Protein Supplementation during Mid-Gestation Alters the Amino Acid Patterns, Hepatic Metabolism, and Maternal Skeletal Muscle Turnover of Pregnant Zebu Beef Cows.

From 100 to 200 days of gestation, 52 cows carrying male ( n = 30) or female ( n = 22) fetuses were assigned to CON (basal diet-5.5% of CP, n = 26) or SUP (basal diet + protein supplement [40% CP, 3.5 g/kg BW]-12% of CP, n = 26) treatments. Glucose concentrations decreased at 200 ( p ≤ 0.01; CON = 46.9 and SUP = 54.7 mg/dL) and 270 days ( p ≤ 0.05; CON = 48.4 and SUP = 53.3 mg/dL) for CON compared to SUP. The same pattern occurred for insulin ( p ≤ 0.01). At parturition, the NEFA concentration was greater ( p = 0.01, 0.10 vs. 0.08 mmol/L) for CON than for SUP. Total AA increased in SUP ( p ≤ 0.03) at mid- and late-gestation compared to CON. At 200 days, CON dams carrying females had less essential AA ( p = 0.01) than cows carrying males. The SUP dams had greater expressions of protein synthesis markers, namely eIf4E and GSK3β ( p ≤ 0.04), at day 200 and of MuFR1 (protein degradation marker, p ≤ 0.04) at parturition. Supplemented cows had higher hepatic pyruvate carboxylase expressions ( p = 0.02). Therefore, PS alleviates the restriction overload on maternal metabolism.