Effects Of Precursor Complex Of Glucose On Nutritional Metabolism Disease,Serum Ions,Immune Function,Rumen Fermentation Index And Microorganism In Perinatal Cows

This experiment was conducted tor analyze the effects of glucose precursor complex on the negative energy balance,nutritional metabolic disease,immune performance,rumen fermentation and microbial diversity of perinatal dairy cows by measuring the effects of glucose precursor complex on the production performance,blood ketone glucose,serum ions,immune indicators and rumen fermentation of perinatal dairy cows,in order to provide theoretical basis and technical support for production practice or pasture.In the experiment,40 Holstein cows with similar physical condition（3.25±0.5,5-point system）,body weight（570±50 kg）and pregnancy days were selected.They were randomly divided into two groups,one group was the control group of conventional diet,and the other group was the test group supplemented with precursor complex of glucose 350 g/head·day.The precursor complex of glucose was fed 28 days before delivery,7 days before delivery,and stopped feeding 30 days after delivery.This study is divided into six parts:Experiment 1:Collect 100 m L milk samples from each of the two groups of dairy cows on the 7th,14th,30th,60th and 90th day after delivery.By recording the milk yield and detecting the milk components（milk protein,milk fat,lactose,urea nitrogen,solid and non-fat solid）,explore the effect of adding precursor complex of glucose to the diet of dairy cows during the perinatal period on the milk yield and milk quality,and the difference of milk yield and milk quality at different times.The results showed that the milk yield and lactation duration of the test group fed with precursor complex of glucose were significantly higher than that of the control group（P<0.05）,and the lactose content of the test group was significantly lower than that of the control group（P<0.05）,which had no significant effect on other milk components.Experiment 2:The blood ketone and blood sugar values of the two groups of cows were measured on the 20th and 14th day before delivery,the 1st,3rd,7th,14th and 21st day after delivery,and the content of non-esterified fatty acids on the 7th day before delivery,the 1st,7th,14th and 21st day after delivery by using the oxtail root vein blood sampling technology,to explore the effect of adding precursor complex of glucose to the feed of cows in the early and late peripartum on blood ketone,blood sugar and non-esterified fatty acids（NEFA）.The results showed that the content of blood glucose in the test group was significantly higher than that in the control group（P<0.05）,and the content of NEFA in the test group was significantly higher than that in the postpartum period（P<0.05）.Experiment 3:The content of serum cations(Na⁺,K⁺,Ca²⁺)in the cows of the two groups was measured on the 7^th day before delivery and the 1st,7^th,14^th and 21^st day after delivery,to explore the effect of adding precursor complex of glucose to the cow diet on serum sodium,serum potassium and serum calcium.The results showed that the content of serum sodium ion in the test group was significantly lower than that in the control group（P<0.05）,and the content of potassium ion in the control group was significantly higher than that in the test group and higher than the normal value（P<0.05）.Experiment 4:Determine the immune indexes（bovine haptoglobin,bovine serum amyloid A,bovine immunoglobulin A,bovine immunoglobulin G,bovine immunoglobulin M,and bovine interleukin-1）of the two groups of dairy cows on the 7th day before delivery and the 1st,7th,14th and 21st day after delivery using Elisa ELISA kitβ,Bovine interleukin 4,Bovine interleukin 6,BovineγInterferon,bovine tumor necrosis factor-α),To explore the effect of adding precursor complex of glucose to dairy cow diet on immune function of dairy cows.The results showed that the two groups of cows had significant effects on Hp,Ig A,Ig G,Ig M,IL-1β,IL-4,IL-6,INF-γ,TNF-αat different times（P<0.05）.Ig M,IL-1β,IL-6,INF-γ,and TNF-αin the test group were significantly lower than those in the control group（P<0.05）.Experiment 5:The oral rumen fluid collection technology was used to collect the rumen fluid of dairy cows 7 days before delivery,7 days after delivery,and 14 days after delivery.The content of volatile fatty acids（formic acid,propionic acid,butyric acid,isobutyric acid,valeric acid,isovaleric acid）was determined by gas chromatography,and the content of ammonia nitrogen（NH₃-N）was determined by phenol-hydrochloric acid colorimetry to explore the effect of adding precursor complex of glucose to dairy cow diet on rumen fermentation parameters.The results showed that there was no significant difference in volatile fatty acids between the two groups,and the content of ammonia nitrogen in the test group was significantly lower than that in the control group（P<0.05）.Experiment 6:The oral rumen fluid collection technology was used to collect the rumen fluid of dairy cows 7 days before delivery,7 days after delivery and 14 days after delivery.The high-throughput sequencing method was used to study the effect of adding precursor complex of glucose to dairy cow diet on rumen microbial diversity through species abundance difference.The results showed that the dominant bacteria at the gate level and genus level in the test group and the control group were consistent before and after delivery.The richness of the bacterial community at the genus level in the test group was significantly higher than that in the control group on the 7th day after delivery（P<0.05）,and the microbial community structure in the test group was also different from that in the control group.The content of norank＿f＿＿norank＿o＿＿Clostridia＿UCG-014 was significantly higher than that on the 7th day after delivery and the 7th day after delivery in the control group（P<0.05）.It showed that the precursor complex of glucose could increase the species richness of bacteria in the rumen of dairy cattle norank＿f＿＿norank＿o＿＿Clostridia＿UCG-014 content has increased effect.