Variation of six bioactive milk proteins from milk from Chinese commercial dairy farms: Effect of season, farm, breed and udder health status

The study investigated potential changes in bioactive milk proteins in relation to the season, breed, farm and udder health status. Nine hundred and sixty bulk milk samples from 12 commercial farms in northwest China were collected during 2020–2021. Six bioactive proteins including fraction of β‐casein proteins, α‐lactalbumin, β‐lactoglobulin, lactoferrin (Lf) and osteopontin were evaluated. It was found that most proteins (with exception of β‐casein A1) of Jersey cows are significantly higher than Holstein cows. Most bioactive proteins demonstrated seasonal variation, and some exhibited geographical variation (with exception of whey albumins). The milk somatic cell count showed a positive correlation with immune proteins such as Lf.