Protein turnover in growing pigs. Effects of age and food intake

• Published in: British journal of nutrition Vol. 43; no. 3; pp. 445 - 455
• Main Authors: Reeds, P. J., Cadenhead, A., Fuller, M. F., Lobley, G. E., McDonald, J. D.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-05-1980
• Subjects: Aging; Animal Nutritional Physiological Phenomena; Animals; Body Temperature Regulation; Body Weight; Diet; Dietary Proteins - metabolism; Energy Metabolism; Female; Leucine - metabolism; Male; Nitrogen - metabolism; Papers on General Nutrition; Protein Biosynthesis; Proteins - metabolism; Swine - metabolism
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN19800112

1. Measurements were made of the nitrogen and energy balances of pigs of 30, 60 and 90 kg given a conventional diet at various daily rates. 2. Body protein synthesis was estimated from the irreversible loss of leucine from the blood following the infusion of [1-14C]leucine, and from the oxidation of the labelled amino acid. 3. Protein synthesis (g/d) increased by 2.17 for each 1 g increase in daily protein accretion and by 1.55 for each 1 g increase in daily protein intake. 4. At 30 kg, pigs close to energy equilibrium synthesized 270 g protein daily compared with 406 g and 512 g when their ration supplied twice and three times their maintenance requirement. 5. There was a close correlation between the daily urinary excretion of urea + ammonia and total amino acid catabolism estimated from the catabolism of leucine, but the latter underestimated the observed excretion by 2.5 g N/d. 6. The results imply that protein turnover accounts for only a proportion of the heat production associated with protein deposition.