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Title: Effects of forage species or concentrate finishing on animal performance, carcass and meat quality

Author
item DUCKETT, SUSAN - Clemson University
item Neel, James
item LEWIS, RON - Virginia Polytechnic Institution & State University
item FONTENOT, JOSEPH - Virginia Polytechnic Institution & State University
item Clapham, William

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2013
Publication Date: 1/23/2013
Citation: Duckett, S.K., Neel, J.P., Lewis, R.M., Fontenot, J.P., Clapham, W.M. 2013. Effects of forage species or concentrate finishing on animal performance, carcass and meat quality. Journal of Animal Science. 91:1454-1467.

Interpretive Summary: Previous research has shown pasture-finished beef to be a highly desirable product when compared to traditional grain-finished. It has also been shown to have an improved ratio of omega-6 to omega-3 fatty acids over grain fed beef. Although differences in fatty acid profile between forage species has been documented, the influence of forage species on beef fatty acid profile and quality has not been adequately addressed. This study was designed to examine how short-term (40 day) grazing of different forage species (traditional pasture vs. improved legume or annual grass pastures) immediately prior to slaughter alters carcass and meat quality in forage-finished steers compared to concentrate-finished. Animal performance increased with use of the improved annual grass versus traditional and legume pastures. Forage finished beef had less fat but similar tenderness and juiciness compared to concentrate finished beef. Beef flavor intensity was higher for legume than other pastures. Traditional pasture exhibited greater off flavor scores than other pastures. Concentration of omega-3 fatty acids was greater in forage finished beef. Forage finished beef had a lower 6:3 fatty acid ratio and that ratio was not impacted by forage species. Improved grass pasture increased performance. Legume pasture increased beef flavor intensity, without compromising the desirable fatty acid profile.

Technical Abstract: Angus-cross steers (n = 128; INWT = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed prior to slaughter versus concentrate finishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) finishing treatments. At 41 d prior to harvest, MP steers were randomly divided into three forage species treatments: alfalfa (AL), pearl millet (PM) or mixed pasture (MP). Average daily gain was greater (P = 0.001) for concentrate-finished (CON) than for forage-finished (FOR) during the early and overall finishing phase. During the late finishing phase when FOR steers were grazing difference forage species, ADG was higher (P = 0.03) for PM than MP or AL. Harvest weight and hot carcass weight were greater (P < 0.001) for CON than FOR due to the differences in animal performance. Total fat percentage of the 9-10-11th rib section was 46% lower (P = 0.028) for FOR than CON due to reductions (P < 0.001) in the percentage of s.c. fat. Warner-Bratzler shear force (WBS) values at 14-d and 28-d of aging did not differ (P > 0.78) between CON and FOR, and were not altered (P > 0.40) by forage species. Trained sensory panel juiciness, initial tenderness and overall tenderness scores did not differ (P > 0.17) by finishing treatment or forage species. Beef flavor intensity was higher (P < 0.001) for CON than FOR. Beef flavor intensity was higher (P < 0.02) for AL and PM than MP. Off-flavor intensity was higher (P < 0.001) for all forage-fed steaks, regardless of forage species, than CON. Finishing on forages reduced (P = 0.003) total lipid content by 61% of the LM compared to CON finished cattle. Forage species grazed prior to harvest did not alter (P > 0.05) total lipid content of the LM. Oleic acid concentration and total monounsaturated (MUFA) fatty acids of the LM were 21% and 22% lower (P = 0.001) for FOR than CON. Concentrations of all individual (linolenic acid, EPA, DPA, DHA) and total n-3 fatty acids were higher (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the level of linolenic acid compared to MP or PM. The ratio of n-6 to n-3 fatty acids was higher (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate finishing increases carcass weight with same time endpoints, and accelerates deposition of MUFA in comparison to FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d prior to slaughter did not alter beef tenderness but FOR had greater off-flavors according to both trained and descriptive sensory panelists.