Suplementação proteica para vacas de corte no final da gestação afeta a expressão gênica no músculo esquelético materno e aminoácidos circulantes no plasma: suplementação proteica para vacas de corte

Abstract

In late pregnancy of beef cows, nutrients requirements increase to meet the growth rate of conceptus and dams may alters metabolism in liver and skeletal tissue, and modify the circulating plasma levels of amino acids (AA) in function of crude protein (CP) supplementation. Fourty tree pregnant Nellore cows gestating male fetuses, [average age = 6 years; average weight = 500 kg] at 193 ± 30 (SD) days (d) of gestation were divided into eight groups (experimental units, with 4 to 5 cows each). Treatments were 1) Control (CON, n = 4), pasture-based (PB) diet without crude protein (CP) supplementation and 2) Supplemented (SUP, n = 4), PB diet supplemented with 2 g/kg of body weight of CP supplement. Liver and muscle biopsies for relative mRNA expression, and circulating plasma levels of AA were recorded. The CON-fed cows tended to have greater (P = 0.057) total circulating AA than SUP-fed cows. Circulating glycogenic AA was greater (p = 0.035) in CON than in SUP cows. CON cows was greater for Histidine (P = 0.015), Methionine (P = 0.007) and Alanine (P = 0.036) than SUP cows. CON and SUP-fed shown no significant differences for gluconeogenesis, fatty acid transport and signaling axis. CON cows tended to be greater than SUP cows in mRNA expression of markers related to Skeletal muscle synthesis, p7056k (P = 0.060) and GSK3B (P = 0.096). No significant differences were found for mRNA expression of markers related to Skeletal muscle degradation. Crude protein supplementation for late pregnant beef cows in a pasture-based diet change the profile of plasma circulating AA and synthesis of skeletal muscle tissue.