INFLUENCE OF PRE-HARVEST WITHDRAWAL PERIOD AT ZILPATEROL HYDROCHLORIDE SUPPLEMENTATION ON CARCASS TRAITS, SPEED FALL pH AND WATER HOLDING CAPACITY OF FEEDLOT HEIFERS

摘要

Water holding capacity (WHC) of retail meat cuts in Baja California, Mexico; represent important economic lost, until a 5% of weight in the final product, because the quality characteristics of fresh meat can be altered and reduces its life of shelf. Habitually zilpaterol hydrochloride (ZH; Zilmax~®; Intervet Schering-Plough Animal Health Intervet) is added into finishing diet of bo vines by 30 d period. For that in packing plant have attributed that the presence Zilmax can to induce changes in the speed fall of pH (SFpH) causing reduction on WHC and meat quality. Crossbred heifers (64; 451 ±23 kg) were used in a 42-d feeding trial to evaluate the influence of withdrawal period pre-harvest zilpaterol by hydrochloride supplementation on carcass traits, SFpH and WHC. Treatments were: 1) (NZ), no hydrochloride zilpaterol supplementation; The remaining treatments, was added Zilmax~® (0.15 mg/kg BW d~(-1)) during 30 d. in the diet with 2) 3 days (Z3d); 3) 6 days (Z6d) and 4) 12 days (Z12d) of withdrawal period to slaughter, respectively. After finishing, heifers were slaughtered, and chilled (±4°C) during 48 h and carcass traits were measured. The pH and temperature were recorded at 1, 3, 6, 12, 24 and 48 hours postmortem into the Longgisimus toracis muscle (LT) between 8th and 10th rib. To determine the SFpH a linear model was applied (P<0.05). Treated groups with ZH increased HCW (4.5%) on average compared with the group NZ. SFpH and WHC values were not affected (P>.05) by Zilmax addition and days of retirement previous at slaughter.