Effects of Non-protein Energy Intake on Whole Body Protein Synthesis, Nitrogen Retention and Glucose Turnover in Goats

  • Received : 2006.04.23
  • Accepted : 2006.08.30
  • Published : 2007.04.01


The responses of whole body protein and glucose kinetics and of nitrogen (N) metabolism to non-protein energy intake (NPEI) were determined using an isotope dilution approach and measurement of N balance in three adult male goats. The diets containing 1.0, 1.5 and 2.0 times ME maintenance requirement, with fixed intake of CP (1.5 times maintenance) and percentage of hay (33%), were fed twice daily for each 21 d experimental period. After an adaptation period of 11 d, N balance was determined over 3 d. On day 17, whole body protein synthesis (WBPS) and glucose irreversible loss rate (ILR) were determined during the absorptive state by a primed-continuous infusion of [$^2H_5$]phenylalanine, [$^2H_2$]tyrosine, [$^2H_4$]tyrosine and [$^{13}C_6$]glucose, with simultaneous measurements of plasma concentrations of metabolites and insulin. Ruminal characteristics were also measured at 6 h after feeding over 3 d. Nitrogen retention tended to increase (p<0.10) with increasing NPEI, although digestible N decreased linearly (p<0.05). Increasing NPEI decreased (p<0.01) ammonia N concentration, but increased acetate (p<0.05) and propionate (p<0.05) concentrations in the rumen. Despite decreased plasma urea N concentration (p<0.01), increased plasma tyrosine concentration (p<0.05), and trends toward increased plasma total amino N (p<0.10) and phenylalanine concentrations (p<0.10) were found in response to increasing NPEI. Increasing NPEI increased ILR of both glucose (p<0.01) and phenylalanine (p<0.05), but did not affect ($p{\geq}0.10$) that of tyrosine. Whole body protein synthesis increased (p<0.05) in response to increasing NPEI, resulting from increased utilization rate for protein synthesis (p<0.05) and unchanged hydroxylation rate of phenylalanine ($p{\geq}0.10$). These results suggest that increasing NPEI may enhance WBPS and glucose turnover at the absorptive state and improve the efficiency of digestible N retention in goats, with possibly decreased ammonia and increased amino acid absorption. In addition, simultaneous increases in WBPS and glucose ILR suggest stimulatory effect of glucose availability on WBPS, especially when sufficient amino acid is supplied.


