Does vitamin C supplementation in milk improve growth and health of diarrheic calves?

The objective of this study was to investigate how supplementing vitamin C (VC) in milk affects growth, starter intake, blood metabolites, and the health of young calves classified into healthy or diarrheic groups. Calves were classified as diarrheic if they experienced diarrhea for at least 3 days from birth to day 7, otherwise, they were classified as healthy (i.e., days with diarrhea < 3). From day 8 of age, a total of 48 Holstein calves were divided into four groups based on a 2 × 2 factorial arrangement, with calf health status (healthy or diarrheic) and VC supplementation (VC + or VC – ) to pasteurized milk (0 or 2 g/d; 50% purity) being the main experimental factors. Calves were fed equal amounts of milk until weaning (d 60). Calves continued to be monitored until they reached 74 days of age. Calves in the VC + group were heavier at weaning (74.3 vs. 72.2 kg; P  = 0.04) compared to those calves that did not receive VC. Blood total antioxidant capacity (d 53 and 67) and superoxide dismutase activity (d 53) were greater ( P  < 0.01) in VC + vs. VC – calves. Calf health status and VC supplementation interacted ( P  = 0.03) for blood β -hydroxybutyrate on d 53, with the lowest concentration observed in diarrheic/VC – calves. Calves in the diarrheic group had a lower total antioxidant capacity ( P  = 0.01) but a greater neutrophil-to-lymphocyte ratio on d 53 and 67 ( P  < 0.01) than calves in the healthy group. Before weaning (d 53), neutrophil-to-lymphocyte ratio was greater, but hemoglobin was lower ( P  = 0.02) in calves classified into the diarrheic group that did not receive supplemental VC. The number of days medicated for diarrhea treatment was lower in VC + calves than those in VC – group ( 1.73 vs. 2.47 days; P  = 0.05). Overall, VC supplementation in pasteurized milk improved calf growth and health. Calves that experienced elevated episodes of diarrhea within the first week of life benefited more from supplemental VC than those classified into the healthy group.