Effects Of Dietary Yeast Culture On Growth Performance,Meat Quality And Fat Metabolism Of Yard Finishing Sheep

With the rapid development of China’s economy and the increase of residents’income level,meat consumption in China is growing rapidly.At present,mutton is becoming more and more popular with in consumers,and the demand for quality of mutton is also rising.As an important meat source,mutton has rich nutritional value,rich in protein,minerals and vitamins necessary for human health.In recent years,improving the quality of animal products has become the focus of scholars’research.Yeast culture(YC),as a kind of feed additive,has been widely concerned by domestic and foreign scholars in animal production.A large number of studies have shown that adding YC to animal feed can improve production performance,stabilize rumen environment and improve meat quality.The purpose of this experiment was to explore the effects of yeast culture added to meat sheep diet on performance,meat quality,muscle fatty acid composition and m RNA expression levels of genes related to fat metabolism of meat sheep,and to establish the relationship between fat metabolism and meat quality,so as to further study the mechanism of YC on meat sheep.A total of 20 Australian Han sheep(average weight 30kg)were randomly divided into two groups,10 in each group.The control group was fed with basal diet,and the YC group was fed with 0.625 g/kg basal diet.They were fed with total mixed ration(TMR).The pre-test lasted for15 days and the formal test lasted for 50 days.After the feeding experiment,each treatment group was slaughtered successively,and the slaughter time was not more than 48 hours.The growth performance,meat quality and fat metabolism of fattening sheep were measured.The results show:(1)Dietary supplementation of yeast culture had no significant effects on growth performance of finishing sheep(P>0.05),but increased dry matter intake(DMI),average daily gain(ADG)and the trend of decreasing feed/gain(F/G).Dietary addition of yeast culture significantly increased the eye muscle area(EMA)of 50-day fattening sheep(P<0.05).(2)Dietary addition of yeast culture had significant effects on blood biochemical indexes of fattening sheep,and significantly increased the concentration of triglyceride(TG)in blood of fattening sheep at 50d(P<0.05).Total cholesterol(TC),low-density lipoprotein(LDL-C),high-density lipoprotein(HDL-C),free fatty acid(FFA)and other blood indexes did not significantly affect(P>0.05)(3)Dietary yeast culture had significant effects on meat quality of fattening sheep,and significantly increased the L~*and a~*values of fattening mutton color(P<0.05);The muscle shear force value of fattening sheep was significantly decreased(P<0.05).It had no significant effect on cooked meat percentage of fattening sheep muscle(P>0.05).It significantly increased the content of intramuscular fat(IMF)of fender sheep(P<0.05).The content of crude protein(CP)in muscle of fattening sheep was significantly decreased(P<0.05).(4)Dietary supplementation of yeast culture had significant effects on the fatty acid content of fattening longisoundsi muscle,and significantly decreased the contents of saturated fatty acid(C17:0)and stearic acid(C18:0)in saturated fatty acid(SFA)(P<0.05).The content of unsaturated fatty acid(UFA)palmitoleic acid(C16:1)was significantly improved(P<0.05).(5)The expression of genes related to fat metabolism in different fat parts and longissimus dorsi muscle of fattening sheep was significantly affected by dietary yeast culture.Peroxisome proliferator activated receptor-γ(PPARγ),a key transcription factor for fat synthesis,is significantly decreased in subcutaneous fat,and sterol regulatory element binding protein-1(SREBP-1)expression levels(P<0.05).The expression level of hormone sensitive lipase(HSL),a key enzyme of fat decomposition,was significantly decreased(P<0.05),and the expression level of lipoprotein lipase(LPL),a key enzyme of fat metabolism,was significantly increased(P<0.05).In abdominal fat,the expression level of SREBP-1,a key transcription factor for fat synthesis,was significantly increased(P<0.05).In tail fat and pelvic fat,there was no significant effect on the expression of genes related to fat metabolism(P>0.05).In the intermuscular fat of biceps femoris,the expressions of key transcription factors PPARγand SREBP-1 for fat synthesis were significantly increased(P<0.05),and the expressions of key lipolysis enzyme LPL were significantly decreased(P<0.05).In longissimus dorsi muscle,the expressions of key transcription factors PPARγand SREBP-1 of fat synthesis were significantly increased(P<0.05),and the key enzyme fatty acid synthase of fat synthesis was significantly increased(P<0.05).The expression levels of FAS and acetyl-co A carboxylase(ACC)were significantly decreased(P<0.05),and the expression levels of LPL,a key lipolysis enzyme,were significantly decreased(P<0.05).In conclusion,adding 0.625g/kg YC in TMR granules can improve the growth performance of house feed fattening sheep,improve the meat quality of fattening sheep,improve the m RNA expression of lipid metabolism-related genes in adipose tissue of different parts of fattening sheep,and thus have a certain effect on fat deposition in fattening sheep.This study provided theoretical basis for the study of yeast culture on product quality and fat metabolism of fattening sheep,and molecular basis for the study of biological functions of genes related to lipid metabolism of fattening sheep.