Indian Journal of Poultry Science
Year : 2000, Volume : 35, Issue : 1
First page : ( 17) Last page : ( 23)
Print ISSN : 0019-5529.

Inheritance of egg shell-quality over the laying year in egg-type chickens

Khatkar M.S., Sandhu J.S., Brah G.S., Chaudhary M.L.

Department of Animal Breeding and Genetics, College of Veterinary Sciences, Punjab Agricultural University, Ludhiana - 141 004.

Received:  25  July,  1998; Accepted:  1  November,  1999.

Abstract

Two strains of White Leghorns (PL1 and PL2) were studied at three stages of laying viz; 36–40; 52–56 and 68–72 weeks of age for % shell weight; shell weight per unit surface area (SWUSA) and egg weight. The means for % shell and SWUSA showed a consistent decline over stages with decline being more sharper from stage II to III than from I to II. The coefficients of variation showed an increase over stages. The heritabilities for both the measures of shell-quality showed a decline over stages which was attributable to both the decrease in genetic variance and the increase in phenotypic variances. The genetic correlations among different stages for % shell and SWUSA were close to unity in PL 2 but PL 1 had a very low correlation with stage III. It is concluded that selection in strain PL 2 may be based on early shell-quality but in PL 1 selection at middle stage (52–56 weeks) would be more effective.

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Key words

Chicken, egg shell, inheritance.

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