日粮能量水平对乌金猪肌纤维类型基因表达的影响

Effects of Dietary Energy Levels on Gene Expression of Muscle Fiber Types in Wujin Pigs

为了研究日粮能量水平对乌金猪肌肉组织肌纤维类型基因表达的影响,揭示能量水平对肉品质的影响机制,并为通过营养措施调控猪肉品质提供科学依据,试验选取健康、体重约15 kg的乌金猪18头,随机分为3组,设低、中、高3个能量水平(11.84、12.96、14.18 MJ/kg),于体重100 kg时屠宰,取适量腰大肌、半腱肌、股二头肌、菱形肌、背最长肌组织样品,于-80℃保存,并检测不同肌肉组织中MyHCⅠ、2a、2x、2b基因的m RNA相对表达量。结果表明:乌金猪菱形肌以Ⅰ型纤维为主,腰大肌以2a和2x型为主,半腱肌以Ⅰ型、2a和2x型为主;背最长肌以Ⅰ型和2b型为主,股二头肌以Ⅰ型、2b和2x型为主。在低、中、高能量水平下,菱形肌Ⅰ型mRNA的比例极显著高于其他部位(P<0.01);背最长肌2a型m RNA的比例显著低于其他部位(P<0.05);菱形肌2b型mRNA的比例极显著低于其他部位(P<0.01);半腱肌2x型mRNA的比例最高,极显著高于菱形肌(P<0.01)。不同肌肉组织中同一亚型mRNA比例随着能量水平的不同而变化,其中半腱肌高能量水平的2b型mRNA比例极显著高于低能量水平(P<0.01)。首次发现改变日粮能量水平可调控乌金猪肌纤维类型基因表达水平,并能引起肌纤维类型的转化,并首次确定乌金猪腰大肌、半腱肌、菱形肌为氧化型肌肉,股二头肌和背最长肌为酵解型肌肉。

The aim of this experiment was to study the effect of dietary energy level on gene ex⁃pression of muscle fiber types in muscle tissue of Wujin pigs,reveal the mechanism of effect of di⁃etary energy level on meat quality,and provide scientific basis for regulating pork quality through nutritional measures.A tolal of eighteen healthy Wujin pigs with the body weight of about 15 kg were randomly divided into 3 groups with low,me⁃dium and high energy levels(11.84,12.96 and 14.18 MJ/kg).The pigs were slaughtered when the body weight was 100 kg.Appropriate tissue samples of psoas major,semitendinosus,biceps femoris,rhomboid and Longissimus dorsi were collected and stored at-80℃.mRNA relative expression levels of MyHCⅠ,MyHC 2a,MyHC 2x and MyHC 2b genes in different muscle tissues were detected.The results showed that the typeⅠfibers were predominant in rhomboid muscle,type 2a and 2x fibers in psoas major,and typeⅠ,2a and 2x fibers in semitendinosus.Type I and type 2b were predominant in the longissimus dorsi muscle,and typeⅠ,type 2b and type 2x in the biceps femoris muscle.The proportion of typeⅠmRNA in rhomboid muscle was significantly higher than that in other parts(P<0.01).The proportion of type 2a mRNA in longissimus dorsi was significantly lower than that in other parts(P<0.05).The propor⁃tion of type 2b mRNA in rhomboid muscle was significantly lower than that in other parts(P<0.01).The proportion of type 2x mRNA in semitendinosus muscle was the highest,significantly higher than that in rhomboid muscle(P<0.01).The proportion of 2b mRNA in semitendinosus was significantly higher in high energy level than in low energy level(P<0.01).In this study,it was found for the first time that changing dietary energy level could regulate the expression level of muscle fiber type genes and cause the transformation of muscle fiber types in Wujin pigs.It was also found that the psoas,semitendinoids and rhomboids of Wujin pigs were oxidized muscles,and the biceps femoris and longissimus dorsi were glycolic muscles for the first time.