Effect of subclinical mastitis caused by ss-haemolytic streptococci on milk yields in kenyan camels (Camelus dromedaries)

Mastitis is a major constraint to milk production in camels. We conducted a survey in Marsabit and Isiolo counties of Kenya to quantify losses in milk yield associated with subclinical mastitis caused by ß-haemolytic Streptococci in the one-humped camel (Camelus dromedarius). Four hundred and twenty (420) pair wise quarter milk yield comparisons were obtained from randomly selected camels. Mastitis prevalence was determined by clinical examination, physical milk examination, on-the-spot screening by CMT and isolation of ß-haemolytic Streptococci from hygienically collected quarter milk samples using standard culture methods. Data were submitted to the analysis of variance for comparing 2 means. Differences in milk production within fore and hind quarters were attributed to mastitis. Milk loss was 0.114L and 0.172L per mastitic fore and hind quarter per camel per day respectively. Regardless of quarter, loss in milk production was significant (F = 30.51, p<0.001). In the studied camel herds, the prevalence of subclinical mastitis due to Lancefield Group B Streptococcus (GBS) was 64 %, 5.4% for Lancefield Group C Streptococcus (GCS), 2.2 % for Lancefield Group G Streptococci (GGS) and 23 % for untypable ß-haemolytic Streptococci. To the authors’ best knowledge this is the first report on the involvement of Lancefield Group G Streptococci in mastitis of camels. Investigation of the impact of high level of milk contamination with GBS to elucidate camel-human transmission dynamics is necessary. A more sustainable approach to control of camel GBS infection using vaccine is recommended.Key words: camels, subclinical mastitis, Streptococcus agalactia

Structural, Micromechanical and Tribological Characterization of Zn–Ni Coatings: Effect of Sulfate Bath Composition

International audienceZn and Zn-Ni alloy coatings were electrode-posited on mild steel from sulfate-based bath containing Sn as additive. The effect of Ni content on the microstructure, morphology, micro hardness and the tribological behavior of these coatings were studied and discussed. Adding Sn in the sulfate bath had a significant effect on the surface morphology, particularly on the Zn-8 wt% Ni coatings. By increasing the Ni concentration from 8 to 14 wt%, the X-ray patterns showed that the phase structure of Zn-Ni alloy coatings was changed from g-phase Ni 3 Zn 22 to c-phase Ni 5 Zn 21. The plastic deformation and delamination were found to be wear mechanisms for the investigated coatings. While the Zn-14 wt% Ni alloys had the best wear resistance, Zn films had the most severe wear volume loss and the highest friction coefficient