Performing Department
(N/A)
Non Technical Summary
This proposal aims to fill a gap in understanding how both parents' diets affect the health, productivity, and reproduction of their offspring, along with the underlying epigenetic processes. The first part involves studying how the combined diets of both parents impact future generations. Specifically, we will provide methionine supplements to male and female sheep before breeding and then observe the traits of their offspring over multiple generations. We will also investigate how the fathers' diets influence traits through changes in sperm DNA. The second part focuses on the effects of the mothers' diet on oocytes and embryos. We expect that supplementing methionine to ewes during conception will alter the genetic makeup of the eggs and embryos, affecting the development of the offspring. This research will help us understand how nutrition before pregnancy shapes the growth and performance of the offspring.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Goals / Objectives
Objective 1: Assess the impacts of the combined maternal and paternal nutrition on the phenotypic traits of subsequent generations. The working hypothesis of this objective is that a moderate increase in dietary methionine (as a methyl donor) fed to rams and ewes around conception will lead to altered programming of the offspring's phenotypes.Objective 2: Elucidate the epigenetic mechanisms by which a combined maternal and paternal diet affects offspring traits. Our working hypothesis is that methionine intake will subsequently contribute methyl groups to the sperm and oocytes' DNA and embryos (DNA methylation), which in turn will be inherited by the offspring. Changes in DNA methylation will alter gene expression and result in phenotypic changes in the offspring.Objective 3: Assess the impacts of maternal nutrition alone on oocytes and embryos. The working hypothesis of this objective is that methionine supplementation to ewes around the time of conception will alter the epigenomic and transcriptomic landscapes of the oocytes and embryos, affect fetal programming, and lead to phenotypic changes in the offspring.
Project Methods
In this proposal, we will evaluate the influence of rumen-protected methionine supplemented in both paternal and maternal diets on offspring and grand-offspring's production and reproduction traits. For males, the methionine supplementation in this proposal will span the developmental stages from weaning to puberty, where heritable DNA methylation is established. We will supplement ewes with methionine eight weeks before pregnancy until eight days after conception. We hypothesize that the methionine treatment will lead to epigenetic changes in the oocytes and preimplantation embryos, leading to long-term phenotypic changes in the offspring.For objective 1, the experimental design includes supplementation of methionine to the F0 generation of growing pre-puberal rams and periconception ewes, then breeding of methionine-treated rams and ewes to produce F1 and F2 generations, breeding of control rams and ewes (no methionine treatment) to produce the F1 and F2 generations, and collecting growth, carcass, and reproduction phenotypes of F1 and F2 generations. A total of 400 animals will be produced in F1 and F2 generations, and production and reproduction traits will be collected for all individuals. Statistical analysis will be performed using a linear mixed model, in which the diet will be included as a fixed effect and twin pair as a random effect. Relevant fixed and random effects will be included in the model according to the phenotype analyzed.For objective 2, we hypothesize that the parental diet will alter the DNA methylation profiles and RNA content in the sperm of F0, F1, and F2 generations. DNA methylation analysis will identify genes or genomic regions differentially methylated between treatment and control animals. We will analyze the association between gene expression and DNA methylation of the rams at the single-nucleotide resolution level and phenotypes of the F1 and F2 generations.Differentially methylated cytosines (DMCs) and differentially methylated regions (DMRs) will be defined as those having methylation percentage changes between methionine-treated and control groups greater than 20% and P-values with FDR (false discovery rate) lower than 1%. The outcome of this specific objective is a panel of DNA methylation signatures and transcriptomic profiles that can be used as biomarkers for predicting traits of the next generations. DNA methylation signatures found across generations will be evidence of transgenerational effects of the parental diet.For objective 3, we will assess the impacts of maternal nutrition alone on oocytes and embryos. We will supplement methionine to half of the Polypay twin pair ewes from weaning to puberty, while the other half will be fed with the standard diet. To test the effects of maternal diet on oocytes, we will perform ovum pick up following standard protocols as described below. Oocytes will be analyzed for DNA methylation and transcriptomic analyses.