Abstract :
Dorset (D) rams heterozygous for the Callipyge gene were single—sire mated to non-carrier ewes to produce Callipyge heterozygous
(CLPG, n = 49) and normal (D, n = 33) lambs. Suffolk (S) and Texel (T) rams were mated to similar ewes to produce
non-carrier crossbred S (n = 55) and T (n = 52) lambs. Lambs were finished on a high-energy diet to a target live weight of 57 kg.
Pre-slaughter weight was recorded for each lamb prior to its transfer and slaughter through a commercial facility. Hot carcass weight
and kidney and pelvic fat (KPF) were recorded at slaughter. Chilled carcasses were measured then fabricated into trimmed retail
cuts by plant personnel. Each cut was weighed, and two loin chops were collected from each carcass for later cooking. CLPG lambs
had the highest dressing % (53.6 versus 49.8–50.6; P < 0.05). At the same cold carcass weight, CLPG lambs had larger longissimus
muscle areas (19.5 cm2 versus 14.0–15.2 cm2 for the rest; P < 0.05), less KPF (0.9 kg versus 1.04–1.13 kg; P < 0.05), less carcass
fat (P < 0.05 for all measures), shorter carcasses (60.7 cm versus 61.8–64.7 cm; P < 0.05), and heavier trimmed sirloins, legs, and
shoulders than any other group (a11 P < 0.05). They were similar to S lambs in receiving the lowest mean USDA yield grade. CLPG
carcasses had the highest proportion of carcass weight represented by trimmed cuts (70% versus 65.7–67.8% for the rest; P < 0.05),
the highest proportion of trimmed cuts (62.2% versus 59.7–60.6% for the rest; P < 0.05) represented by the most valuable cuts
(leg + loin + rack + sirloin), and the highest composite carcass value ($135.8 versus $125–129 for the rest; P < 0.05). CLPG lambs
also produced loin chops with the highest mean Warner–Bratzler shear values (5.4 kg versus 2.8–2.9 kg for the rest; P < 0.05) and
the highest % cooking loss (31% versus 29–29.6% for the rest; P < 0.05).
© 2006 Elsevier B.V. All rights reserved.
Keywords :
Lamb , Callipyge , Carcass , meat
