Occurrence of high udder infection rates in dairy cows in Ungunja Island of Zanzibar, Tanzania

Abstract

A 2-week screening was performed in small holder dairy farms in 4 districts of Ungunja Island of Zanzibar in August and September 2002. A total of 128 cows from 49 farms were screened for mastitis using the California Mastitis Test (CMT). Of the dairy cows screened, 63% (80 of 128) were dairy breeds such as Friesian, Jersey, Guernsey, and Ayrshire or their crosses, and 37% (48 of 128) were crosses with the local Zebu cattle. The 128 cows had a total of 506 functional quarters, with six cows having lost one quarter each from either past mastitis or teat obstruction. This left a potential total of 512 quarters.

Of the 506 quarters screened, 32% (162 of 506) were negative on CMT and the remaining 68% (344 of 506) were positive. Of the positive quarters, 16% (82 of 506), 16% (83 of 506), and 35% (179 of 506) were 1+, 2+, and 3+, respectively, on the CMT scale. Of the 189 milk samples cultured, 84% (158 of 189) yielded growth; there was no growth in 16% (31 of 189) of the samples, resulting in a quarter infection rate of 84%. After the cultures were identified through colony characteristics and microscopic examination, 85% (135 of 158) were found to be Staphylococcus species, and the remaining 15% (23 of 158) were Streptococcus species. Both hygiene of the milkers and the farm were thought to be associated with the high subclinical rate of Staphylococcus mastitis.