The Effect Of Feeding Methods On AMPK,Glycolysis And Meat Quality Of Postmortem Sunit Sheep

The gene expression of AMPK(PRKAA1,PRKAA2 and PRKAG3),AMPK activity,glycolysis indexs (hexokinase activity, lactic acid content and muscle glycogen), slaughter performance and meat quality (shear force, color and pH value) were measured in different feeding methods(grazing and captivity)and parts(longissimus muscle, biceps femoris and triceps brachii) of the 12-month-old Sunit sheep, in order to investigate the effect of different feedings and parts on these indexs of Sunit sheep and analyze the correlation coefficients beteeen AMPK, glycolysis and meat quality.The results were as follows:There were differences in the gene expression of AMPKal, α2 and γ3 subunit Between grazing and captivity.The gene expression of PRKAA1 in captivity was higher than that in grazing,and there are remarkable difference in longissimus muscle and biceps femoris between the two feeding methods (p< 0.05). The gene expression of PRKAG3 in captivity was markedly higher than that in grazing (p<0.05),and the gene expression of PRKAA2 were opposite. The expression of the three gene had differences among the there parts.AMPK activity in captivity is higher than that in grazing, which was significantly different in biceps femoris (p<0.05) and undifferentiated in the other two parts (p> 0.05). There was no difference between the three parts of the AMPK activity (p> 0.05).Hexokinase activity in captivity was not significantly higher than that in grazing (p> 0.05). Hexokinase activity of Biceps femoris was significantly higher than that of longissimus muscle in grazing (p<0.05). There was no difference between the three parts of the hexokinase activity in captivity (p>0.05). Lactic acid content in captivity was remarkably higher than that in grazing (p<0.05). In grazing, the lactic acid content of the three parts was not markedly different (p >0.05).In captivity,the lactic acid of triceps brachii was markedly higher than that of longissimus muscle (p<0.05). Muscle glycogen content in grazing is higher than that in captivity, which was significantly different in biceps femoris (p<0.05).Both of these feeding methods were the same that muscle glycogen content of longissimus muscle was significantly higher than that of the other parts, (p<0.05).The live weight, carcass weight, meat weight,meat percentage and carcass meat percentage of captivity were significantly higher than those of grazing (p< 0.05)The tenderness of captivity was better than grazing in longissimus muscle and triceps brachii, and shear force of longissimus muscle in grazing is significantly higher than that in captivity (p<0.05). Among the three parts, tenderness of longissimus muscle was the best. The L*,a* and b* of Sunit sheep in grazing was higher than that in captivity. There was no significant difference between grazing and captivity in pH value (p> 0.05).According to the analysis of the correlation, PRKAA1 and PRKAG3 gene positively regulated expression of AMPK protein.Activated AMPK induced hexokinase activity, accelerated the process of glycolysis, and leaded to the increasing of lactic acid content. Lactic acid content affected pH of postmortem muscle,which have an effect on meat quality.