Abstract
Maternal nutrition during gestation can cause epigenetic effects that translate to alterations in gene expression in offspring. This 2-year study employed RNA-sequencing technology to evaluate the pre- and post-vaccination muscle transcriptome of early-weaned Bos indicus-influenced beef calves born from dams offered different supplementation strategies from 57 ± 5 d prepartum until 17 ± 5 d postpartum. Seventy-two Brangus heifers (36 heifers/yr) were stratified by body weight and body condition score and assigned to bahiagrass pastures (3 heifers/pasture/yr). Treatments were randomly assigned to pastures and consisted of (i) no pre- or postpartum supplementation (NOSUP), (ii) pre- and postpartum supplementation of protein and energy using 7.2 kg of dry matter/heifer/wk of molasses + urea (MOL), or (iii) MOL fortified with 105 g/heifer/wk of methionine hydroxy analog (MOLMET). Calves were weaned on d 147 of the study. On d 154, 24 calves/yr (8 calves/treatment) were randomly selected and individually limit-fed a high-concentrate diet until d 201. Calves were vaccinated on d 160. Muscle biopsies were collected from the same calves (4 calves/treatment/day/yr) on d 154 (pre-vaccination) and 201 (post-vaccination) for gene expression analysis using RNA sequencing. Molasses maternal supplementation led to a downregulation of genes associated with muscle cell differentiation and development along with intracellular signaling pathways (e.g., Wnt and TGF-β signaling pathway) compared to no maternal supplementation. Maternal fortification with methionine altered functional gene-sets involved in amino acid transport and metabolism and the one-carbon cycle. In addition, muscle transcriptome was impacted by vaccination with a total of 2,396 differentially expressed genes (FDR ≤ 0.05) on d 201 vs. d 154. Genes involved in cell cycle progression, extracellular matrix, and collagen formation were upregulated after vaccination. This study demonstrated that maternal supplementation of energy and protein, with or without, methionine has long-term implications on the muscle transcriptome of offspring and potentially influence postnatal muscle development.
Highlights
During the last trimester of gestation, the protein, energy, and amino acid requirements of beef cows increase in order to meet the demand of the growing fetus [1]
Forty-four RNA samples were successfully analyzed from the Longissimus dorsi of early weaned Bos indicus-influenced calves to determine the effect of maternal supplementation with molasses, with or without methionine fortification, during the last 57 ± 5 d of gestation until 17 ± 5 d postpartum
1Treatments consisted of: no supplementation (NOSUP); supplementation of protein and energy using sugarcane molasses + urea (MOL; 7.2 kg of DM/heifer/wk; Westway Feed Products LLC, Clewiston, FL); or MOL fortified with 105 g/heifer/wk of methionine hydroxy analog (MOLMET; MFP, Novus International Inc., Romance, AR)
Summary
During the last trimester of gestation, the protein, energy, and amino acid requirements of beef cows increase in order to meet the demand of the growing fetus [1]. Previous studies observed that supplemental protein during the last trimester of gestation increased calf weaning body weight, carcass weight, and marbling scores at slaughter [2–4]. In the beef cattle fetus, secondary myogenesis predominately occurs during the second trimester of gestation [6]. Modifications to the maternal diet, either nutrient excess or restriction, during midto late gestation can modulate the expression of genes involved in myogenesis and adipogenesis of the muscle [7, 8]. Nutrient restriction during the last 40 d of gestation alters the muscle transcriptome of beef calves at weaning [9], indicating that maternal nutrition during late gestation can program long-term gene expression in the offspring
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