Effects Of Different Energy Feeding Strategies On Fat Differential Deposition And Autophagy In Hu Sheep

With the improvement of people’s living and economic level,the demand for animal meat and meat quality is becoming higher and higher.Dietary energy supply and feeding methods have important effects on animal performance and carcass fat deposition.In recent years,the industry of Hu sheep has developed rapidly.The use of high-precision feed in production will increase the fat deposition in different parts,thus affecting the meat quality.Autophagy can transport damaged proteins and organelles in cells to lysosomes for degradation and recycling.It plays a key role in regulating cell energy metabolism and nutrient storage.It is closely related to body fat metabolism and is greatly affected by dietary energy level,especially sensitive to changes in dietary energy level.In this experiment,Hu sheep were used to study the regulation of autophagy by different energy feeding strategies and the effects on the differential deposition of fat in different parts of the body.96 weaned Hu sheep male lambs aged 3 months(17.22±0.14 kg)were randomly divided into 4 groups with 6replicates in each group and 4 lambs in each replicate.Each replicate was arranged in the same column.The pre-test period was 15 days,and the test period was 90 days.There were two energy levels and four energy feeding strategies,which were divided into two stages: early fattening(1～60 days)and late fattening(61～90 days).Group I was low-energy group(L-L);The second group was low high group(L-H);Group III is high-low group(H-L),and group IV is high-energy group(H-H).The results are as follows :Experiment 1: Effects of energy feeding strategies on fattening effect of Hu Sheep.The final weight,weight gain and average daily gain of H-H group and H-L group were significantly higher than those of L-L group and L-H group(P<0.05),and the weight gain,average daily gain and average food intake of H-H group were significantly higher than those of H-L group,L-L group and L-H group(P<0.05).The digestibility of dry matter,organic matter and crude fat in L-L group was significantly lower than that in other groups(P<0.05),and the digestibility of crude protein in L-L group and H-L group was significantly lower than that in L-H group and H-H group(P<0.05);The digestibility of L-L group was significantly higher than that of L-H group and H-H group(P<0.05).The content of serum total protein in H-L group was significantly higher than that in L-L group and H-H group(P>0.05),and the content of low density lipoprotein in H-H group was significantly higher than that in H-L group(P<0.05).The slaughter performance,back fat thickness and GR value of H-H group were significantly higher than those of other groups(P<0.05).H-H group has the best economic benefit and the largest cost.Experiment 2: Effects of energy feeding strategies on differential fat deposition in Hu sheep.The total fat index,subcutaneous fat index,visceral fat index and intramuscular fat content of H-H group were significantly higher than those of other groups(P<0.05).For Hu sheep adipocyte diameter and area,there was no interaction between energy feeding strategy and different parts(P>0.05);in terms of energy feeding strategy,the diameter of adipocytes in H-H group was significantly higher than that in L-L group and L-H group(P>0.05),the area of adipocytes in H-H group was significantly higher than other groups(P<0.05);in terms of location,the diameter and area of intramuscular adipocytes were significantly lower than those of subcutaneous adipocytes and perirenal adipocytes(P>0.05).Specific size:subcutaneous adipocytes>perirenal adipocytes>intramuscular adipocytes.In the detection of fatty acid synthase(FAS),hormone-sensitive lipase(HSL)and fatty acid binding protein 4(FABP4)enzyme activities in adipose tissue of different parts of Hu sheep,there was no interaction between energy feeding strategy and different parts(P>0.05);but different parts had significant effects on the enzyme activities of FAS,HSL and FABP4 in Hu sheep adipose tissue(P<0.05),indicates that there are site differences in enzymatic activity.Serum leptin levels in H-L and H-H groups were significantly lower than those in L-L and L-H groups(P<0.05),and serum adiponectin levels in L-H group were significantly higher than those in other groups(P<0.05).Experiment 3: Effects of different energy feeding strategies on the expression of fat-related genes and proteins in different parts of Hu sheep.For the expression of microtubule-associated protein light chain 3(LC3),HSL m RNA and protein,and FABP4 protein in different parts of adipose tissue of Hu sheep,the energy feeding strategy interacted with different parts(P<0.05),and the energy feeding strategy was not related to different parts.All parts had significant effects on the expression of LC3,HSL m RNA and protein and FABP4 protein in Hu sheep(P<0.05).For the expression of P62,FAS m RNA and protein and FABP4 m RNA in different parts of Hu sheep adipose tissue,the energy feeding strategy did not interact with different parts(P>0.05);the energy feeding strategy had a significant effect on the expression of P62 and FABP4 m RNA in Hu sheep(P<0.05),in terms of energy feeding strategy,the FABP4 m RNA in the H-H group was significantly lower than that in the other groups(P<0.05),and the P62 m RNA expression in the H-H group was significantly lower than that in the L-H and H-L groups(P<0.05).Energy feeding strategies and different parts had significant effects on the expression of P62 protein in Hu sheep(P<0.05).In terms of energy feeding strategy,the P62 protein of H-H group was significantly lower than that of other groups(P<0.05).In terms of site,subcutaneous fat P62 protein was significantly lower than that in intramuscular fat and perirenal fat(P<0.05),indicating that autophagy was different in site.In summary,in the energy feeding strategy,with sufficient energy supply,the high-energy group had the best fattening effect,but increased carcass backfat thickness and GR value,and decreased lipid synthesis and autophagy,indicating that long-term high energy levels It may induce autophagy damage or in order to maintain its own lipid balance,build health for animals and then regulate its expression in molecules,indicating that autophagy activation by high energy levels is conditional;compared with the high energy group,the high and low groups can significantly reduce the The fat deposition,lipolysis and autophagy LC3 were the highest at the site,and there were site differences in enzyme activity,and the growth performance was better than the low-high group and the low-energy group.The lipid synthesis and autophagy P62 protein expression in the low-high group was the highest,indicating that the ability to promote cell fat synthesis was promoted,while autophagy was inhibited,and the compensatory growth effect of Hu sheep was fully exerted.The changes of autophagy are specific to the site,which is shown as: subcutaneous fat>intramuscular fat>perirenal fat,indicating that there are differences in autophagy in different parts,which may be one of the ways for animals to form differential fat deposition at the same energy level.