TREATMENT OF SWINE SUMMER INFERTILITY SYNDROME BY MEANS OF OXYTOCIN UNDER FIELD CONDITIONS

Endogenous oxytocin is released by the sow at the time of mating in re sponse to stimulation by the boar, which may explain, at least partial ly, the importance of the relationship between the boar's courting act ivity and the subsequent reproductive performance of the sow. The aim of this study was to determine the effects on reproductive performance of supplementing AI doses with exogenous oxytocin during the low fert ility season. At an intensive piggery in northwest Spain 3 experimenta l groups were randomly formed and observed throughout the year. Group 1 sows were inseminated with semen supplemented with 4 IU oxytocin. Gr oup 2 sows received 4 IU oxytocin injected through the vulvar lips muc osa at the time of insemination. Group 3 sows were inseminated without oxytocin and served as the controls. During the low fertility season the results for each group were as follows: farrowing rate 77.02, 56.2 5 and 54.39%, and litter size 10.77+/-0.28, 10.45+/-0.31 and 8.53+/-0. 34 respectively. It is concluded that the addition of oxytocin to semi nal doses just before AI is an easily applicable, effective method for increasing fertility and litter size during the summer months. (C) 19 98 by Elsevier Science Inc.