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An assessment of progress with different stocks and methods of selection in egg layers
Published online by Cambridge University Press: 27 February 2018
Abstract
Data from 10 years of German random sample tests (1978-87) were analyzed to document recent changes in 5 white-egg and 5 brown-egg strains which had participated fairly regularly in the tests. In the absence of a control population, it is only possible to compare rates of changes between strains and the overall trends of white-egg vs. brown-egg strains. The data show that improvement continues at average levels of performance which must have seemed utopian 20 years ago, when it was popular to question whether any genetic progress was being made.
The methods used by different breeders to achieve the apparent improvements are generally not disclosed, but it seems reasonable to assume that all programs more or less follow the same pattern: combined pure-line and cross-line testing, approximations to classical index selection using individual and family information, with emphasis on different traits depending on economic importance and pressures to keep pace with competitor stocks.
The five brown-egg strains on average have made more progress than the five white-egg strains, but there are also obvious differences in rate of change among strains with the same shell colour. In some instances, the changes may involve the replacement of one or more lines making up the strain cross, which is not reflected by a change in product name.
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- Trait Improvement
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- Copyright © British Society of Animal Production 1988