| This experiment was conducted to study the changes of fattening Ways(natural grazing and grazing with supplementary feeding) on fatty acids (FA) and amino acids (AA) in Hulunbeier lambs (HL) and Hulunbeier×Dorper crossbreed lambs(HZ),and from blood and tissue biochemical indexes, gene and protein expression and the relationship between lipid and protein metabolism and diets to discuss the main reason for differences and to look for the key factors related to the composition of FAA and AA in lambs.The results provided theoretical basis for the improvement of the quality and flavor of mutton by the improvement of diets. The experiment adopted 2x2 factorial arrangement. Sixty healthy weaned HL and Sixty HZ with the similar weight and body condition were selected and then divided into 4 groups of thirty animals each, the first factor was fattening ways (NG vs. GS) and the second factor was breed(HL vs. HZ). The experiment lasted for 60 days divided into the early stage of the fattening (1-30d) and the late stage of the fattening (31-60d)The test was divided into six parts. Part one was conducted to compare the effects of fattening ways on the composition of FA and AA in diets of lambs. Part two and part three were conducted to compare the effects of fattening ways on the composition of FA and AA of HL and HZ lambs in mutton, to explore the effects of fattening ways and breed on the meat quality. Part four was conducted to study the effects of fattening ways on blood biochemical indicators and enzyme activity related to fat and protein metabolism in HL and HZ lambs, to explore the effects of fattening ways and breed on fat and protein metabolism in lambs. Part five and Part six was conducted to study the effects of fattening ways on the gene transcription and protein translation related to fat metabolism、protein metabolism and then discussed its mechanism from the Wnt signaling pathways and the mTOR signaling pathways.The results were showed as followed under the present experimental conditions:Compared with NG, the content and feed intake of SFA in GS group were higher, mainly C16:0 and C18:0, C17:0 were lower. The MUFA were higher, mainly C18:1c9, C15:1 were lower. The ω-6 PUFA were higher, mainly C18:2c6,C18:2t6 were lower. The other way around, ω-3 PUFA in NG were higher, mainly C18:3n3,C20:5n3 were lower.Compared with NG, the content of and feed intake of EAA in GS group were higher, mainly Leu,Phe and Lys were lower. The NEAA of GS were higher, mainly Glu, Asp were lower. The BCAA of GS were higher, mainly Leu,Ile and Val were lower. The FAA of GS were higher, mainly Glu, Leu and Arg were lower. The DAA were higher, mainly Glu,Met and Asp were lower. The LAA were also higher,mainly Met,Lys were lower.Compared with NG, the contents of SFA in fat and muscle tissue were higher in GS, mainly C18:0, C14:0, C24:0 were lower. The MUFA of GS were higher, mainly C18:1c9, C17:1were lower. The ω-6 PUFA of GS were higher mainly C18:2n-6c,C18:3n-6 were lower. The co-3PUFA of fat and muscle tissue of NG were higher, mainly C18:3n-3, C20:5n-3 were lower. Compared with HL the SFA of muscle and fat tissue of HZ were higher, mainly C16:0 and C18:0, C24:0 were lower. The MUFA of HZ were higher, mainly C18:ln-9c.Compared with GS, the contents of EAA,NEAA and BCAA in plasma and muscle tissue were higher in NG; Compared with HL, there was an increased tendency of the concentrations of EAA、NEAA、TAA、FAA、LAA and DAA in plasma and muscle tissue in HZ.Compared with GS, the contents of T3/T4、GH、Leptin and TNFa in plasma were significant higher in NG, the contents of TP,TG and LDL-C were significant higher in NG; the enzyme activaty of HSL, BCAT2 and BCKD were significant higher in NG; but the concentration of INS was obviously lower in NG; the enzyme activaty of FAS and ACC in plasma and tissue were significant lower. Compared with HL, the contents of T3/T4,PG,NEFA and enzyme activaty of HSL were significant lower in HZ, but the concentrations of IGF-1, TG, HDL-C and the enzyme activaty of ACC were significant higher in plasma.Compared with NG, the mRNA expression of ADD1, FAS, ACC and DGAT1 in muscle, fat and liver tissue were higher in GS, but the mRNA expression of HSL was lower in GS; Compared with HL, the mRNA expression of ADD1, FAS, ACC and DGAT1 were higher in HZ, but the mRNA expression of HSL was lower in GS.Compared with GS, the mRNA expression of PPARy in Wnt signaling pathways was significant higher in NG, but the mRNA expression of β-catenin was on the contratry. Compared with HZ, the mRNA expression of PPARy and C/EBPa were significant lower in HL, but the mRNA expression of β-catenin was significant higher in HL. The rule of protein expression basic consistent with the law of gene transcription in Wnt signaling pathways.Compared with GS, the mRNA expression of mTORCl、S6K1 and eIF-4G were significantly lower in NG, the mRNA expression of 4E-BP1was significantly higher in NG; Compared with HL, the mRNA expression of mTORCl, S6K1 and eIF-4G in tissue were significantly higher in HZ, but the mRNA expression of 4E-BP1 was significantly lower in HZ. The rule of protein expression basic consistent with the law of gene transcription in mTOR signaling pathways.Integrated the above, From the perspective of the fatty acids nutrition, the results concluded that compared with GS group, meat quality in muscle and adipose tissue are better in NG group; Compared with HZ, meat quality in muscle and adipose tissue are better in HL group. Under the condition of two kinds of fattening ways, the differences between FA contents and composition in diet were the main reason for the differences of meat nutrition value. The dietary content of PUFA was lower in the GS group comparing with the NG group, leading to the higher expression level of gene of ACC, FAS and PPARy which are related to fatty acid de novo synthesis, higher enzyme acitivities of ACC, FAS, SCD and profiles of INS and IGF-1 in blood, and finally increased the contents of SFA as well as MUFA in the body tissue. Diet C18:2n6 and C18:3n-3 contents was the main factors resulting in the differences profiles of corresponding fatty acids in the body tissue, thereby resulting in the changes of meat quality.From the perspective of the protein nutrition, compared with GS group, protein nutritional value in muscle is lower in NG group; Compared with HZ group, protein nutritional value in muscle is lower in HL. Under the condition of two kinds of fattening ways, the differences between AA contents and composition in diet were the main reason for the differences of meat nutrition value. The dietary content of Leu was lower in the GS group comparing with the NG group, leading to the higher profiles of INS and IGF-1 in blood, which activate of mTOR signaling pathways, higher expression level of mTORCl、S6K1、4EB-P1 mRNA and phosphorylation proteins, and finally increased protein synthesis; Lead to lower enzyme acitivities of BCAT1 and BCKD, increased the contents of BCAA in the muscle, thereby resulting in the changes of nutrition value of muscle. |
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