The effect of 20-week pullet weight on full-sexual maturity characteristics in a parent-stock layer strain

Abstract

The body weight of 20-week-old pullets (PW20) could be managed to influence desired performance at full sexual maturity (FSM) in layers. This was examined in Bovan Nera (BN) parent stock using 22 batches of average of 3896 birds per batch at 20 weeks, raised from year 1999 to 2008. Data were collected on fourteen performance and hatching traits. The GLM, means procedure, Pearson’s correlation for association study, Multiple linear regression (MLR) for relationship analysis and Tukey’s HSD procedure for mean separation (α=0.05) of SAS/STAT (2013) were employed in a completely randomized design (CRD). PW20 had direct effect (p < 0.05) on weight gain from 21 weeks to full maturity (WTF), age at full maturity (AFM) and egg weight at full maturity (EWF). The 20-week low body weight of 1500-1600g had positive effect on compensatory WTF, increased AFM and EWF, produced an auto-correlation with AFM, fertility of eggs set (FES), hatchability of eggs set (HES) and day-old pullet chicks (DPC) hatched at full maturity (PDC, r = 0.906 – 0.959, p = 0.05). The medium body weight (1601-1700g) positively associated with AFM (r = 0.594, p = 0.05), with birds in the weight group attaining full maturity at the earliest age of 199 days. The high body weight (1701-1800g) class produced the highest egg weight (60.20 g), was positively correlated with hen day egg production (HDF, r = 0.998; p =0.05) and negatively associated with WTF and PFM (r > - 0.974, p = 0.05) due to the feed restriction leading to reduced weight gain to full maturity. The medium weight produced earliest AFM and high positive associations with fertility, hatchability and day-old pullets hatched at full sexual maturity. For optimum performance, the PW20 medium weight of 1601 – 1700 g/bird is recommended to breeders and producers.