Epidemiology and Risk Factors of Subclinical Mastitis in Smallholder Dairy Systems
Keywords:
Subclinical mastitis Dairy cattle Smallholder dairy farms California Mastitis Test (CMT) Somatic cell countAbstract
Background: Subclinical mastitis [SCM] remains one of the most economically relevant diseases of dairy cattle on the global level, characterized by elevated somatic cell counts and impaired milk quality without any obvious clinical symptoms. It is a disproportionate burden on smallholder dairy producers who usually have no access to regular diagnostic testing and preventive veterinary care. Aim: To determine the prevalence of subclinical mastitis at both the cow and quarter levels, and to identify the key risk factors associated with its occurrence in smallholder dairy farms. Methods: The cross-sectional study was done on 320 dairy cows that were lactating in 64 smallholder farms. The screen at the quarter level was the California Mastitis Test [CMT]. Bacteriological culture and identification of milk samples in CMT-positive quarters was carried out. The measurements of the management practices were obtained using a structured questionnaire. To determine the significant risk factors, the Univariable and multivariable logistic regression analyses were conducted. Findings: Cow-level and quarter-level prevalence rates of SCM were 43.1 and 24.4% respectively. The front quarters were not as affected as the rear quarters. The most common isolate was Staphylococcus aureus [31.4%], then coagulase-negative staphylococci [22.8%] and Streptococcus agalactiae [17.3%]. In the multivariable model, poor milking hygiene (OR = 4.92; 95% CI: 2.46–9.85), moderate milking hygiene (OR = 2.04; 95% CI: 1.18–3.53), advanced parity (OR = 3.14; 95% CI: 1.74–5.67), and absence of pre-milking teat disinfection (OR = 2.01; 95% CI: 1.29–3.13) were significantly associated with subclinical mastitis. Conclusion: It was found that the prevalence of subclinical mastitis was high among the smallholder dairy farms, which could be traced mainly to the management shortcomings that are rectifiable. The most effective control measures suggested are specific training in milking hygiene, frequent CMT screening, and more intensive use of dry-cow therapy.
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