Background Dairy cows are at high risk of fatty liver disease in early lactation,but current preventative measures are not always effective.Cows with fatty liver have lower circulating branched-chain amino acid(BCAA)c...Background Dairy cows are at high risk of fatty liver disease in early lactation,but current preventative measures are not always effective.Cows with fatty liver have lower circulating branched-chain amino acid(BCAA)concentra-tions whereas cows with high circulating BCAA levels have low liver triglyceride(TG).Our objective was to determine the impact of BCAA and their corresponding ketoacids(branched-chain ketoacids,BCKA)on production performance and liver TG accumulation in Holstein cows in the first 3 weeks postpartum.Methods Thirty-six multiparous Holstein cows were used in a randomized block design experiment.Cows were abomasally infused for the first 21 d postpartum with solutions of 1)saline(CON,n=12);2)BCA(67 g valine,50 g leu-cine,and 34 g isoleucine,n=12);and 3)BCK(77 g 2-ketovaline calcium salt,57 g 2-ketoleucine calcium salt,and 39 g 2-ketoisoleucine calcium salt,n=12).All cows received the same diet.Treatment effects were determined using PROC GLIMMIX in SAS.Results No differences were detected for body weight,body condition score,or dry matter intake averaged over the first 21 d postpartum.Cows receiving BCK had significantly lower liver TG concentrations compared to CON(6.60%vs.4.77%,standard error of the mean(SEM)0.49)during the first 3 weeks of lactation.Infusion of BCA increased milk yield(39.5 vs.35.3 kg/d,SEM 1.8),milk fat yield(2.10 vs.1.69 kg/d,SEM 0.08),and lactose yield(2.11 vs.1.67 kg/d,SEM 0.07)compared with CON.Compared to CON,cows receiving BCA had lower plasma glucose(55.0 vs.59.2 mg/dL,SEM 0.86)but higherβ-hydroxybutyrate(9.17 vs.6.00 mg/dL,SEM 0.80).Conclusions Overall,BCAA supplementation in this study improved milk production,whereas BCKA supplementa-tion reduced TG accumulation in the liver of fresh cows.展开更多
Exploiting light to drive redox reactions is currently a hot topic since light is considered as an environmentally friendly source of energy.Consequently,cyanobacteria,which can use light e.g.,for generating NADPH,are...Exploiting light to drive redox reactions is currently a hot topic since light is considered as an environmentally friendly source of energy.Consequently,cyanobacteria,which can use light e.g.,for generating NADPH,are in the focus of research.Previously,it has been shown that various heterologous redox enzymes could be expressed in these microorganisms.Here we demonstrated the successful inducer-free expression of𝛼-keto-acid dehydroge-nases(L-HicDH and D-HicDH)from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008 in Synechocystis sp.PCC 6803ΔhoxYH mutant using replicative plasmids.While the L-HicDH showed poor activity limited by the amount of expressed enzyme,the D-HicDH was applied both in vivo and in vitro,transforming the selected𝛼-keto acids to the corresponding optically pure(R)-𝛼-hydroxy acids(ee>99%)in up to 53%and 90%conversion,respectively.展开更多
基金This work is supported by the Agriculture and Food Research Initiative competitive grant No.2021-67015-33383 from the USDA National Institute of Food and Agriculture(Washington,DC)and USDA,AgBioResearch,Michigan State University.
文摘Background Dairy cows are at high risk of fatty liver disease in early lactation,but current preventative measures are not always effective.Cows with fatty liver have lower circulating branched-chain amino acid(BCAA)concentra-tions whereas cows with high circulating BCAA levels have low liver triglyceride(TG).Our objective was to determine the impact of BCAA and their corresponding ketoacids(branched-chain ketoacids,BCKA)on production performance and liver TG accumulation in Holstein cows in the first 3 weeks postpartum.Methods Thirty-six multiparous Holstein cows were used in a randomized block design experiment.Cows were abomasally infused for the first 21 d postpartum with solutions of 1)saline(CON,n=12);2)BCA(67 g valine,50 g leu-cine,and 34 g isoleucine,n=12);and 3)BCK(77 g 2-ketovaline calcium salt,57 g 2-ketoleucine calcium salt,and 39 g 2-ketoisoleucine calcium salt,n=12).All cows received the same diet.Treatment effects were determined using PROC GLIMMIX in SAS.Results No differences were detected for body weight,body condition score,or dry matter intake averaged over the first 21 d postpartum.Cows receiving BCK had significantly lower liver TG concentrations compared to CON(6.60%vs.4.77%,standard error of the mean(SEM)0.49)during the first 3 weeks of lactation.Infusion of BCA increased milk yield(39.5 vs.35.3 kg/d,SEM 1.8),milk fat yield(2.10 vs.1.69 kg/d,SEM 0.08),and lactose yield(2.11 vs.1.67 kg/d,SEM 0.07)compared with CON.Compared to CON,cows receiving BCA had lower plasma glucose(55.0 vs.59.2 mg/dL,SEM 0.86)but higherβ-hydroxybutyrate(9.17 vs.6.00 mg/dL,SEM 0.80).Conclusions Overall,BCAA supplementation in this study improved milk production,whereas BCKA supplementa-tion reduced TG accumulation in the liver of fresh cows.
文摘Exploiting light to drive redox reactions is currently a hot topic since light is considered as an environmentally friendly source of energy.Consequently,cyanobacteria,which can use light e.g.,for generating NADPH,are in the focus of research.Previously,it has been shown that various heterologous redox enzymes could be expressed in these microorganisms.Here we demonstrated the successful inducer-free expression of𝛼-keto-acid dehydroge-nases(L-HicDH and D-HicDH)from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008 in Synechocystis sp.PCC 6803ΔhoxYH mutant using replicative plasmids.While the L-HicDH showed poor activity limited by the amount of expressed enzyme,the D-HicDH was applied both in vivo and in vitro,transforming the selected𝛼-keto acids to the corresponding optically pure(R)-𝛼-hydroxy acids(ee>99%)in up to 53%and 90%conversion,respectively.
