Stimulating a fertile oestrus during lactation in pigs allows increased piglet weaning age without decreasing farrowing frequency. However it is important that ovarian follicle growth and oocyte quality is not reduced when mating in lactation. Anti-Mullerian Hormone (AMH) is a marker for ovarian reserve in many species and low AMH levels have been linked to poor oocyte quality in humans (Lekamge et al., 2007). We hypothesised that lactating sows with HIGH AMH on day 21 post-parturition would have a larger and more mature ovarian follicle pool and oocytes with greater developmental competence in vitro than sows with LOW AMH.
On day 18 post-parturition, 33 Large White x Landrace lactating multiparous sows commenced daily 15 minute boar contact. On day 21 post-parturition, a blood sample was collected, sows were slaughtered, surface ovarian follicles were counted and cumulus-oocyte complexes were collected for in vitro embryo production (Kelly et al., 2010). Plasma AMH was measured with the Human MIS/AMH DuoSet ELISA Kit (Beckman Coulter, Roissy, France) previously validated for bovine. Sows were divided into HIGH (77.0 ± 8.5 ng/mL) or LOW (9.0 ± 9.0 ng/mL) AMH groups using the median value of AMH. ANOVA was used to determine the effects of HIGH or LOW AMH on all variables (GenStat Version 11, VSN International, England, UK).
Sows with HIGH AMH tended to have more surface follicles > 6 mm (17.8 ± 2.1 versus 12.4 ± 2.1; P<0.1). AMH concentration did not affect embryo cleavage or blastocyst development rates, however, blastocysts from HIGH AMH sows had greater total cell number than those from LOW AMH sows (37.2±3.6 versus 21.8±4.3; P<0.05). These results indicate that HIGH AMH sows have a more mature ovarian follicle pool during lactation, and while embryo development rates were unaffected by AMH levels, embryo quality was improved in HIGH AMH sows.