Fixed-time post-cervical artificial insemination in sows receiving porcine luteinising hormone at oestrus onset

Fixed-time post-cervical artificial insemination (FTPCAI) allows a wider use of high indexing boars and a considerable reduction in labour requirements in swine production. The aim of this study was to evaluate fixed-time artificial insemination (FTAI) efficiency using different artificial insemination protocols and porcine luteinising hormone (pLH) to induce ovulation. A total of 597 weaned sows in which oestrus detection was performed once daily (08:00 am) was allocated to three groups: FTPCAI1 (n = 199) – sows received a 5-mg (4 ml) intramuscular injection of pLH at oestrus onset, and were inseminated 24 h later; FTPCAI2 (n = 199) – sows received 5 mg of pLH and were inseminated at oestrus onset (0 h) and 24 h after; and MultPCAI (n = 199) – sows did not receive pLH, and the first AI was performed at oestrus onset (0 h) and repeated every 24 h during oestrus. Homospermic doses (1.5 × 109 total sperm cells/50 ml) were used in post-cervical artificial insemination (PCAI) in all the treatments. Hormonal treatment did not affect (P > 0.05) the interval between oestrus onset and ovulation (overall 32.4 h) and there were no differences (P > 0.05) in farrowing rate (overall 91.6%) or litter size (overall 12.6 piglets born) among treatments. In sows treated with pLH at oestrus onset, a single PCAI with 1.5 billion sperm cells did not compromise reproductive performance compared with a double PCAI at 24 h intervals.