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Title: Effect of finishing steers on different forages or high concentrate diet on fatty acid composition of beef

item Duckett, S
item Neel, James - Jim
item Fontenot, J
item Clapham, William
item Swecker, W

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2008
Publication Date: 7/11/2008
Citation: Duckett, S.K., Neel, J.P., Fontenot, J.P., Clapham, W.M., Swecker, W. 2008. Effect of finishing steers on different forages or high concentrate diet on fatty acid composition of beef. Journal of Animal Science Supplement. 86(2):382.

Interpretive Summary:

Technical Abstract: Angus-crossbred steers (n = 128) were used to determine the effects of forage species grazed in the last 41 d or high concentrate finishing on rib composition, color, and palatability of beef. Steers grazed mixed pastures (bluegrass/white clover) for 93 d and then grazed alfalfa (AL; n = 36), pearl millet (PM; n = 24), or mixed (MP; n = 36) pastures for the final 41 d of finishing. Due to drought conditions in year 3, steers did not graze PM pastures. Steers were also finished on traditional high concentrate diets (C; n = 32) for 134 d. Hot carcass weight (HCW) was on average 97 kg heavier (P < 0.01) for C than MP, AL, and PM for the three year period. Percentage total fat was 45% greater (P < 0.05) and percent fat-free lean was 27% lower for C than forage-finished in the 9-10-11th rib section. No differences were detected in lean, fat and bone composition among forage species. In year 1, lightness (L*) of LM was higher (P < 0.01) for C than AL and MP. Lightness values were also higher (P < 0.05) for AL and MP than PM. In year 2, LM lightness was higher (P < 0.05) for C than forage-finished treatments. In year 3, LM lightness did not differ (P > 0.05) among treatments. Yellowness (b*) of s.c. fat was higher (P < 0.01) for AL, MP, and PM than C in all three years. In year 1 and 2, ultimate LM pH was lower (P < 0.05) for C than PM or MP with AL being intermediate. In year 3, LM pH was lower (P < 0.05) for C than MP or AL. Warner-Bratzler shear force did not differ (P = 0.90) among finishing treatments and averaged 2.6 kg. Descriptive flavor panel evaluation found that C had higher (P < 0.05) beef flavor identification and less (P < 0.05) off-notes than AL or MP. Steaks from MP had higher (P < 0.05) organ meat (livery) flavor than AL, C, or MP. Finishing steers on forages versus concentrates to an equal animal age endpoint lowered carcass weight and fat content with no change in tenderness. Forage species utilized during the final 41 d of finishing had little to no effect on rib composition, color, tenderness or palatability.