Efeito de pastagem consorciada e diferentes níveis de concentrado no desempenho produtivo e qualidade da carne de novilhos

Abstract

The objective of this study was to evaluate the effects of three finishing systems based on concentrate and legume-grass pasture on pasture and growth performance, carcass traits, presence of rumenitis, abomasitis, and liver abscesses, and beef quality. Steers were finished for 91 days with an exclusively whole corn grain-based (GRAIN) diet, grazed on legume-grass pasture plus 1.4% of body weight of whole corn grain supplementation (SUPP), or grazed on legume-grass pasture (PAST) only. The legume-grass pasture provided high levels of protein (more than 19% DM) and improved digestibility (more than 88% DM) over all three periods. Pasture of paddocks where steers were assigned to SUPP and PAST treatments showed similar nutritional quality. When compared to PAST, SUPP diet increased total weight gain per hectare, stocking rate, daily and total weight gains. The increase of weight gains was high to GRAIN than SUPP and PAST (1.81, 1.51, and 1.20 kg/animal/day respectively). Steers finished on GRAIN had higher fat thickness and marbling score when compared to PAST. There were no differences on hot carcass weight for cattle finished on GRAIN and SUPP. Abomasum lesions were more prevalent in steers finished on GRAIN when compared to PAST. Pasture diets (PAST and SUPP) led to lower n-6/n-3 ratio (P < 0.001), and highest deposition of C18:2 cis-9 trans-11 (P < 0.001) in the lean. Beef from steers fed GRAIN had the highest values of volatile compounds associated with lipid oxidation. Off-flavor intensity was significantly greater on beef from steers fed GRAIN when compared to PAST. Steaks from steers fed GRAIN were less red (P < 0.001), showed higher lipid oxidation (P < 0.001) during retail display, and higher metmyoglobin formation (P < 0.001) from day 7 to 13 when compared to PAST. Levels of α-tocopherol were higher in steaks from steers fed diets containing legume and grass (P < 0.001). Inclusion of concentrate on finishing diet of steers increase growth performance, however, carcass from steers finished on legume-grass pasture has desirable traits. The roughage, independently of what level was offered, is essential to improve fatty acid profile, decrease volatile compounds associated with lipid oxidation, minimize off-flavor, maintain retail color and prevent lipid and myoglobin oxidation.