Article history: Received: 17-01-2018, Accepted: 07-05-2018, Published online: 12-06-2018
Corresponding author: P. V. Jadhav
E-mail: email@example.comCitation: Jadhav PV, Das DN, Suresh KP, Shome BR (2018) Threshold somatic cell count for delineation of subclinical mastitis cases, Veterinary World, 11(6): 789-793.
Aim: Somatic cell count (SCC) is the most widely used single reliable indicator of udder health. The present study was carried out with an objective to find the exact threshold of SCC.
Materials and Methods: Milk samples collected from a total of 214 Holstein Friesian crossbred dairy animals were subjected to bacterial DNA extraction and SCC estimation by digital PortaCheck. California Mastitis Test and polymerase chain reaction based on amplification of organism using reported primers were performed to diagnose subclinical mastitis. Receiver's operating characteristic (ROC) curve analysis and discriminate function analyses were performed using SPSS 18 software.
Results: ROC curve analysis represented that the area under the curve was 0.930 with the standard error of 0.02. Results indicated that 93% of the case could be correctly predicted as mastitis infected using SCC as a marker (p<0.001). At cut score level of 282 000 cells/ml, 285,000 cells/ml and 288,000 cells/ml, sensitivity remained 92.6% and specificity augmented as 86.3%, 87.2%, and 88%, respectively. At SCC value of 310,000 cells/ml of milk, sensitivity and specificity were optimal, namely, 92.6% and 91.5%, respectively. The function fitted demonstrated 89.2% accuracy with p<0.001. The functions at group centroids were -0.982 and 1.209, respectively, for normal and mastitis-infected animals and log_SCC value was the most important factor contributing 38.30% of the total distance measured.
Conclusion: Our study supports that the threshold value to delineate subclinical mastitis case from the normal is 310,000 somatic cells/ml of milk and a model so fitted using the variable SCC can be successfully used in field for the diagnosis of subclinical cases of mastitis which otherwise would be difficult to differentiate based on clinical signs.
Keywords: discriminate function, mastitis, receiver's operating characteristic curve, somatic cell count, threshold.
1. Hamann, J. (2005) Diagnosis of mastitis and indicators of milk quality. In: Hogeveen, H., editor. Mastitis in Dairy Production: Current Knowledge and Future Solutions. Wageningen Academic Publishers, Wageningen. p82-90.
2. Jadhav, P.V., Tarate, S.B., Bhuvana, M., Das, D.N. and Shom, B.R. (2016) Somatic cell count as a monitoring system for hygienic milk production in India. Asian J. Dairy Food Res., 35(4): 270-277. [Crossref]
3. Mellenberger, R. and Roth, C.J. (2000) California Mastitis Test (CMT) Fact Sheet. Department of Animal Sciences, Michigan State University and Department of Dairy Science. University of Wisconsin-Madison, Florida.
4. Tarate, S.B., Jadhav, P.V., Ghadhigaonkar, D.D., Khade, P., Bhatt, V., Khan, A., Joshi, C.G. and Rank, D.N. (2012) Evaluation of breed-dependent variation in microbial load during subclinical mastitis in cattle using Real-Time PCR. Indian J. Dairy Sci., 65(1): 60-65.
5. Shome, B.R., Das Mitra, S., Bhuvana, M., Krithiga, N., Velu, D., Shome, R., Isloor, S., Barbuddhe, S.B. and Rahman, H. (2011) Multiplex PCR assay for species identification of bovine mastitis pathogens. J. Appl. Microbiol., 111(6): 1349-1356. [Crossref] [PubMed]
6. Pepe, M., Janes, H., Longton, G., Leisenring, W. and Newcomb, P. (2004) Limitations of the odds ratio in gauging the performance of a diagnostic, prognostic, or screening marker. Am. J. Epidemiol., 159: 882-890. [Crossref] [PubMed]
7. Dang, A.K. and Singh, M. (2006) Udder the most important asset of dairy industry, its care and management. Indian Dairyman, 58(8): 57-63.
8. Singh, M. (2002) Somatic Cell Counts During Lactation in Bovines as an Index of Subclinical Mastitis. In: Process All India Dairy Husbandry Officers Workshop NDRI, Karnal. p64-77.
9. Narayan, T. and Iya, K.K. (1954) Studies on bovine mastitis. Indian J. Dairy Sci., 7: 147-158.
10. Sheldrake, R.F. and Hoare, R.J.T. (1981) The detection of mastitis in individual quarters using electrical conductivity or somatic cell concentration, N. Z. Vet. J., 29: 211-213. [Crossref] [PubMed]
11. Jha, V.C., Thakur, R.P., Yadav, J.N. and Rai, L.B. (1993) Epidemiological investigation of subclinical bovine mastitis in the eastern hills of Nepal. Vet. Res. Kathmandu, 8(2): 35-39.
12. International Dairy Federation. (1971) A Monograph of Bovine Mastitis. International Dairy Federation. London. p45.
13. Samantal, A., Prasad, S. and Ghosh, C.P. (2006) Incidence of subclinical mastitis in Karan Swiss and Karan Fries crossbred cows. Indian J. Dairy Sci., 57(5): 329-333.
14. De, U.K. and Mukherjee, R. (2009) Prevalence of mastitis in crossbred cows. Indian Vet. J., 86: 858-859.
15. Elango, A., Dorisamy, K.A., Rajrajan, G. and Kumaresan, G. (2010) Bacteriology of subclinical mastitis and antibiogram of isolates recovered from cross breed cows. Indian J. Anim. Res., 44(4): 280-284.
16. Gera, S. and Guha, A. (2012) Effect of subclinical mastitis on milk biochemical constituents in crossbred cows. Indian Vet. J., 89(7): 33-34.
17. Singh, M. and Garg, A. (2011) Incidence of different pathogens and milk compositional changes in subclinical and clinical milk samples of cows. Indian J. Anim. Res., 45(1): 51-55.
18. Singh, M. and Garg, A. (2012) Milk compositional changes in subclinical and clinical mastitic milk of crossbred cows. Indian Vet. J., 89(5): 66-68.
19. Das, S.C., Guin, S., Ghosh, A.K., Mitra, J., Das, D.K., Mitra, K. and Das, S.K. (2008) Evaluation of total bacterial count (TBC) and somatic cell count (SCC) for detection of latent and subclinical mastitis in cow and buffalo. Indian J. Anim. Sci., 78(8): 827-829.
20. Petzer, I.M., Karzis, J., Donkin, E.F., Webb, E.C. and Etter, E.M.C. (2017) Somatic cell count thresholds in composite and quarter milk samples as an indicator of bovine intramammary infection status. Onderstepoort J. Vet. Res., 84(1): a1269. [Crossref]
21. Thirunavukkarasu, M. (2003) A model to discriminate mastitic and non-mastitic milch animals. Indian Vet. J., 80: 890-894.22. Ghosh, C.P., Nagpaul, P.K. and Shiv Prasad. (2004). Subclinical mastitis in cattle and buffalo and it's impact on somatic cell count and milk composition, Indian Journal of Dairy Science, 57: 329-333