中文摘要：

以12月龄不同饲养条件下（放牧和圈养）苏尼特羊背最长肌作为实验材料，用ATP酶染色法和实时定量聚合酶链式反应技术研究不同饲养方式下肌纤维类型组成。结果表明：放牧苏尼特羊背最长肌Ⅰ型和ⅡB型肌纤维直径和横截面积均显著小于圈养（P＜0.05）；同时，放牧苏尼特羊背最长肌Ⅰ型和ⅡA型肌纤维数量比例和面积比例、MyHCⅠ和MyHCⅡa基因的mRNA表达量均显著大于圈养（P＜0.05），ⅡB型肌纤维数量比例和MyHCⅡb型基因mRNA表达量则呈现相反趋势。

英文摘要：

The aim of this study was to investigate the influence of different feeding systems(stall feeding and grazing)on muscle fiber types of longissimus doris from Sunit sheep by ATPase histochemical staining and real-time polymerase chain reaction.The results showed that the diameters and cross-sectional areas of typeⅠandⅡB muscle fibers in longissimus doris from grazing sheep were significantly lower than those from stall-fed sheep(P<0.05).The number and area percentages of typeⅠand typeⅡA,and MyHCⅠand MyHCⅡa gene expression in grazing sheep were significantly higher than those in stall-fed sheep(P<0.05),but the expression of typeⅡB and MyHCⅡb genes present the opposite trend.