ABSTRACT

Two experiments were conducted in this study to evaluate the performance of main and reciprocal F₁ and F₂ crossbred chickens bearing normal feather, naked neck and frizzle feather genes in the humid tropics. In experiment 1, a base population of 90 adult chickens comprising 45 local strains (normal feathered chickens, frizzle and naked necked) and 45 exotic broiler breeder (Anak) strain were used at a mating ratio of 5:40 and 5:40, respectively for the experiment in a Randomized Complete Block Design. The main cross constituted the mating of the exotic cocks (Anak male) to the local hens (Normal, frizzle and naked neck). The reciprocal cross consisted of the reverse mating involving the mating of the local cock (Normal, frizzle and naked neck) to the exotic broiler breeder hens. Data collected were subjected to Analysis of Variance technique. Results of growth performance revealed that the reciprocal F₁ hybrids were significantly (P<0.05) heavier in body weight than their main cross counterpart throughout the period of the study. Average daily feed intake were also higher (P<0.05) in the reciprocal F₁ crosses and also the best feed conversion ratios. Brooding and rearing mortalities were significantly higher (P<0.05) in both the main and reciprocal crosses of naked neck (E x Na and Na x E) in F₁. Sexual dimorphism was observed in the body weight and Linear body measurement (LBM) with the male weighing heavier than females at all stages of the cockerels and pullets. The frizzle males and females were superior in body weight and most LBM at 18 weeks. Body weight at first age, egg at first egg, average weight of egg at first lay and short term egg number at 90 days were significantly (P<0.05) better in the reciprocal crosses with the frizzle chicken having the highest body weight at first lay (2000g), egg weight (47.55g) and egg number (41.02). The reciprocal cross of frizzle also had the lowest number days for first egg (146days). The egg quality traits were also significantly (P<0.05) higher in the reciprocal F₁crosses. The correlation values between body weight at first egg and age at first egg in the genetic groups were all positive and ranged from low to high (0.287 – 0.996) with the exception of F x E where a highly significant (P<0.01) negative correlation between these traits were found. A significant negative correlation (r = -0.999) was also found between body weight at first egg and egg number at 90 days in E x F hybrid. The live weight, dress weight, dressing percentage, breast cut, back cut, thigh, wings and shank of the reciprocal crosses were significantly higher (P<0.05) than in the main crosses. Among the reciprocal crosses, F x Ehad the highest live weight and shank length, followed by Na x E. The Na x E was significantly higher  in dress weight, dressing percentage, breast cut, back cut and thigh, followed by F x E. Significant differences (P<0.05) were seen in heart, proventriculus, lungs and kidney, where the reciprocal crosses where significantly different (P<0.05) from the main crosses. The reciprocal crosses were significantly higher (P<0.05) than the main crosses in heart, proventriculus, lungs and kidney. The reciprocal F₂ backcrossed chickens [E x (NF x E), E x (Na x E) and E x (F x E)] were superior to their main cross counterparts in body weight throughout the study periods. They also had better FCR and higher LBM when compared to their main cross F₂ backcross counterparts. The reciprocal crosses were also superior in egg production parameters with the frizzle having the highest body weight at first egg and least age to attain sexual maturity in both main and reciprocal crosses. However, the normal feathered had higher number of eggs lay. The reciprocal F₂ backcrosses also were superior in egg qualities. The experiments showed clear evidence of maternal influence in the expression of growth and in egg production traits. The reciprocal crosses were significantly higher (P<0.05) than the main crosses in carcass characteristics. From experiment 1 and 2, it was clear that the reciprocal crosses produced off springs with superior growth, egg production and egg quality characteristics traits. It was concluded that backcrossing the F individuals to the exotic broiler breeder cocks increased the genetic profile of the backcross lines resulting in enhanced growth performance of progenies. Crossbreeding of exotic and local chicken varieties generated progenies that had higher genetic potentials for growth relative to the local strains and better adaptability relative to the exotic breed. It is therefore concluded that reciprocal crossbreeding should be adopted in other to achieve rapid improvements in the traits studied. Frizzle gene was superior in body weight and egg production and egg quality traits followed by naked neck gene, which showed improvement especially in egg quality traits.