S100 calcium-binding protein A12 as a diagnostic index for subclinical mastitis in cows

Diagnosis of subclinical mastitis is very important in management of the dairy industry and improvement of dairy cow productivity. S100A12, that is found in related tissues of mammals, is considered as an index for diagnosing inflammatory reaction. To evaluate whether S100A12 is involved in subclinical mastitis, milk somatic cell mRNA from 276 dairy cows was used to detect the transcriptional level of S100A12 by real-time quantitative polymerase chain reaction. A predictive analysis for mastitis was performed, and the correlation between S100A12 and other subclinical mastitis indicators was also assessed. The transcriptional levels of S100A12 in the milk of cows with mastitis were significantly higher than those in the milk of healthy cows (p < 0.05). The correlation analysis showed that S100A12 was positively associated with the somatic cell count and the sodium and chloride concentrations of milk. In contrast, a negative correlation was found between S100A12 and the potassium concentration and pH of milk. However, no significant correlation was detected between S100A12 and the other parameters, such as protein, lactose, ash, fat, density, Ca²⁺ and SNF. These results suggested that the S100A12 level in milk may serve as a diagnostic tool for subclinical mastitis in cows without obvious clinical signs.