EVALUATION OF BULK MILK COLLECTED FROM SELECTED DAIRY FARMS IN CHATTOGRAM

Abstract

Dairying is an important source of subsidiary income generation for farmers in Chattogram. At present, there is an enormous development in the dairy sector. But milk quality issues are a concern among milk consumers and producers who collect milk from Chattogram. Although, measures have been taken to increase the quality of milk has not been thoroughly evaluated in this area. A cohort study was conducted on 24 randomly selected commercial dairy farms with 72 samples (3 samples from each of 24 farms with 2 months interval) in Chattogram for six months (from May to October 2018) and data were recorded using validated questionnaire. The aims of the study were to determine the hygienic quality and zoonotic hazard of bulk milk by measuring somatic cell count (SCC) and total bacterial count (TBC), determination of prevalence of Staphylococcus (S.) aureus and the proportion of MRSA isolated from S. aureus, and by assessing the relation between bulk milk somatic cell count (BMSCC) and other farm factors. The BMSCC varied from 291,000 - 1,156,670 cells/mL and TBC varied from 400-1,890,567 CFU /mL of milk during three repeated counts. The prevalence of S. aureus was 16.7% (95% CI: 4.7 to 37.2%) and methicillin resistant S. aureus (MRSA) was 8.3% (95% CI: 1 to 27%). Two isolates were MRSA and found resistant against penicillin, oxacillin, cefoxitin, gentamicin and tetracycline. Negative correlation (r=-0.71; p=0.07) was estimated for total staphylococcal count (TSC) vs. BMSCC at Pearson’s correlation. In a linear regression model, own stock as replacement was positively correlated (p=0.09) with lower level of BMSCC. This study suggests that dry floor condition and introducing own stock at dairy herds can reduce bulk milk somatic cell count. Findings of this study shows that the bulk milk at Chattogram are contaminated with multidrug resistant S. aureus which can be a potential risk of MRSA infection which is a great concern for both human and animal health.