A low concentration of choline chloride alters the developmental program of the bovine preimplantation embryo.

Abstract

Choline is a known developmental programming agent of the bovine preimplantation embryo. Culture of the embryo with 1.8 mmol/L choline, a concentration much higher than in blood, alters development to cause increased weaning weight and other changes during the postnatal period. It was hypothesized here that choline exerts similar effects on the developmental program of the embryo when added at concentrations similar to those in peripheral blood (i.e., 4 mol/L). Oocytes were collected via ovum pick up and embryos were produced in vitro. Embryos were cultured until day 7 after fertilization in medium with 4 mol/L choline chloride, or, as a vehicle control, with an additional 4 mol/L sodium chloride. Blastocysts were transferred into recipients and pregnancy was diagnosed at approximately 28 d of gestation. Subsequent calves (n=37 for vehicle and n=35 for choline) were weighed at birth and at weaning. Addition of choline to culture medium did not affect the proportion of embryos that became blastocysts or the proportion of transferred blastocysts that produced a pregnancy. Birth weight was unaffected by treatment but calves derived from choline-treated embryos were heavier at time of weaning and gained more per day from birth until weaning than calves derived from embryos treated with vehicle. Results demonstrate that choline can act on the preimplantation embryo at a physiologically-relevant concentration to alter postnatal phenotype. Observations are further evidence for the importance of the first days of embryonic development for the phenotype of the resulting calf.