A cross sectional study was conducted during October and November 2006 on 69 smallholder dairy farms with lactating cows in Mvomero and Njombe districts Tanzania, to determine the prevalence of
mastitis and to assess the milk quality on the study farms. Clinical
mastitis was investigated using clinical changes of udder and milk at animal level. Cow-side California
Mastitis Test (CMT) and microbiological cultures were used to assess subclinical
mastitis at quarter level. Milk quality was determined on bulk milk samples at herd level using alcohol and acidity tests, butter fat content, total solids, ash content as well as Delvotest for antimicrobial residues. Overall prevalence of clinical
mastitis at herd level in both districts was 21.7% (n = 69). Based on CMT, prevalence of subclinical
mastitis at animal level was 51.6% (n = 91). Prevalence of bacterial isolates at animal level was 35.2% (n = 91) while for fungal it was 16.7% (n = 90). Based on CMT results, prevalence of subclinical
mastitis at quarter level was 30% (n = 353), while for bacteria and fungi it was 16% and 6% respectively. Contamination of milk with antimicrobial residues was 4.5% (n = 67). The milk quality parameters for most of the milk samples were within acceptable levels. Findings in this study have demonstrated high prevalence of subclinical
mastitis that may contribute to low productivity of dairy cattle in both districts. About 20% of CMT subclinical cases had no involvement of microbial pathogens that suggested the need for minimal interventions with
antimicrobial agents. These findings call for use of udder
disinfectants and improved milking hygiene as intervention strategies to control
mastitis on the smallholder dairy farms in Tanzania.