Hawkins R R, Moody W G, Kemp J D
J Anim Sci. 1985 Nov;61(5):1154-63. doi: 10.2527/jas1985.6151154x.
Histological properties from the longissimus (LD) and semimembranosus (SM) muscles of 51 wether and ewe lambs from Hampshire rams and two ewe genetic types (SR, 1/2 Suffolk and 1/2 Rambouillet, and FS, 1/2 Finnish Landrace and 1/2 Southdown) and three slaughter live weights (32, 41 and 50 kg) were compared. Fibers in both muscles were classified as beta R (red), alpha R (intermediate) or alpha W (white). All LD muscle fiber types from FS ewe lambs increased in diameter from 32 to 41 kg, but decreased in diameter from 41 to 50 kg. Also, this quadratic effect with slaughter weight was found in alpha R and alpha W fibers from the SM muscle of FS wether and ewe lambs. However, diameters of alpha R and alpha W fibers from SR wether and ewe lambs and beta R fibers from SR ewe lambs increased linearly in the SM muscle with increasing slaughter weight. As slaughter weight increased, the proportion of alpha R fibers decreased in both the LD and SM muscles for SR wether and FS wether and ewe lambs. Concurrent with the increase in slaughter weight and decrease in alpha R fiber percentage, the proportion of alpha W fibers increased in the LD muscle of SR wether lambs, the SM muscle of SR ewe lambs and both muscles of FS wether and ewe lambs. Genetic type and sex groups, except SR ewe lambs, support the theory of transformation of alpha R to alpha W fibers with increasing slaughter weights. Fat-cell diameters increased in both muscles of SR wether and FS ewe lambs with increasing slaughter weights. Increases in fat traits of lamb carcasses were related to increases in red-fiber size. Alpha red fiber numbers were inversely related (P less than .05) to alpha W fiber numbers in both the LD and SM muscles (r = -.83 and -.79). The proportion of alpha R to alpha W fibers might be used as an indicator of physiological maturity for lambs.
对来自汉普郡公羊与两种母羊遗传类型（SR，1/2萨福克羊和1/2兰布耶羊；以及FS，1/2芬兰长白猪和1/2南丘羊）的51只阉公羊和母羊羔羊的背最长肌（LD）和半膜肌（SM）的组织学特性进行了比较，这些羔羊有三个屠宰活重（32、41和50千克）。两块肌肉中的纤维被分类为βR（红色）、αR（中间型）或αW（白色）。FS母羊羔羊的所有LD肌纤维类型直径从32千克增加到41千克，但从41千克增加到50千克时直径减小。此外，在FS阉公羊和母羊羔羊的SM肌的αR和αW纤维中也发现了这种与屠宰体重的二次效应。然而，SR阉公羊和母羊羔羊的SM肌中，αR和αW纤维以及SR母羊羔羊的βR纤维直径随着屠宰体重增加呈线性增加。随着屠宰体重增加，SR阉公羊和FS阉公羊及母羊羔羊的LD和SM肌中αR纤维比例均下降。随着屠宰体重增加和αR纤维百分比下降，SR阉公羊羔羊的LD肌、SR母羊羔羊的SM肌以及FS阉公羊和母羊羔羊的两块肌肉中αW纤维比例均增加。除SR母羊羔羊外，遗传类型和性别组支持随着屠宰体重增加αR纤维向αW纤维转化的理论。随着屠宰体重增加，SR阉公羊和FS母羊羔羊的两块肌肉中脂肪细胞直径均增加。羔羊胴体脂肪性状的增加与红色纤维大小的增加有关。在LD和SM肌中，α红色纤维数量与αW纤维数量呈负相关（P小于0.05）（r = -0.83和-0.79）。αR与αW纤维的比例可作为羔羊生理成熟度的指标。
