PSV-12 Allometric growth of serially harvested calf-fed Holstein steers supplemented zilpaterol hydrochloride.

摘要

Holstein steers (n = 110) were randomly assigned to 1 of 2 dietary treatments: a ration supplemented with zilpaterol hydrochloride (ZH) or a control (CON) ration with no ZH included during a 280-d serial harvest study. Cattle were harvested every 28 d beginning at 254 d on feed (DOF) and concluding after 534 DOF. Non-carcass component weights were collected during slaughter; after a 48 h chill carcasses were fabricated into boneless closely trimmed subprimals, lean trim, trimmable fat, and bone. An allometric model y = a was used to quantify the growth rates of carcass and non-carcass components; variables were log transformed and analyzed via simple linear regression. Allometric growth coefficients between CON and ZH differed ( ≤ 0.04) only for 3 carcass components (round lean trim mass, round fat trim mass, and shoulder clod mass). Non-carcass components including tongue (4.03), kidney-pelvic-heart fat (2.13), pancreas (1.92), and intestines (1.75) had a growth coefficient greater than the empty body (1.0). In contrast heart (0.71), liver (0.49), kidneys (0.28), and lungs (0.15) had a growth coefficient less than the empty body. Carcass primals varied in allometric growth; the growth coefficient of plate (1.30), and flank (1.22) were greater than the empty body whereas chuck (0.98), rib (0.95), loin (0.90), brisket (0.86), and round (0.65) had growth coefficients less than the empty body. Total empty body fat (2.01) and total empty body lean (1.03) growth coefficients were greater than total empty body bone (0.54). These data suggest that allometric growth during the finishing period of calf-fed Holstein steers resulted in growth coefficients for fat that were approximately 2-fold that of lean, which were approximately 2-fold of bone.