Interpretive Summary: Epigenetic changes in the offspring of heifers fed a restricted maternal diet
By: Anne Kamiya, MS
Residual feed intake (RFI) is a desired heritable trait in beef cattle. Animals with lower RFI are more feed efficient although epigenetic variations can impact this trait. The environmental circumstances and molecular mechanisms behind how epigenetics leads to variations in RFI however are not well understood. One such potential contributor to epigenetic variations in RFI is maternal nutritional status, which may subsequently impact the lifelong performance and growth of offspring. In this recent Journal of Animal Science article, researchers aimed to elucidate how maternal nutrition and epigenetics might impact RFI, a desired trait that improves performance.
The offspring of purebred Angus heifers who were fed a moderate or restricted maternal diet were evaluated for differences in DNA methylation patterns. Specifically, this included DNA methylation analysis of differentially methylated regions (DMR) of genes for insulin-like growth factor 2 (IGF2) and IGF2R in liver and muscle tissue. Insulin-like growth factors are hormones vital for optimal metabolism, muscle development and fetal growth, particularly in early development. Offspring included those with high (HRFI) and low (LRFI) potential for RFI.
The LRFI offspring had increased IGF2 and IGF2R methylation in the liver compared to HRFI cattle. Methylation in muscle tissues were higher in the offspring of heifers fed maternally restricted diets, regardless of if they were HRFI or LRFI. Of note, methylation levels increased at weaning and slaughter from levels at birth. The authors concluded that pre-natal nutrition impacts the methylation status of IGF2 and IGF2R in muscle and liver tissue and that methylation status of specific genes may eventually become a valuable addition to heritable trait databases. More studies looking into how epigenetic changes impact desired heritable traits is justified.
The original article, Genetic potential for residual feed intake and diet fed during early- to mid-gestation influences post-natal DNA methylation of imprinted genes in muscle and liver tissues in beef cattle, will soon be viewable in the Journal of Animal Science.