398 IOWA DEPARTMENT OF AGRICULTURE 



on mixing oil meal and tankage which Professor Evvard presented. 

 The cost per 100 pounds gain when oil meal was used as a corn sup- 

 plement was $5.62. When tankage was used as a supplement the cost 

 per 100 pounds gain was less, $5.30. Now, any hog which understood 

 even the rudiments of mathematics would know that, if it received a 

 ration in which these two feeds were mixed in equal proportion, it 

 should make 100 pounds gain at an average of these two costs; i. e., 

 $5.46. A hog works in total disregard of this rule, however, and the 

 cost of 100 pounds gain when oil meal and tankage are mixed half 

 and half is only $5.04, considerably less than when either food is given 

 alone. This fact amounts virtually to a demonstration of the propo- 

 sition, that the only way to find out how best to feed a pig is to feed 

 it, the several possible conditions and combinations must be tried, the 

 results carefully recorded, and the verdict given on the evidence 

 obtained. A never-ended work lies here for the experimental animal 

 husbandman. 



However, the pig is not altogether without knowledge on dietary mat- 

 ters. In fact, he shows astonishing skill in compounding his own ration, 

 exhibiting in this regard, a fineness of discrimination not possessed by 

 man himself. A bunch of sows weighing 260 pounds was divided into 

 two lots and both put on the same forage. Lot 1 received shelled corn 

 in a self feeder; the sows gained 2.4 pounds a day and 457 pounds of corn 

 were required for each 100 pounds of gain. Lot 2 was put in the care of 

 an expert feeder with instructions to secure the very greatest gains pos- 

 sible, but the corn was fed out by hand; the sows only gained 2.09 pounds 

 a day and there were required for each 100 pounds gain 478 pounds of 

 corn, twenty-one more pounds than when the corn was taken out of a 

 self feeder. Or again, two lots of pigs were fed on shelled corn and 

 tankage. The pigs in Lot 1 had access to the corn and the meat meal, 

 each in a self feeder, at whatever moment of the day or night they chose 

 to nibble. Lot 2 was fed with greatest possible care, by hand. 



Lot 1. 

 Lot 2. 



The results, as shown in the above table, indicate the advisability, within 

 limits, of giving to the pigs greater freedom in eating what and when 

 they choose. 



In the discussion which followed Professor Evvard's report it devel- 

 oped that certain hog raisers discriminated against tankage because of 

 its supposed liability to carry hog cholera infection. Professor Evvard 

 pointed out that although undesirable, animal refuse, often cholera- 

 infected hogs, is used in tankage manufacture, nevertheless, in the process 

 of manufacture the mass is raised to a heat great enough to kill all 

 cholera germs. The only chance of meat meal carrying cholera infec- 

 tion is from contamination while it is being sacked, or afterwards, by 

 contact with a contaminated body. In well-organized packing houses, 

 this possibility is carefully guarded against, and this most excellent 



