Temporal candidate gene expression in the sow placenta and embryo during early gestation and effect of maternal Progenos supplementation on embryonic and placental development.

The present study characterised gene expression associated with embryonic muscle development and placental vascularisation during early gestation in the pig and examined effects of Progenos supplementation in early pregnancy. Tissues were collected from commercial multiparous sows (n = 48) from Days 16 to 49 of gestation. In the placenta, qPCR revealed that vascular endothelial growth factor (VEGFA) expression did not change from Day 17 to 49 of gestation; however, KDR receptor and angiopoietin-1 and -2 expression were differentially regulated, with periods of high expression corresponding to two critical phases of angiogenesis in the pig. In the embryo, the pattern of myogenesis-related gene expression was consistent with available literature. A commercially available nutritional supplement Progenos (20 g day⁻¹ L-arginine) added to the diet of sows from either Day 15 to 29 (P15-29; n = 33), Day 30 to 44 (n = 29) or from Day 15 to 44 (n = 76) of gestation tended to increase (P = 0.058) embryonic growth rate compared with non-supplemented controls (n = 79) and angiogenin expression was higher (P = 0.028) at Day 30 of gestation in placentae from sows on the P15-29 Progenos treatment. These results are consistent with proposed beneficial effects of l-arginine on early embryonic development and placental vascularisation.

Restricted feed intake in lactating primiparous sows. II. Effects on subsequent litter sex ratio and embryonic gene expression.

Expression of panels of candidate genes controlling myogenesis, angiogenesis and gender-specific imprinting of development were analysed in embryonic, placental and endometrial tissues recovered at Day 30 of gestation from a subset of primiparous sows that were either feed restricted (Restrict; n=17) or fed to appetite (Control; n=15) during the last week of the previous lactation. Embryos were also sex typed to investigate gender bias in response to treatments. Average embryonic weight was lower in the subset of Restrict compared with Control litters (1.38±0.07vs 1.59±0.08g, respectively) and the male:female sex ratio was higher (P<0.05) in embryos (litters) recovered from Restrict sows. Treatment affected (P≤0.05) the expression of embryonic and placental genes involved in insulin-like growth factor (IGF) 2 signalling, including IGF2, INSR and IGF2R. Embryonic expression of ESR1 was also affected by treatment (P<0.03) and sex×treatment interactions were observed for the expression of embryonic ESR1 (P<0.05) and placental ANGPT2 (P<0.03). At the molecular level, these results support the suggestion that changes in placental function are not the primary mechanism mediating detrimental effects of previous sow catabolism on early embryonic development in the feed-restricted lactational sow model. However, perturbations in the IGF2 system are implicated as mediators of these effects.