Crossbreeding for dairy production in the lowland tropics of Kenya. II. Prediction of performance of alternative crossbreeding strategies

Publikations-Art

Zeitschriftenbeitrag (peer-reviewed)

Autoren

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

Erscheinungsjahr

2000

Veröffentlicht in

Livestock Production Science

Band/Volume

63/

Seite (von - bis)

55 - 63

Predicted performance of 9 crossbreeding strategies for milk production, reproductive traits and cow live weights (LW) were compared. Strategies were selected because of their superiority. Data were from crosses of Ayrshire (A), Brown Swiss (B), Friesian (F) and Sahiwal (S) cattle. Performance was predicted from a genetic model based on additive breed differences, dominance and additive x additive interaction effects. Strategies were: first cross (F x S), two-breed rotation (AS)Rot, three-breed rotation (BFS)Rot and two- (F and S), three- (B, F and S) and four-breed synthetic breeds based on equal and unequal contribution of the foundation breeds. Lactation milk yield (MY) of production systems based on F x S, (AS)Rot or (BFS)Rot cows with replacements from within was predicted under varying number of calvings (NL) and reproductive performance (RP). At the individual cow level, differences in predicted MY between F x S cross, three-breed rotation and synthetic breeds were small. While the F x S cross was superior to the two-breed rotation for predicted MY, its performance per unit of metabolic weight was similar for MY. differences were small among the synthetic breeds. At the production system level, it was predicted that MY for production systems based on F x S cows become superior to those based on (AS)Rot cows only at a NL higher than 4 and were inferior to those based on (BFS)Rot. F x S cows were closely rivalled by the (BFS)Rot and the synthetics. Its inferiority was marked at the production system level. Conclusion: first cross is not generally the best suited for dairy production systems in the tropics. Awareness of the potential of synthetic breeds needs promoting and strategies for developing and exploiting them should be formulated. It is expected that the economic benefits from the development of two breed synthetic breeds based an A, B or F would also be comparable in production systems achieving lower yields.