Evaluation of Colostrum Components and Milking Status Affecting Colostrum IgG Concentration

This study investigated IgG concentrations, bacterial contamination, and nutrient components of colostrum on dairy farms in eastern Hokkaido, Japan, to examine the factors making it possible to obtain high-quality colostrum. Colostrum samples were collected from 266 Holstein cows. The general criteria for high-quality colostrum are an IgG concentration of 50 g/L or higher and a total plate count of less than 100,000 CFU/mL. The percentage of samples with the criteria for IgG concentration was low, at 48.9%, but the percentage with the criteria for total plate count was high, at 86.5%. The colostrum Brix value was significantly correlated with the colostrum IgG concentration (r² = 0.233, p < 0.001) and provided a rough estimate of that concentration. There was no association between the colostrum IgG concentration and milk components other than protein. For colostrum milking conditions, the time from calving to milking tended to be shorter for high-IgG colostrum than for low-IgG colostrum (p < 0.01). The likelihood of high-IgG colostrum increased 1.28-fold with first parity higher and decreased 0.92-fold with a 1 L higher milking volume (p < 0.01). The results suggest that, in addition to estimating the colostrum IgG concentration via the Brix value, the likelihood of obtaining high-IgG colostrum is increased by taking into account parity, milking volume, and time from calving to milking.