Protein supplementation during mid-gestation alters the amino acid patterns, hepatic metabolism, and maternal skeletal muscle turnover of pregnant zebu beef cows

Abstract

Pregnant beef cows raised on extensive pasture systems in tropical regions commonly experience nutrient restriction during gestation. Herein, it was postulated that a strategic maternal protein supplementation (PS) might reduce maternal tissue mobilization intensity. Therefore, this study aimed to assess how protein supplementation (~40% of crude protein at the level of 3.5 g/kg BW/day, achieving 12% CP) for cows fed low-quality forage (corn silage + sugarcane bagasse, achieving 5.5% of crude protein) affects the maternal blood profile and the mRNA abundance of skeletal muscle turnover markers and glycogenic enzymes in the liver. This study also aimed to assess if these responses were related to the fetal sex. The PS resulted in a greater nutritional status, which in turn was demonstrated by the greater insulin, IGF1, and glucose concentrations. The effects of PS in mid-gestation persisted into late pregnancy. Protein supplementation also enhanced hepatic gluconeogenesis from AA and altered skeletal muscle turnover. In conclusion, protein supplementation during mid-gestation promotes a greater hepatic glucose production from AA, preserving the maternal tissue reserves and benefiting the longevity of the cows of the herd.