FEEDING SWINE 421 



It has long been known that, as pigs grow older, other things 

 being equal, it requires more grain for 100 pounds of gain in 

 live weight. If we apply the relationship of age to weight, 

 then of a large number of animals fed at different weights, as 

 shown by Henry and Morrison,* the amount of food required 

 for 100 pounds gain in live weight steadily increased from 

 293 for a pig weighing from 15 to 50 pounds, up to 535 pounds 

 for one weighing from 300 to 350 pounds. It is important, 

 however, to note that, as the pig gained in weight, there was 

 a decrease in the amount of food eaten daily for each 100 

 pounds of live weight. The average daily gain in live weight 

 increased up to 300 pounds, after which it fell off slightly. 



The influence of breed in pork production, so far as the 

 relationship of food consumed to gains in weight is con- 

 cerned, is problematical. In experiments reported upon by 

 Prof. G. E. Day, of Canada, f in which five tests were con- 

 ducted upon six breeds at the Ontario Agricultural College, 

 and in three tests at the Iowa station, no very satisfactory 

 results were secured. "Why, for instance," writes Prof. 

 Day, "do Berkshires, Yorkshires, Duroc-Jerseys and Poland- 

 Chinas range all the way from the top to the bottom of the 

 list in the different tests; and why would an average of the 

 Ontario tests give a rating of the breeds which is entirely 

 different from an average of the Iowa tests? " In the opinion 

 of many practical swine breeders, some breeds produce pork 

 more economically than others, but we have very insufficient 

 evidence to prove that one breed is better than another. 



Mineral food for swine is of first importance. When 

 we realize that an animal can not live without iron in its 

 blood, and that over 90 per cent of the bony system con- 

 sists of calcium and phosphorus, we must appreciate the 

 importance of these substances in the food. For many 

 years swine growers in the corn belt have been accustomed 

 to placing ashes or soft coal in the pig lots. This was eaten 



*Feeds and Feeding, 1917. 

 fProductive Swine Husbandry, 1915. 



