Size of Litters 103 



most hog-men, and experience supplies many instances 

 which seem to prove this claim. On the other hand, 

 the known facts relating to the reproductive process do 

 not seem to supply any ground on which to base this 

 belief; in fact, they indicate that such influence under 

 normal conditions is an impossibility. It is known, 

 for example, that there cannot be a larger number of 

 pigs in the litter than there are eggs produced by the 

 sow at breeding time ; also, that in normal breeding serv- 

 ice the boar supplies a thousand sperms and more for 

 each egg produced by the sow. Under conditions, there- 

 fore, in which the sow and boar are both vigorous, there 

 would seem to be no chance or possibility for the num- 

 ber of pigs farrowed to be in any way affected by the 

 boar. 



But the sow and boar are not always vigorous, and 

 the facts also support the view that when this is 

 the case the union of the sperms with the eggs may 

 be so weak that not all of them develop completely in 

 embryo; the result is a smaller litter. A boar that is 

 over-used during the breeding season, or is run down 

 and out of condition, or that is lacking in normal fer- 

 tility or vigor, may produce a considerable number of 

 sperms which, although strong enough to fertilize the 

 eggs, lack the life to insure the full embryonic develop- 

 ment of the pigs from these unions. There is good reason 

 for believing, therefore, that in such instances the size 

 of the litter may be influenced below the normal by the 

 boar with which the sow was mated. It should be 

 understood that in no case, however, can the boar cause 

 the number of pigs to be increased beyond that num- 

 ber of eggs produced at the time the sow was mated. 

 (See p. 17.) 



