Prevalence Of Mastitis And Associated Risk Factors In Dairy Goats In Machakos County, Kenya

Abstract

Dairy goat production is playing an important role in the improvement of income of the poor farmers, poverty and hunger alleviation, though the enterprises are still faced with numerous challenges such as diseases, inbreeding, poor feeding, lack of market and poor management practices. One of the major diseases that affect the dairy goat production is mastitis. It occurs after several microbes invades and colonizes the secretory tissue leading to inflammation of the mammary gland. This study was carried out on dairy goats kept under zero grazing, semi-zero grazing and free range system in Machakos County, Kenya, from February 2014 to January 2015. The objectives of the study were to: (1) Characterize the bacteria causing mastitis in dairy goats in Machakos County; (2) Estimate the prevalence of clinical and sub clinical mastitis in dairy goats in Machakos County; and (3) Determine the risk factors for mastitis in dairy goats in Machakos County. A cross-sectional survey was conducted to determine the prevalence of mastitis and the associated risk factors in dairy goats in Machakos County, Kenya. Four wards with the highest density of dairy goats in Machakos County were purposively selected. Each of the four wards had an average dairy goat population of 1100. Thereafter, 320 lactating dairy goats were selected randomly from 280 households within the four wards for the study. Data was collected at both farm and animal level. The data collected at farm level included, name of the ward, gender and age of the farmer, number of dairy goats kept, other livestock kept, size of the farms, duration of the dairy goat farming, housing status of the goats, frequency of manure removal, grazing system, type of feeds, prevalent goat xix diseases in the area, state of extension services, marketing of milk and whether hygiene milking was practiced. At the animal level data collected included, breed, age, stage of lactation, parity, kidding date, breeding method, pregnancy status, the current health status, length of teats and lesions on teats and udder of the lactating does. Later milk samples were aseptically collected from the does. Clinical mastitis was determined by palpation and visualization of the udder and use of strip cup to check for abnormalities such as clots, flakes and discolored milk. Subclinical mastitis was determined using California Mastitis Test and bacterial culture. Bacterial isolation was done in blood agar. The biochemical tests for bacterial characterization included gram stain, catalase test, coagulase test, MacConkey agar, Triple Sugar Iron, CAMP test and the Imvic test. A panel of eight antimicrobials was used to test for the sensitivity of the bacterial isolates. The antimicrobials included ampicillin, tetracycline, cotrimoxazole, kanamycin, gentamycin, norfloxacin, sulphamexazole and streptomycin. The sensitivity tests were done using the disc diffusion test on Mueller-Hinton agar. Tests of association between potential risk factors and the development of mastitis were done using the Chi-Square (χ2) statistic (P<0.05) and the strength of the association using the odds ratio (OR). A univariate logistic regression analysis was additionally done to screen for risk factors potentially associated with occurrence of mastitis. Variables with a p value of ≤ 0.1 were considered significant in the univariate analysis and were included in the multivariate logistic regression model where p-values of less than 0.05 were considered significant. Kappa statistic was used to test for the agreement between the results of the California Mastitis Test (CMT) and bacterial culture. xx The prevalence of clinical mastitis was 1.9% while the estimated prevalence of subclinical mastitis was 30.3% by CMT and 15% by bacterial culture. There were no significant (P<0.05) differences in the prevalence between the four study wards. A variety of bacteria were isolated in the milk samples, including Coagulase negative Staphylococcus (58.1%), Coagulase positive Staphylococcus (25.8%0, Streptococcus epidydimis (8.1%), Streptococcus agalactiae (4.8%) and Citrobacter (3.2%). Resistance of the bacterial isolates was common to most of the tested antimicrobials. Multidrug resistance was observed especially by the Streptococci and Citrobacter isolates. Several factors were positively associated with the development of mastitis including poor milking hygiene (P=0.029, OR=2.2), high parity (P=0.037, OR=2.6), late stage of lactation (P=0.026, OR=2.2), infrequent removal of manure from goats house (P=0.025, OR=2.03) and the presence of lesions on teats and udder (P=0.0099, OR=2.73). In conclusion, mastitis was detected in the dairy goat herds of Machakos County and a variety of bacteria were isolated some of which exhibited multidrug resistance. There is a need to educate the dairy goat farmers of Machakos County on the risk factors of mastitis with the aim of reducing the levels of mastitis.