APPLICATION OF STEPWISE REGRESSION ANALYSIS IN BODY WEIGHT PREDICTION OF CROSSBRED CHICKENS

Abstract

Prediction of body weight with linear measurement traits of 531 day-old crossbred chickens was determined by stepwise regression analysis for mixed sexes at 4 and 8 weeks and separate sexes at 12, 16 and 20 weeks. The best single predictor of body weight was shank length in Isa Brown x naked neck (IBxNa) at 4 weeks (coefficient of determination, R2 = 65%) and frizzle feathered x Isa Brown (FxIB) at 8 weeks (R2 = 96%). For males, it was drumstick length (DL) in IBxNa (R2 = 90%) at 12 weeks and in Isa Brown x frizzle feathered (IBxF) at 16 (R2 = 85%) and 20 (R2 = 81%) weeks. Those of females were body length (BL) (R2 = 91%), body girth (BG) (R2 = 90%) and body width (BW) (R2 = 90%) in naked neck x Isa Brown (NaxIB) at 12, 16 and 20 weeks, respectively. The best partial predictors of body weight were BG and wing length at 4 weeks (R2 =97%) and BG, BL and keel length (KL) at 8 weeks (R2 =97%) in IBxF; BW and DL (R2 =76%) in normal feathered x Isa Brown (NxIB) males at 16 weeks and BW and DL (R2 =97%) in NxIB females at 20 weeks. Body weight of chickens should best be predicted using body girth, body length, keel length, body width and drumstick length in single or partial state in each genotype for mixed and separate sexes at different ages.