PREVALENCE OF MASTITIS AND ANTIMICROBIAL RESISTANCE AMONG DAIRY CATTLE IN UASIN GISHU COUNTY – KENYA

Abstract

A random sample consisting of one hundred and fifty lactating dairy cows; fifty from each of the three study sites, of different breeds, parities, stages of lactation and average daily milk yields from several farms spread across Uasin Gishu County, Kenya were tested in a study of mastitis. We evaluated the use by forty randomly chosen dairy farmers of routine testing of foremilk and teat dipping as mastitis control measures. Mastitis causative microbes were identified both by cultural morphology and biochemical tests. Culture and sensitivity tests were done to determine their in vitro resistance to various antimicrobial agents. The Draminski Mastitis Detector was used to screen individual udder quarters of every cow sampled for mastitis. Readings below 300 units were recorded as suspect for subclinical mastitis whilst those with visible changes to the udder and /or the milk from a strip cup were recorded as having clinical mastitis. At the sampled population level the prevalence of mastitis was found to be 50.7% of which 24.7 % had clinical mastitis while 17.3% had subclinical mastitis. The remaining 8.7% of the samples had both clinical and subclinical mastitis. The prevalence of mastitis at quarter level was 21.8% and of these, 11.5% were clinical while 10.3% were subclinical. Out of the 76 positive samples obtained at screening, 72 samples had bacterial growth/ isolates while 4 had none. Of those samples with growth 66 grew one type of microbe while 6 grew mixed infections. Six genera of bacteria and one of yeasts were isolated. The most common bacterial or fungal genus isolated was Staphylococcus sp 31.6%, followed by Escherichia sp 22.4%, Klebsiella sp 18.4%, Streptococcus sp 17.1%, Corynebacterium sp 2.6%, Pseudomonas sp 1.3% and Candida sp 1.3%. Resistance by the isolated microbes was greatest to the two sulphonamides; sulphamethoxazole 17.3% and cotrimoxazole 17.3% followed by chloramphenicol 16.6%, nalidixic acid 15.9%, ampicillin 15.2%, tetracycline 11.2%, streptomycin 5.1%, kanamycin 2.8% and gentamicin 2.2% in that decreasing order. However there was no significant difference in the mean resistance across the bacterial genera to ampicillin, nalidixic acid, chloramphenicol, sulfamethoxazole and cotrimoxazole. Tetracycline and streptomycin were next with medium resistance but with no statistical difference between them. The group to which there was least resistance was kanamycin and gentamicin. The incidences of mastitis were found to increase as parity/age of cow increased; with parities between 4 and 10 having the highest number of cases. The breed of cow was found to have no influence on the incidence of mastitis. Cows in early lactation (the first 2 months post calving) had the highest incidence compared to those in mid and late lactation. The cows with higher milk production had higher mastitis incidences compared to those with lower production. There was, among the forty respondent farmers, widespread ignorance about routine management practices that can be used to control the incidences of mastitis at milking such as regular testing, pre and post milking teat dipping in suitable germicides and the timing of fresh feeding after milking. It was concluded that there is widespread lack of knowledge by the farm managers about the cow factors, the environmental factors and management factors that exacerbate mastitis within the farms, hence the high prevalence of mastitis and high resistance to antimicrobials among the causative microorganisms. It was recommended that there is need for capacity building by veterinarians and other dairy stakeholders to alleviate this. The overall objective is to increase the production of clean wholesome milk of high market value which ultimately increases profits to the farmers and all stakeholders in the dairy subsector and hence help alleviate poverty.