This study aimed to evaluate the influence of inoculation of isolated soy protein (P.I.S.) in embryonated eggs of semi-heavy with different ages. 320 embryonated eggs were used from semi-heavy breeders of Rhode Island Red lineage with 35 and 70 weeks of age. In the 17th day of incubation, the eggs were inoculated with 0.5 ml of solution in the allantoic cavity. The experimental method was completely randomized in factorial scheme (2 x 4), consisting of two factors: matrices ages (young and old matrices) and inoculation solutions (non-inoculated eggs; 0.5% of saline solution; 1% of P.I.S. + 0.5% of saline solution; and 2% of P.I.S. + 0.5% of saline solution, totalling eight treatments containing 40 eggs each. The inoculation of isolated soy protein showed positive effect on the chick-egg relation, albeit without improving incubation yields, organ development and chicks’s performance in the pre-initial phase. The age of the breeder directly influenced the variables evaluated, with eggs from older breeder showing better weight, higher embryonic mortality in late phase, heavier chicks and worse feed conversion.
chick performance; embryo mortality; hatchability; in ovo nutrition