Production of dairy goats is on the increase in East African countries. As in cows,
prevalence of mastitis in dairy goats appears to be high but studies on the influence of this
disease on milk yield and composition are scarce. This study was, therefore, carried out to
determine the effect of sub-clinical mastitis on milk yield and composition in dairy goats of
Magadu dairy farm in Morogoro, Tanzania. Does were screened for mastitis using the
California Mastitis Test (CMT), milk yield was recorded and 80 ml samples collected for
laboratory analyses. A total of 184 quarter milk yield samples were available for analyses.
Milk samples were analysed for butterfat (BF) by the Gerber method, crude protein (CP) by
the Kjeldahl method, lactose by IDF Standard No.28 method and chloride by titration using
silver nitrate solution. Data were analysed using least squares analysis of variance based on General Linear models procedures. The fixed effects considered were CMT score, parity,
stage of lactation, sampling occasion and quarter of the udder. Sub-clinical mastitis had a
significant negative effect on quarter milk yield (P