Effect of Two Pasteurization Protocols on IgG Concentration in Mare Colostrum, preliminary results

Abstract

Colostrum is the primary source of passive immunity in foals, providing high concentrations of immunoglobulin G (IgG) necessary for adequate transfer of maternal antibodies during the first hours of life. Colostrum bacterial contamination may represent a risk for neonatal health, therefore pasteurization has been proposed as a strategy to reduce microbial load. However, heat treatment may affect the stability of immunoglobulins, reducing colostrum quality. Consequently, it is essential to determine pasteurization conditions that preserve IgG concentrations in mare colostrum. The objective of this study was to evaluate the effect of two pasteurization protocols on IgG concentration in mare colostrum. Thirty-three colostrum samples were collected from mares within the first 24 hours postpartum on farms located in Spain. Each sample was divided into three aliquots: untreated raw colostrum (RC), colostrum pasteurized at 56 °C for 60 minutes (SP), and colostrum pasteurized at 63 °C for 30 minutes (HP). Immunoglobulin G concentration was determined using an ELISA commercial assay and expressed in mg/mL. Data distribution was assessed using the Shapiro–Wilk test and showed non-normality for all treatments (P < 0.001), therefore non-parametric tests were applied. Differences among treatments were evaluated using the Friedman test followed by Wilcoxon paired comparisons. Mean IgG concentrations were 27.79 mg/mL in RC, 26.34 mg/mL in SP, and 22.41 mg/mL in HP. Median values were 18.55, 15.80 and 11.46 mg/mL, respectively. The Friedman test indicated differences among treatments (P = 0.0024). Post-hoc analysis revealed no differences between RC and the SP treatment (P = 0.155), indicating that this protocol preserved IgG concentration. In contrast, HP resulted in lower IgG concentrations compared with RC (P = 0.002) and with SP (P < 0.001). These results suggest that moderate-temperature pasteurization (56 °C for 60 minutes) better preserves IgG levels in mare colostrum than higher-temperature short-time treatment. Therefore, this protocol may represent a suitable approach in case colostrum pasteurization is necessary without compromising its immunological quality.