Mass and composition of carcass and organs in pure and cross breed beef cows grazing different forage allowances of native pastures

Abstract

The aim was to evaluate the effect of two herbage allowances of native pastures on the mass and carcass and organs composition. Mature beef cows (n = 32) were used in a randomized complete block design with a factorial arrangement of herbage allowance (4 and 2.5 kg DM / kg BW; HI vs. LO) and cow genotype (pure: Hereford and Aberdeen Angus and their reciprocal crosses F1, PU vs. CR). The experiment was conducted during three years; at the end of the third year, cows were slaughtered at 190 ± 10 days postpartum and carcass and organs were dissected, weighed and samples were collected and immediately frozen for chemical composition analysis. The absolute and relative carcass weight was greater (P ≤ 0.02) for HI than LO cows, and tended to be greater (P = 0.08) for CR than PU cows. Cows grazing HI showed greater (P ≤ 0.05) carcass yield and greater (P = 0.03) proportion of soft tissues in the carcass than LO cows. Absolute weight of total organ mass was greater (P = 0.05) for HI than LO cows while relative weight of total organ mass (expressed relative to carcass weight) cows was greater (P = 0.05) for PU than CR cows. These results would indicate that animals grazing HI and of CR genotype would be more efficient in the use of the energy for beef production, given a greater carcass yield and reduced total organ and carcass weights ratio.