AAB Archives Animal Breeding AAB Arch. Anim. Breed. 2363-9822 FBN Dummerstorf Göttingen, Germany 10.5194/aab-42-295-1999 Variance and covariance component analysis of incubational mortality in chickens Brah G. S. 1 Sandhu J. S. 1 Chaudhary M. L. 1 Department of Animal Breeding and Genetics, Punjab Agricultural University, Ludhiana-141004, India 10 10 1999 42 3 295 302 Copyright: © 1999 G. S. Brah et al. 1999 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://aab.copernicus.org/articles/42/295/1999/aab-42-295-1999.html The full text article is available as a PDF file from https://aab.copernicus.org/articles/42/295/1999/aab-42-295-1999.pdf

A total of 1,33,507 eggs obtained from 7864 pullets of two selected White Leghorn strains over four generations representing 304 sires and 1669 dams were incubated. The unhatched eggs were broken-open for examination of embryonic development and classified as early-dead (0-11d), late-dead (12-22d) and pips. The sire component heritabilities (%) pooled over years in the two strains, respectively were 10.5±3.4 and 11.0±3.2 for total incubation mortality; 2.2 ± 2.2 and 5.1 ± 2.4 for early-dead; 6.8 ± 3.0 and 8.0 ± 3.0 for late-dead and 8.7 ± 3.1 and 4.8 ± 2.4 for pips. Total embryonic mortality as well as its three components had high genetic correlations amongst each other. However, the genetic correlations of pipping mortality with early and late mortality were weaker as compared with those of early and late mortality.