Evaluation of the differences in proteomics of high‐quality bovine colostrum and low‐quality bovine colostrum

Abstract Background Although there are studies on colostrum and milk proteomics of different species in the literature, there is no published report about different quality bovine colostrums’ proteomics. Objectives The aim of this study was to compare the proteome content of high‐ and low‐quality bovine colostrums for the first time. Methods Colostrum samples were collected from 32 Holstein cows from the same farm that had just calved. Brix% levels of colostrums were measured, and then, those with a Brix% value of ≥27% were classified as high‐quality and those with a Brix% value of <22% as low‐quality. Three samples from high‐quality and low‐quality colostrums were selected and proteomic analyses were performed by pooling separately. Results Totally 95 proteins were identified in the colostrums, and 19 of them showed significant changes between high‐ and low‐quality colostrums. Expressions in colostrum of glycosylation‐dependent cell adhesion molecule‐1, cofilin‐1, alpha‐S2‐casein, alpha‐lactalbumin, alpha‐1B‐glycoprotein, actin_cytoplasmic‐1, nucleobindin‐1, cathelicidin‐4, inter‐alpha‐trypsin inhibitor heavy chain H4, chitinase‐3‐like protein 1 and monocyte differentiation antigen CD14 were lower, whereas tetranectin, secreted frizzled‐related protein‐1 (SFRP1), perilipin‐2, coatomer subunit epsilon (COPE), butyrophilin subfamily 1 member A1, polyubiquitin‐B, lactadherin and albumin levels were higher in high‐quality colostrum than low‐quality colostrum. Moreover, SFRP1, COPE and cathelicidin‐4 proteins were identified for the first time in bovine colostrum. In high‐quality colostrum, the most prominently down‐regulated proteins were cathelicidin‐4 (26.01‐fold) and cofilin‐1 (17.42‐fold), and the most prominently up‐regulated proteins were COPE (3.37‐fold) and tetranectin (3.07‐fold). Conclusions It was detected that the proteome contents of high‐ and low‐quality bovine colostrums were different from each other. As new functions are added to the protein databases regarding these proteins detected in colostrums, the interactions of proteins with each other and with other molecules will be detailed and the effects of high‐quality colostrums on passive transfer immunity and calf health will be understood in full detail.