Relationship between serum zinc concentration, teat canal keratin thickness and somatic cell count in dairy cows

The aim of this study was to evaluate the relationship between serum zinc concentration, teat canal keratin layer thickness and somatic cell count (SCC) in dairy cows. The study included 26 dairy cows excluded from production and sent to slaughter, with a total of 104 udder quarters examined. Prior to slaughter, blood samples were collected for determination of serum zinc concentration and milk samples from each udder quarter were obtained for SCC analysis. After slaughter, teats were collected for histopathological examination and the thickness of the teat canal keratin layer was measured. A significant negative correlation was observed between serum zinc concentration and SCC (r = -0.62, p < 0.01), indicating that higher serum zinc levels were associated with lower SCC values. Serum zinc concentration was positively correlated with teat canal keratin layer thickness (r = 0.58, p < 0.01), while keratin layer thickness showed a significant negative relationship with SCC (r = -0.54, p < 0.05). The lowest SCC values were recorded in teat canals with a keratin layer thickness of 201-300 μm, whereas higher SCC values were found in canals with both very thin (0-100 μm) and excessively thick (301-400 μm) keratin layers. These results indicate that adequate serum zinc concentration and optimal teat canal keratin layer thickness are associated with improved udder health and lower SCC values, suggesting a potential role of zinc status and teat canal integrity in reducing the risk of subclinical mastitis in dairy cows.