# Evaluation of Colostrum Components and Milking Status Affecting Colostrum IgG Concentration

## TL;DR

This study identifies factors affecting the quality of colostrum in dairy cows, focusing on IgG concentration and milking conditions in eastern Hokkaido, Japan.

## Contribution

The study introduces the use of Brix value as a practical tool for estimating colostrum IgG concentration and identifies optimal milking conditions for high-quality colostrum.

## Key findings

- Colostrum Brix value is significantly correlated with IgG concentration (r² = 0.233, p < 0.001).
- High IgG concentration is associated with high parity, low milking volume, and short time from calving to milking.
- Only 48.9% of samples met the IgG concentration criteria for high-quality colostrum.

## Abstract

The objective of this study was to examine the factors that contribute to high-quality colostrum in dairy farms in eastern Hokkaido, Japan. The percentage of samples with a high colostrum IgG concentration, an indicator of passive transfer (≥50 g/L), was low, at 48.9%, but the percentage of those with a low total plate count, an indicator of bacterial contamination (<100,000 CFU/mL), was high, at 86.5%. Measurement of colostrum Brix value, a measure of solid component concentration, provided a practical estimate of colostrum IgG concentration. The criteria for obtaining colostrum with high IgG concentration were high parity, low milking volume, and a short time from calving to milking. The estimation of colostrum IgG concentration by Brix meter and the approaching of ideal milking status were thought to lead to the obtaining of high-IgG colostrum.

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.