Abstract:
This study was done to evaluate reproductive and lactation performance of crossbred dairy cattle in Kagera region, Tanzania. Traits studied were age at first calving (AFC), calving internal (Cl), lactation milk yield (LMY) and lactation length (LL). Records for the various traits were compiled covering the period between 1979 and 1999. The General Linear Models procedure of SAS was used in data analyses. The mean AFC and CI were 39.0 months and 464. 7 days, respectively. The mean IMY and LL were 2332.5 kg and 367.2 days respectively. The influences of year of birth and genetic group on AFC were highly significant (P<0.001). Heifers having 5/8 Friesian blood tended to calve 3. 4.6 and 5 months earlier than 5/8 Friesian crosses FI and F2 respectively. Genetic group parity, district and the interaction between season and year of calving highly significantly (P<0.001) influenced CI. Cows in fourth parity out yielded those in first parity by 276 kg of milk. Year of calving and genetic group x district interaction were highly significant (P< 0.001) sources of variation in LMY. LL was significantly (P < 0.00l) influenced by genetic group, parity and year of calving. LL in Bukoba rural district was 28 days longer (P<0.05) than in Biharamulo district. It is concluded that both genetic and non-genetic factors considerably influenced reproduction and lactation performance of crossbred dairy cattle in Kagera region. Increased level of exotic blobd has led to having animals with shorter AFC and CI and higher LMY up to 5/8 Friesian blood. Genetic group by district interactions revealed that some genetic groups performed differently among districts reflecting differences in environmental effects between.
