Background: To our knowledge, most research demonstrating a link between maternal nutrition and both fetal growth and offspring development after birth has been performed with nonruminants. Whether such relationships exist in large ruminants is largely unknown.Objective: We aimed to investigate whether increasing the
methionine supply during late pregnancy would alter uteroplacental tissue nutrient transporters and
mammalian target of rapamycin (mTOR) and their relation with newborn
body weight.Methods: Multiparous Holstein cows were used in a randomized complete block design experiment. During the last 28 d of pregnancy, cows were fed a control diet or the control diet plus ethylcellulose rumen-protected
methionine (0.9 g/kg dry matter intake) (
Mepron; Evonik Nutrition & Care GmbH) to achieve a 2.8:1 ratio of
lysine to
methionine in the metabolizable
protein reaching the small intestine. We collected placentome samples at parturition and used them to assess
mRNA and
protein expression and the phosphorylation status of mTOR pathway
proteins.Results: Newborn
body weight was greater in the
methionine group than in the control group (44.1 kg and 41.8 kg, respectively; P ≤ 0.05). Increasing the
methionine supply also resulted in greater feed intake (15.8 kg/d and 14.6 kg/d), plasma
methionine (11.9 μM and 15.3 μM), and plasma
insulin (1.16 μg/L and 0.81 μg/L) in cows during late pregnancy. As a result,
mRNA expression of genes involved in neutral
amino acid transport [solute carrier (SLC) family members SLC3A2,
SLC7A5, SLC38A1, and SLC38A10],
glucose transport [SLC2A1, SLC2A3, and SLC2A4], and the mTOR pathway [mechanistic target of
rapamycin and
ribosomal protein S6 kinase B1] were upregulated (P ≤ 0.07) in
methionine-supplemented cows. Among 6
proteins in the mTOR pathway, increasing the
methionine supply led to greater (P ≤ 0.09)
protein expression of α
serine-threonine kinase (AKT), phosphorylated (p)-AKT, p-eukaryotic
elongation factor 2, and the p-mTOR:mTOR ratio.Conclusion: Supplemental
methionine during late gestation increases feed intake and newborn
body weight in dairy cows, and this effect may be mediated by alterations in the uteroplacental transport of nondispensable and dispensable
amino acids and
glucose at least in part through changes in gene transcription and mTOR signaling.