Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 2. Meat quality, fatty acid composition and overall palatability

¹ Agriculture & Agri-Food Canada, Sherbrooke, QC, J1M 1Z3, Canada
² Département des sciences animales, Université Laval, Québec, QC, G1V 0A6, Canada
³ Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, J2S 8E3, Canada
⁴ Department of Animal & Poultry Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
⁵ Agriculture & Agri-Food Canada, Kapuskasing, ON, P5N 2Y3, Canada

^* To whom correspondence should be addressed. E-mail: faucitanol{at}agr.gc.ca.

	Abstract

Five beef cattle management regimens were evaluated for their effect on meat quality, fatty acid composition and overall palatability of the longissimus dorsi (LD) muscle in Angus cross steers. A 98-d growing phase was conducted using grass silage with or without supplementation of growth promotants (Revalor®G and Rumensin®) or soybean meal. Dietary treatments in the finishing phase were developed with or without supplementation of growth promotants based on exclusive feeding of forages with no grain supplementation, or the feeding of grain/forage (70:30) diets. Growth promotants increased (P < 0.01) shear force and tended (P = 0.06) to increase toughness of the LD muscle due to limited post mortem proteolytic activity (lower myofibrillar fragmentation index value; P = 0.02). Grain feeding increased dry matter and intramuscular fat content (P = 0.03 and P = 0.05, respectively) in the LD, but decreased the sensory panel tenderness score (P = 0.01). Growth promotants increased (P 0.05) the proportion of C18:0, C20:0, trans isomers of C18:1 and c-9, t-11 C18:2. Exclusive feeding of forages increased the proportion of c-9, c-12, c-15 C18:3 as well as several other isomers of the omega-3 family, and decreased in the ratio of omega-6 to omega-3 fatty acids in the in the LD muscle as compared to supplementing grain (P < 0.05). In addition the forage based diet increased (P < 0.01) the concentration in the intramuscular fat of several intermediates (c-9, t-11, c-15 C18:3, t-11, c-15 C18:2, t-11 C18:1) of ruminal biohydrogenation. Forage feeding also increased the proportion of c-9, t-11 C18:2 (P < 0.01), and decreased the concentration of t-10 C18:1 in the LD muscle (P = 0.03). It is concluded that quality demands of health conscious consumers can be met through forage-finishing and growth promotants-free beef production system.

Key Words: beef cattle, beef production systems, beef quality, fatty acids, shear force, taste panel