Provision of choline chloride to the bovine preimplantation embryo alters postnatal body size and DNA methylation.

Choline is a vital micronutrient that can be utilized in the formation of betaine and multiple phospholipids. In this study, we aimed to confirm, and expand on previous findings, how choline impacts embryos from the first 7 days of development to affect postnatal phenotype. Bos indicus embryos were cultured in a choline-free medium or medium supplemented with 1.8 mM choline. Blastocyst-stage embryos were transferred into crossbred recipients. Once born, calves were evaluated at birth, 94 d, 178 d and at weaning (average age=239 d). Following weaning, all calves were enrolled into a feed efficiency trial before being separated by sex, with males being slaughtered at approximately 580 d of age and females followed until their first pregnancy check. Results confirm that exposure of 1.8 mM choline chloride during the first 7 d of development alters postnatal characteristics of the resultant calves. Calves of both sexes from choline-treated embryos were consistently heavier through weaning. Males had heavier testes at 3 mo of age. There were sex-dependent alterations in DNA methylation in whole blood caused by choline treatment. After weaning, feed efficiency was affected by an interaction with sex, with choline calves being more efficient for females and less efficient for males. Calves from choline-treated embryos were heavier, or tended to be heavier, than calves from control embryos at all observations after weaning. Carcass weight was heavier for choline calves and the cross-sectional area of the Longissumus dorsi muscle was increased by choline. Few females became pregnant during the experiment although numerically more choline females were pregnant than control females. Results confirm that exposure of the preimplantation embryo to 1.8 mM choline altered phenotypes of the animal through the first 19 months after birth. Whole blood samples were collected from the jugular vein of a randomly selected subset of 6 animals from each treatment-sex subgroup (i.e., n=24 total, 6 females derived from control embryo, 6 males derived from control embryo, 6 females derived from cholin-treated embryo and 6 males derived from cholin-treated embryo) and used to determine DNA methylation using whole whole genome enzymatic methyl sequencing.