Fisher A V, Green D M, Whittemore C T, Wood J D, Schofield C P
Division of Food Animal Science, University of Bristol, Langford, Bristol, UK.
Meat Sci. 2003 Sep;65(1):639-50. doi: 10.1016/S0309-1740(02)00266-8.
The growth of carcass tissues and developmental changes in tissue distribution were studied in three pig types which were selected to have morphologies that could be described as attenuated, blocky and flabby. These were achieved by incorporating, respectively, Landrace, Pietrain and Meishan genes to give commercial 'types' (designated L, P and M,) exhibiting some of the phenotypic qualities of these breeds. Twenty-five female pigs of each type with an average start weight of 27.2 kg were fed ad libitum and slaughtered over a (nominal) live weight range of 35-115 kg. Relations were quantified using the logarithmic transformation of data in the allometric model. Significant type differences in relative growth rates (the b coefficient or slope in the logarithmic plot) were not common, occurring in 14% of the relationships examined, whereas 61% of differences in the constant term (a or intercept in the logarithmic plot) were significant. Increase in carcass weight with age was not different between the types but in relation to slaughter live weight (dressing percentage) P had the highest value, M the lowest. Carcass dimensions showed that, relative to body length, P had the widest ham and shoulder over the whole size range whereas M had a deep (ventral-dorsal) shoulder and wide belly, attributes of shape that would be regarded as undesirable by the meat trade. Relative to carcass weight, L was only slightly longer (3 mm) in the body than M at the heavy end of the weight range but markedly longer (29 mm) than P. These differences in carcass conformation were also evident in the shape of pelvic limb muscles which, at a given length, were lightest and narrowest in M and, in some cases, heavier and wider in P than in L. Pelvic limb volume relative to limb length was greatest in P and least in M. Carcass composition (at a given prepared side weight) of P was characterized by low fat and high lean weights, and a high lean to bone ratio. Subcutaneous fat b was lowest in P, indicating that P was early maturing, but M carcasses had the most subcutaneous and intermuscular fat, also indicative of early maturing. There was, thus, no simple relation between maturity characteristics and carcass composition. M carcasses also had the greatest weight of skin. P had a light hindloin and heavy pelvic limb, M a heavy shoulder, hindloin and flank but a light pelvic limb; L had a light shoulder but a heavy foreloin. The distribution of individual tissues mirrored these differences in joint weights to a varying extent; in most cases the match (relatively heavy/light) was with a single tissue. These data, thus, indicated some pig type differences in tissue distribution and of particular significance was the relatively light lean mass in the pelvic limb of M. The results showed important differences in carcass quality between commercially available pig types differing in conformation.
对三种猪的胴体组织生长和组织分布的发育变化进行了研究，这三种猪被选来具有可描述为消瘦型、短粗型和松弛型的形态。这是通过分别引入长白猪、皮特兰猪和美系梅山猪的基因来实现的，从而得到具有这些品种某些表型特征的商业“类型”(分别指定为L、P和M)。每种类型的25头母猪，平均初始体重为27.2千克，自由采食，在（名义）活重35 - 115千克范围内屠宰。使用异速生长模型中数据的对数变换对关系进行量化。相对生长率（对数图中的b系数或斜率）的显著类型差异并不常见，在所研究的关系中占14%，而常数项（对数图中的a或截距）的差异有61%是显著的。胴体重随年龄的增加在各类型之间没有差异，但相对于屠宰活重（屠宰率），P型最高，M型最低。胴体尺寸表明，相对于体长，P型在整个体型范围内火腿和肩部最宽，而M型肩部（腹背方向）深且腹部宽，这些形状特征在肉类行业中会被认为是不理想的。相对于胴体重，在体重范围的上限，L型猪的身体仅比M型略长（3毫米），但比P型明显长（29毫米）。这些胴体形态的差异在盆腔肢肌肉的形状中也很明显，在给定长度下，M型的盆腔肢肌肉最轻且最窄，在某些情况下，P型比L型更重且更宽。相对于肢长，盆腔肢体积在P型中最大，在M型中最小。P型胴体组成（在给定的一侧胴体重下）的特点是脂肪含量低、瘦肉重量高以及瘦肉与骨骼的比例高。P型的皮下脂肪最少，表明P型早熟，但M型胴体的皮下和肌间脂肪最多，这也表明早熟。因此，成熟特征与胴体组成之间没有简单的关系。M型胴体的皮肤重量也最大。P型猪的后腰部轻而盆腔肢重，M型猪的肩部、后腰部和胁腹重但盆腔肢轻；L型猪的肩部轻但前腰部重。各个组织的分布在不同程度上反映了这些关节重量的差异；在大多数情况下，匹配（相对重/轻）是与单一组织相关的。因此，这些数据表明了不同猪类型在组织分布上的一些差异，特别重要的是M型猪盆腔肢中相对较轻的瘦肉量。结果表明，在体型上不同的市售猪类型之间，胴体质量存在重要差异。
