The maternal environment during gestation influences fetal development, with long-lasting effects on postnatal health and productivity. This study evaluated the effect of prenatal heat stress (PNHS) o Show more
The maternal environment during gestation influences fetal development, with long-lasting effects on postnatal health and productivity. This study evaluated the effect of prenatal heat stress (PNHS) on blood DNA methylation of dairy calves immediately after birth and whether such modifications persist into early life. Holstein calves were born to dams exposed to either PNHS (n = 36, temperature-humidity index >68, access to shade of a freestall barn) or prenatal cooling (PNTN; n = 37, access to shade and evaporative cooling) during the last 54 ± 5 d of gestation. Whole-genome enzymatic DNA methyl sequencing was performed on blood samples collected at birth (d 0; n = 3 PNHS, n = 5 PNTN) and 1 wk post-weaning (d 63 of age; n = 8 PNHS, n = 8 PNTN). From birth onward, all calves were actively cooled and managed under the same conditions. At birth, 682,898 differentially methylated cytosines (DMC) were identified genome-wide. Principal component analysis using 55,304 DMC located in genes expressed in blood cells revealed a clear clustering by prenatal treatment. However, at weaning, clear clustering by treatment was no longer observed using 23,977 treatment-associated DMC in blood-expressed genes, despite 97,289 DMC persisting genome-wide from birth to weaning. Immune cell deconvolution showed only minor differences in granulocytes (d 0) and CD4/CD8 Show less