Subclinical mastitis in crossbred dairy cows: Staphylococcus spp. and risk factors in small holder dairy farms

Subclinical mastitis (SCM) is one of the major economic diseases of dairy cows. In the present cross-sectional study, dairy cows (n=205) of small holding dairy farms were screened using California mastitis test (CMT) and prevalence of 12.19% was recorded. Holstein Friesian and Jersey crossbred cows showed highest CMT score of 2 followed by 3, 1 and T; linear scores of somatic cell counts (SCC) of 3.14 +/- 0.08, 4.721-0.25. 6.171-0.12, 7.99 +/- 0.11 and 9.84 +/- 0.45 were observed for CMT scores N. T, 1, 2 and 3, respectively. Risk factors associated with SCM were studied in 25 randomly selected cows. Staphylococcus species were detected in 54% of quarters based on PCR amplification of 16s rRNA gene; thermonuclease (nuc gene) PCR categorized Staphylococcus species as S. aureus (SA, 37%) and non-aureus Staphylococci (NAS, 26%). Significant association between CMT score 2 and Staphylococcus species was established. Staphylococcus species. SA and NAS, were detected in 30.7, 20.5 and 17.9% of SCM negative as well as 68.85, 47.54 and 31.14% SCM positive quarters, respectively. Significant association between SCM and Staphylococcus species and Staphylococcus aureus was observed. Study indicated strong association between SCM. Staphylococcus aureus and certain risk factors among cows reared under small holding dairy farms of the tropical region.