Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2004
Publication Date: 7/25/2004
Citation: Frank, J.W., Escobar, J., Suryawan, A., Nguyen, H.V., Liu, C.W., Kimball, S.R., Jefferson, L.S., Davis, T.A. 2004. Influence of dietary protein and lactose levels on protein synthesis and translation initiation factor activation in neonatal pigs [abstract]. Journal of Animal Science, Proceedings of the 2004 Joint Annual Meeting of the American Society of Animal Sciences. 82(Suppl. 1):Abstract 766, p. 419. Interpretive Summary: Not required for an abstract.
Technical Abstract: Parenteral infusion of insulin (INS) and amino acids increases protein synthesis (PS) and eukaryotic translation initiation factor (eIF) activation in skeletal muscle and liver. Pigs (N = 25; BW = 1.6 kg) were enterally fed isocaloric milk diets with three levels of protein (5, 10, and 15 g/kg/d) and two levels of lactose (11 and 23 g/kg/d) from 1 to 7 d of age. On d 7, pigs were gavage fed after a 4 h fast and blood samples were collected every 30 min for 1.5 h. Pigs were then euthanized and tissues harvested. Daily gain and PS in the longissimus dorsi and gastrocnemius muscles and liver were not influenced by lactose level, but increased with dietary protein and plateaued at the 10 g/kg/d level (P < 0.01). Plasma INS was greater in the high lactose fed pigs (P < 0.01) and lower in pigs fed the lowest protein diet (P < 0.001). Plasma branched-chain amino acids were influenced by dietary protein level (P < 0.001). Liver and muscle protein kinase B phosphorylation was greater in the high lactose fed pigs (P < 0.05). Liver and muscle ribosomal protein S6 kinase and liver 4E-BP1 phosphorylation increased with dietary protein and plateaued at the 10 g/kg/d level (P < 0.01), while muscle 4E-BP1 phosphorylation continued to increase to the highest protein level (P < 0.001). The association of eIF4G to eIF4E increased with dietary protein level (P < 0.05) and was not influenced by lactose level. The results suggest that growth and PS in neonatal pigs are influenced by dietary protein intake. These changes involve modulation of the availability of eIF4E for eIF4F complex assembly and may be mediated by plasma insulin and amino acid levels.