CHAPTER XX 



THE GENERAL INFECTIONS OF THE 

 GENITALIA OF SWINE 



The general infections of the genitalia of swine are of far 

 greater economic importance than has yet been generally 

 recognized. Adult sows (and probably also gilts) ordinarily 

 discharge at each estrum twelve to eighteen or more ova. 

 If each ovum were physiologically healthy, the genital tract 

 healthy, and the sow copulated with a thoroughly healthy 

 boar, there would be a vigorous live pig born for each ovum 

 discharged. It was stated, while considering reproduction 

 in cattle, that in purebred dairy herds there is born as a 

 rule about one viable calf for each three copulations, or 

 that about 67 per cent, of the efforts at reproduction fail. 

 A similar condition exists in the production of swine, but 

 the result is screened from general observation. Since the 

 sow is muciparous, if infection of her genital tract is mod- 

 erate only, some of the ova may be fertilized, develop, and 

 be born in viable health. The same is true of the boar. If 

 infection exists in his genitalia which destroys but a part 

 of the spermatozoa or later brings about the death of only 

 a portion of the embryos, some pigs are born, but the num- 

 ber is depressed in harmony with the amount of the infec- 

 tion existing within the uterus of the sow at the date of 

 coitus, plus the infection ejaculated with the semen of the 

 boar. So far as I am able to estimate, these infections re- 

 duce the number of pigs born upon the average 50 per cent, 

 which means that swine breeders maintain two brood sows 

 to perform the ideal work of one. The swine breeder ordi- 

 narily does not comprehend the meaning of a litter of four 

 to six pigs, and unconsciously attributes the low fertility to 

 some vagary of "nature", but a careful study of gravid 

 swine uteri in the abattoir permits a quite different inter- 

 pretation. 



Abattoir studios of pregnanl swine uteri reveal several 

 very interesting and important farts which are highly il- 



