Journal of Animal Science, Vol 72, Issue 12 3177-3187, Copyright © 1994 by American Society of Animal Science

JOURNAL ARTICLE

Diminishing returns in weight, nitrogen, and lysine gain of pigs fed six levels of lysine from three supplemental sources

M. J. Gahl, T. D. Crenshaw and N. J. Benevenga
Dept. of Meat and Animal Sci., University of Wisconsin, Madison 53706.

Diminishing returns responses to increments of lysine intake were evaluated in 82 crossbred barrows (10.2 +/- SE = .31 kg) fed one of six concentrations of lysine expressed as 55, 80, 90, 100, 115, or 140% of a concentration (10.9 g/kg of diet) that supported maximum weight gain. Supplemental lysine was provided from either soybean meal (SBM), SBM+synthetic lysine (SBM + L), or SBM+corn gluten meal (SBM + CGM) additions to a basal diet consisting of corn, minerals, and vitamins. A logistic equation was used to describe weight (kilograms/day), nitrogen (grams/day) and lysine (grams/day) gain as a function of lysine intake from each diet. The parameter Rmax, asymptotic maximum response at infinite intake, was shared for SBM and SBM+L (.70 +/- .02, 17.6 +/- .4 and 7.6 +/- .5, respectively) but was different (P < .05) for SBM + CGM (.62 +/- .02, 15.7 +/- .4 and 6.4 +/- .4, respectively) diets. A plateau in weight gain response was observed at approximately 100% of our estimate of the lysine requirement (9.8 g/kg, based on analyzed values), but nitrogen and lysine gain responses did not approach a plateau until 120 or 145% of the requirement. No differences were detected among pigs fed the SBM and SBM+L sources; however, the efficiency of lysine use by pigs fed the SBM+CGM diet was lower. Maximum marginal efficiency (dr/dI) occurred at 45, 40, and 35% of Rmax for weight, nitrogen, and lysine gain, respectively. The maximum marginal efficiency of lysine gain was 81% for pigs fed the SBM and SBM+L diets but only 68% for pigs fed the SBM+CGM diet. Consequently, diminishing returns were apparent for at least the upper 55 to 65% of the response curve. Whole-body lysine content increased (P < .03) from 5.5 to 6.0 g/16 g of N and glycine (9.6 to 7.9) and proline (6.4 to 5.4) content decreased (P < .001) as lysine intake increased. No changes were detected in body threonine content (pooled average = 2.8).

This article has been cited by other articles:

				D. C. Kendall, A. M. Gaines, G. L. Allee, and J. L. Usry Commercial validation of the true ileal digestible lysine requirement for eleven- to twenty-seven-kilogram pigs J Anim Sci, February 1, 2008; 86(2): 324 - 332. [Abstract] [Full Text] [PDF]

				L. Doepel, D. Pacheco, J. J. Kennelly, M. D. Hanigan, I. F. Lopez, and H. Lapierre Milk Protein Synthesis as a Function of Amino Acid Supply J Dairy Sci, May 1, 2004; 87(5): 1279 - 1297. [Abstract] [Full Text] [PDF]

				A. P. Schinckel, N. Li, B. T. Richert, P. V. Preckel, and M. E. Einstein Development of a model to describe the compositional growth and dietary lysine requirements of pigs fed ractopamine J Anim Sci, May 1, 2003; 81(5): 1106 - 1119. [Abstract] [Full Text] [PDF]