Application of Non-linear Models to Egg Production Curves in Chickens.

Abstract

Four mathematical models (compartmental (C), modified compartmental (MC), Wood (W), and Adams-Bell (AB)) were fitted to different patterns of egg production data in laying hens to compare the fits of these models. The egg production data were obtained from the two lines which were founded on a basis of divergent selection for egg quality traits. Egg production data of individual hens were classified in six patterns. The average hen-day rates of lay were calculated for every 10 days from the first egg for each pattern. The comparison of fits was based on the R2 adjusted for degrees of freedom and Akaike's information criterion (AIC). The fits of C, MC and AB models were similar for the egg production data showing a general pattern of curve. However, the model parameters could not be estimated by these three models for the data whose patterns showed abrupt decreases after the peak of egg production. The data in which the period from the first egg to the peak of egg production was short and linearly decreased after reaching the peak showed poor fits of the models. The parameters of all patterns could be estimated by the W model, but the fits were lower than those of the others.

Comparison of the Clutch Traits and Egg Production Predicted by the Multiphasic Model Among the Laying Strains.

“…The overestimation of the model can be explained by the persistency of egg production. The hens that are poor laying show a rapid decline on persistency of lay after peak as observed by MIYOSHI et al (1996). The accuracy of prediction was the same for both predictions of EP 270 and EP360 in the J line, indicating that hens of this line maintained persistency of lay in the whole production period.…”

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

“…Nonlinear models are widely used to flt egg production data (Cason and Ware, 1990;Miyoshi et al, 1996;Narushin and Takma, 2003;Savegnago et al, 2011). Mathematically, egg production curves can be divided into 3 phases.…”

A statistical analysis of nonlinear regression models for different treatments for layers

“…The data analyzed have been described in detail by Shim et al (2013) ( Table 1 ). Six functions were included in these analyses because they have been commonly used to fit response variables from egg production research (Adams-Bell model; Adams and Bell, 1980 ), modified compartment model ( Miyoshi et al, 1996 ), and egg weight and feed intake Lokhorst model ( Lokhorst, 1996 ), Gompertz equation ( Gompertz, 1825 ) and Richards equation ( Richard, 1959 ). All models were fitted using the nonlinear procedure (“proc nlin”) of SAS ( SAS Institute, 2006 ) with the Marquardt algorithm ( Marquardt, 1963 ).…”

“…The modified compartmental equation has been applied to fit egg production y 1 and egg output y 2 by Miyoshi et al (1996) : where y corresponds, respectively, to y 1 egg production (%) or y 2 egg output, t is age in weeks and a, b, c , and d are parameters. These parameters have no particular interpretation.…”

“…Several models depicting curves have been proposed. For instance, the Adams-Bell (1980) and modified compartmental ( Miyoshi et al, 1996 ) models have been applied to fit egg production; Lokhorst (1996) introduced models to fit egg weight and feed intake. Gompertz (1825) and Richard (1959) proposed models to fit the body weight curves of hens.…”