PREVALENCE OF SUBCLINICAL MASTITIS AND ASSOCIATIONS WITH RISK FACTORS IN BUFFALOES IN NOAKHALI DISTRICT OF BANGLADESH

Abstract

Bovine mastitis is one of the most prevalent and economically significant diseases affecting dairy herds globally. Mastitis causes physical and chemical changes in milk as well as pathological changes in the udder. The cost of milk production rises as a result of high somatic cell count in milk along with significant decrease in milk production. Bulk milk somatic cell count (BMSCC) from bulk milk samples is used worldwide as an indicator of monitoring farm hygiene and udder health. Bangladesh represents 1.5 million buffalo heads of which 40% are reared in the saline coastal region. Buffalo contributes up to 4% of the total milk production demand in Bangladesh. There is a substantial lack of studies on the physiological threshold of the somatic cell count on milk quality in the case of buffalo milk. The present cross sectional study was designed to investigate the multilevel (farm, animal and quarter) prevalence of subclinical mastitis (SCM) along with the association of potential risk factors and causal pathogens in buffalo quarter milk samples in Noakhali district of Bangladesh. A total of 45 buffalo farms (n=1660): 8.9% coastal (n=4), 66.7% semi coastal (n=30), and 24.4% inland (n=11) farms with lactating buffalo (n=183) and functioning udder quarters (n=732) were investigated during March-April, 2021 in 6 buffalo concentrated zones of Subarnachar and Hatiya upazila of Noakhali district. Small (33%), Medium (38%) and Large (29%) size herds were observed with <15 buffaloes per farm, 15-40 buffaloes per farm and >40 buffalo per farm, respectively in the study area. Among the studied lactating buffaloes (n=183), majority (58%) of the buffaloes were indigenous (95% CI: 51-65) and the rest of them were cross-bred (42%) (95% CI: 35-49) buffaloes. The Geometric (G) mean of BMSCC (413 ×103 cells per mL of milk) (95% CI: 349-488) of the studied herd was two times higher than the threshold level (200×103 cells/mL of milk). Overall farm, animal, and quarter level prevalence of SCM were found 86.7% (95%CI: 0.73-0.94), 47% (95%CI: 0.40-0.54), and 27% (95%CI: 0.24-0.30), respectively based on BMSCC threshold level (200×103 cells/mL of milk) CMT score (≥ 2 =positive). Prevalence of SCM was observed high in buffaloes those were being reared in bathan or free ranging area at both animal (71%) and quarter (75%) (P=0.02) level. Prevalence of SCM among the quarters did not differ significantly. However, a significant (P=0.05) prevalence of SCM was found in hind quarter of the buffaloes that were being reared in bathan. MALDI-TOF results of the culture samples (n=292) obtained from quarter milk samples (n=320) from the lactating