Effect of source and amount of vitamin D on function and mRNA expression in immune cells in dairy cows

Objectives were to determine the effect of supplementing 2 sources vitamin D, cholecalciferol (CH) or calcidiol (CA), at 1 (1mg) 3 mg/d (3mg) prepartum on concentrations D metabolites in plasma, measures innate immune function, and leukocyte mRNA expression. Parous Holstein cows (n = 99) assigned a daily treatment administered as top-dress containing either mg CH (CH1 CH3) CA (CA1 CA3) from 250 d gestation until calving. Plasma cell population blood, adhesion markers, granulocyte phagocytosis oxidative burst evaluated pre- postpartum. The expression leukocytes was determined 270 postpartum for genes involved migration, pathogen recognition receptors, signaling, cytokines, antimicrobial mechanisms, burst, Ca metabolism. Concentrations D3 increased fed CH, whereas those 25-hydroxyvitamin CA. Percentage granulocytes total differed with amount (1mg 24.5 vs. 3mg 37.9%) 22.0 31.0%), thus shifting mononuclear cells opposite direction 75.5 62.1%) 78.0 69.0%). Granulocytes displaying 69.0 62.9%) intensity 7.46 7.28) tended be less compared 1mg. During prepartum, related migration (CD44, ICAM1, ITGAL, ITGB1, LGALS8, SELL), receptor (NOD2, TLR2, TLR6), signaling (FOS, JUN, NFKB2), cytokine (IL1B, IL1R1, IL1RN), mechanisms (CTSB, LYZ), metabolism (ATP2B1, STIM1, TRPV5) CH. Similarly, postpartum, (CXCR2, SELL, TLN1), (AKT2), cytokines (CCL2, ILRN), (DEFB3), (RAC2), calcium (CALM3) Feeding additional last wk changed profile blood attenuated during transition period, including effects leukocytes.