Changes Of Milk IgG And Factors Affecting Its Transfer Into Milk Of Dairy Cows

This study focused on the technology of immune milk production and the regulation mechanism of IgG production and transfer. Six experiments were conducted to study the dynamics of specific IgG and change of IgG transfer, factors affecting the transfer of IgG into milk, association of transfer receptor gene heliotypes with IgG transfer, and gene expression of FcRn after immunostimulation.Experiment 1 used three statistical analysis methods to study the factors affecting the transfer of IgG into the Milk of Holstein Cows. The results of One-way Analysis of Variance and multiple correlation analysis indicated that milk IgG concentrations were found to be significantly correlated with lactation number, stage of lactation, daily milk production and somatic cell count. However, the result of path analysis data suggested the lactation number was associated with IgG concentration in milk directly, and the other factors were the combining factors of direct effects and indirect effects. The results of canonical correlation analysis indicated that four canonical variables relating milk Igs and Lf concentration as y variables with lactation number, stage of lactation, daily milk production, milk fat, protein, lactose, milk total solids and somatic cell score (SCS) as x variables were created. The canonical correlations of the first and second pairs of canonical variables were 0.662 and 0.469 respectively with highly significance, and accounted for 30% information of IgG variability, 10% of IgA,20% of IgM and 60% of Lf. The DHI data in this study were not sufficient to account for variability in Igs concentration, which suggested there were some unknown factors affecting Igs concentration still. This study presented Lf Index and IgG Index first time. The concentrations of IgG and Lf in raw milk were improved 19.4%, 40.2% respectively using the two indexes.Experiment 2 was conducted to study association of transfer receptor gene heliotypes with IgG transfer. The results indicated that: four single nucleotide polymorphisms (SNPs), assorted into six haplotypes, were identified in promoter of FCGRT, but the haplotypes were not correlative with IgG concentration and transfer. Three SNPs, assorted into four haplotypes, were identified by sequencing regions of B2M exons. A homozygous double base-pair deletion in B2M gene may reduce IgG concentration and mass in milk.Experiment 3 studied the preparation of ISCOM based vaccine using Lipase as antigen model. The ISCOM particles were cage-like and icosahedron structures, average 27.0 nm in diameter.Experiment 4 successfully produced antigen release devices (ARD) under the condition of ISCOM based vaccine preparation and using the implantation technology in mammary gland and antigen control release technology. Lots of items were conducted to evaluate the safety and efficiency of ARD implantation in producing immune milk. The results indicated that: ARD implantation brought no negative effects on the health status, production performance of cows, and caused neither subclinical nor acute mastitis. The levels of specific IgG in serum and whey increased in the cows implanted with ARDs, and the dynamics of specific IgG titer demonstrated a clear and consistent pattern with the release of the antigen from three types of ARDs. There were considerable variations among different individual cows in specific transfer. And a transiently up-regulated IgG transfer occurred on 11d and 20d after ARD implantation.Experiment 5 compared the specific IgG titer in colostrum, normal milk and immune milk. The results indicated that: the average specific IgG titer in ARD immune milk reached the level seen in day-2 and 3 colostrum.Experiment 6 studied the FCGRT and B2M gene expression of FcRn after ISCOM based vaccine immunostimulation using mouse as animal model. The results indicated that: the relative expression of FCGRT and B2M gene in the mammary gland increased significantly after immunostimulation. The expression of FCGRT and B2M gene on 4d were higher than that on 8d after immunostimulation.