EVALUATION OF MATERNAL AND PATERNAL GERMPLASM FOR INCREASING EFFICIENCY OF SHEEP IN WESTERN RANGELAND PRODUCTION SYSTEMS
Location: Range Sheep Production Efficiency Research
Title: Live and carcass leg characteristics in terminally-sired lambs.
Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 22, 2010
Publication Date: July 10, 2010
Citation: Mousel, M.R., Leeds, T.D., Notter, D.R., Zerby, H.N., Moeller, S.J., Lewis, G.S. 2010. Live and carcass leg characteristics in terminally-sired lambs. [abstract]. American Society of Animal Science. 88: 579.
Interpretive Summary: Terminal sire breed can affect body shape and carcass composition of crossbred lambs. Scientists at the U.S. Sheep Experiment Station determined whether breed of terminal sire affected live lamb hind leg width, carcass leg width, leg score, bone-in leg weight, and boneless leg weight. All of those traits are important determinants of carcass value. Terminal sire rams, Columbia, MARCIII, Suffolk, and Texel, were mated to mature Rambouillet ewes over a period of 3 years to produce 521 wether lambs. Lambs were finished in a feedlot to an average weight of 138 pounds. Live leg width and live weight were measured before the lambs were harvested. The Texel-sired lambs had wider legs and better leg scores than did lambs of the other 3 sire breeds. The Suffolk-sired lambs had heavier legs than did lambs of the other 3 sire breeds. The results from this study indicate that producers can select for heavier legs or wider legs, but not both, in market lambs.
Live and carcass leg characteristics of F1 wether lambs were investigated to determine whether there were terminal-sire breed differences. Over a 3-yr period, Columbia, MARCIII, Suffolk, and Texel rams were mated with mature Rambouillet ewes to produce the lambs (n=521). Lambs were finished in a feedlot to a mean BW of 61.9 kg (SD = 9.5 kg) and harvested at comparable ages. Before transport to slaughter, width of hind legs was measured at the widest point of the hind legs above the twist and BW was recorded for all lambs. For each carcass, weight and leg width were measured and a subjective leg score was assigned. Carcasses were fabricated into subprimal cuts, which were weighted. Live leg width (LLW), carcass leg width (CLW), leg score (LS), bone-in leg weight (BIL), and boneless leg weight (BLL) were described using mixed models that included fixed effects of breed of sire (breed), year of birth (YR), age of dam (ADAM), and type of rearing (TR) to weaning (i.e., single or as twins) and random effects of sire and maternal grandsire. The ADAM was not significant in any model, but YR and TR affected (P<0.01) LLW, CLW, BIL, and BLL. The TR, but not YR , affected (P<0.01) LS. Leg widths, scores, and weights were greater for single-reared than for twin-reared lambs. Breed affected (P<0.01) LLW, CLW, and LS. Texel-sired lambs had the greatest leg widths, and MARCIII-sired lambs had the least. Texel-sired lambs had the greatest LS, and Columbia-sired lambs had the least. The BIL and BLL differed with breed (P<0.01). Suffolk-sired lambs had the heaviest weights and MARCIII-sired lambs had the lightest. Even though breed of terminal sire affected F1 lamb live and carcass leg traits, breeds that excelled for progeny leg shape differed from those that excelled for progeny leg weights. With this information, producers could select a terminal sire breed that would fit their production system to improve market lamb leg shape or weights.