Supported by : Educational Ministry of Japan


  1. Asplund, J. M., E. R. Orskov, F. D. D. Hovell and N. A. Macleod. 1985. The effects of intragastric infusion of glucose, lipids or acetate on fasting nitrogen excretion and blood metabolites in sheep. Br. J. Nutr. 54:189-195.
  2. Fujita, T., M. Kajita, H. Sano and A. Shiga. 2006b. Effects of nonprotein energy intake on the concentrations of plasma metabolites and insulin, and tissue responsiveness and sensitivity to insulin in goats. Asian-Aust. J. Anim Sci. 19:1010-1018.
  3. Galyean, M. L. and F. N. Owens. 1991. Effects of diet composition and level of feed intake on site and extent of digestion in ruminants. In: Physiological Aspects of Digestion and Metabolism in Ruminants (Ed. T. Tsuda, Y. Sasaki and R. Kawashima). Academic Press, San Diego, pp. 483-514.
  4. Kennedy, P. M. and L. P. Milligan. 1980. The degradation and utilization of endogenous urea in the gastrointestinal tract of ruminants: a review. Can. J. Anim. Sci. 60:205-221.
  5. Nolan, J. V. 1993. Nitrogen kinetics. In: Quantitative Aspects of Ruminant Digestion and Metabolism (Ed. J. M. Forbes and J. France). CAB International, Oxon, pp. 123-143.
  6. Obitsu, T., D. Bremner, E. Milen and G. E. Lobley. 2000. Effects of abomasal glucose infusion on alanine metabolism and urea production in sheep. Br. J. Nutr. 84:157-163.
  7. Piwanka, E. J., J. L. Firkins and B. L. Hull. 1994. Digestion in the rumen and total tract of forage-based diets with starch or dextrose supplements fed to Holstein heifers. J. Dairy Sci. 77:1570-1579.
  8. SAS. 1996. SAS/STAT$^{\circledR}$Software: Changes and Enhancement through Release 6.11. SAS Inst. Inc. Cary, NC.
  9. Sim, A. J., B. M. Wolfe, V. R. Young, D. Clarke and F. D. Moore. 1979. Glucose promotes whole-body protein synthesis from infused aminoacids in fasting man: isotopic demonstration. Lancet 1:68-72.
  10. Tesseraud, S., J. Grizard, E. Debras, I. Papet, Y. Bonnet, G. Bayle and C. Champredon. 1993. Leucine metabolism in lactating and dry goats: effect of insulin and substrates availability. Am. J. Physiol. 265:E402-E413.
  11. Wester, T. J., G. E. Lobley, L. M. Birnie, L. A. Crompton, S. Brown, V. Buchan, A. G. Calder, E. Milne and M. A. Lomax. 2004. Effect of plasma insulin and branched-chain amino acids on skeletal muscle protein synthesis in fasted lambs. Br. J. Nutr. 92:401-409.
  12. Weatherburn, M. W. 1967. Phenol-hypochloride reaction for determination of ammonia. Anal. Chem. 39:971-974.
  13. Asplund, J. M. 1994. The influence of energy on amino acid supply and utilization in the ruminants. In: Principles of Protein Nutrition of Ruminants (Ed. J. M. Asplund). CRC Press, Boca Ration, pp. 179-186.
  14. Merchen, N. R., J. L. Firkins and L. L. Berger. 1986. Effect of intake and forage level on ruminal turnover rates, bacterial protein synthesis and duodenal amino acid flows in sheep. J. Anim. Sci. 62:216-225.
  15. Whitt, J., G. Huntington, E. Zetina, K. Casse, K. Taniguchi and W. Potts. 1996. Plasma flow and net nutrient flux across gut and liver of cattle fed twice daily. J. Anim. Sci. 74:2450-2461.
  16. Taussky, H. H. 1956. A procedure increasing the specificity of the Jaffe reaction for the determination of creatine and creatinine in urine and plasma. Clin. Chim. Acta. 1:210-224.
  17. Fujita, T., M. Kajita and H. Sano. 2006a. Responses of whole body protein synthesis, nitrogen retention and glucose kinetics to supplemental starch in goats. Comp. Biochem. Physiol., B 144:180-187.
  18. Schmidt, S. P. and P. K. Keith. 1983. Effects of diet and energy intake on kinetics of glucose metabolism in steers. J. Nutr. 133:2155-2163.
  19. Taylor, K. A. 1996. A simple colorimetric assay for muramic acid and lactic acid. Appl. Biochem. Biotechnol. 56:49-58.
  20. Coulombe, J. J. and L. Favreau. 1963. A new simple semimicromethod for colorimetric determination of urea. Clin. Chem. 9:102-108.
  21. Volpi, E., B. Mittendorfer, B. B. Rasmussen and R. R. Wolfe. 2000. The response of muscle protein anabolism to combined hyperaminoacidemia and glucose-induced hyperinsulinemia is impaired in the elderly. J. Clin. Endocrinol. Metab. 85:4481-4490.
  22. Eskeland, B., W. H. Pfander and R. L. Preston. 1974. Intravenous energy infusion in lambs: effects on nitrogen retention, plasma free amino acids and plasma urea nitrogen. Br. J. Nutr. 31:201-211.
  23. Motil, K. J., D. M. Bier, D. E. Matthews, J. F. Bruke and V. R. Young. 1981. Whole body leucine and lysine metabolism studied with $[1-^{13}C]$leucine and $[{\alpha}-^{15}N]$ lysine: response in healthy young men given excess energy intake. Metabolism 30:783-791.
  24. Reeds, P. J., M. F. Fuller, A. Cadenhead and G. E. Lobley. 1981. Effects of changes in the intakes of protein and non-protein energy on whole-body protein turnover in growing pigs. Br. J. Nutr. 45:539-546.
  25. Matras, J. and R. L. Preston. 1989. The role of glucose infusion on the metabolism of nitrogen in ruminants. J. Anim. Sci. 67:1642-1647.
  26. Smith, R. H. 1980. Comparative amino acid requirements. Proc. Nutr. Soc. 39:71-78.
  27. National Research Council. 1985. Nutrient Requirements of Sheep. 6th rev. ed. National Academy Press, Washington, DC.
  28. Rapp, R. D. 1963. Determination of serum amino acids. Clin. Chem. 9:27-30.
  29. Nissen, S. and P. Ostaszewski. 1985. Effects of supplemental dietary energy on leucine metabolism in sheep. Br. J. Nutr. 54:705-712.
  30. Miller, S. L., K. D. Tipton, D. L. Chinkes, S. E. Wolf and R. R. Wolfe. 2003. Independent and combined effects of amino acids and glucose after resistance exercise. Med. Sci. Sports Exerc. 35:449-455.

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