This randomized clinical trial aimed to determine the extent to which injectable micronutrient supplementation at birth can improve intranasal vaccine response by ameliorating oxidative stress in dairy calves from birth to weaning. For this, 120 Holstein heifer calves were enrolled at birth and randomly allocated into one of 4 groups. The 4 groups included 3 commercially available micronutrient supplements (Selenium, Copper, Zinc, and Manganese; Selenium & Vitamin E; and Vitamins E, A, and D) and one control (saline). Calves received an intranasal vaccine against the respiratory viruses parainfluenza 3, bovine herpesvirus type 1 (BHV-1), and bovine respiratory syncytial virus (BRSV) within the first wk of life. Weight (BW) and hip height (HH) were recorded, and a blood sample and nasal secretion sample were collected at birth before treatment and vaccine administration as well as weekly until weaning at 8 wk. Health scores, including thoracic ultrasound assessment, were recorded weekly from wk 1 to wk 8. Farm treatment records were collected after the completion of the study. Serum micronutrient concentrations were determined from birth to weaning to identify micronutrient status, and serum blood metabolites were analyzed as markers of nutrient utilization. Redox balance was determined in serum as a ratio of reactive oxygen and nitrogen species (RONS) to antioxidant capacity (AOP), known as the oxidant status index (OSi). Intranasal vaccine response was quantified as anti-BRSV and anti-BHV-1 immunoglobulin A (IgA) concentrations in nasal secretions. Linear mixed models with repeated measures were built for the following outcome variables: micronutrient concentrations, blood metabolites, redox balance, IgA concentrations, BW, and HH. Pre-planned contrasts of control vs supplemented were also built for the primary outcome of IgA concentrations. A logistic regression mixed model was built for health events and treatment of disease. Serum selenium concentrations were greater in calves receiving supplements containing Se throughout the first 4 wk of life. However, we did not observe any consistent differences in the other micronutrients. The metabolic biomarkers indicate that supplemented calves had better energy status, as suggested by lower BHB and nonesterified fatty acids (NEFA) concentrations. Supplemented calves showed improved redox balance, as indicated by lower OSi throughout the first wk of life. Calves supplemented with antioxidants at birth had higher anti-BRSV IgA than control calves. Our results indicate an improved immune response to vaccines in calves supplemented with antioxidants at birth. However, this did not translate to growth and health performance as there were no differences in average daily gain (ADG) or incidence of health events throughout the pre-weaning period. This study provides evidence that improving the antioxidant capacity might improve vaccine response, and further research is required to investigate the appropriate frequency and dose of supplementation to improve calf growth and health.
Keywords: Antioxidants; Calves; Oxidative Stress.
The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).