Study The Effects Of Fasting And Gender On The Slaughter Performance And Meat Quality Of Dezhou Donkey And Its Mechanisms

With the improvement of people’s living standards,people’s requirements for meat quality have been improved.Studies have shown that proper fasting treatment before slaughter can improve meat quality by affecting pre-slaughter stess level,limiting pH value,energy metabolism and tenderizing enzyme activity.Due to the different physiological characteristics and growth patterns of different gender,the slaughter performance and meat quality will also be different.As an emerging and healthy meat donkey,meat has become more and more popular among consumers,but there are few studies on the effects of fasting management and gender factors on donkey meat.This study explored the effects of fasting treatment and gender factors on slaughter performance and meat quality of donkeys and its mechanisms,in order to provide data reference and theoretical basis for determining the optimal fasting time and selecting the dominant gender of donkeys.Part I: Effects of fasting on the slaughter performance and meat quality of Dezhou donkey and its mechanismsTest one: The effects of pre-slaughter fasting time on blood parameters and stress response of Dezhou donkeys were studied.Fifteen Dezhou male donkeys with good homogeneity were selected and divided into three treatments: fasting 24 h,12 h and non-fasting group.Stress index,energy metabolism index and enzyme activity in serum were measured by kit.The results showed that the contents of cortisol,triglyceride and glycerol in serum of fasting 24 h group were higher than those of non-fasting group and fasting 12 h group,and the activities of AMPK,creatine kinase and lactate dehydrogenase were also significantly higher than those of other two groups.It is concluded that long fasting(fasting 24 h)can increase the pre-slaughter stress of donkeys and significantly affect the energy metabolism of donkeys before slaughter.Test two: The effects of different fasting treatments on slaughter performance and muscle energy metabolism of Dezhou donkeys were studied.Fifteen Dezhou donkeys with good homogeneity were weighed on an empty stomach before slaughter,and immediately after slaughter,their carcass weight and bone weight were weighed and slaughter indices were calculated.At the same time,20 g of liver tissue was placed in liquid nitrogen for reserve,and the Longissimus was taken at 24 h after slaughter to determine various energy indicators.After slaughter,the pH value of donkey carcass was continuously recorded during low temperature ripening at 4 ℃.The results showed that there was no significant difference in slaughter indices among different fasting groups.The energy substance content in fasting group was significantly lower than that in non-fasting group.The limit pH value,ADP content,creatine kinase and pyruvate kinase activity in fasting 24 h group were significantly higher than those in other two groups,and the AMP,IMP and lactate content were significantly lower than those in other two groups.It is concluded that long fasting(fasting 24 h)can reduce the energy reserve of donkeys,increase the limit pH value and reduce energy consumption.Test three: The effects of different fasting treatments on the edible quality and tenderizing enzyme activity of Dezhou donkey meat were studied.The Longissimus of donkeys,which were fasting for 24 h,12 h and 0 h and matured at 4 ℃ for 24 h,was continuously measured for pH value and edible quality for 1 to 10 d.At the same time,the Longissimus 20 g was taken at 24 h after slaughter to determine the tenderizing enzyme activity.The results showed that the calpain activity,tenderness and L* value of 12 h fasting group were higher,and the tenderness rate was the fastest.The tenderization rate of fasting 24 h group was second,cooking loss was greater,cathepsin L activity was lower,and there was no significant difference in other meat quality indexes among the three groups.The results showed that the tenderness and chroma of donkey meat treated with fasting for 12 h were better.Fasting for 24 h would increase the cooking loss of donkey meat.Fasting for 12~24 h might accelerate the tenderness of muscle after relieving stiffness.Part II: Effects of gender on the slaughter performance and meat quality of Dezhou donkeyThe effects of gender on slaughter performance and eating quality of Dezhou donkey meat were studied.Five male and five female donkeys with good homogeneity were selected to weigh their live weight before slaughter and their carcass weight and bone weight immediately after slaughter.The changes of pH value of donkey carcass were recorded continuously during low temperature ripening at 4 ℃.After 24 h of ripening,the Longissimus of donkey was taken to continue ripening at 4 ℃.The pH value of Longissimus of donkey and meat quality index were determined continuously 1 to 10 d after slaughter.The results showed that the live weight,carcass weight,skin weight and bone weight were significantly better than those of female donkeys,and the shear force was lower than that of female donkeys.The tenderization speed was faster than that of female donkeys,and the limit pH and other meat quality indexes were not significantly different.It indicated that the slaughtering performance and tenderness of male donkeys are better than that of female donkeys.This study showed that different fasting treatments had little effect on the slaughter performance of Dezhou donkeys,but had significant effect on the meat quality of donkeys.It was suggested that the fasting time of donkeys should be 12 h,and the slaughter performance and tenderness of male donkeys was better than that of female donkeys.