The effect of cloprostenol alone or with oxytocin on induction of parturition, litter characteristics and subsequent fertility of the sow

The present trial investigates the effect of cloprostenol (CLO) injection (175 mu g 0.175 mg per animal, per injection) on the 111th, 112th or 113th day of pregnancy, alone, or followed by an oxytocin (OXY) injection (10 IU) 24 h later, on the induction of parturition, litter characteristics and subsequent fertility of the sows. For this purpose 180 healthy pregnant crossbred sows (Large White x Landrace) were used. The sows were randomly divided into the following three treatment groups (60 sows per group): T1 controls (placebo 1 + placebo 2), T2 (CLO + placebo 2) and T3 (CLO + OXY). The sows of each group were further divided into three subgroups (20 sows per each subgroup) according to the time of the first injection (111th, 112th and 113th day of pregnancy). The results indicated that treatment with CLO + OXY on days 111, 112 and 113 of pregnancy is effective for the induction of parturition within an 8-h working day. However, treatment with CLO + OXY on day 111 should be avoided because in the present trial it led to a longer (p < 0.05) first-to-last piglet delivery interval, a larger number of sows requiring manual assistance and showing signs of MMA and a larger number of stillborn piglets; the weaning-to-conception interval was also higher, while the number of weaned piglets was lower (p < 0.05). Although treatment with CLO + OXY on day 112 and 113 did not improve the litter characteristics (the number of live-born and weaned piglets), it can be safely used for the induction of parturition within the working hours of the day.