Evaluation of Closed Adult Nucleus Multiple Ovulation and Embryo Transfer and Conventional Progeny Testing Breeding Schemes for Milk Production in Tropical Crossbred Cattle
2005
Kosgey, I. S. | Kahi, A. K. | Arendonk, J. A. M van
The potential benefits of closed adult nucleus multiple ovulation and embryo transfer (MOET) and conventional progeny testing (CNS) schemes, and the logistics of their integration into large-scale continuous production of crossbred cattle were studied by deterministic simulation. The latter was based on F₁ (Bos taurus x Bos indicus) production using AI or natural mating and MOET, and continuous F₂ production by mating of F₁ animals. The gene flow and the cumulative discounted expressions (CDES) were also calculated. Both schemes had 8, 16, 32, or 64 dams with 2, 4, 8, 16, or 32 sires selected. In the MOET nucleus scheme (MNS), the test capacity was 1, 2, 8, or 16 offspring, and the number of matings per dam per year was 1, 2, or 4. A scheme of 8 sires with 64 dams and a test capacity of 4 female offspring per dam per year resulted in an annual genetic gain (in phenotypic standard deviation) of 0.324 and 0.081 for MNS and CNS, respectively. In the MNS, there was substantial genetic gain with a relatively small number of animals compared with a CNS. The F₁ had the highest, and the F₂ scheme the lowest CDES. However, a very large number of B. indicus females would be required in the F₁ scheme. This scheme may not be practical under conditions in developing countries. The F₂ scheme was logistically attractive because it produces its own replacements, and the number of B. taurus females required would be easy to attain. Accompanying technical and financial constraints of nucleus schemes should be addressed before applying them.
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