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Title: EFFECTS OF WINTER STOCKER GROWTH RATE AND FINISHING DIET ON BEEF RIB COMPOSITION AND COLOR

Author
item Sonon, R
item Duckett, S
item Neel, James - Jim
item Realini, C
item Fontenot, J
item Clapham, William

Submitted to: American Society of Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2005
Publication Date: 7/24/2005
Citation: Sonon, R.N., Duckett, S.K., Neel, J.P., Realini, C., Fontenot, J.P., Clapham, W.M. 2005. Effects of winter stocker growth rate and finishing diet on beef rib composition and color. #257 J. Anim. Sci., Vol. 83, Suppl. 1, p203.

Interpretive Summary:

Technical Abstract: Angus-cross steers (n=68, year 1; n=63, year 2; n=67 year 3) were used in a three-year study to assess the effects of winter stocker growth rate (LOW, MED, or HIGH) and finishing diet (corn silage-concentrate, CONC or pasture, PAST) on rib composition and color. The steers were slaughtered in a commercial meat plant and ribs (IMPS 107) from each carcass were removed, vacuum-packaged and shipped to the University of Georgia Meat Science Technology Center. At 14-d postmortem, the ribs were unpacked and allowed to bloom for 30 min prior to reading objective color score, L* (lightness), a* (redness), and b* (yellowness) in the exposed LM and s.c. fat using a Minolta colorimeter. The 9-10-11th rib section was then removed and separated into LM, s.c. fat, lean-trim, seam fat, and bone. The percentage of s.c. fat differed between years and was greater (P < 0.01) for CONC than PAST (13.57% vs 7.90%) whereas, PAST was higher (P < 0.01) than CONC in percentages of LM (28.94% vs 26.49%) and lean-trim (26.63% vs 21.32%). Seam fat percentage in year 1 for steers at LOW was similar to HIGH but was greater (P < 0.01) than MED, while in year 3, steers at MED and HIGH had larger (P < 0.05) proportions than those at LOW. Percent seam fat did not differ between growth rates in year 2. Percent bone of steers at HIGH was similar to MED but was higher (P < 0.05) than those at LOW in years 1 and 2. The proportion of bone was similar between growth rates on the third year. Longissimus muscle was lighter (P < 0.01; L* 42.1 vs 38.9), redder (P < 0.01; a* 25.0 vs 23.2) and yellower (P < 0.01; b* 11.8 vs 10.7) for CONC than PAST. Subcutaneous fat was yellower (P < 0.01; b* 17.4 vs 13.8) and darker (P < 0.01; L* 74.9 vs 77.0) for PAST than CONC. Total rib weight and weight of the 9-10-11th rib section was greater for CONC than PAST, however, about 62% of the difference was accounted for by higher proportions of s.c. and seam fat in CONC.