28 SOUTHERN rORK PRODUCTION 



Fecundity is determined to a ver_y large extent by en- 

 vironmental conditions, such as exercise, confinement, 

 climate, food supply, and season; in addition, it is in- 

 fluenced by such factors as age, size, condition, disease 

 and health, constitution and conformation. The most 

 common causes of a low fecundity are lack of exercise 

 and too high a condition. As to age, usually the number 

 of pigs in the first litter is less than the number in the 

 next few litters ; then, after five or six years of rather 

 heavy production, there is a more or less gradual, some- 

 times rapid, decline, until the breeding powers cease, at 

 about ten years, a few remaining active breeders beyond 

 this age. Of course, the higher producing sows are more 

 desirable. Even though under the most favorable con- 

 ditions natural selection will assist materially in weeding 

 out the poorer breeders, care should always be taken 

 in the making of selections of breeding animals to choose 

 only those animals coming from large litters. 



Determination of sex. — Rules for the control of sex 

 seem to have always existed, and they still flourish. 

 Thousands of theories have been propounded, and all 

 have failed to survive the tests of time. 



The hog breeder. — To be a successful hog breeder one 

 must have a high-class breeding herd and yet be able to 

 produce each )ear individuals that are an improvement 

 over their parents. This requires a man of more than 

 ordinary ability and skill. He must of necessity' give his 

 work great thought. He should know the demands of the 

 market and breed accordingly. The known laws of 

 breeding should be utilized. Men capable of becoming 

 successful hog breeders are few, especially as compared 

 with those who would make successful producers of 



