Effectiveness of a milk safety intervention by smallholder dairy farmers on bacterial and aflatoxin M1 contamination in milk in Kisumu county, Kenya

Abstract

Milk, important in the human diet especially that of children, is prone to contamination by bacteria and aflatoxins. The leading public health hazard from poor milk safety are microbial (bacterial) followed by chemical milk contaminants; and aflatoxin M1 (AFM1) which is implicated in stunting, immune suppression and carcinogenicity. Young children, infants, pregnant women, elders and immunocompromised people are the primary groups at risk for milk safety problems. Similar to much of Kenya, milk production in Kisumu County is dependent on smallholder dairy farmers who sell unregulated milk with high risk of contamination with aflatoxin and bacteria. No single intervention offers a comprehensive solution to reducing both AFM1 and total bacterial counts in milk. The simultaneous use of Mazzican, a hygienic milk container, and NovaSil mycotoxin binder offers promising results and investigation of their potential to improve milk safety is warranted. The main objective of the study was to assess the effectiveness of a milk safety intervention comprising of training in milk hygiene and feeding practices; and use of Mazzican, plus NovaSil binder, on the bacterial and aflatoxin M1 contamination in milk produced by smallholder dairy farmers in Kisumu County. Specific objectives were to determine: the proportion of farmers producing milk contaminated with AFM1 and bacteria at levels above the recommended limit; the milk hygiene and feeding practices of farmers before and after intervention; the effect of Mazzican and NovaSil binder on milk safety; and the willingness of farmers to use the intervention. A quasi-experimental study design was used. Milk samples and data on milk handling and dairy feeding practices were collected at baseline from 100 urban and peri-urban smallholder dairy farmers randomly selected from a list obtained from the County veterinary office. Thirty of these farmers producing milk with AFM1 levels above 20ppt were selected for the intervention. Farmers in the treatment group (n = 20) were trained on safe milk handling and feeding practices and use of Mazzican container and NovaSil binder while control farmers (n = 10) were not subjected to the intervention. Milk samples were collected fortnightly from all study farmers (n = 30) for three months. Data on milk hygiene and feeding practices was collected using a questionnaire. Enzyme-linked immunosorbent assay was used to asses AFM1 and milk cultures for total bacterial counts (TBC).Independent t-test was used to determine effects of Mazzican and NovaSil binder. Of the total 77 milk samples collected 28.6% had AFM1 levels above the recommended limits, 36.4% of samples had TBC above one million and 13% had both high levels of AFM1 and TBC. There was improvement in farmers’ milk handling practices: cleaning of the milking shed, cleaning of udder before milking, checking of mastitis and storage equipment used (p<0.05).NovaSil binder use reduced AFM1 levels by 188.76 ppt (p<0.001) while use Mazzican reduced TBC by 5.2×10⁷ Cfu/ml (p<0.05). Most farmers (86.2%), were willing to use the intervention in future. Findings of the study indicate that use of NovaSil binders, Mazzican containers and good milk handling practices improves safety of milk produced by smallholder dairy farmers in Kisumu; and can be scaled up.