PSXIV-30 Effect of aggressive growth promotant strategy on head dimensions of Jersey steers

Abstract

Abstract Head dimensions of Jersey steers (n = 30) were assessed to quantify differences related to aggressive implant strategy and to determine their correlation to live, carcass performance, and grading traits. Steers were either implanted with Revalor 200 (REV; n = 15) on d0, d70, d140, d210, d280, and d360 or utilized as a control group (CON; n = 15). Every 70 d, steers were digitally imaged with a 100 cm2 standard placed on the head; head length (HL, measured from top of poll to end of hairline superior of nose-pad) and head width (HW, measured from outermost canthus across sagittal plane to opposite canthus) were measured from digital images. All steers were fed a common finishing ration for 420d and humanely harvested on d421. Head length, HW, and ratio of HL:HW a were analyzed in a repeated measures analysis with day as the repeated measure and animal as subject. Head length did not differ between CON and REV groups (P = 0.52; HL = 44 cm). Head width was greater (P < 0.01) for REV (21.8 cm) than CON (20.7 cm). The ratio of HL:HW differed (P < 0.01); CON averaged 2.1 cm, and REV averaged 2.0 cm. Head length was correlated to marbling score (r = 0.50) and yield grade (YG, r = 0.39) whereas HW was correlated to live weight (LW, r = 0.70), hot carcass weight (HCW, r = 0.68), dressed yield percentage (r = 0.44), and LM area (r = 0.38). Correlations of HL:HW were linearly related to HCW (r = -0.40), dressed yield percentage (r = -0.40), KPH percent (r = 0.67), LM area (r = -0.40), marbling score (r = 0.63), and YG (r = 0.49). Correlations between dimensional head-measures and carcass grading outcomes may support the use of such measurements to improve sorting of cattle into appropriate marketing groups.