Genotypic and 20-week body weight effects on full sexual maturity traits of parent stock layers raised in commercial deep-litter system

The influence of genotype (GTY) and 20-week body weight (PW20) on full-sexual maturity (FSM) productivity and hatching traits were investigated on two parent-stock layers in Ibadan, Nigeria. Data were obtained on twenty-two batches of BOVAN NERA (BN) and ISA BROWN layers (IB) each, between 2009-2019, from a breeding company in Ibadan. These were grouped based on strain and 20-week body weight. Experimental design was randomized block design (RBD). Data were subjected to general linear model (GLM) factorial and Tukey’s HSD, α=0.05, procedures of Statistical Analytical Systems^® (SAS, 2002) software. BN had better pullet weight (P<0.05, ds=0.88), while IB possessed higher hen-day egg production, persistency of egg production and pullet day-old chicks hatched (P<0.05, ds=-0.86 to -1.44) at FSM. The 20-week low weight birds required intensive skillful management for compensatory weight-gain to FSM, while egg weight was higher in 20-week high weight class at full maturity (P<0.05, ds=0.06 to -1.19). Genotype by 20-week pullet-weight interaction revealed better genetics of BN genotype on compensatory growth between 20th week and FSM, and on PFM (P<0.05, ds=0.24 to 1.62). The better HDF and P80 (P<0.05, ds= -1.73, -1.61) of medium weight IB genotype signals its genetic ability for higher percent day-old chicks production (P>0.05, ds= -0.72 to -1.11).