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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Scott, R. A. Articles by Prior, R. L. Search for Related Content PubMed Articles by Scott, R. A. Articles by Prior, R. L.

Effects of Dietary Energy and Biological Type on Lipogenic-Related Enzymes in Beef Steers^{1 ,2,}

US Department of Agriculture, Clay Center, NE 68933

Abstract

Large and small type steers that differed in mature size and potential for growth were used to investigate the influence of dietary energy density and slaughter weight on the lipogenic process. Three energy treatments were imposed: 1) 2.96 Meal of metabolizable energy (ME) per kilogram of feed dry matter (DM); 2) 2.57 Meal of ME per kilogram of feed DM; or 3) 2.57 Meal per kilogram feed DM until mean pen weight averaged 340 kg and then 2.96 Meal per kilogram feed DM until slaughter. Small type cattle were slaughtered when treatment mean live weights reached 440 or 489 kg while the large type cattle were slaughtered at either 614 or 670 kg live weight. Subcutaneous and perirenal adipose samples were assayed for glucose-6-phosphate dehydrogenase, 6-phospho-gluconate dehydrogenase, NADP-isocitrate dehydrogenase (ICDH), fatty acid synthetase (FAS) and acetyl CoA carboxylase. Enzyme activities were expressed as units per milligram of adipose tissue protein and (or) per gram of adipose tissue. Increased dietary energy density caused increased enzyme activities; dietary energy density had a greater influence on enzyme activities in the small type compared to the large type cattle. Enzyme activities were more active in the subcutaneous than perirenal adipose tissue of both types of cattle. Enzyme activities decreased or were unchanged as weight at slaughter increased. The activity of FAS in small type cattle was greater than in large type cattle and all other activities measured were similar in both types with the exception of ICDH in subcutaneous tissue which was higher in the large type cattle. Results point to FAS as a key enzyme affected by the various energy treatments employed and therefore important in regulating the rate of fatty acid synthesis in ruminant adipose tissue.

¹ Cooperation of the Nebraska Agr. Exp. Sta., Univ. of Nebraska, Lincoln, is acknowledged.

² Roman L. Hruska US Meat Animal Research Center, Agr. Research, Science and Education Administration, or specific equipment does not constitute a guarantee or warranty by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.