| As a carrier of one carbon unit in the liver,folic acid(FA)participates in the process of liver lipid metabolism by regulating DNA methylation,phosphatidylcholine(PC)synthesis and lipid gene expression,which has an important impact on improving liver function and production performance.The study investigated the effects and mechanism of dietary supplementation with palm fat powder(PFP)and coated folic acid(CFA)on transition cow performance,rumen fermentation,blood lipidomics and hepatic lipid metabolism.The main research contents and results are as follows:1.Effects of CFA and PFP on growth performance,rumen fermentation and hepatic lipid metabolism of Holstein bulls.In the experiment,fourty-eight Holstein were selected and divided into 4 groups using 2×2 factor design:0 and 120 mg FA/d CFA and 0 and PFP 30 g/kg DM were added to the basal diet,respectively.The results showed that:①Supplement CFA increased average daily gain(ADG),improved feed conversion ratio(FCR),and increased digestibility of dry matter(DM),organic matter(OM),crude protein(CP)and neutral detergent fiber NDF(P<0.05);Lower rumen pH,increase rumen total volatile acid(TVFA)concentration and a acetate to propionate ratio(P<0.05);increased the expression level of peroxisome proliferator-activated receptor α(PPARα),decreased the total lipid content of hepatic and the expression of sterol regulatory element binding protein 1(SREBP1)and acetyl CoA carboxylase(ACACA)(P<0.05).②Supplementation with PFP increased the ADG,improved FCR,increased digestibility of ether extract(EE)and decreased digestibility of NDF(P<0.05);the pH and propionate molar ratio were increased(P<0.05),TVFA concentration,acetate molar ratio and acetate to propionate ratio were decreased;increased the total lipid content of hepatic and the PPARα,and decreased the expression of SREBP1 and ACACA(P<0.05).③The interaction between CFA and PFP were significant on the TG content of heaptic,and the expression of CPT-1 and FAS.2.Effects of CFA and PFP on performance and rumen metabolism of transition dairy cowsThirty-two Holstein dairy cows were selected and divided into 4 groups using 2×2 factors design:0 and 135 mg FA/d CFA and 0 and 500 g/d PFP were add to the basal diet,respectively.The results showed that:①Addition of CFA,improved the EB and FE(P<0.05),increased the milk yield,and milk fat and milk protein content,improved the digestibility of DM,OM,CP,EE,NDF and ADF in the postpartum(P<0.05);TVFA concentration and acetate to propionate ratio were increased(P<0.05);increase the blood glucose(GLU),total protein(TP),albumin(ALB),folic acid(FA)and blood hormone content,reduce TG,total cholesterol(TC),non-esterified fatty acid(NEFA),β-hydroxybutyric acid(BHBA)and acetoacetate(ACAC)content.②Addition of PFP improved the EB and FE,increased milk yield and milk fat content(P<0.05);increased the propionate molar ratio(P<0.05);increased the GLU,TP,ALB,HDL and blood hormone content,reduce TG,TC and ACAC content(P<0.05).③The interaction between CFA and PFP were significant on the TG,very low density lipoprotein(VLDL)and homocysteine(Hcy)content.3.Effects of CFA and PFP on blood lipidomics of perinatal dairy cowsMetabolome analysis was performed on the blood samples of dairy cows 21 days before delivery and 21 days after delivery.The results showed that:in prepartum period ①Addition of CFA,the abundance of PCs and PEs was increased(P<0.05),and the abundance of DGTSs and TGs was reduced(P<0.05).②Addition of PFP increased the abundance of SMs and Cers(P<0.05),and decreased DGTS,PEs and TGs(P<0.05).③Addition of CFA and PFP at the same time increased the abundance of PEs and Cers(P<0.05).In the postpartum ①Addition of CFA increased the abundance of PCs,PEs and Cers(P<0.05),and decreased the abundance of TGs(P<0.05).②Addition of PFP increased the abundance of TGs and PCs(P<0.05),and decreased the abundance of TGs(P<0.05).③Addition of CFA and PFP at the same time increased the abundance of Cers and PCs(P<0.05),and decreased the abundance of TGs(P<0.05).4.Effects of CFA and PFP on lipid metabolism in hepatic of transition dairy cowsTranscriptome analysis was performed on the hepatic tissues of dairy cows 21 days before delivery and 21 days after delivery.The results showed that:in prepartum period ①Supplementation with CFA,the expression of ACSL4 and ACOX3 was significantly up-regulated(P<0.05).②Supplementation with PFP,the expression of PPARa was significantly up-regulated,and the expression of CYP7A1 was significantly down-regulated(P<0.05).③Supplementation with CFA and PFP at the same time,the expression of ACSL4 and SCD-1 was significantly up-regulated,and the expression of APOA1 was significantly down-regulated(P<0.05).In the postpartum ①Supplementation with CFA,the expression of FASN,SCD-1 and SREBP-1c was significantly up-regulated,and the expression of RXRγ,CD36,CYP7A1,APOA1,HMGCS2 and ADIPOR2 was significantly down-regulated(P<0.05).②Supplementation with PFP,the expression of FASN was significantly up-regulated,and the expression of RXRγ,ACSL4,CD36 and ELOVL2 was significantly down-regulated(P<0.05).③Supplementation with CFA and PFP at the same time,APOA1,ACSL4 and HMGCS2.the expression of FASN,HMGCR,CD36 and SCD-1 were significantly up-regulated,and the expression of RXRγ,ELOVL2,APOA1 and GK was significantly down-regulated(P<0.05).In conclusion:There was interaction between CFA and PFP,CFA could reduce the negative effect of PFP and reduce the liver lipid accumulation caused by PFP;CFA or PFP can improve the production performance,energy balance and feed efficiency of perinatal dairy cows;CFA or/and PFP are profit to the synthesis and secretion of VLDL in blood,and regulating the genes expression of fatty acid oxidation and fatty acid synthesis and down regulating the genes expression of fatty acid transport and ketone body synthesis,CFA or PFP can improve the body oxidative energy supply and milk fat synthesis,reduce the hepatic takeup on LCFA intake and ketone body production,and reduce the hepatic lipid accumulation.. |
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