ABSTRACT. A total of 1,080 one-day-old broiler chicks were used, distributed into a completely randomized design in a 6 x 2 x 4 factorial scheme, with six replications of 30 birds each (15 males and 15 females). Chicks were classified into six breeds (Cobb 500 Slow, Cobb Fast, Ross 308, Ross 508, Hybro Plus and Avian 48), male or female and four slaughter ages (43, 45, 46 and 49 days). Ten birds from each experimental unit (5 males and 5 females) were slaughtered to evaluate carcass yield and commercial cuts. Cobb 500 Slow males showed the maximum potential for weight gain at 47 days old, while the other breeds, between 33 and 35 days old, regardless of sex. Carcass and breast fillet yield showed significant differences, independent of breed, sex and slaughter age, highlighting Cobb breeds. Significant interactions were observed for breast yield, boned and deboned legs among breeds, sex and slaughter age; sex was the determining factor. Wing yield has not been affected by any of the studied factors.

Because of their membrane constitution, sperm cells of male broiler breeders are prone to lipid peroxidation, which affects their fertilizing capacity. The aim of the present study was to evaluate the effects of antioxidant diet supplementation on the reproductive characteristics of 12 male broiler breeders (Cobb) older than 50 weeks. The roosters were randomly distributed in a completely randomized experimental design with two treatments (treatment 1: commercial feed; treatment 2: commercial feed supplemented with canthaxanthin, lycopene, and vitamin C) and 6 replicates. Semen samples were collected by abdominal massage, and then underwent evaluation of semen volume, sperm concentration, motility, vigor, and morphology. Morphometric analyses of testes, combs, and dewlaps were performed at 68 weeks. Testes samples were collected for morphometric analysis of seminiferous tubules and analysis of cellular proliferation in the germinal epithelium by using immunohistochemical staining with anti-proliferating cell nuclear antigen (anti-PCNA) antibodies. Statistical data analysis was performed using the SAS software (SAS, 2002). No significant effects of antioxidant supplementation were observed on semen characteristics (p > 0.05). A significant positive effect of the antioxidant blend was observed on the percentage of normal sperm, dewlap weight and width, and testes weight and length (p < 0.05). PCNA-positive cell counts and morphometry of the seminiferous tubules were not affected by the treatment. Dietary antioxidant supplementation may represent a nutritional tool to increase fertility in male broiler breeder flocks during the post-peak production phase. Key words: Canthaxanthin. Roosters. Lycopene. Lipid peroxidation. Vitamin C. ResumoOs espermatozoides de machos reprodutores de frango de corte são células propensas a peroxidação lipídica, dada à constituição biológica de sua membrana, influenciando a capacidade fertilizante do macho. O objetivo deste trabalho foi avaliar o efeito da suplementação dietética de antioxidantes

This study aimed to evaluate the effects of antioxidant supplementation in diets of breeding roosters during the post-peak phase on reproduction characteristics and muscle performance of offspring in two similar breeder houses from a local company. Treatments consisted of a control diet and a diet supplemented with antioxidants (8 ppm canthaxanthin + 40 ppm lycopene + 150 ppm vitamin C). During the 66th week of age, eggs were incubated, and offspring were housed. Dietary supplementation of the blend of antioxidant resulted in higher (p<0.05) weights of testicles, crests, dewlaps, dewlap thickness, and number of perforations (53.35 x 25.30) in relation to non-supplemented roosters. There was no significant effect (p>0.05) of supplementation of the antioxidant blend on weight gain and breast weight and count and diameter of muscle fibers of offspring at 7 days of age. Feed conversion and weight gain from 14 to 35 days were better (p<0.05) in offspring from supplemented roosters. The supplementation of an antioxidant blend in roosters improved reproductive characteristics assessed and feed conversion and weight gain of offspring.