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The Effect of Diet on Serum Antibody Response to Vaccine in Horses
It is important to identify management strategies, which contribute to optimal horse health. One strategy is to select diets that support health through increased antibody response to disease or vaccination. The objective of this study was to evaluate the effects of test diets on serum antibody concentrations in adult horses following vaccination. Testing was completed as third party blind analysis. Horses (n= 10 per treatment) were fed a control diet or one of two proprietary diets beginning 111 days prior to vaccination. The control group received a pelleted feed meeting the NRC minimum nutrient requirements. Test diet 1 (TD1) was a pelleted feed, which provided a higher plane of nutrition and added functional ingredient matrix. Test diet 2 was comprised of the control diet with added fatty acid. Serum samples were collected from each horse on day 0, 7, 14, 28, 35, and 42 post-vaccination. Vaccine response was measured through analysis of antibody production. Horses are assumed to be naïve to bovine diseases. The experiment was designed to test the equine antibody response to vaccine for bovine diseases: bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and infectious bovine rhinotracheitis (IBR). Four subclasses of IgG have been identified in the equine body; IgGb, IgGt, IgGa, and IgGc. These four subclasses of IgG and IgM were included in testing. The immune response to each of these diseases was measured separately through Enzyme Linked Immunosorbent Assays (ELISA). ELISAs were completed using IDEXX BRSV IgG Antibody Test Kits, IDEXX BVDV Antibody Test Kits, and IDEXX Infectious Bovine Rhinotracheitis Virus Antibody Tests Kits respectively. Manufacturer’s instructions were followed with the exception of using our own detection antibodies at a dilution of 1:20,000. IgGb, IgGt, IgGa, IgGc, and IgM antibodies were pooled and included in each ELISA. No difference of antibody response was found between horses from the three dietary groups, with the exception of an elevated antibody response to BVDV in horses fed TD1 & 2 compared to the control group on day 21 post-vaccination (P < 0.05). Therefore, IgGb, IgGt, IgGa, and IgM isotypes were tested individually from the day 21 BVDV sample. No differences were observed between the groups for individual isotypes, although there was a trend for enhanced antibody response in horses fed test diets. The test diets may support elevated antibody response in the horse.
Keywords: equine, antibody, immune, diet, vaccine response