Effects of Intranasal Mineral Administration on Clinical and Immune Responses in Dairy Calves Following Bovine Herpesvirus-1 (BHV-1) Challenge

Abstract

The bovine respiratory disease complex (BRDC) remains the main cause of economic loss affecting cattle and a major cause of morbidity, mortality, and reduced performance. Trace minerals (TM) play important roles in immune function and may influence immunity to respiratory pathogens. Previous studies have demonstrated improved immune responses following administration of injectable TM; however, the effects of intranasal (IN) TM administration during respiratory viral and bacterial infection are unknown. The objective of this study was to evaluate the effects of IN administration of a mineral formulation containing Zn, Cu, and Mg on clinical and immune outcomes in dairy calves following bovine herpesvirus-1 (BHV-1) challenge. Fourteen 3-month-old dairy calves were randomly assigned to one of two experimental groups. Group Intranasal (INM, n = 7) received 4.4 mL of a mineral solution containing 14 mM Zn-EDTA, 0.25 mM Cu-EDTA, and 1.5 mM Mg-EDTA intranasally on days -2, 2, and 6 relative to BHV-1 challenge day (Day 0). Group Control (CON, n = 7) received 4.4 mL of phosphate-buffered saline (PBS) administered at the same time points and by the same methodology. On day 0, all calves were challenged intranasally with BHV- 1. From days 0 to 28, clinical signs were assessed using a respiratory scoring system, nasal swabs were collected for virus isolation, and serum samples were collected to evaluate BHV-1 neutralizing antibody titers. All calves were seronegative to BHV-1 before challenge. Clinical outcomes and isolation of BHV-1 in nasal swabs were similar between CON and INM calves throughout the study period. No significant differences in serum neutralizing antibody titers were observed among treatment groups. Under the conditions of this study, IN administration of a TM formulation containing Zn, Cu, and Mg did not significantly affect clinical outcomes, antibody responses, or virus isolation in dairy calves experimentally challenged with BHV-1.