Effect of growth path on carcass and meat-quality traits of Hereford steers finished on pasture or in feedlot

Abstract

The objective of this study was to evaluate the effect of nutritional management during rearing and finishing phases on beef fatty acid composition, and carcass and beef quality traits of Hereford cattle. The study used 240 castrated male calves weaned at 8 months of age, and with an average weight of 170 +/- 17 kg. After weaning, the experiment was divided in to three phases in a 4 x 2 factorial design: a 93-day winter period with four treatment groups (on pasture or in feedlot and at high or low feeding levels); a 196-day compensatory-growth phase on pasture; and a finishing phase either on pasture or in feedlot. Animals were slaughtered when each group attained a mean liveweight of 500 kg. The winter growth x finishing management interaction significantly affected hot carcass weight (P = 0.0029). There was no differences observed for feedlot-finished steers, but for pasture-finished steers, those pasture-reared had higher hot carcass weight (kg) than those feedlot-reared (low pasture 256.30 +/- 1.60, high pasture 253.72 +/- 1.60, low feedlot 249.85 +/- 1.66, high feedlot 247.60 +/- 1.62). Feedlot-finished steers showed higher (P < 0.05) mean values than pasture-finished steers for ribeye area (55.61 +/- 0.69 cm(2) vs 53.18 cm(2)), backfat thickness (8.62 +/- 0.32 mm vs 6.21 mm), marbling score (237.97 +/- 13.06 vs 171.70) and final pH (5.53 +/- 0.02 vs 5.48). Additionally, feedlot-finished steers raised in feedlot during the winter-growth period displayed the heaviest hindquarter cuts. Meat from pasture-finished steers had lower (P < 0.05) shear-force values than from feedlot-finished cattle (2.95 +/- 0.18 vs 3.66 +/- 0.17 kg), and when reared on either high or low pasture during winter-growth, they showed the highest (P < 0.05) conjugated linoleic acid (cis-9, trans-11) and n-3 polyunsaturated fatty acid concentrations. In conclusion, growing and finishing cattle on pasture improved the carcass yield of retail cuts because of low fat concentration, and improved the nutritional and health value of the beef fatty acid profile.