Effects Of Dietary Copper Levels On Meat Quality And Muscle And Body Fat CLA Regulation Of Tan Mutton

In this experiment,four diets with different copper levels were fed to Tan sheep in house.The effects of different copper levels on the growth performance,slaughter performance,rumen microorganisms,FAS?SCD and CLA contents in muscle and fat of Tan sheep were studied through feeding and slaughtering experiments,which provided theoretical basis for the healthy growth and improvement of meat quality and production performance of Tan sheep.Forty healthy and disease-free Tan sheep weighing about 20 kg were selected.The control group was not supplemented with copper(dietary copper content was 9.0 mg/kg),while the test group I,test group II and test group III were supplemented with 3.0,5.0 and 7.0 mg/kg(dietary copper content was 12,14.5 and 16 mg/kg,respectively).The pre-test period is 10 days and the positive test period is 60 days.Feed 2 times a day and drink water freely.At the end of the experiment,three animals were slaughtered randomly in each group.The results showed that:1)There were no significant differences in initial weight,final weight,average daily gain,body length,body height and chest circumference among the four groups(P>0.05).Relative growth of body height in group I was significantly higher than that in control group and group II(P<0.05),There was no significant difference in economic benefits among the four groups(P>0.05),but the economic benefits of group III showed a growing trend.2)There were no significant differences in premortem live weight,carcass weight,bone weight,carcass fat weight,GR value,eye muscle area,bone-meat ratio and carcass meat yield among the four groups(P>0.05).The net meat weight of group I and group II was significantly higher than that of control group(P<0.05),and the tail fat weight of group III was significantly higher than that of control group(P<0.05).3)There were no significant differences in muscle pH,initial water content,water loss rate,drip loss and cooked meat rate among the four groups(P>0.05).The flesh color redness of group I was significantly higher than that of control group and group II and III(P<0.05),and the muscle shear stress of group I and II was significantly higher than that of group III(P<0.05).The results showed that the slaughter performance,meat quality and economic benefit of Tan sheep could be improved by adding appropriate copper level in diet.Under the experimental conditions,7.0 mg/kg copper(16.0 mg/kg copper content in diet)was suitable.At the end of the feeding experiment,three sheep in each group were slaughtered randomly.Muscle and fat were collected and the contents of SCD,FAS and CLA were determined.The results showed that there was no significant difference in SCD content between muscle and fat in each group(P>0.05),but there was significant difference in fat SCD between control group and three experimental groups(P<0.05).There was no significant difference in FAS content in muscle and fat between groups(P>0.05),and there was no significant difference in CLA content among groups(P>0.05),but with the increase of dietary copper content,CLA content had a significant upward trend.The results showed that under the experimental conditions,7.0 mg/kg of copper(16.0 mg/kg of copper in diet)was beneficial to CLA synthesis.After the feeding experiment,the rumen fluid was collected on an empty stomach in the morning,and the rumen bacteria and Vibrio fibrinolyticus were detected.The results showed that there was a significant difference in the amount of OTU in rumen juice between group ? and group ?(P<0.05).There was no significant difference in Chao 1 index of rumen juice among groups(P>0.05).There was no significant difference in Shannon index of rumen fluid among groups(P>0.05).There was a significant difference in Vibrio fibrinolyticus between group III and group ?(P<0.05),but there was no significant difference between group I and control group(P>0.05).The results showed that diets containing copper could effectively promote the growth and reproduction of microorganisms in the rumen environment,and contribute to the absorption and utilization of nutrients.Under the experimental conditions,Vibrio fibrinolyticus with 7.0 mg/kg copper(16.0 mg/kg copper in diet)had the highest content which contributed to the hydrogenation of linoleic acid to form conjugated linoleic acid(CLA)in the rumen.In conclusion,proper dietary copper supplementation could improve the performance,meat quality,rumen bacteria,content of conjugated linoleic acid in muscle and fat of Tan sheep.Copper supplementation of 7.0 mg/kg of copper(16.0 mg/kg of copper in the diet)was helpful to the improvement of mutton quality and the deposition of CLA.