Development of selection indices for indigenous hens of Iran
1995
Kamali, M.A. (Jahad Fars, T.V. Avenue, Animal Husbrandy Dep., Shiraz (Iran Islamic Republic)) | Toth, S. | Szalai, I. (Kisallattenyesztesi es Takarmanyozasi Kutatointezet, Godollo (Hungary))
Data of body weight at 12 weeks of age (WW12), egg weight (AEW30-32) egg production (EP) and age at sexual maturity (ASM) of 2853 indigenous Iranian birds were used to construct one conventional and four restricted selection indices. In the restricted indices one of the four variables was restricted (kept at the original level). Heritability of traits and indices, expected gain in traits and net merit, relative efficiency of indices, correlation between indices and net merit were evaluated. It was shown that the lowest heritability had the egg production (0.28) and the highest one (0.70) the body weight at 12 weeks of age. Heritability of indices did not differ significantly except in the restricted index of egg production (R2; h2,=0.734). The conventional index showed the most improvement in net merit (4.04) and the restricted index of egg production showed the least (1.767). Relative efficiency of restricted indices changed between 0.44-0.94 in comparison with the conventional index. It was proved that evaluation of efficiency of an index on the basis of its heritability alone can be misleading. There were no big differences in the number of generations (4.04-4.66 generations) necessary to exploit the whole standard deviation of indices except for the restricted index for egg production (2.04 generations). This study shows that restricted indices result in lower efficiency of improvement than the unrestricted ones, but they provide good means for profit maximization in populations of gene reservation
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