COMPARISON OF EARLY SEXUAL MATURITY CHARACTERISTICS BETWEEN BOVAN NERA AND ISA BROWN PARENT STOCK LAYER STRAINS AS INFLUENCED BY 10-WEEK BODY WEIGHT

Abstract

The study was conducted to compare early sexual maturity characteristics between Bovan Nera and Isa Brown Parent stock chickens reared in a commercial breeding system in Ibadan, humid Tropical Nigeria. Records on Pullet weight at 10 weeks (PW10, g), Feed-intake at 10-weeks (FI10, g), Total feed intake from11 weeks to first egg (FI11FE, kg), weight gain from 11 weeks to first egg (WG11FE, g), Feed intake at first egg (FIFE, g), pullet-weight at first egg (PWFE, g) and pullet-age at first egg (PAFE, days) were culled from the parent stock breeding farm records of CHI Farms Ltd. Ibadan; covering 1999 to 2008. The effect of PW10on FI10, FI11FE, WG11FE, FIFE, PWFE and PAFE was investigated. A total of 20 flocks of each strain were compared. Data were analyzed using ANOVA, GLM, Tukey’s T-test, correlation and regression procedures of SAS® (1999) in randomized complete block (RCBD) design. Findings revealed that three body weight classes at 10-weeks (<700, 801-900 and >900 g) caused significant differences between strains in WG11FE, PWFE and PAFE. The 701-800 g body weight group produced no significant (p>0.05) difference between the two strains. PWFE was positively related with PAFE in BN (R2=0.11) and IB (R2=0.71). Strain averages revealed significant (p<0.05) differences between strains in all characteristics, and this led to 6-day difference in PAFE between BN and IB strains. The prediction of PWFE was highly influenced (p<0.0001, R2≥0.82) by PW10 and WG11FE in both strains. All equations obtained were significant (P<0.0006-0.04), revealed minimal basal genotypic differences between strains, and gave varying R2 values from 0.00-0.86. The equations elicited the underlining causes of variability between Bovan Nera and Isa Brown parent stock chicken. Study also revealed the importance of PW10 for breeding and management of chicken from the 11th week to first egg.