112 Pork Production 



produce germ-cells endowed with the maximum of vigor 

 or growth energy ; while those in a run-down, weakened, 

 or unthrifty condition produce germ-cells which lack 

 the life necessary for the conception of vigorous young. 



Sows bred immediately after weaning large litters of 

 pigs, when "pulled down" and weakened in condition, 

 before they have had the opportunity to recuperate, 

 produce not only small litters but also pigs which in- 

 dividually are lacking in strength and development. 

 For the same reason, sows in a state of extreme fatness 

 at breeding time, especially if closely confined, do not 

 produce, as a rule, strong pigs. Each pig is the product 

 of two germ-cells, one produced by the sow and one by 

 the boar. If the breeding condition of the boar is at 

 low ebb at this time, as the result of insufficient or 

 excessive feed, lack of exercise, over-use, or disease, his 

 germ-cells, like those of the sow, will lack the life necessary 

 to insure vigorous pigs. It is reasonable to conclude 

 that one of the causes responsible for small weak pigs 

 is the practice of breeding the sows when they and the 

 boar are not in vigorous breeding condition. These 

 observations emphasize the need of more careful attention 

 to feeding and exercise prior to and during the breeding 

 season. 



Nutrition. 



Probably the fundamental factor determining the 

 size and development of pigs at birth is the completeness 

 of their nourishment during embryonic development. 

 Both the amount and kind of feed are important in 

 determining the supply of this nourishment. When 

 the ration is deficient in lime and protein, as is not un- 

 common in the corn-belt, the result is a weak and im- 



