Effect of diets containing n-3 fatty acids on muscle long-chain n-3 fatty acid content in lambs fed low- and medium-quality roughage diets

• Published in: Journal of animal science Vol. 79; no. 3; pp. 698 - 706
• Main Authors: Ponnampalam, E. N, Sinclairt, A. J, Egan, A. R, Blakeley, S. J, Leury, B. J
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01.03.2001; American Society of Animal Science; Oxford University Press
• Subjects: Animal Feed; Animal productions; Animals; Biological and medical sciences; Dietary Fats - analysis; Dietary Fats - pharmacology; Dietary Fiber - administration & dosage; Dietary Supplements; Fatty acids; Fatty Acids, Nonesterified - metabolism; Fatty Acids, Omega-3 - administration & dosage; Fatty Acids, Omega-3 - pharmacology; Feeds; Female; Fundamental and applied biological sciences. Psychology; Male; Nutrition; Phospholipids - metabolism; Random Allocation; Sheep; Sheep - metabolism; Terrestrial animal productions; Vertebrates; Farming animal; Low content; Nutrition; Ruminant animal; Animal feeding; Fodder; Phospholipid; Mutton; Experimental study; n-3 fatty acid; Vertebrata; Mammalia; Health food; Unsaturated fatty acid; Sheep; Chemical composition; Muscle; Artiodactyla; Ungulata; Food supplement
• ISSN: 0021-8812; 1525-3163; 0021-8812
• DOI: 10.2527/2001.793698x

In two experiments, each with 32 cross-bred ([Merino x Border Leicester] x Poll Dorset) wether lambs (26 to 33 kg weight range), animals were randomly assigned to one of four treatments. A mixture of lucerne chaff:oaten chaff was used as a basal diet, offered in different ratios. Animals were allowed to consume on a free-access basis in Exp. 1 or 90% of ad libitum intake in Exp. 2 in order to provide a low- (6.5 MJ ME/d) and medium- (9.5 MJ ME/d) quality basal diet, respectively. Isoenergetic amounts of lipid supplements, fish meal (80 g DM), canola meal (84 g DM), and soy meal (75 g DM) were tested in Exp. 1. In Exp. 2, fish meal (9% DM), unprotected rapeseed (7% DM), and protected canola seed (6% DM) were fed as supplements. At the end of 53-d (Exp. 1) or 46-d (Exp. 2) experimental periods, lambs were slaughtered at a commercial abattoir and at 24 h postmortem longissimus thoracis (LT) muscle was collected for the analysis of fatty acid (FA) composition of structural phospholipid and storage triglyceride fractions. Fish meal diet increased LT muscle long-chain n-3 FA content by 27% (P < 0.02) in Exp. 1 and 30% (P < 0.001) in Exp. 2 compared with lambs fed the basal diet, but fish meal decreased (P < 0.01) the n-6 FA content only in Exp. 1. Soy meal and protected canola seed diets increased (P < 0.01) LT muscle n-6 FA content but did not affect long-chain n-3 FA content. Longissimus thoracis muscle long-chain n-3 FA were mainly deposited in structural phospholipid, rather than in storage triglyceride. In both Exp. 1 and Exp. 2, the ratio of n-6:n-3 FA in LT muscle was lowest (P < 0.01) in lambs fed fish meal supplement compared with all other treatments. Protected canola seed diet increased the ratio of n-6:n-3 FA (P < 0.01) and PUFA:saturated fatty acid (P < 0.03) content from those animals fed the basal, fish meal, and unprotected rapeseed diets in Exp. 2. This was due to an increase in muscle n-6 FA content, mainly linoleic acid, of both phospholipid (P < 0.001) and triglyceride (P < 0.01) fractions and not to an increase in muscle n-3 FA content. The results indicate that by feeding fish meal supplement, the essential n-3 FA can be increased while lowering the ratio of n-6:n-3 content in lamb meat to an extent that could affect nutritional value, attractiveness, and the economic value of meat.