

 to use before it was fed the maximum quantity. 



Jt has been found that the influence of high protein feed- 

 ing will, under normal conditions, continue in the metabolism 

 of the pig indefinitely and that the factor of waste is re- 

 duced with very great difficulty. Consequently, a pig after 

 having once been fed an excess of protein, is not as economical 

 a meat producer as it was before. Only an extended period of 

 feeding on a materially smaller quantity of feed and especially 

 protein will improve but not restore it to the original basis. 



The amount of protein that is necessary in developing pigs 

 is as follows: 



For Market Pigs. — The following figure applies to market 

 pigs that are started at two months of age and are to be finished 

 when eight months old. It shows the amount of digestible 

 crude protein required by the pigs daily for every 100 pounds 

 live weight, according to the data determined, for maximum 

 and most economical production. 



In this as well as in succeeding figures the vertical spaces 

 indicated by the top row of numerals represent weeks. The 

 second line of figures gives the age of the pigs by months. The 

 left hand or beginning space represents two months of age and 

 the right or close, eight months. The horizontal spaces indi- 

 cated by the numerals at the left refer to crude protein, carbo- 

 hydrates, ether extract, and water. These numerals represent 

 the amounts in pounds that are to be fed every day for every 

 100 pounds of live weight. In each case the amount is calcu- 

 lated upward from the base line. 



