Impact of Embryo Transfer on the phenotype of the offspring in pigs

Abstract Background The increased use of assisted reproductive technologies led to a higher risk of specific alterations in the offspring, as already described in human and other mammalian species. Nonetheless, it is yet to be totally understood how and which specific techniques are inducing these changes. The use of animal models may represent an advantage to find out answers to these questions due to the minimization of confounding factors. The pig is not only a great human reproductive model, but it is also of interest in the livestock industry to develop further technologies that may enhance meat production. This study was designed to decipher the impact of one of these technologies, namely embryo transfer, on mother´s reproductive performance and on the phenotype of the offspring in pigs. Results Embryo transfer of in vivo derived embryos (ET) showed similar results in terms of pregnancy length, litter size and total litter weight per sow than sows artificially inseminated (AI). Bodyweight at birth was higher for ET-females than AI-females, but this difference was no longer observed at day 15 of postnatal life. Some of the major findings after haematological analyses were that concentration of red blood cells, haemoglobin and haematocrit in female-ET piglets at day 3 showed higher values than AI-females. Additionally, higher concentration of white blood cells was found at day 3 in both ET-derived piglets (males and females) in comparison to AI-piglets. Biochemical analysis showed a higher level of albumin at day 3 for ET-derived male piglets than AI but ET-females showed lower levels of bilirubin than AI in the same day. Despite the statistical differences between groups, all values were within the normal ranges, so that we cannot give them any clinical significance. Conclusions Piglets derived from in vivo embryo transfer seem to be phenotypically similar, which provides evidence that the embryo transfer procedure is a safe technique, without relevant health implications to the offspring. Additionally, these findings may be of interest to the pig industry regarding the reference values provided for haematological and biochemical parameters in this species.