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

Abstract

A study was carried out to examine the effects of lines on the clutch traits and the prediction of egg production in laying hens. Data of oviposition time were recorded at four stages from the 120th day to the 330th day of egg production for two years. The duration of observation in each stage was 30 days. The four lines were abbreviated as H, L, J and X. The H and L lines were obtained from long-term divergent selection for high and low yolk-albumen ratios. The J and X lines were the commercially obtained. The clutch traits were intra-clutch mean lag of oviposition time (LAG), mean delay of pause day between clutches (DELAY), the rate of internal laying (IP), the number of clutches (CN), the average length of clutches (CL) and the average size of clutches (CS).There were significant differences between lines and stages for all clutch traits. LAG values in the J and X lines (0.28 hours and 0.22 hours, respectively) were significantly shorter than those in the H and L lines (1.04 hours and 1.32 hours, respectively). Accordingly, the values of CL and CS were significantly larger, and CN values were significantly smaller in the J and X lines. The values of DELAY in the H and L lines significantly differed from those in the J and X lines. IP values were 9.94%, 7.75%, 4.22% and 5.54%, respectively, for the H, L, J and X lines.The clutch traits obtained from the first stage were used to predict total egg number of 270 and 360 days of laying periods (EP270 and EP360) by the multiphasic model. Correlation coefficients between actual and predicted values of the four lines were 0.72 and 0.67 for EP270 and EP360, respectively. The correlation coefficients in the J and X lines that laid more than 300 eggs in 360 days of laying period ranged from 0.75 to 0.88, being higher than those in the H and L lines (0.60∼0.75) with 240 eggs in the same laying period.