Abstract
As a method for easily detecting a suitable time for inseminating sows in swinebreeding farmers for wider popularization of artificial insemination, pH of vaginal mucus of sows in estrus was determined so as to know whether or not this would serve for grasping the optimal time for insemination.
The results were as follows.
Differences were noted between the determination results with BTB test paper and those with a portable pH meter. The BTB test paper readily reacts with polluted air in piggeries and tends to be inaccurate. It is therefore recommendable to use the pH meter for this determination.
From the results of determination with a pH meter, it was noted that the pH of vaginal mucus on the day of the oncet of estrus is higher than 7.3, slightly alkaline, regardless of breeds and age of tested swine and that during the period of acceptance of boars the pH of vaginal mucus was within the range from 7.2 to 7.3 in all the breeds. This condition seemed to continue during the period of boar acceptance. When the estrus is over and sows no longer accept boars the pH of the vaginal mucus tends to be slightly lower than it is during the boar acceptance.
The relationship between the pH of the vaginal mucus on the day of insemination and the conception rate was investigated to know that the insemination to sows on the day with pH of 7.2-7.3 turned out to be 93.8% in Landrace Breed, 66.7% in Large White Breed, and 92.3% in Hampshire Breed, proving to be good conception results. Considerably good results could be obtained with guts if the pH of vaginal mucus was 7.2-7.3 at insemination, although it was difficult to obtain as good results as in sows.
Generally speaking, the pH of the vaginal mucus turns into slightly alkaline, higher than 7.3, following the oncet of estrus, and subsequently is lowered to 7.2-7.3 in the period suitable for insemination, but tends to be further lower following termination of the estrus after the suitable period for insemination to sows would be the day when the pH of the vaginal mucus shows 7.2-7.3 and the behaviors of sows after the oncet of estrus and the conditions of external genitals are regarded upon inspection as accepting the insemination.
