Impact Of Feeding Regimens On Fat Distribution And Fatty Acids Profile Of Sunit Sheep And Its Underlying Mechanism

The effects of fat distribution and fatty acids（FAs）profile on meat quality of Sunit sheep in Inner Mongolia region were studied by using metabonomics,real-time fluorescent quantitative PCR and gas chromatography technology,in order to improve meat quality and economic benefits of sheep industry by regulating fat distribution and FAs profile of stabling sheep with changing the diet composition and increasing the amount of exercise,the feasibility of adding Lactobacillus to diets was confirmed,and then exploring its influence mechanism,so as to provide theoretical basis and method guidance for adding Lactobacillus to diet to improve mutton quality.The results are as follows:The carcass width,pH₀,a^*,b^*,cooking loss,shear force and intramuscular fat（IMF）of muscular tissue of Sunit sheep in grazing feeding group（GG）were significantly higher than those in barn feeding group（BG）（P<0.05）,while the total weight gain,daily weight gain and growth rate,body weight,carcass weight,carcass length,rib weight,net meat weight,carcass meat yield,meat-bone ratio and slaughter rate,pH₂₄and moisture content of muscular tissue in the GG were significantly lower than those in the BG（P<0.05）.There was a significant correlation between fat distribution and FAs profile and meat quality indexes of Sunit sheep（P<0.05）,indicating that fat distribution and FAs profile of Sunit sheep can affect its meat quality.The growth performance and meat production performance of Sunit sheep in grazing condition were reduced,but its edible quality and nutritional value were improved.The contents of IMF,polyunsaturated fatty acid（PUFA）in muscle and accumulated adipose tissue in GG were significantly higher than those in BG（P<0.05）,the contents of abdominal fat and tail fat,and the contents of saturated fatty acid（SFA）and monounsaturated fatty acid（MUFA）in muscle tissue were significantly lower than those in BG（P<0.05）;The content of IMF and SFA in Sunit ewe was significantly higher than that in ram（P<0.05）,and the content of PUFA was significantly lower than that in ram（P<0.05）;The content of subdermal fat and SFA in Sunit sheep was significantly higher than that in muscle tissue（P<0.05）,and the content of PUFA was significantly lower than that in muscle tissue（P<0.05）,indicating that there were significant differences in fat distribution and FAs profile in Sunit sheep with different feeding methods,gender and parts.The content of SFA in the accumulated adipose tissue of Sunit sheep in the exercise group was significantly higher than that in the control group（CG）（P<0.05）,and the content of PUFA and MUFA in muscle tissue were significantly lower than that in the CG（P<0.05）;The proportion of subdermal fat,tail fat and PUFA content of Sunit sheep in flaxseed group were significantly higher than those in the CG（P<0.05）,and the content of SFA in fat,muscle and accumulated adipose tissue of BF were significantly lower than that in the CG（P<0.05）;The IMF content and MUFA of BF in the Lactobacillus group（LG）were significantly higher than those in the CG（P<0.05）,the proportion of abdominal subcutaneous fat and tail fat,and the content of trans linoleic acid in muscle tissue were significantly lower than those in the CG（P<0.05）.In addition,the growth rate,body weight,ocular muscle area,net meat rate,muscle brightness value,yellowness value,fat and ash content in the LG were significantly higher than those in the CG（P<0.05）,and the thickness of backfat,cooking loss,shear force and water content in the LG were significantly lower than those in the CG（P<0.05）,indicating that Lactobacillus can regulate the meat quality.In the LG,the of ACC,the content of ACC with its mRNA relative expression of LT were significantly higher than those in the CG（P<0.05）,the mRNA relative expression of AMPKα1/α2 and CPT1B of LT,AMPKα1,AMPKα2,ACC and CPT1B of tail fat were significantly lower than those in the CG（P<0.05）,indicating that lactobacillus could inhibit the metabolic pathway of AMPK-ACC-CPT1 in Sunit sheep.TCA cycle（citric acid,succinic acid and cis-aconitic acid）,fatty acid metabolic pathway（oleic acidα-Linolenic acidγ-Linolenic acid,palmitoleic acid,EPA,9R,10S Ep OME）and other pathways（metabolites）were significantly changed（P<0.05）.These results indicated that Lactobacillus can inhibit the AMPK-ACC-CPT1metabolic pathway of Sunit sheep,and affect fat and energy metabolism.