Quantification of milk losses due to spoilage microorganisms and antibiotic residues in rural and peri-urban dairy sub-value chains in Nakuru, Kenya

Abstract

Dairy losses due to spoilage microorganisms have remained high from previous studies in Kenya. Poor hygiene has been reported to be the main cause of milk contamination with these microorganisms. Antibiotic residues are also continually reported in Kenyan milk due to misuse of veterinary drugs in treating animals by unskilled personnel or farmers themselves. The aim of this study was to quantify milk losses due spoilage microorganisms and determine levels of antibiotic residues in rural and peri-urban dairy sub value chains in Nakuru County. Risk factors were identified by use of questionnaires and observation checklist. Sampling was done following a nested design .Microbiological analysis was based on standard procedures (ISO). Antibiotic residues were screened using Charm II Blue-Yellow and confirmation by High performance liquid Chromatography (HPLC-UV). Data was analysed using statistical package for social scientists (SPSS) and statistical analysis software (SAS). Survey showed that lack of hand and udder drying was done by 11% in rural and 50% in peri urban. There was an increase of 0.5 log cycle in TVC between udder and farm gate in rural location. Regression of risk factors versus microbiological quality of milk revealed that udder swabs were the highest contributor (r=2.73) to milk contamination with spoilage microorganisms. The incidence of occurrence of Staphylococcuss, Streptococcuss, Bacillus, and E.coli was 26%, 13%, 26% and 23 % in rural and 82%, 64%, 87% and 76% in peri urban respectively. From antibiotic screening, 31.45% (72/229) samples in rural and 28.8% (23/80) in peri urban were positive. None of the positive samples showed presence of tetracyclines while the highest percentage of sulphonamides were detected at cooling centres of rural (23%) and peri urban (100%). Losses of milk as a result of TVC were 8.6% in rural and 10.2% in peri urban. Antibiotic residues contributed to 23% losses in rural and 83.5% in peri-urban. Losses due to spoilage microorganisms are as a result of poor hygiene of hands, udder and water in both locations which recorded counts ranging between 1.8 CFU/ml to 5.5 CFU/ml. Losses due to spoilage microorganisms can be prevented by observing hygiene during milking. Antibiotic residues in milk can be prevented by training farmers on observation of withdrawal periods and use of qualified veterinary personnel.