ABSTRACT The objective was to evaluate the digestive tract characteristics, metabolizability and nutrient retention of broilers fed diets supplemented with enzyme complex (EC). To evaluate the characteristics of the digestive tract 600 female Cobb 500 birds were used, distributed in a completely randomized design, with 5 inclusion levels of the EC (0; 100, 200, 300 and 400 g/ton) and 6 replicates of 20 birds each. To evaluate the metabolizability and the retention of nutrients 200 female Cobb 500 birds at 15 days of age were used, distributed in a completely randomized design with 5 levels of supplementation of the EC and 4 replicates of 10 birds each. No significant effects (P>0.05) were observed for the supplementation of the EC in the intestinal pH, digestive organ weight, intestinal length and metabolizable coefficients of dry matter and crude protein. The metabolizable coefficient of ethereal extract was influenced in a quadratic decreasing form (P<0.01). The metabolizable coefficients of calcium (Ca) and phosphorus (P) were influenced in a quadratic increase (P<0.01), resulting in increased Ca retention in 21.39% and P in 9.56%. Supplementation of the EC in broiler diets improves the metabolizability and retention of P and Ca, without affecting the other parameters evaluated.

RESUMO Em galos de matriz pesada sabe-se que o peso dos testículos pode ser associado positivamente com a produção diária de espermatozoides e que alterações nos testículos irão refletir na fertilidade. Nas aves, os testículos estão localizados dentro da cavidade celomática, e, portanto, não são acessíveis para exame andrológico direto, como em mamíferos. A avaliação reprodutiva de galos se baseia principalmente em características fenotípicas. Buscou-se avaliar o potencial de associação de alguns parâmetros fenotípicos, como peso corporal (PC), escores de crista (ECR), escores de cloaca (ECL) e escores de pés (EP), com parâmetros morfológicos de testículos em galos Cobb® Mx em duas idades (25 e 45 semanas de idade). Galos leves apresentaram menor peso testicular (PT), menor diâmetro de túbulo seminífero (DT), e menores ECR e ECL que galos médios e pesados (P≤0.05). Galos pesados apresentaram os maiores ECR e maiores valores para altura do epitélio seminífero (AE), e DT. Não houve diferença estatisticamente significativa entre as categorias de peso para escores de pé e proporções de túbulo seminífero (TS) e interstício (INT). Considerando-se o efeito da idade, galos com 45 semanas de idade apresentaram menores PT e TS que galos com 25 semanas de idade. Correlação positiva, moderada e significativa foi encontrada entre peso de testículo e características fenotípicas como ECR, ECL e PC em galos de 45 semanas de idade. Foi encontrada correlação positiva, moderada e significativa entre PC e características testiculares como DT e AE nas duas idades avaliadas. Conclui-se que em galos Cobb® Mx ocorre regressão do testículo com o avanço da idade, e ela é mais intensa em galos com menor peso corporal. Conclui-se que o PC tem influência positiva no peso e índices histomorfométricos dos testículos, e que escores de crista e de cloaca podem ser utilizados com potencial moderado de predição para identificar galos com baixo peso de testículos em galos com 45 semanas de idade.

ABSTRACT In broiler breeder roosters, the weight of the testes is positively associated with daily sperm production and fertility. In birds, the testes are located in the coelomic cavity, not being accessible to reproductive evaluation as mammalian testes. The reproductive evaluation of roosters is based on phenotypic traits. Any changes on testes will be reflected on fertility levels. The aim of this paper was to evaluate the potential of association of phenotypic traits as body weight (BW), comb scores (COS), cloaca scores (CLS) and feet scores (FS) with testicular morphometric parameters in adult Cobb® Mx roosters in two ages (25 and 45 weeks of age). The low BW roosters had lower testes weight (TW), smaller seminiferous tubule diameter (STD) and lower comb and cloaca scores than the medium and high BW roosters (P≤0.05). Heavy roosters had the highest COS and bigger seminiferous epithelium height (SEH). There was no statistical difference between the BW categories in FS and volumetric proportion of seminiferous tubule (ST) and interstitial tissue (IT). Considering the age effect, roosters with 45 weeks of age had lower TW and ST than 25-week roosters. Positive, moderate and significant correlation was found between testes weight and phenotypic characteristics as BW, COS and CLS in 45week roosters. A positive, moderate and significant correlation was found between body weight and histologic testicular characteristics as STD and SHE in both evaluated ages. In conclusion, there is a regression in the testes weight with age and it is more intense in Cobb® Mx roosters with lower BW. Furthermore, it is concluded that the BW positively influences the testes weight and histological quality of the testes. COS and CLS can be used with moderate potential prediction to identify roosters with low testes weight at 45 weeks of age.