PSXII-29 Dietary protein impacts neonatal piglet muscle growth and protein synthesis.

Abstract

Dietary protein intake during the neonatal period is critical for lifetime muscle development. Appropriate nutrition during the neonatal period may have lifelong impacts on animal growth and muscle development. We hypothesized that minor changes (25% ± adequacy) in dietary protein during the neonatal phase of life will impact future lean growth potential. The goal of this project was to determine the effects of a diet with a 25% deficiency (D), adequacy (A), and 25% excess in protein (E) on neonatal muscle hypertrophy. Dietary crude protein level in the adequate group (27%) was based upon sow’s milk composition and an extrapolation of NRC recommendations. Thirty, individually housed, 1-day-old piglets were divided into 3 groups and fed milk replacers with a 25% deficiency (D), adequacy (A), or 25% excess in protein (E) over a 17-day period. Body weight and feed intake were recorded daily, and a section of the Longissimus dorsi were collected for molecular and histological evaluation at the end of the experiment. Piglets fed E had significantly greater final body weight, (P<0.05) average daily weight gain (P<0.05), and improved feed efficiency (P<0.05) than the piglets in the D group. Additionally, gene expression of AMPKα and succinate dehydrogenase, were significantly upregulated in the E treatment as compared to the A and D treatments (P<0.05). Our preliminary data is supportive of a decrease in phosphorylation of mTOR and 4EBP1 in treatment E compared to D. Evaluation of muscle fiber cross-sectional area revealed an ~40% increase (D =462 ± 28.4μm²; E = 691 ± 68.0μm²) from the deficient to the excess treatment (P<0.05). Our results suggest that neonatal protein requirement for maximal muscle growth is higher than previously thought, and that minor changes in dietary protein intake during the neonatal period can impact muscle growth.