Effects of pasture type and level of concentrate supplementation on quality and fatty acid profile of lamb meat

Abstract

Objectives of this study were to evaluate effects of grazing tropical forage species and level of supplementation with grain on characteristics of lamb meat. Ninety-day-old lambs (n = 36) (22.54 ± 2.72 kg) were randomly assigned to a 2 x 3 factorial arrangement of pasture types (Aruana and Marandu) and levels of concentrate supplementation (0%, 1.5% and 3% of bodyweight). Water retention capacity, shear force, weight loss after cooking, pH, colour, and intramuscular lipid content of the meat were evaluated. A panel of 145 consumers evaluated the appearance, flavour, fat flavour, odour, and softness of the meat and provided an overall assessment. Supplementation at 3% of bodyweight reduced the luminosity of the meat. The appearance of meat from lambs that grazed Aruana grass was deemed preferable to that of meat from lambs that grazed Marandu grass. Total branched-chain fatty acids (BCFAs) were increased when grazing Marandu grass compared to Aruana grass. Lambs supplemented with concentrate had reduced BCFA/kg of meat and its content of both monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids were increased. Supplementation with concentrate at 1.5% and 3.0% of bodyweight increased n-6 PUFAs by 16.8% and 90.0%, decreased n-3 PUFAs by 49.7% and 35.9%, and thus increased the n-6/n-3 ratio by 135.0% and 183.8%, respectively. Lambs that were finished on grass without supplementation had a more healthful fatty acid profile and received better scores for flavour and global appreciation. To improve the quality of fatty acids in the meat, the pasture system is recommended.

Keywords: Brachiaria brizantha, lipid content, Longissimus thoracis et lumborum, Panicum maximum, sheep feeding