Differences between groups of lamb carcasses chosen for good and poor conformation

Abstract

Ninety-six lamb carcasses drawn from six batches of lambs commercially consigned to an abattoir were analysed for characteristics which may affect their economic value. From each batch carcasses were selected in equal numbers into two classes of 'good' or 'poor' conformation according to traditional standards. Carcasses selected for 'good' conformation were heavier (P<0-05) and fatter (P<0-05), slightly shorter in carcass length and hind leg length (P<0-05), greater in circumference (P<0-001) and width (P<0-001) of the hind leg, slightly greater in muscle weight (P<0-05) but no greater in bone weight than those of poor conformation. The yield of prime retail joints was similar in the two conformation classes but the 'good' conformation class had a higher proportion of loin and rib joints and lower proportion of hind leg joint (P < 0-01) although these differences were not considered to be of commercial importance. There was a lower proportion of the carcass fatty tissue in the hind leg joint of the 'good' conformation class (P < 0-05). Muscle-to-bone ratio and area of 'eye muscle' (M. longissimus thoracis) appeared to be little affected by selecting for conformation differences. Depth of fleshing as indicated by the weight of muscle in the hind leg per 10 cm length, was 40 g (6 %) heavier in the carcasses of the 'good' conformation class. This contrasted with the much greater differences, between batches, of 290 g (40 to 50 %). Between batches there were significant differences for all the measures taken except the yield of preferred retail cuts. In the main the batch differences were greater and commercially more important than the conformation class differences.

Comparison of objective external carcass measurements and subjective conformation scores for prediction of lamb carcass quality

“…Relationships between subjective conformation scores and objective carcass measurements are shown in Table 3. The results of this study confirm the findings of Kirton and Pickering (1967), Jackson and Mansour (1974) and Lirette et al (1984), namely that carcasses of good conformation had a more compact trunk and shorter hind limbs than those of poorer conformation. In the present study, carcass length Can.…”

“…This study confirms the accuracy of the subjective conformation score system in identifying compact, muscular carcasses. This should be of value, given that consumers tend to prefer cuts of meat from compact "blocky" carcasses with thicker muscles (Jackson and Mansour 1974;Harrington and Kempster 1989).…”

“…A number of researchers (Kirton and Pickering 1967;Jackson and Mansour 1974;Kempster et al 1981) have concluded that lamb carcasses with good conformation tend to be fatter than those with poor conformation. In an earlier study (Stanford et al 1995) we also showed a trend toward increasing GR measurement with increasing conformation score under the Canadian Classification System.…”

Genetic relationships between visual and objective measures of carcass composition in crossbred lambs

“…Despite the considerable volume of research which has indicated that there is little to no value of conformation as a predictor of carcass lean proportion (Kirton and Pickering, 1967;Jackson and Mansour, 1974;Kempsteret al, 1981;Simm and Murphy, 1996), current commercial classification schemes place a premium On carcasses of higher conformation as well as reduced fat content. Kempsterer ct. (1981) suggested that, regardless of its valuein predicting lean content, if conformation is a factor in commercial classification schemes it should also be included to some extent as a selection objective in breeding schemes.…”

Variabilité de la répartition du tissu musculaire du membre postérieur de l'agneau. — I. Muscles individuels

“…La musculature striée des animaux est un (Hammond, 1932 ;Pàlsson, 1940 ; Dumont, 1960 ;Boccard et al, 1961 ;Fourie, 1965 ; Dumont, 1973 ;Jackson et Mansour, 1974 ;Jury, Fourie et Kirton, 1977 ;Anous, 1980 ;Taylor, Mason et McClelland, 1980 ; Thorgeirsson, 1981 ;Teyssier et Prud 'hon, 1982 ;Butterfield et al, 1983 ;Butler-Hogg et Whelehan, 1984 ;Butterfield et al, 1984). Mais dans cette espèce, comme dans les autres, on manque d'information sur l'amplitude de la variation rencontrée entre individus présentant des types morphologiques très différents et chez lesquels on sait maintenant qu'il existe des contraintes particulières du développement musculaire en liaison avec la masse et les dimensions des supports osseux (Anous, 1986a fig.…”