Increase of egg weight with age in normal and dwarf, purebred and crossbred laying hens

F. Minvielle, P. Mérat, JL Monvoisin, G. Coquerelle, A. Bordas
1994 Genetics Selection Evolution  
An exponential curve, W = P -Q exp (-Rt) was fitted to egg weights (W) of individual hens from 8 genetic groups tested for egg production from 18-51 weeks of age (t). The groups were constituted of the combination of genotype at the sex-linked dwarfism locus (normal or dwarf) and line (White Leghorn, Brown Egg and both reciprocal crosses). The least-squares mean of the residual standard deviation about the curve was between 1.27 and 1.74 g in the 8 groups and estimated values of the initial P-Q
more » ... of the initial P-Q and mature egg P weights were between 26.9 and 33.9 g and 56.9 and 65.8 g, respectively. Effects of genotype and line as well as heterosis were estimated for both egg weights and for rate of growth relative to the remaining expected growth (R). R was smaller for dwarf hens which thus reached mature egg weight later than normal females. Significant heterosis was found for both egg weights of dwarf hens (12.6 and 9.5%) and for the initial egg weight of normal ones (12.8%). Negative heterosis for R obtained for dwarf hens (-17.4%) corresponded to a flatter egg weight curve of these crossbreds. egg weight / age of hen / heterosis / dwarfism / exponential curve Résumé -Évolution comparée du poids de l'oeuf avec l'âge de la poule chez des femelles normales ou naines et pures ou croisées. On a ajusté individuellement une courbe de la forme W = P -Q exp (-Rt) au poids de l'ceuf (W) mesuré entre 18 et 51 sem d'âge (t) chez des poules de 8 groupes génétiques définis par la corn.binaison du
doi:10.1051/gse:19940505 fatcat:awexqry7vfdnpc462xbjcruqse