Egg production curve fitting using nonlinear models for selected and nonselected lines of White Leghorn hens

Abstract

Egg production curves describe the laying patterns of hen populations over time. The objectives of this study were to fit the weekly egg production rate of selected and nonselected lines of a White Leghorn hen population, using nonlinear and segmented polynomial models, and to study how the selection process changed the egg-laying patterns between these 2 lines. Weekly egg production rates over 54 wk of egg production (from 17 to 70 wk of age) were measured from 1,693 and 282 laying hens from one selected and one nonselected (control) genetic line, respectively. Six nonlinear and one segmented polynomial models were gathered from the literature to investigate whether they could be used to fit curves for the weekly egg production rate. The goodness of fit of the models was measured using Akaike's information criterion, mean square error, coefficient of determination, graphical analysis of the fitted curves, and the deviations of the fitted curves. The Logistic, Yang, Segmented Polynomial, and Grossman models presented the best goodness of fit. In this population, there were significant differences between the parameter estimates of the curves fitted for the selected and nonselected lines, thus indicating that the effect of selection changed the shape of the egg production curves. The selection for egg production was efficient in modifying the birds' egg production curve in this population, thus resulting in genetic gain from the 5th to the 54th week of egg laying and improved the peak egg production and the persistence of egg laying.

Egg production and certain behavioural characteristics and mortality pattern of indigenous chicken of India

“…If the broody hen is allowed to incubate the eggs the length of pause extends to 121.75d. The analysis of egg production in indigenous chicken revealed a shift in the pattern with delayed peaking compared with breeds like White Leghorn (Savegnago et al, 2012). The number of eggs per cycle in the present study was higher than the previous reports (FAO, 2009) but comparable with that of Iqbal and Pampori (2008).…”

Effect of age on production characteristics of Boschveld indigenous chickens of South Africa reared intensively

“…However, none of these studies reported on optimizing the egg production parameters of Boschveld indigenous chicken from 21 week until 44 weeks of lay. Savegnago et al (2012)recorded that non-linear regression and multi-stage modelling methods couldbe used in modelling egg production. Among the non-linear regression models, Adams-Bell and logistic are reputed to be good egg production models, with the Adams-Bell model or a simple linear regression exhibiting better fitting performance from peak production to 20 or 24 weeks of production (Faridi et al, 2011).…”

The association of very low-density lipoprotein receptor (VLDLR) haplotypes with egg production indicates VLDLR is a candidate gene for modulating egg production

“…One advantage of MME is that the statistic not only evaluates the goodness of fit of a model, but also reflects the direction in which observed values deviate from predicted values (Savegnago et al , 2012). A positive MME means that the model overestimates the egg production rate as a whole; correspondingly, a negative MME indicates that the egg production rate is underestimated.…”