HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wright, M. D. Articles by Loerch, S. C. Search for Related Content PubMed PubMed Citation Articles by Wright, M. D. Articles by Loerch, S. C.

Effects of Rumen-Protected Amino Acids on Ruminant Nitrogen Balance, Plasma Amino Acid Concentrations and Performance^1,2,

The Ohio State University and Ohio Agricultural Research and Development Center, Wooster 44691

Abstract

A series of trials was conducted to determine the effects of supplemental rumen-protected methionine (RPMet) and lysine (RPLys) on nutrient metabolism and performance. In situ RPMet N disappearance was less than 4% following 48 h of incubation and was not affected (P > .05) by diet or resultant ruminal pH differences, indicating that RPMet was well protected from ruminal microbial degradation. Thirty-five Dorset-sired crossbred wether lambs (avg wt 28 kg) fed ground corn-soybean hull diets supplemented with urea were randomly assigned to one of the following treatments: 1) 0% RPMet, 2) .03% RPMet, 3) .06% RPMet, 4) .09% RPMet or 5) .12% RPMet. Dry matter, fiber and N digestibilities and N retention were not affected (P > .05) by treatment. Plasma methionine concentration tended to increase linearly (P < .07) with dietary RPMet level. Six Simmental x Angus steers (avg wt 427 kg) were fed a corn grain-corn silage diet supplemented with urea and five levels of RPMet: 1) 0%, 2) .04%, 3) .08%, 4) .12% and 5) .16%. The plasma methionine concentration increased linearly (P < .01) with dietary RPMet level. In a steer performance trial, no improvements in feedlot performance resulted due to these RPMet levels (P > .05), suggesting that the control diet (0% RPMet) was meeting the methionine requirement of these steers. The effects of RPMet and RPLys on growing and finishing steer feedlot performance also were evaluated. Treatments were 1) urea control, 2) soybean meal positive control, 3) .09% RPMet + .06% RPLys, 4) .12% RPMet + .08% RPLys and 5) .15% RPMet + .10% RPLys. In the growing trial, added RPMet and RPLys did not improve steer feedlot performance. In the finishing trial, only steers fed .09% RPMet + .06% RPLys had higher (P < .05) gains than those fed the urea control diet. These trials indicate that postruminal methionine and lysine supplies were not limiting feedlot steer performance.

¹ Salaries and research support provided by State and Federal Funds appropriated to the Ohio Agric. Res. and Dev. Center, The Ohio State Univ., Journal Article No. 148-87.

² Partial research support and rumen-protected amino acids provided by Eastman Chemicals Div., Rochester, NY 14603.

³ Dept. of Anim. Sci.

⁴ Reprint requests: Dept. of Anim. Sci., Ohio Agric. Res. and Dev. Center, Wooster 44691.