Effects Of N-Carbamylglutamate On Lactation Performance,rumen Flora And Plasma Metabolome Of Dairy Cows

This experiment used 16S rDNA and LC-MS technology to study the effects of NCarbamylglutamate(NCG)on lactation performance,antioxidant capacity,rumen flora and plasma metabolome of dairy cows through feeding experiments.To explore the mechanism of the effect of NCG on the lactation performance of dairy cows.Experiment 1 Effect of dietary supplementation of N-Carbamylglutamate on lactation performance of dairy cowsIn this experiment,240 Holstein dairy cows were selected.According to the parity,body condition score,lactation days,and milk production,they were divided into the experimental group and the control group according to the matching principle.Each group was 120 cows.The control group was fed the basic diet day.The experimental group was fed the basal diet+20 g/d/head of NCG.The test period was 60 days,including 15 days for the pre-test period and 45 days for the positive test period.The results showed that the addition of NCG had no effect on the dry matter intake of dairy cows(P>0.05),and the milk production increased by 1.08 kg/d,but the difference was not significant(P>0.05);it significantly decreased the milk urea nitrogen content(P<0.01),the milk fat rate and milk protein rate increased,and t somatic cell count decreased(P>0.05).It showed that adding 20 g/d NCG to the diet had a certain effect on increasing milk yield and improving milk quality.Experiment 2 Effects of dietary supplementation of N-carbamylglutamic acid on plasma biochemical indexes and antioxidant indexesThe experimental design is the same as that of Experiment 1.On the 30th day of the positive trial period,8 cows with similar parity,lactation days and milk production were selected from the control group and the experimental group for tail vein blood collection to determine plasma biochemical and antioxidant indexes.The results showed that the addition of NCG significantly decreased the concentration of β-hydroxybutyrate in plasma(P<0.01)and the concentration of blood urea nitrogen in plasma decreased(P=0.09);significantly increased plasma superoxide dismutase and glutathione peroxidation Serum enzyme concentration(P<0.05),plasma catalase concentration showed an upward trend(P=0.06),and had no significant effect on other indicators(P>0.05).It was shown that adding 20 g/d NCG to the diet may affect the body’s fat and nitrogen metabolism and improve the body’s antioxidant capacity.Experiment 3 Effects of dietary N-carbamylglutamic acid supplementation on rumen fermentation parameters and bacterial floraThe experimental design is the same as that of Experiment 1.The selection of test cows was the same as that of test 2.The rumen juice was collected orally for the determination of rumen fermentation parameters and rumen bacterial flora.The results showed that NCG supplementation significantly reduced the NH3-N concentration in the rumen(P<0.05),but had no effect on the rumen pH value and volatile fatty acid concentration(P>0.05).Dietary supplementation of 20 g/d NCG had a significant effect on the rumen bacterial flora.The alpha diversity index and beta diversity index had no significant effect.At the phylum level,the addition ofNCG had no significant effect on rumen bacteria(P>0.05),Firmicutes,Bacteroidetes,Proteobacteria,Patella bacteria,Plasmodium The phylum Nematode is the dominant phylum in the rumen;at the genus level,the addition of NCG significantly reduced the expression abundance of unranked Bacteroides_RF-16 in the rumen,Ruminococcus_NK4A214,Prevotella Genus,Vibrio succinolyticum and Muribaculaceae are the dominant genus in the rumen.Experiment 4 Effects of dietary supplementation of N-carbamylglutamate on plasma metabolomics of dairy cowsThe experimental design was the same as that of Experiment 1,and the collection of blood samples was the same as that of Experiment 2.The prepared plasma was stored at-80℃,and plasma metabolites were determined by LC-MS non-targeted metabolome assay technology.The results showed that a total of 42 differential metabolites(28 up-regulated and 14 down-regulated)were screened out in the experimental group and the control group;using MetaboAnalyst 5.0 metabolic pathway analysis,a total of D-glutamine and D-glutamate metabolic pathways,There are three metabolic pathways:phenylalanine,tyrosine and tryptophan biosynthesis pathway,and biotin metabolic pathway.It was shown that dietary supplementation of NCG may affect the lactation performance and antioxidant function of dairy cows by regulating amino acid metabolism in the body.In conclusion,the addition of 20 g/d NCG to the diet can improve milk production and milk quality,and can improve the body’s antioxidant capacity.The mechanism may be that NCG is achieved by regulating the body’s amino acid metabolism.