| Under the background of the deterioration of grassland ecological environment and the decline of livestock carrying capacity of the grassland,house feeding fattening has become the main fattening method for cashmere goat breeding,resulting in the decrease of the content of n-3 long-chain unsaturated fat fatty acids(n-3PUFA)such as C18:3n3,C20:5n3 and C22:6n3 in mutton,thus reducing the nutritional value of fatty acids in adipose tissue.Our previous research found that Artemisia Ordosica has a positive effect on regulating fat deposition and immune antioxidant activity in cashmere goats.This thesis mainly discussed the effect of Artemisia Ordosica on the fatty acid content in many adipose tissues of cashmere goats,and explored its mechanism from the fatty acid composition and metabonomics of rumen fluid,the transcriptome of subcutaneous fat,and the changes of lipid metabolism related enzymes.The results provide a theoretical basis for regulating the fatty acid composition of adipose tissue in cashmere goats under house feeding conditions,improving nutritional value,and rational utilization of Artemisia Ordosica resources.Using a single factor fully randomized experimental design,40 weaned capricorn sheep with similar body weight and age(120 ± 10 days)were randomly divided into 2groups,with 20 sheep in each group and 4 replicates in each group.The control group was fed with a basic diet,while the Artemisia Ordosica group was replaced with an equal proportion of mixed roughage with 3% Artemisia Ordosica in the basic diet.The experimental period was 90 days.After finishing the fattening test,the slaughter test was carried out,and the rumen fluid and subcutaneous fat,perirenal fat,omental fat,mesentery fat,tail fat and other adipose tissues of cashmere goats were collected for the analysis of fatty acid content,rumen fluid metabolomics,subcutaneous fat metabolism related enzyme activities and transcriptome.This thesis consists of four experiments:Experiment 1 studied the effect of adding Artemisia Ordosica to the diet on the content of fatty acids in the rumen fluid and many adipose tissues of cashmere goats.The results showed that compared with the control group,the Artemisia Ordosica group could significantly reduce the SFA content in the rumen fluid and adipose tissue(P<0.05),significantly increase the n-3 PUFA content,UFA/SFA,and PUFA/SFA values in the rumen fluid mainly C18:3n3(P<0.05).It significantly reduced the n-6/n-3 values of subcutaneous fat,omental fat and mesentery fat(P<0.05),and significantly increased the contents of C20:5n3 and C18:3n3 in subcutaneous fat and omental fat(P<0.05).The content of C20:4n6 in subcutaneous fat(P=0.063),C20:3n6 and C22:6n3 in omental fat(P=0.084,P=0.071)in the Artemisia Ordosica group also increased.The Artemisia Ordosica group significantly increased the C18:1n9c content of perirenal fat and mesentery fat,as well as the n-3PUFA content mainly composed of C18:3n3 and C20:3n3(P<0.05),and significantly increased the C20:3n3 and C20:5n3 content of tail fat(P=0.009,P=0.022).Experiment 2 studied the mechanism of the effect of Artemisia Ordosica on the fatty acid composition of rumen fluid in cashmere goats based on metabolomics.The experimental results showed that compared with the control group,the differential metabolite putrescine and β-Alanine content significantly decreased(P=0.008,P=0.008),succinic acid content increased(P=0.009),D-arginine and D-ornithine metabolism,β-Alanine metabolism,TCA cycle metabolism,Glyoxylic acid and dicarboxylic acid metabolism,and glutathione metabolism were significantly enriched(P<0.05).It is suggested that Artemisia ordosica can reduce the De novo synthesis of fatty acids and the hydrogenation of dietary PUFA,increase the antioxidant capacity of fatty acids in rumen fluid,and increase the rumen bypass content of C18:3n3.Experiment 3 studied the effect of adding Artemisia Ordosica to the diet on the activity of lipid metabolism enzymes of subcutaneous fat of cashmere goats.The results showed that Artemisia Ordosica significantly increased the activities of HSL,ELOVL2,ELOVL5,CD36,SLC27A4,and FABP4 in subcutaneous adipose tissue(P<0.05),and significantly decreased the activities of FAS,LPL,and SCD(P<0.05).It is suggested that Artemisia Ordosica inhibited the De novo synthesis of fatty acid,promoted fat decomposition,fatty acid transport and the conversion of C18:1n9 to n-3PUFA.Experiment 4 was based on Transcriptome to study the effect of Artemisia Ordosica on the gene transcription level in the subcutaneous fat of cashmere goats,and screened the potential and key differential genes and metabolic pathways of Artemisia Ordosica promoting n-3PUFA deposition in subcutaneous adipose tissue.The results showed that compared with the control group,the expression levels of differential genes ADCY2,ADCY5,SCD1,LPL,GYS1,ERBB4,and CPT1 B in the subcutaneous fat of cashmere goats in the Artemisia Ordosica group were significantly reduced(P<0.05),while the expression levels of ACSL4 gene were increased(P<0.01).The insulin signaling pathway,AMPK signaling pathway,and PI3K-Akt signaling pathway were significantly enriched(P<0.05),while the PPAR pathway tended to be significantly enriched(P=0.051).It shows that Artemisia Ordosica can reduce insulin resistance of subcutaneous adipose tissue,increase TG decomposition and n-3PUFA antioxidant capacity,and increase n-3PUFA deposition mainly consisting of C18:3n3,C20:5n3 and C22:6n3.In summary,adding Artemisia Ordosica to the diet can promote the deposition of n-3PUFA in cashmere goats,such as C18:3n3,C20:5n3,C22:6n3,etc..The possible mechanism is that Artemisia Ordosica can reduce the hydrogenation of C18:3n3 in the rumen,enhance antioxidant capacity and increase the rumen bypass content of C18:3n3.It can increase gene expression and enzyme activity related to n-3PUFA synthesis and transportation in adipose tissue,promoting the deposition of n-3PUFA such as C18:3n3and C22:6n3 in adipose tissue. |
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