Effects Of Betaine On Growth Performance And Fat Metabolism Of Geese And Its Regulatory Mechanism

Betaine,also known as trimethylglycine,can participate in body lipid metabolism and improve carcass composition.Betaine is also a very important methyl donor in the body,which participates in epigenetic regulation by controlling the degree of methylation reaction.At present,betaine as a feed additive has been widely promoted and used in livestock and poultry production,but there are few studies on the effect of betaine as a methyl donor on goose fat metabolism and DNA methylation and its mechanism of action.Therefore,this experiment systematically studied the effects of adding betaine to the diet to regulate the growth performance and fat metabolism of geese and its regulation mechanism through animal experiments and cell experiments.1.Effects of betaine on growth performance and protein metabolism of geeseA total of 360 one-day-old healthy male Jiangnan geese with similar body weight were randomly divided into 5 groups with 6 replicates per group and 12 geese per replicate.Geese in the control group(group A)were fed a basal diet,and geese in experimental groups were fed the basal diets supplemented with 0.06%(group B),0.12%(group C),0.18%(group D)and 0.24%betaine(group E).The experiment lasted for 63 days.The results showed as follows:(1)The body weight increased with the rise of betaine at 42 days of age(P<0.05);the body weight of groups of C,D and E was significantly lower than that in groups of A and B(P<0.05).The average daily feed intake(ADFI),average daily gain(ADG)decreased with the rise of betaine,however,the feed/gain(F/G)increased with the rise of betaine at 43 to 63 days of age(P<0.05);(2)The serum contents of GH and IGF-I increased with the rise of betaine at 42 days of age(P<0.05);(3)The percentage of thickness of the sebum of geese decreased with the rise of betaine at 63 days of age(P<0.05);The liver index of geese increased with the rise of betaine at 63 days of age(P<0.05);(4)The contents of leucine,phenylalanine,valine and alanine increased with the rise of betaine at 63 days of age(P<0.05).2.Effects of betaine on fat metabolism and DNA methylation of goose and its r egulatory mechanismBetaine treatment and test arrangement were the same as Test 1.The results showed as follows:(1)The serum contents of triglyceride(TG)and total cholesterol(TCHOL)decreased with the rise of betaine at 63 days of age(P<0.05);(2)The HSL activity in the liver increased with the rise of betaine at 63 days of age(P<0.05),the FAS activity in the liver decreased with the rise of betaine at 63 days of age(P<0.05);(3)The percentage of abdominal fat decreased with the rise of betaine at 63 days of age(P<0.05),The percentage of total area of abdominal lipid droplet of groups of C,D and was significantly lower than that in groups of A and B(P<0.05);(4)The addition of betaine to the diet significantly increased the levels of lipid metabolites Cer,PC,PE,Pet,PG,PMe of liver in the geese,and down-regulated the level of TG,which improved the efficiency of the fat metabolism of the geese and promoted the lipid metabolism of the geese.Through KEGG Patheway analysis,it was found that betaine mainly changed the lipid metabolism pathways of the geese including glycerophospholipid,linoleic acid,linolenic acid and α-linolenic acid;(5)The addition of betaine to the diet significantly increased the DNA methylation level of the VNN-1 gene promoter region in the liver of young goose,but its gene expression level was significantly reduced.3.Effects of betaine on lipid metabolism and DNA methylation in geese embryo genic primary hepatocytes and its regulation mechanismGeese primary germinal hepatocytes were used as the research material in this experiment.We studied the effects of different concentrations(0,2.5,5.0 and 10.0 mmol/L)of betaine on DNA methylation related enzyme activity and DNA methylation in promoter region of VNN-1(pantetheinase)in geese primary germinal hepatocytes.DNA methylase inhibitor(AZA)were used to explore the molecular mechanism of DNA methylation regulating gene expression in the promoter region of the VNN-1 gene.The results showed as follows:(1)The levels of low-density lipoprotein(LDL)in betaine culture medium containing 2.5,5.0 and 10.0 mmol/L was significantly lower than that in the control group(P<0.05).(2)The ratio of SAM/SAH in betaine culture medium containing 10.0 mmol/L was significantly higher than that in the control group(P<0.05).(3)The expression of VNN-1 gene in betaine culture medium containing 5 and 10.0 mmol/L was significantly lower than that in the betaine medium of 0 and 2.5 mmol/L(P<0.05).The DNA methylation level in the promoter region of the VNN-1 gene in the culture medium of 5.0 and 10.0 mmol/L betaine was significantly higher than that in the control group(P<0.05);(4)When treated by AZA for 96h,the expression of VNN-1 gene was significantly increased,VNN-1 gene expression was significantly increased in the AZA and AZA+Betaine group,fatty acid synthase(FAS)gene expression was significantly increasedin the AZA group at 48h compared to the control group(P<0.05).In summary,the addition of betaine to the diet can promote the growth of geese by increasing the serum GH and IGF-I content at 1 to 42 days of age,and promote lipid metabolism of geese by mediating the methylation of the promoter region of the VNN-1 gene at 43 to 63 days of age.Cell experiments verified that betaine promotes lipid metabolism by mediating the methylation of the promoter region of the VNN-1 gene.