Maina Ngotho1 , John Kagira2* , Daniel Nkoiboni2, Janet Njoroge2, and Naomi Maina3
1 Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Kenya
2 Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
3 Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology (JKUAT), Nairobi, Kenya * Corresponding author: John Kagira, Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya. Email: jkagira@jkuat.ac.ke
Abstract:
Introduction: Worldwide, there is a paucity of literature on subclinical mastitis, and antimicrobial resistance patterns of bacteria isolated from dairy animals kept in peri-urban areas. This study aimed at determining the prevalence of sub-clinical mastitis (SCM) and the sensitivity of the isolated bacteria to selected antibiotics in dairy cows kept by smallscale farmers in Kajiado North Sub-County, Kenya. Simultaneously, a questionnaire was administered to determine and assess the risk factors associated with mastitis. Materials and methods: Milk was obtained from all quarters of 101 lactating dairy cows, sampled from 50 farms, and screened for SCM using California Mastitis Test. The samples were cultured and bacteria identified using standard bacteriological methods. Antibacterial sensitivity of Staphylococcus spp. and Escherichia coli isolates were tested using the Kirby-Bauer disk diffusion method, against commonly used antibiotics. Results: The prevalence of SCM at cow and udder quarter levels were 51.2% and 47.5%, respectively. The prevalence of the bacteria was Staphylococcus spp. (51.4%), Klebsiella spp. (40.5%), Pseudomonas spp. (34.6%) and E. coli (11.8%). The risk factors significantly associated with SCM were breed, parity, lactation stage, and milking hygiene. The highest prevalence of SCM was found in cows in late-stage lactation (78%) with the lowest in those in early-stage lactation (37.5%). A higher prevalence of SCM was found in cows housed in farm structures having poor hygiene (95%). The highest prevalence of SCM was in Friesian breeds (67.3%) and the least affected were the indigenous cows (27.3%). Cows in the fourth and higher parities were the most (64.7%) affected by SCM. Most of the Staphylococcus spp. isolates were found to exhibit resistance to oxytetracycline (73%) but had high sensitivity to gentamycin (69%). All E. coli isolates showed resistance to oxytetracycline while a 75% were sensitive to Chloramphenicol. In conclusion, the study showed that a large proportion of cows were affected by SCM, with the main causative agent being Staphylococcus spp. Conclusion: The study shows that antibiotic resistance was alarmingly high in the study animals. The predisposing factors should be further investigated with a view of developing necessary interventions.
1.Introduction
The dairy industry in Kenya is one of the largest in the African region and is an important player in the economic and nutritional aspects of the local and growing population1. The sector contributes to about 8% of the gross domestic product with annual milk production of 3.43 billion liters1. Kenya’s dairy cattle population is estimated at 4.3 million, mainly in the semiintensive and intensive production systems1. The main breeds for dairy production are Friesian, Guernsey, Ayrshire, Jersey, and their crosses2. In recent years, urban and peri-urban dairy production systems have gained prominence in Kenya and spread to nomadic livestock husbandry practices in counties such as Kajiado1. Dairy farming involves milk production in such areas, targeting major market outlets in urban centers, including Nairobi, Kenya3. Several studies have shown that urban and peri-urban dairy farming is mainly motivated by better prices for animal products, which also creates employment opportunities3-5. There are many challenges in peri-urban dairy farming, such as inadequate quantity and quality of feeds, poor access to breeding, and poor access to credit facilities and output markets, mainly diseases, such as mastitis5-7. Bovine mastitis is a major concern as it affects milk production negatively3. It is the most costly disease for dairy animals, and losses mainly occur through rejected milk, reduction in milk yield, extra labor, cost of drugs, premature culling of animals, and replacement of breeding animals1. The disease can be managed by treating the clinical cases and designing appropriate mastitis control measures8. The clinical form of the disease can be detected easily by the farmers since it is associated with visible changes in milk composition and appearance, decreased milk production, and the presence of signs of inflammation8. However, sub-clinical mastitis is more difficult to detect because symptoms are not readily apparent8, so its diagnosis is challenging. Studies have shown that sub-clinical mastitis is up to 40 times more prevalent than the clinical form9. Further, the sub-clinical form is chronic and thus acts as a continuous source of infection on a farm10. The prevalence of sub-clinical mastitis in cows in high agricultural potential areas of Kenya ranges from 36% to 87% in different studies11-14. In recent years, overuse and misuse of antibiotics in Kenya have encouraged the evolution of bacteria towards resistance, resulting in therapeutic failure 14-16. In Kenya, most studies on mastitis in cattle have been done in high agricultural potential areas where intense dairy farming is practiced. There is a paucity of data on subclinical mastitis in dairy animals kept in urban and peri-urban areas. The present study aimed to evaluate the prevalence of subclinical mastitis, risk factors, and sensitivity of isolated bacteria to commonly used antibiotics. The study was undertaken in a peri-urban area of Kajiado North subcounty, Kenya.
