日粮添加乳酸菌对苏尼特羊肌纤维类型及肉品质的影响

以6月龄苏尼特羊为研究对象,利用ATP酶(ATPase)组织化学染色法和实时荧光定量技术,对苏尼特羊背最长肌的肌纤维特性、肌球蛋白重链(myosin heavy chains,MyHCs)的基因表达量、代谢酶活性及肉品质进行了研究,并分析了肌纤维特性、MyHCs基因表达量与肉品质间的相关关系,探究日粮添加乳酸菌对苏尼特羊肌纤维类型及肉品质的影响。结果表明,日粮添加乳酸菌使Ⅰ型肌纤维的数量比例,MyHCⅠ、MyHCⅡa和MyHCⅡx的基因表达量显著升高(P<0.05),乳酸脱氢酶(Lactate dehydrogenase,LDH)活性、肌肉pH、L*值和剪切力显著降低(P<0.05),a*值显著升高(P<0.05)。相关性结果显示,苏尼特羊背最长肌的pH₀与MyaHCⅡx基因表达量成极显著负相关(P<0.01),pH₂₄与Ⅰ型肌纤维的数量比例和面积比例成显著负相关(P<0.05)。L*值与MyHCⅠ基因表达量成显著负相关(P<0.05),a*值与Ⅰ型肌纤维的数量比例、MyHCⅡx基因表达量成显著正相关(P<0.05)。综上所述,日粮添加乳酸菌可以通过提高氧化型肌纤维的比例改善肌肉色泽,提高肌肉嫩度,从而提高羊肉品质。

Effects of Dietary Lactic Acid Bacteria Addition on Muscle Fiber Types and Meat Quality in Sunit Sheep

The muscle fiber characteristic, MyHCs gene expression, metabolic enzyme activity and meat quality traits in Longissimus dorsi of 6-month-old Sunit sheep were measured by ATPase histochemical staining technique and real-time fluorescence quantitative technique to investigate the effects of dietary lactic acid bacteria on muscle fiber types and meat quality of Sunit sheep. In addition, the relationship between muscle fiber properties, MyHCs gene expression and meat quality were analyzed. The results showed that the proportion of typeⅠmuscle fibers and the genes expression of MyHCⅠ, MyHCⅡa and MyHCⅡx were increased significantly (P<0.05), lactate dehydrogenase activity, muscle pH, L* and shear force value were significantly decreased (P<0.05), and a* value was significantly increased in the lactic acid bacteria group (P<0.05). Correlation results showed that the pH₀ of Longissimus dorsi was significantly negatively correlated with MyHCⅡx gene expression (P<0.01), the pH₂₄ was significantly negatively correlated with the proportion and area ratio of typeⅠmuscle fibers (P<0.05). L* value was significantly negatively correlated with MyHCⅠ gene expression (P<0.05), and a* value was significantly positively correlated with the number of typeⅠmuscle fibers and MyHCⅡx gene expression (P<0.05). In summary, dietary lactic acid bacteria could improve the muscle color and tenderness by increasing the proportion of oxidized muscle fibers, thereby improving the meat quality of Sunit sheep.