Measurement of New Biomarkers of Immunity and Welfare in Colostrum and Milk of Pigs : Analytical Validation and Changes During Lactation

The colostrum and milk of sows may contain substances that could be used to evaluate immunity and welfare in pigs. This study aimed to quantify in these fluids four analytes associated with immunity: total adenosine deaminase (tADA) and its isoenzymes, myeloperoxidase (Mpx), calprotectin (S100A8/A9) and calgranulin (S100A12) and two analytes which are linked to welfare: alpha-amylase and cortisol. In addition, it aimed to evaluate how these analytes change during lactation and how they relate to each other and to immunoglobulin G (IgG) and immunoglobulin A (IgA). All the assays tested were able to quantify the analytes in a precise and accurate way. In addition, the analytes showed different dynamics through lactation, with adenosine deaminase being more concentrated in colostrum than in milk, while myeloperoxidase was more active in mature milk than in colostrum. Alpha-amylase was correlated with both IgG and IgA and S100A8/A9 was correlated with S100A12 and Mpx. Overall, the immune system and welfare analytes of this study can be measured in sow colostrum and milk samples and could have a potential use as biomarkers in these fluids. Colostrum is a mammary secretion released from the time of farrowing to 36 h post-farrowing. After this time and during all the rest of lactation, the mammary secretion is considered milk. The objectives of this study were: (1) to perform an analytical validation in the colostrum and milk of sows of assays for four analytes related to immunity: total ADA (tADA) and its isoenzymes (ADA1 and ADA2), myeloperoxidase (Mpx), calprotectin, and calgranulin, and two analytes related to welfare: cortisol and alpha-amylase. (2) To evaluate the changes in these analytes during lactation (3) To assess the correlations between these new analytes, as well as with IgG and IgA. In the analytical validation, all the assays were precise and accurate. When changes during lactation were evaluated, the concentration of tADA and ADA2 was found to be higher in colostrum than in milk (p < 0.02), while the activity of Mpx was observed to be higher in mature milk than in colostrum (p < 0.03). Furthermore, cortisol and alpha-amylase activity were found to be higher in colostrum compared to mature milk (p < 0.04 and p < 0.0001, respectively). Regarding the relation between analytes, alpha-amylase showed a significant correlation with both IgG and IgA and calprotectin was correlated with calgranulin and Mpx. Further studies should be performed to elucidate the possible practical application of the analytes evaluated in this study as biomarkers of colostrum and milk in sows.