Effect of environmental and genetic factors on the productivity crossbred dairy cattle in smallholder farms in Northeast Tanzania

Tanzania Journal of Agricultural Sciences 2002, Vol. 5(2) : 109-113Cow productivity rneasured as annual milk. was calculated as lactation milk yield calving interval x 365. The least squares mean for first lactation annual milk yield was 1803 25.81 and significant sources of variation were year of calving genotype, district and herd size. The mean annual milk yield for cows with repeated measurements was 1912 = 33. 61 and the signtficant sources of variation were genotype district and herd size. In the first lactation there waa a continuos drop in yield with years, a reflection of deterioration in management. The significant difference between years could as well mean that as more farmers join the system resources per animal in a given location decrease. The superior genotype was that of animals with 58B. taurus blood. Animals in the peri-urban district and those in herds of more than one milking animal out-yielded the other