Sub-clinical mastitis and associated risk factors on lactating cows in the Savannah Region of Nigeria

The overall herd-level prevalence rate for SCM was 85.33% (256/300 heads of cows) while the quarter-level prevalence rate of SCM was 43.25% (519/1,200 quarters). The prevalence of SCM was 50.67%, 43.67%, 39.67% and 39.13% for the left fore-quarter, right hind-quarter, left hind-quarter and right fore-quarter, respectively. The Rahaji breed had the highest prevalence of SCM with 65.91% (29/44), while the White Fulani breed had the least with 32.39% (57/176). A total of 32.33% (97/300) had only one mammary quarter affected, 30.33% (91/300) had two quarters affected, 16.00% (48/300) had three quarters affected while 6.67% (20/300) had all the four quarters affected. A total of 53.00% had SCM in multiple quarters (159/300). The risk of SCM decreased significantly among young lactating cows compared to older animals (OR？=？0.283; P？<？0.001; 95%CI？=？0.155; 0.516). The Rahaji breed had significantly higher risk compared with the White Fulani breed (OR？=？8.205; P？=？0.013; 95% CI？=？1.557; 43.226). Improved sanitation (washing hands before milking) will decrease the risk of SCM (OR？=？0.173; P？=？0.003; 95% CI？=？0.054; 0.554).SCM is prevalent among lactating cows in the Nigerian Savannah; and this is associated with both animal characteristics (age, breed and individual milk quarters) and milking practices (hand washing).Good knowledge of the environment and careful management of the identified risk factors with improved sanitation should assist farm managers and veterinarians in implementing preventative programmes to reduce the incidence of SCM.Sub-clinical mastitis (SCM) remains an economically important condition for the dairy industry [1]. SCM is one of the major causes of animal suffering, responsible for poor growth in young animals, reduced milk quality, poor product hygiene and undesirable changes in the milk’s composition [2-5]. Mastitis is characterized by physical, chemical and bacteriological changes in the milk and pathological changes in the glandular tissue of th