Crossbreeding for dairy production in Kenya: Parameter estimates for defining optimal crossbreeding systems

Publication Type

Contribution to conference

Authors

Kahi,A.K.; Thorpe,W.; Nitter,G.; Gall,C.F.

Year of publication

1999

Published in

International Conference on Tropical and Subtropical Agriculture and Forestry

Editor

Humboldt University, Berlin

Page (from - to)

nnb

Conference name

International Conference on Tropical and..... Subtropical Agriculture and Forestry

Conference location

Humboldt University, Berlin

Conference date

14th - 15th October 1999

Data from a crossbred herd in the lowland tropics of Kenya were used to estimate crossbreeding parameters for milk production, reproductive traits and cow live weight (LW). An individual animal model was fitted to estimate breed cross means for 25 genotypes with different proportions of Ayrshire (A), Brown Swiss (B), Friesian (F) and Sahiwal (S) genes. These means were regressed on gene proportion of breeds and on coefficients of heterosis and recombination loss. Per lactation, F contributed 1802 kg and 18.4 kg more milk and milk per unit of metabolic weight (MW), respectively, than the S. Performance of A and B were intermediate. Contribution of F for most traits was superior to that of the other Bos taurus breeds. The heterosis effect between B and S was large for lactation milk yield (MY) (296 kg) and calving interval (CI) (-36 days). Heterosis between A and B for most traits was small, consistent with the literature. Recombination loss was negative in A x B and B x S for MY, daily milk yield (DMY) and MY per unit MW. Modelling of crossbreeding systems for MY indicated that the performance of the F x S cross for MY was not significantly different from that of the three-breed rotation and the synthetic breeds. It was estimated that the two-breed rotation involving A and S would attain 81 % of the MY of the F x S. Among the synthetic breeds, differences in MY were small. Each crossbreeding strategy should be considered in relation to the ecological and socio-economic characteristics of its production system. F x S cows were closely rivalled by the three-breed rotation and the synthetics. Conclusion: the first cross is not generally the best suited for dairying in the tropics. There is need to promote greater awareness of the potential of synthetic breeds and to formulate strategies for developing and exploiting them.