GROWTH AND FATTENING 95 



confined in pens, with exercise yards floored with boards, so the pigs 

 could eat no dirt. The pigs fed corn alone soon failed to grow and be- 

 came unduly fat and dwarfed. Those receiving wood ashes or bone meal 

 in addition grew quite well for a time, but later their gains were poor. 

 On corn alone 629 Ibs. of corn was required for 100 Ibs. gain in weight, 

 while only about 490 Ibs. of corn was required when wood ashes or bone 

 meal was added. Also the bones of the pigs fed corn alone were only 

 half as strong as those of the others. These trials clearly showed that 

 adding a liberal supply of lime to the ration was of some benefit but did 

 not entirely remedy the deficiencies of corn for growing animals. 



In later years numerous trials have been carried on by scientists to 

 study this matter further. These investigations have clearly shown that 

 to make a complete and satisfactory ration for growing animals, there 

 must be added to corn not only a supply of lime, but also an additional 

 supply of protein, and furthermore protein which is better balanced in 

 composition than that which the corn grain furnishes. (118) Recent 

 studies have also shown plainly that for pigs not on pasture, the amount 

 of fat-soluble vitamine in white corn is too low for normal growth. 

 (202, 939) 



The earlier trials with corn alone were carried on chiefly with pigs 

 which were fairly well grown when the experiments began. Extensive 

 experiments carried on at the Kansas Station by Waters, Cochel, Hogan, 

 and Vestal have shown in a striking manner that young pigs can not be 

 raised on corn alone. In a trial reported by Hogan* 2 pigs weighing 

 about 25 Ibs. were fed corn with various supplements. On corn plus a 

 mixture of mineral matter containing an ample supply of lime, pigs made 

 practically no growth, gaining only 12 Ibs. each in 180 days ! However, 

 when not only mineral matter but also milk casein, a well-balanced pro- 

 tein, was added to corn, the pigs gained 179 Ibs. each in the same time. 



The effect of feeding varying amounts of protein when an abundance 

 of mineral matter was supplied was studied by Grindley and colleagues 

 at the Illinois Station. 43 Pigs fed rations very high in protein had 

 larger livers and kidneys, and heavier and stronger bones than when a 

 smaller amount of protein-rich feed (blood meal) was supplied. No dif- 

 ference was found in the forms of nitrogenous compounds in the protein 

 tissues or in the distribution of the mineral matter among the various 

 organs of the body. 



135. Discussion of the pig-feeding experiments. These experiments 

 are of profound importance in pointing out the requirements of growing 

 animals and in showing the effects of feeding them rations which are 

 not properly balanced. Only by paying heed to these basic facts can 

 live stock be raised on the farm at the minimum of expense and, espe- 

 cially, only thus can the breeder of pure-bred stock make the desired 

 improvement in his herds or flocks. 



^Jour. Biol. Chem., 29, 1917, pp. 485-493. 

 ni. Buls. 168, 169, 171, 173. 



