Prevalence of subclinical mastitis and intramammary infections in camels with clinically healthy udders in Kenya

Sammanfattning: For pastoralists in Kenya camel milk is an important source of nutrition and income. Previous studies have revealed that subclinical mastitis (SCM) is both common in camels and unknown amongst the pastoralists themselves. The purpose of this study was to investigate the prevalence of SCM and the prevalence of intramammary infections (IMI) in dairy camels (Camelus dromedarius) from two different ranch herds in the Laikipia district, Kenya, to examine teat morphology of these camels and to investigate if an association between teat morphology and SCM or IMI exists. In addition to this the association between teat morphology and three camel factors (age, number of parties and days in milk) will be examined. A further aim was to investigate which bacterial species were present in IMI and the association between IMI and SCM. The possible association between IMI or SCM and three camel factors will be investigated. All lactating camels with clinically healthy udders in the two herds were included in the study, 35 in total. For each camel milk samples were collected from each quarter and all quarters were examined by California Mastitis Test (CMT). One of the herds was visited twice and the other herd three times, and all lactating females were sampled on each occasion. In total, 138 individual udder quarters from 35 camels were included in the study. Out of the 35 camels, 13 were sampled once, 13 were sampled twice, and 9 were sampled three times. One of the camels in the study had 2 blind teats and one sample was lost during transport to the lab. In total, this resulted in 261 quarter milk samples and 253 CMT-results. In addition, each udder was photographed from both sided with a ruler underneath for scale (35 udders altogether). Information about age, days in milk (DIM) and number of parities was collected for each camel. Bacteriological analysis was done locally at Analabs laboratories ltd, Nairobi, Kenya and species determination using MALDI-ToF at Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden. In this study SCM was defined as CMT ≥3 and IMI as bacterial growth of monoculture. The teat width (TW) and teat length (TL) were measured digitally using the pictures of the udders. T-test and univariable mixed-effect linear regression analyses were used to investigate associations between TL or TW and age, parity, DIM, prevalence of SCM and IMI. The Chi2 test was used to compare age, parity, DIM, IMI and SCM. The quarter level prevalence of SCM was 11% and the animal level prevalence was 29%. The quarter level prevalence of IMI was 48% and the animal level prevalence was 89%. Average TL was 50mm and average TW was 32mm. There was a strong correlation between TL and TW. Front teats were significantly longer and wider than hind teats but no significant difference was found between left and right side for either front or hind teats. A significant association was found between TW and parity, where camels in parity one or two had wider teats than camels in parity four. No significant association between TL or TW and SCM or IMI was found. The bacterial species identified in quarter milk samples with IMI were: S. simulans (26%), Str. pluranimalium (17%), S. hyicus (5%), S. haemolyticus (5%), S. chromogenes (5%), S. aureus (5%), S. agalactiae (5%), S. gallolyticus (5%), S. ovis (2%), C. efficiens (2%) and S. epidermidis (2%). It was not possible to identify 21% of the bacterial species found. The association between IMI and SCM was not significant in this study.