457 - Influence of Season of Birth, Breed and Reproductive Status on Carcass Traits of Male Hair Sheep Lambs

Compared to intact males, castrated lambs generally grow slower and have lighter and fatter carcasses. However, short-scrotum lambs can retain growth and carcass composition of intact males. This study evaluated carcass traits of castrated and short-scrotum Barbados Blackbelly (BB; n = 16) and St. Croix (STX; n = 15) hair sheep lambs. Ram lambs born in December (DEC; n = 10) and April (n = 21) were used in the study and were either rendered short scrotum (SS; n = 17) or castrated (CA; n = 14) using elastrator bands at weaning (63 d). All lambs transitioned in dry lot for 2 mo before return to pasture. Lambs co-grazed in a rotational system, were moved based on visual assessment of forage availability and provided Bermuda grass hay when forage was limiting. Lambs were provided soy hull at 3% BW to ensure diet continuity between forage environments. At target weights of 40 kg, SS and CA lambs were slaughtered and carcass data recorded. Carcass data were analyzed with reproductive status, breed and season born as main effects. DEC (230 d) and STX lambs (251 d) attained target weights earlier (P < 0.02) than APR (307 d) and BB (317 d) lambs. APR lambs had lower (P < 0.04) breast (0.9 kg) and loin cut weights (2.1 kg) than DEC lambs (1.1 and 2.4 kg, respectively). Carcass length was greater (P < 0.05) for SS (109 cm) than CA lambs (106 cm). There were also significant interactions (P < 0.05). APR-STX lambs had the lowest dressing% (42%) compared to APR-BB (48%), DEC-STX (47%) and DEC-BB (46%) lambs. DEC-STX (109 cm) and APR-BB (109 cm) carcasses were longer than DEC-BB (104 cm) and APR-STX (106 cm) lambs. DEC-SS lambs (84 cm) had the greatest leg circumference, while CA-STX (16 mm) lambs had the greatest body wall thickness in this study. Data suggest that reproductive status, breed and birth season all had varying influences on carcass traits of lambs in this study.