Effects of 25-hydroxyvitamin D3 on growth performance, fecal scores, vitamin D3 metabolites, antioxidant status, and inflammatory and stress-related parameters in weaning calves

The objectives of this study were to evaluate the effects of milk replacers containing 25-hydroxyvitamin D-3 [25(OH)D-3] and enriched with vitamin D3 on the growth performance, fecal scores, vitamin D-3 metabolites, biochemical blood parameters and antioxidant, inflammatory and stressrelated parameters of Holstein male calves. Thirty Holstein male calves (body weight = 41.4 +/- 2.79 kg) were randomly assigned to three groups for a 56-day experimental period. The control group received milk replacer containing 1.2 mg/kg vitamin D3, the VD group received milk replacer containing 13.2 mg/kg vitamin D-3, and the 25D group received milk replacer containing 300 mg/kg 25(OH)D-3 plus 1.2 mg/kg vitamin D-3 until weaning at day 54. On days 52, 57 and 59, which were defined as days -2, 3 and 5 postweaning, blood samples were collected to measure biochemical blood parameters and antioxidant, inflammatory and stressrelated indicators. Calves that received milk replacer containing 25(OH)D3 consumed more calf starter at one week postweaning (P < 0.01) than those in the control and VD groups. Calves in the VD and 25D groups had a significantly (P = 0.02) greater ADG than calves in control during the overall period. Calves in the VD and 25D groups had greater body weight and withers height on day 60 than calves in the control group. Calves fed 25(OH)D3 displayed lower fecal scores and incidence of fecal scores > 2 overall periods. Calves fed 25(OH)D3 had increased serum 25(OH)D-3 during the preweaning (P < 0.0001) and postweaning (P < 0.0001) periods. A treatment x time interaction (P < 0.0001) was detected for serum vitamin D-3 and 25(OH)D-3 in preweaning calves, however, there was no significant time effect on serum vitamin D-3 and 25(OH)D-3 during the weaning period. Abrupt weaning increased concentrations of total protein, glucose, cholesterol, tCa and tP. Calves fed 25(OH)D-3 had a higher tCa (P = 0.04) and tP (P = 0.02) concentrations than those fed other diets. Weaning challenge significantly decreased the CAT concentration and increased the MDA concentration, and calves fed 25(OH)D3 displayed higher GSH-Px and CAT and lower MDA concentrations during the weaning period. Weaning also significantly increased the cytokine contents, including IL-1 beta, IL-6 and TNF-alpha, and stress indicators, including cortisol and haptoglobin. Significantly lower cytokine (IL-6 and TNF-alpha) and stress indicator (cortisol and haptoglobin) contents were observed in calves fed 25(OH)D-3 than in those from the VD and control groups at 3 and 5 DPW, respectively. In conclusion, feeding milk replacer with 25(OH)D-3 had the potential to improve the growth performance, fecal scores, serum 25(OH)D-3, and tCa and tP concentrations of calves, and may reduce weaning stress by enhancing the antioxidant capacity and decreasing the proinflammatory and stress indicators of calves.