# The Influence of Genotype and Seasonality on the Sow Colostrum Quality and Immunoglobulin G Content

## TL;DR

This study shows that sow colostrum quality depends on the pig's genotype and the season, with winter having the highest fat and protein levels, which can improve piglet health and survival.

## Contribution

The study demonstrates that genotype and seasonality interact to influence colostrum quality and validates the Brix refractometer as a practical on-farm tool for measuring IgG.

## Key findings

- Genotype and season significantly affect colostrum fat and protein content, with winter showing the highest concentrations.
- The Brix refractometer is a reliable on-farm method for estimating IgG concentration in sow colostrum.
- Genotype explains the largest variance in fat and IgG content, while seasonality and interactions affect protein and lactose.

## Abstract

Colostrum is the first milk that piglets consume after farrowing. It is rich in various nutrients, the most important of which are immunoglobulins, which are responsible for the development of immunity. The composition of colostrum is influenced by the genotype and changes depending on the season. The results of this study showed that the genotype and season significantly influence the colostrum fat and protein contents, while the lactose content varied only by genotype. The highest fat and protein concentrations were observed during the winter period, indicating seasonal adaptation. We also found that the Brix refractometer is a reliable and on-farm method for determining the IgG concentration in the colostrum of sows. Selecting the specific genotypes based on seasonal performance could enhance colostrum quality and also improve piglet health and survival rates. This could benefit pig producers by improving piglet survival rates, animal welfare and potentially economic performance.

The aim of this study was to investigate the influence of genotype (GT) and seasonality (NP) on the quality parameters of sow colostrum and evaluate the efficiency of the radial immunodiffusion (RID) analysis and the Brix refractometer in determining the IgG concentration. This study was conducted on 240 sows that originated from two genotypes, namely GT1 (TOPIGS, n = 120) and GT2 (Pig Improvement Company, n = 120), during the three farrowing periods: the winter farrowing period (WNP, n = 80), the summer farrowing period (SMP, n = 80) and the spring farrowing period (SSP, n = 80). The significant interaction effect was observed for protein (p < 0.0001), lactose (p < 0.05) and non-fat solids (SNT) (p < 0.001). At the same time, the interaction effect influenced the IgG concentration measured with the Brix refractometer (p < 0.0001) and RID (p < 0.0001). Pearson’s correlation coefficient showed that Brix percentage was positively correlated with RID results (r = 0.52, p < 0.0001), while the Bland–Altman plots indicated a mean bias of −1.93. Partial eta-squared analysis (η2) showed that the genotype explained the largest proportion of variance in fat content (η2 = 0.136) and IgG concentration (η2 = 0.164), while interaction effects were largest for protein (η2 = 0.072). The results of this study show that genotype and seasonality influence sow colostrum quality, which indicates the importance of genotype−seasonality interactions in breeding programs for optimizing the colostrum quality and piglet survival.