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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #194534
Title: EVALUATION OF THE EFFECTS OF DIETARY FAT, CONJUGATED LINOLEIC ACID, AND RACTOPAMINE ON GROWTH PERFORMANCE, PORK QUALITY, AND FATTY ACID PROFILES IN GENETICALLY LEAN GILTS

Author
item Weber, Thomas
item RICHERT, BRIAN - PURDUE UNIVERSITY
item BELURY, MARTHA - OHIO STATE UNIVERSITY
item GU, Y - BASTYR UNIVERSITY
item ENRIGHT, KENDRA - PURDUE UNIVERSITY
item SCHINCKEL, ALLAN - PURDUE UNIVERSITY

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2005
Publication Date: 3/1/2006
Citation: Weber, T.E., Richert, B., Belury, M., Gu, Y., Enright, K., Schinckel, A. 2006. Evaluation of the effects of dietary fat, conjugated linoleic acid, and ractopamine on growth performance, pork quality, and fatty acid profiles in genetically lean gilts. Journal of Animal Science. 84:720-732.

Interpretive Summary: The pork industry is constantly seeking economical methods to increase production efficiency and carcass quality. Adding conjugated linoleic acid (CLA) to swine diets reduces carcass fat and increases belly firmness. Pigs fed CLA have an increased proportion of saturated fatty acids in carcass tissues. Feeding pigs rendered animal fats increases feed efficiency and has the potential to alter the fatty acid compostion of the carcass. The use of the beta adrenergic agonist, ractopamine, increases growth rate, feed efficiency, and carcass leanness. Ractopamine decreases fatty acid synthesis in porcine tissues, and may therefore alter carcass fatty acid composition. In this study we determined whether rendered animal fats and ractopamine altered the fatty acid content of porcine tissues, and whether CLA could counteract the effects of dietary fat and ractopamine on the lipid content of carcass tissues. We also sought to determine if there were interactive effects of CLA, ractopamine, and rendered animal fat on growth and carcass quality. It was found that feeding CLA, rendered animal fat, or ractopamine enhanced feed efficiency. Adding rendered animal fat decreased feed intake and slighlty increased backfat depth, but had no effect on the predicted percent of carcass lean tissue. Adding ractopamine or rendered fat to the diets increased carcass weights. Dietary CLA improved carcass quality by increasing belly firmness. Furthermore, adding CLA to the diet resulted in a more saturated fatty acid profile in belly fat, backfat, and muscle tissue. Feeding ractopamine decreased the fat content of muscle tissue, but had relatively little effect on the fatty acid profiles of the tissues when compared to CLA. These findings indicate that CLA, rendered animal fat, and ractopamine work mainly in an additive fashion to enhance pig growth and carcass quality. Feeding CLA results in a more saturated fatty acid profile of carcasses. It was also determined that ractopamine and rendered animal fats have a smaller impact on the fatty acid composition of porcine tissues than does CLA. Research results described in this report provide nutritionists at universities, feed companies, allied industries, and swine production facilities data showing that dietary CLA enhances carcass fatty acid content and that ractopamine has little to no effect on meat quality in finishing pigs.

Technical Abstract: An eight week study of the effects of conjugated linoleic acid (CLA), rendered animal fats, and ractopamine, and their interactive effects on growth, fatty acid composition, and carcass quality of genetically lean pigs was conducted. Female pigs (n = 228; initial body weight of 58.1 kg) were assigned to a 2 x 2 x 3 factorial arrangement consisting of CLA, ractopamine, and fat treatments. The CLA treatment consisted of 1% CLA oil or 1% soybean oil. Ractopamine levels were either 0 or 10 ppm. Fat treatments consisted of 0% added fat, 5% choice white grease, or 5% beef tallow. The CLA and fat treatments were initiated at an average body weight of 59.1 kg , 4 weeks before the ractopamine treatments. The ractopamine treatments lasted for the final 4 weeks of the study after which carcass data were collected. Lipids from belly, outer and inner layers of backfat, and loin muscle were analyzed for fatty acid composition from 6 pigs per treatment at weeks 4 and 8. Feeding CLA increased feed efficiency during the final 4 weeks of the study. Pigs fed added fat as either choice white grease or beef tallow exhibited decreased average daily feed intake and increased feed efficiency. Adding ractopamine to the diet increased average daily gain, feed efficiency, and final body weights. The predicted carcass lean percentage was increased in pigs fed CLA or ractopamine. Feeding either 5% fat or ractopamine increased carcass weight. Adding fat to the diets increased the 10th rib backfat depth, but did not affect the predicted percent lean. Bellies collected from pigs fed CLA were subjectively and objectively firmer. Dietary CLA increased the concentration of saturated fatty acids and decreased the concentration of unsaturated fatty acids of the belly fat, both layers of backfat, and loin muscle. Ractopamine decreased the intramuscular fat content of the loin muscle, but had relatively little effect on the fatty acid profiles of the tissues when compared with CLA. These results indicate that CLA, added fat, and ractopamine work mainly in an additive fashion to enhance pig growth and carcass quality. Furthermore, these results indicate that CLA results in more saturated fat throughout the carcass.