2009). It was reported that the IL‐2 level was significantly lower in cows with retention secundinarum compared with healthy cows (Li et al. 2021). Šerstņova et al. (2022) reported that when mastitis and healthy cows were compared, milk IL‐2 concentrations were higher in mastitis cows and remained stable in measurements made for 3 days. However, another study indicated that in bovine mammary glands experimentally infected with S. aureus, IL‐2 concentration showed a significant decrease during the early stages of inflammation (Alluwaimi et al. 2003). Here, IL2 is linked to mastitis.