Abstract
BACKGROUND AND AIM: Previous findings regarding the effects of farrowing induction on the farrowing characteristics of sows are controversial. This study aimed to investigate the effects of farrowing induction on the following characteristics: (1) Proportion of sows that farrowed during working hours, (2) stillbirth rate, (3) number of stillbirths per farrow, (4) dystocia rate per farrow, (5) dystocia rate (the proportion of farrowings that had at least one dystocia event), (6) number of dystocia events per farrow, (6) farrowing duration, (7) birth interval, and (8) birth weight. MATERIALS AND METHODS: Thirty-eight Landrace x Yorkshire sows were randomly allocated into two groups; the control group and the treatment group. In the control group (n = 18), sows farrowed spontaneously. In the treatment group (n = 20), farrowing was induced approximately 2 days earlier than the herd's average length of gestation (7:00 am on day 114) by injecting cloprostenol into the perivulval region. All sows were supervised throughout their farrowing. We recorded the interval between induction and farrowing; total number of births; number of live, stillborn, and mummified piglet births; number of dystocia events; birth interval; farrowing duration; and birth weight. A generalized linear mixed model, a linear mixed-effects model, the Chi-squared test, and Student's t-test were used to compare outcomes between the two groups. RESULTS: Farrowing induction did not influence the percentage of sows that farrowed during working hours (7 am-5 pm), stillbirth rate, birth weight, and number of dystocia events per farrow. Farrowing induction led to an increase in birth interval, dystocia rate, dystocia per farrow (p < 0.05) and in addition to the percentage of sows that farrowed on the day following induction (60% vs. 27.8%; p < 0.05). CONCLUSION: Farrowing induction using a single dose of cloprostenol 2 days before the expected farrowing date can be performed with care to concentrate farrowing into a short interval. This can enhance the optimization of cross-fostering and the practice of an all-in-all-out strategy in the swine breeding industry.