Mathematical Modelling of Egg Production Curves of Shikabrown® Parents
This study was conducted to evaluate egg production curves of Shikabrown® parents, using mathematical models. A total of 200 birds: 100 from each of the two strains of Shikabrown® parents (sire and dam) lines at the Breeding Unit of Poultry Research Programme, National Animal Production Research Institute (NAPRI) were used for the study. The birds were obtained from the selected lines (sire and dam) and were denoted as Strain A and Strain B, respectively. Body weight (BWT), age at sexual maturity (ASM), egg number (EGGNO), and egg weight (EWT) were examined. Four non-linear models (Logistic, Richard, Gompertz, and Exponential) and a linear model were used to predict the efficiency of weekly bodyweight and egg production traits. The adequacies of the models were fitted using R Package, version 3.0.3. High coefficients of determination for BWT (R2 = 0.84 - 0.93) were recorded in the models for both Strains. Strain A had higher R2 (0.93) for BWT in Richard, Gompertz and Exponential models while Strain B recorded (R2 = 0.89) in Logistic, Richard and Gomprtz models. High coefficient of determination was obtained in a reproductive trait; egg number; in which almost all the models gave (R2 = 0.70). Exponential model recorded a higher R2 (0.93) for EGGNO in strain A. EWT in strain A recorded higher R2 (0.96) coefficient of determination across the four nonlinear models except linear model with (R2 = 0.95) for egg weight. Significant differences (P<0.05) were observed in the birds' performance for BWT and EWT, with strain B having a higher BWT (1.59±0.01) and Strain A having a higher EWT (48.75±0.17). Similarly, age of birds in lay had a concomitant significant differences (P<0.05) in their BWT as well as their EWT. The birds performed better for BWT and EWT in week 26 and 27 for both Strains. It was concluded that Strain significantly (P<0.05) had effect on BWT and EWT of Shikabrown® parent with Stain B performing better than Strain A in the former trait and strain A better than strain B in the latter trait. R2 identified differences between Strains in predicting egg production traits. Strain B was adjudged good and profitable because the Strain had the highest mean values in body weight and egg number and it is being recommended as one of the lines for future improvement of Shikabrown®.
Keywords: Mathematical models, Egg Production Curves, Body weight, ASM, Egg Number, Egg weight