Growth and metabolism in somatotropin-treated steers. III. Protein synthesis and tissue energy expenditures

• Published in: Journal of animal science Vol. 68; no. 12; p. 4153
• Main Authors: Early, R.J. (University of Hawaii at Manoa, Honolulu), McBride, B.W, Ball, R.O
• Format: Journal Article
• Language: English
• Published: United States 01.12.1990
• Subjects: Animals; BOEUF; BUEY; BULLOCKS; Cattle - growth & development; Cattle - metabolism; COEUR; CORAZON; CRECIMIENTO; CROISSANCE; ENERGIA; ENERGIE; ENERGY; Energy Metabolism - drug effects; FOIE; GROWTH; Growth Hormone - pharmacology; HEART; HIGADO; HORMONAS PITUITARIAS; HORMONE HYPOPHYSAIRE; INJECTION; INTESTIN; INTESTINES; INTESTINOS; INYECCION; Jejunum - drug effects; Jejunum - metabolism; Kidney - drug effects; Kidney - metabolism; KIDNEYS; LIVER; Liver - drug effects; Liver - metabolism; Male; METABOLISM; METABOLISME; METABOLISMO; MUSCLE; Muscle Proteins - biosynthesis; MUSCLES; Muscles - metabolism; MUSCULOS; Myocardium - metabolism; Oxygen Consumption - drug effects; PITUITARY HORMONES; Potassium - metabolism; Protein Biosynthesis; PROTEIN SYNTHESIS; Random Allocation; Recombinant Proteins - pharmacology; REIN; RINONES; RUMEN; Rumen - metabolism; SINTESIS DE PROTEINAS; Sodium - metabolism; SUBCUTANEOUS INJECTION; SYNTHESE PROTEIQUE
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/1990.68124153x

Rates of in vivo protein synthesis in intercostal, sartorius and semitendinosus muscle and in the heart, liver, kidneys, rumen and jejunum were determined in 20 growing Hereford steers treated for 112 d with daily subcutaneous injections of either saline (S) or recombinantly derived bovine somatotropin (rBST; 20.6 mg/d). In vitro rates of protein synthesis and energy expenditures associated with Na+, K+ transport also were determined in external intercostal muscle, liver, kidneys and jejunum. Neither in vivo nor in vitro tissue protein fractional synthetic rates (mg/[g protein.d]), using either the plasma (P) or intracellular fluid (ICF) phenylalanine specific radioactivity for the precursor pool, were affected by rBST treatments. Energy expended on Na+, K+ transport was greater (P less than .1) in the livers of rBST-treated steers, which would increase the maintenance energy expenditures of these steers. Protein accretion rates in the liver, kidneys, stomach, hide, and head, feet and tail of rBST-treated steers were greater (P less than .05) than in S steers. Tissue amino acid profiles were not affected by rBST treatments except in the rumen, where profiles suggested that less collagen was present in rumen wall tissue protein of rBST steers. Plasma phenylalanine entry rates also were not affected by rBST treatment; muscle protein synthesis accounted for a minimum of 20% of this entry rate.