The Effect Of Vitamin D₃ On Immune Function Of Periparturient Dairy Cattle

Two trials were conducted to study the effect of vitamin D₃ on the immune function of periparturient dairy cattle. One is effect on Blood routine ,Immunoglobulins(Ig) , T helper (CD4⁺) and T-cytotoxic/suppressor (CD8⁺) of peripheral blood cow in vivo,and another is study that effects of diverse concentration 1,25-(OH)₂D₃on the proliferation, secretion of interferon-γ(IFN-γ) and Immunoglobulins of peripheral blood lymphocytes(PBLs) from periparturient dairy cattle in vitro.Trial 1:Sixty Holstein breed cows were randomly assigned to experiment or control peripartum diet to investigate the effect of Vitamin D₃ on Blood routine ,Immunoglobulins(Ig) , T helper (CD4⁺) and T-cytotoxic/suppressor (CD8⁺) of peripheral blood. The results showed that RBC,WBC,HGB were increased by supplement 105IU/d VD₃ in diet of every cow, and the difference is significant (P<0.01). Compear to control, the PLT, LY%, MO%, number of GR, number of MO also were enhanced, but the difference is not significant (P>0.05) . At the same time, the IgG,IgM and IgA were higher than control , but the difference is not significant (P>0.05) . However, CD4+,CD8+T cells in experiment treatment were significantly higher than in control (P<0.01). The results suggest that Ig and T cell subsets decreased in periparturient dairy cattle can be mitigated by supplement VD₃ in diets.Trial 2:This research investigated the in vitro effects of 0, 0.01, 0.1, 1, 10 and 100nM 1,25-(OH)₂D₃ on the proliferation, secretion of interferon-γ(IFN-γ) . The results suggest that 1,25-(OH)₂D₃ have no effect on proliferation of lymphocytes, but inhibited synthesis of IFN-γby ConcanavalinA and Pokeweed mitogen activated PBLs in a dose-dependent fashion. 0.1 nM and 1nM 1,25-(OH)₂D₃ both significantly suppressed (0.1 nM:p<0.05;1nM:p<0.01)synthesis of IFN-γby ConcanavalinA activated PBLs. And 0.1¹00nM 1,25-(OH)₂D₃ have significant suppressed effect on synthesis of IFN-γby Pokeweed mitogen activated PBLs in 48h and 72h(p<0.01). However, 0.01nM 1,25-(OH)₂D₃ have no significant effect on IFN-γin 48h by ConcanavalinA and Pokeweed mitogen activated PBLs,but were significantly suppressed(p>0.05)in 72h.0.01,0.1nM 1,25-(OH)₂D₃ inhenced Ig production, but 1,10,100nM inhibited ones. IgM production in group of 0.01nM were significant higher than control in 7d (p<0.05). And IgA production in group of 0.01,0.1nM ,IgM production in group 0.01nM also significant increased(p<0.01)in 9d. However, 1¹00nM 1,25-(OH)₂D₃ inhibited synthesis of IgA and IgM in a dose-dependent fashion. 0.01, 0.1nM 1,25-(OH)₂D₃ induced IgG production,but have no significant difference in 3d (p>0.05). 10,100nM1,25-(OH)₂D₃ have significant suppressed IgG production 3 days later.However IgG production supplyment 1nM 1,25-(OH)₂D₃ has not significant difference with control group during the culture .