Effect of 25-hydroxycholecalciferol supplementation on turkey performance and immune cell parameters in a coccidial infection model.

This study was conducted to identify the effects of 25-OH cholecalciferol supplementation to turkeys on the immune cells parameters, fecal coccidial oocyst shedding, macrophage nitric oxide production, T regulatory cell cytokine production, and production parameters during a coccidial challenge. A total of 200 1-day-old turkey poults were supplemented with 27.5, 55, 82.5, or 110 μg/kg 25-OH cholecalciferol and challenged or not challenged with coccidial oocysts in a 4 × 2 factorial set up of treatments. Birds fed 110 μg/kg of 25-OH cholecalciferol and infected with coccidial oocyst had 41% lower (P < 0.05) fecal oocyst and 53% higher (P < 0.05) macrophage nitric oxide production than the birds fed 27.5 μg/kg of 25-OH cholecalciferol and infected with coccidial oocyst at 5 d post-coccidial infection. Birds fed 82.5 μg/kg 25-OH cholecalciferol and infected with coccidial oocyst had 5-fold higher (P < 0.05) IL-1 mRNA amounts than the birds fed 27.5 μg/kg of 25-OH cholecalciferol and infected with coccidial oocyst. Birds fed 110 μg/kg 25-OH cholecalciferol and infected with coccidial oocyst had 5.3-fold higher (P < 0.05) IL-10 mRNA amounts than the birds fed 27.5 μg/kg of 25-OH cholecalciferol and infected with coccidial oocyst at 5 d post-coccidial infection. CD4+CD25+ cells from birds fed 110 μg of 25-OH cholecalciferol and infected with coccidial oocyst had 12-fold higher (P < 0.05) IL-10 mRNA than that from the birds fed 27.5 μg/kg of 25-OH cholecalciferol and infected with coccidial oocyst. In conclusion, supplementing birds with 101 μg/kg 25-OH cholicalciferol decreases coccidial oocyst shedding in the feces and could be a nutritional strategy to reduce the coccidial infection and spread in turkeys.