Relationship between somatic cell counts and subclinical mastitis in lactating dairy cows

Abstract

Background and Aim: Subclinical mastitis (SCM) is one of the most prevalent diseases of dairy cows, and somatic cell count (SCC) is widely used to determine SCM and milk quality. However, setting the threshold of SCC is very important. This study aimed to determine the cow-level threshold of SCC to differentiate milk of SCM affected cows from normal milk in Bangladesh. Materials and Methods: Sensitivity (Se) and specificity (Sp) along with other characteristics of different thresholds of SCC were determined considering the bacterial culture as the gold standard test. Three definitions of intramammary infection (IMI) were set based on the group of pathogens involved. Five categories of SCC thresholds were considered for analysis. Results: Se and Sp of thresholds of SCC greatly varied as definitions of IMI changed. Irrespective of SCC thresholds, Se increased when isolation of major pathogens included in IMI definitions. Se decreased when SCC thresholds increased (from 100 to 300 × 103 cells/mL) for all IMI definitions and ranged from 60.6% to 20.3%. The highest Se was found at low SCC threshold (100 × 103 cells/mL), which resulted in less false-negative outcome. On the other hand, Sp increased with the increment of SCC thresholds giving rise to a less false-positive outcome. Conclusion: The cow-level SCC threshold of 100 × 103 cells/mL was found appropriate to identify subclinical IMI of dairy cows.

The Indicators of Clinical and Subclinical Mastitis in Equine Milk

“…Similarly, the PPV, which refers to the probability that a positive SCC’s and ECM’s result correctly predicts the presence of mastitis [ 43 , 61 ], increased in the corresponding groups. These results are in also agree with the recent research in lactating dairy cows, where Sp increased when the threshold was raised [ 62 ]. The cow-level SCC threshold of 100 × 10 3 cells/mL was considered appropriate to identify subclinical mastitis of lactating dairy cows concerning the results in less false-negative outcomes [ 62 ].…”

“…These results are in also agree with the recent research in lactating dairy cows, where Sp increased when the threshold was raised [ 62 ]. The cow-level SCC threshold of 100 × 10 3 cells/mL was considered appropriate to identify subclinical mastitis of lactating dairy cows concerning the results in less false-negative outcomes [ 62 ]. However, the current results are not enough to suggest similar conclusions.…”

“…Similarly, the NPV refers to the probability that a negative SCC’s and ECM’s result correctly predicts the absence of mastitis [ 43 , 61 ] which decreased in the corresponding groups. These results are in agreement with the relationship between SCC and subclinical mastitis in lactating dairy cows, where Se increased when the threshold level of SCC was lowered [ 62 ]. The increase of the Sp values referring to the SCC’s and ECM’s ability to exclude the mastitis when the mastitis is absent [ 43 , 61 ], is justified as well as having the highest value when a threshold is the max NSM since none of the samples in the NSM group can be classified as false-positive.…”

Evaluation of sodium lauryl sulfate for the development of cow-side mastitis screening test

“…After 30 s, the SCC was presented on the instrument display. A milk sample was considered positive when the SCC value was ≥ 100 × 10³ cells/mL [32].…”

Association of Udder Lesions with Subclinical Mastitis in Dairy Cows of Chattogram, Bangladesh

“…Clinical mastitis is readily visible and easily detected by abnormalities in milk, pathological changes in the udder along with clinical signs (Bari et al, 2014). But in subclinical mastitis, there are no visible changes in milk, udder or general condition except high somatic cell count (SCC) (Sumon et al, 2020). Subclinical mastitis (SCM) is highly prevalent in both commercial and household dairy farms in Bangladesh.…”