Uterine Contraction in Sows during Estrus and Puerperium, and in Sows with Multiple Follicular Cysts

Uterine contraction in sows during the estrous and puerperal periods, and in sows with multiple follicular cysts (MFC), were measured using a modified balloon method. On the basis of the graphs thus obtained, the frequency of uterine contractions, their average intensity and Planimeter (Pl) values were compared. In the puerperal period, contraction waves were completely different during suckling and not suckling period. Suckling stimuli affected contraction frequency and Pl values significantly (P<0.01). Immediately after parturition, the frequency of uterine contractions, their average intensity and Pl values tended to be high and decreased with the passage of time. For sows with weak contractions that required assistance in farrowing, intensity and Pl values were significantly low (P<0.05). For sows with small multiple follicular cysts (SMFC) and normal estrus, clear uterotonic activity was observed. Uterine contractile frequencies in sows with SMFC were slightly less frequent than in estrous sows, but greater contractions were observed, showing higher Pl values (P<0.05). These contractions also lasted a long duration. Moreover, intermittent uterine contractions were observed during the puerperal stage, whereas persistent uterotonic activity in SMFC and estrous sows.