A backcrossing experiment was carried out between two strains of turkey, Black Baladi (BB) and commercial White Nicholas (WW) as well as their reciprocal crosses in Maryant experimental station at El-Amria region, desert research center, ministry of agriculture, through three successive years. Results were as follows:
White Nicholas birds were significantly the heaviest at the first generation compared to birds of both BB and the reciprocals crosses at either the second or the third generation, repeated crossing with WW as a sire improved body weight of progeny (3/4 w x 1/4 B and 7/B w x 1/8 B) at all ages studied to be the best averages. Males of the same genotypes had the best weights compared to males or females of the other genotypes in all ages studied. Same trend was found concerning body weight gain, where WW birds had the best weight gains in most ages studied in the 1st generation, while those of (3/4 W x 1/4 B) in the 2nd generation and (7/8 W x 1/ 8 B) in the 3rd generation had the highest averages compared to the other genotypes.
The BB birds grew faster than those of pure WW and the reciprocals birds in the growth period studied in the 1st and 2nd generations while at the 3rd one, both the pure BB and WW birds had the same and the highest growth rate compared to birds of the other genotypes. In contrary at the rearing period (12-20 weeks of age), BB birds had the lowest growth rate compared to the other genotypes. Males surpassed females in growth rate at 4-12, 12-20 and 4-20 weeks of age.
Birds of pure BB had significantly the best growth efficiency (GE) through growth period in the three generations except at 4-8 wks of age in the 3rd one, where both WW and (7/8 B x 1/8W) cross were the best in this trait. Concerning the rearing period, the superiority varied thought the three generations. In general, the pure BB had the best averages in the whole period studied. Also, male's surpassed females in these traits (4.2 vs. 3.9%) (4.3 vs. 3.8%) and (4.9 vs. 4.6%) in the 1st, 2nd, 3rd generation respectively.
As for (½ B x ½ W) and (½ W x ½ B) crosses, heterosis, the average degree of heterosis (ADOH%) and potency ratio indicated that there was no dominance was found towards the high parent but partial dominance and complete dominance were found tends to the low parent (B x B) except for male of (½ W x ½ B) cross at 4 week of age which had positive values. The (3/4 W x 1/4 B) backcross had superior heterotic effect than the (3/4 B x 1/4 W) backcross for body weight at 8 week of age while the (3/4 B x 1/4 W) backcross had higher heterosis percentage than the (3/4 W x 1/4 B) backcross for body weight at 4 week of age. The (3/4 W x 1/4 B) backcross had higher potency ratio values than the (3/4 B x 1/4 W) backcross at all ages studied. Potency ratio values for (3/4 W x 1/4 B) backcross for body weight indicated that there was over dominance towards the high parent for body weights at 4, 8, 20 week of age and complete dominance towards the high parent (W x W) for body weight at 12 and 16 week of age. The ADOH % decreased in the third generation than in the second one at all ages studied except for 8 week.
In general, the second generation had better values of H1 % and H2%, ADOH % and P1 and P2 compared to those of the 1st and the 3rd generations concerning the whole period (4-20 wk of age) for body weight gain.
Concerning growth efficiency percentage, results indicated that over dominance effects were towards the high parent in the first generation, furthermore, complete dominance towards the low parent in the 2nd and the 3rd generations depending on the values of potency ratio P1 and P2 were found.
It could be concluded that the backcrosses for one generation between local Black Baladi and White Nicholas strains of turkey as a sire parent with 1/2B x 1/2W and 1/2W x 1/2B crosses as a dam parent, respectively, enhanced growth traits (body weight, body weight gain, growth rate). Moreover, backcrosses produced progenies have a black feather which has more acceptability by consumers in Egypt.