Post-weaning Growth and Carcass Traits of St. Croix White and Dorper X St. Croix White Lambs Fed a Concentrate Diet in the U.S. Virgin Islands

Growth and carcass traits of St. Croix White (STX; n = 22) and Dorper X St. Croix White (DRP; n = 18) lambs fed a concentrate ration were evaluated. Starting two weeks after weaning (63 d of age) lambs were fed a commercial diet at 4 percent BW•hd-1•d-1. Lambs were slaughtered at a BW of 30 kg. Carcass weight, fat thickness over the 12th rib, rib eye area (REA), percent KPH and leg circumference were measured. Days on feed was greater (P < 0.01) for STX than for DRP lambs (153.2 ± 6.8 d vs. 118.9 ± 7.4 d, respectively). Total weight gained was greater (P < 0.04) for STX than for DRP lambs (16.1 ± 0.5 kg. vs. 14.6 ± 0.5 kg, respectively). The ADG of DRP lambs was higher (P < 0.01) than that of STX lambs (125.1 ± 4.7 g/d vs. 108.1 ± 4.3 g/d, respectively). Carcass weight was not different (P > 0.10) between breed type (12.6 ± 0.2 kg). The REA of DRP lambs was greater (P < 0.02) than that of STX lambs (10.4 ± 0.4 cm2 vs. 9.0 ± 0.4 cm2, respectively). Fat thickness was not different (P > 0.10) between DRP and STX lambs (1.5 mm ± 0.2 mm). Percent KPH was higher (P < 0.001) in STX than in DRP lambs (3.6 ± 0.3 percent vs. 2.2 ± 0.3 percent, respectively). Leg circumference was greater (P < 0.007) for DRP than for STX lambs (37.3 ± 0.4 cm vs. 35.7 ± 0.4 cm, respectively). Cost of gain was higher (P < 0.05) for STX than DRP lambs (4.08 ± 0.02 S/kg. vs. 3.73 ± 0.02 $/kg, respectively). Sales of DRP resulted in greater (P < 0.03) net revenue than sales of STX in each market. Dorper X St. Croix White crossbred lambs fed a concentrate ration are economically feasible due to lower cost of gain, higher ADG and revenue.