155 Evaluation of bovine embryo morphology and subsequent postnatal phenotype following conception in the presence of seminal plasma

The uterine environment at conception is critical for early embryonic development of the conceptus and subsequent pregnancy success. In rodents, swine, and humans, seminal plasma facilitates sperm transport in the female reproductive tract and actively modulates the cellular and molecular maternal environment at the time of conception and early embryo development. Minimal data for a role of seminal plasma in modulating the uterine environment of the cow exists; however, supplementation of seminal plasma at the time of conception in primiparous dams inseminated with X-sorted semen increased birthweight of resultant female calves. Here we hypothesised that intrauterine supplementation of seminal plasma at insemination would improve embryo morphology and reproductive performance of subsequent female offspring. First, we evaluated the impact of seminal plasma supplementation at conception on in vivo-produced embryos. A total of 17 multiparous non-lactating dairy cows were subjected to oestrus synchronisation using a modified Double-Ovsynch protocol with superovulation followed by timed artificial insemination using X-sexed semen. At the time of insemination, cows were randomly assigned to receive an intrauterine infusion of either 0.5 mL of pooled seminal plasma or 0.5 mL of saline as a control using a crossover design in two cohorts. On Day 7 after insemination, cows were nonsurgically flushed to collect in vivo-derived embryos and assess embryo morphology. Data were analysed using a binary logistic regression with the generalised linear mixed model procedure. The total recovered oocytes and embryos from control and seminal plasma supplemented cows (6.8 ± 1.3 vs. 9.0 ± 1.2) and proportion of transferable embryos including blastocyst and morula (55.0% ± 8.7 vs. 61.9% ± 4.9) were not affected by seminal plasma supplementation. Second, we analysed the reproductive performance of female offspring conceived in the presence of seminal plasma. The production records of 214 heifers conceived in the presence of seminal plasma (n = 103) or saline as a control (n = 111) were analysed with the generalised linear mixed model procedure. Age at first insemination (390.6 days ± 2.1 vs. 388.5 ± 2.2), age at first conception (423.0 days ± 4.2 vs. 421.1 ± 4.4), or pregnancy per artificial insemination (2.2 ± 0.1 vs. 2.1 ± 0.1) were similar if heifers were conceived in the presence of saline or seminal plasma, respectively. These data support that there is no negative effect of seminal plasma supplementation on embryo morphology or reproductive performance of offspring. Nonetheless, we intend to further evaluate the impact of seminal plasma supplementation on the molecular quality of in vivo-produced embryos and the milk production of offspring conceived in the presence of seminal plasma.