Assessment of Antibiotics Residues in Milk Supplied by Smallholder Farmers to Processors in Kenya: a Case of Bomet, Nakuru, and Nyeri Counties

Abstract

The consumption of milk and milk products serves as a good source of complete food. In spite of that, the use of antibiotics by farmers for the treatment of domestic dairy animals has increased which has led to antibiotic residues in foods of animal origin such as milk due to antibiotic abuse. The main focus of the current study was to determine knowledge on the antibiotics, the usage, and general practices on handling the same by small holders’ milk producers. The study makes contribution towards improved quality and safety of commercially produced milk from the smallholders in Bomet, Nakuru and Nyeri counties in Kenya. The study was carried out using a mixed method approach where farmers, traders and cooperative society staffs were interviewed, and milk samples taken to determine antibiotic usage and levels. Data was recorded on chemicals and drugs used to treat dairy herds, milk hygiene and rejection of milk among farmers. The study alsodetermined the type of antibiotics and levels of residues in milk supplied by smallholders to processors. A total of 108 milk samples comprising raw milk purchased and sampled from farmers were analyzed for the presence of Beta-lactams, Tetracyclines, and sulphonamides residues using rapid tests in the field and High-Performance Liquid Chromatography (HPLC) for quantification in the laboratory. Majority (93.3%) of the respondents had basic education level of training on dairy management and diseases and reported dairy animals as frequently infected with diseases such as mastitis (86%), East Coast fever, and Foot and Mouth. Almost all (98%) farmers used manual method of milking, and more than half (66%) used aluminium cans during milking. Farmers practiced hygienic milking by cleaning the teats (97%). However, very few (2%) wore gloves during milking. Most farmers (85.9%) did not know the type of antibiotics they used. However, more than half of the farmers (55.6%) reported that milk from a treated cow was discarded, 22.7% of them used the milk to feed calves. Most xiv farmers (93%) stated that they did not experience milk rejection; however, the few who had their milk rejected indicated acidity, bad flavour and adulteration as some of the causes. Antibiotics residues were detected in milk samples from all the counties, differing in concentration and no significant difference (P≥ 0.05) among the three Counties. The most commonly detected antibiotic was oxytetracycline while the common beta-lactam detected was ampicillin in all three sites. The sulphonamides detected were dapsone, sulfachlorpyridazine, sulfadiazine, sulfadimethoxine, sulfadoxine, sulfamerazine, sulfamethoxazole, sulfamethoxypyridazine, sulfamonomethoxine, sulfapyridine, sulfisoxazole, and sulfithiazole at different concentrations. More than half (55.6%) of samples collected tested positive for at least one antibiotic residue. The mean concentrations for oxytetracycline were 0.017mg/l in Bomet, 0.016mg/l in Nakuru and, 0.015mg/l in Nyeri. In conclusion, farmers’ milk handling practices along the value chain was good and this is due to their good knowledge on hygienic practices, however there was lack of knowledge on the use of antibiotics and risks associated with the misuse of the same. The occurrences of such residues pose health risks to consumers hence the need for proper monitoring and control of antibiotics in the milk supply chain.