Browsing by Author "Petersen, P.H."

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    Analysis of genetic Diversity and relationships of Tanzania local goat populations using microsatellite DNA markers
    Chenyambuga, S.W.; Watts, P.C.; Hirbo, J.; Kemp, S.J.; Hanotte, O.; Kifaro, G.C.; Gwakisa, P.S.; Rege, J.E.O.; Petersen, P.H.
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    Analysis of genetic Diversity and relationships of Tanzania local goat populations using microsatellite DNA markers
    (2002) Chenyambuga, S.W.; Watts, P.C.; Hirbo, J.; Kemp, S.J.; Hanotte, O.; Kifaro, G.C.; Gwakisa, P.S.; Rege, J.E.O.; Petersen, P.H.
    Genetic diversity among seven Tanzanian goat populations (Ujiji, Sukuma, Ugogo, Maasai, Mbeya, Newala and Coastal goats) was investigated by determining polymorphisms at 19 microsatellite DNA loci, West African Dwarf Tswana, Landim and Toggenburg were included to serve as reference breeds. Among the Tanzanian populations, mean number of alleles per locus was highest (6.26 ± 0.670) in Sukuma and lowest (5.74 ± 0.545) in Newala. Gene diversity ranged from 0.553 ± 0.036 (Newala goats) to 0.646 ± 0.028 (Mbeya goats). The coefficient of gene differentiation (Gsr) indicated that 13% of the genetic diversity in all populations was due to difference between the populations. The genetic distance values ranged from 0. 068 (between Sukuma and Ugogo goats) to 0.2178 (between Ujiji and Coastal goats). The neighbour-joining dendrogram constructed to show population relationships indicated that the Tanzanian populations were separated from the populations, used as reference, breeds. The dendrogram revealed three, sub-clusters of the Tanzanian populations. Coastal and Maasai goats Ugogo and Ujiji goats and Sukuma Mbeya and Newala goats. The principal component analysis separated the Newala goats from the other Tanzanian goat populations. It is concluded that the level of genetic variation within, the goat populatiions was reasonably high and there was no significant difference between the population with respect to the number of alleles and the level of heterozygosity.
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    Reproductive and lactation performance of crossbred dairy cattle in Kagera region, Tanzania
    (2002) Mwatawala, H.W.; Kifaro, G.C.; Petersen, P.H.
    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.