ABSTRACT Different levels of glycosaminoglycans (chondroitin sulfate and glucosamine sulfate) and vitamin C were injected in ovo to determine whether additive use influences the incubation parameters and bone characteristics of posthatch chicks. Hatchability was not affected by addition of glycosaminoglycans and vitamin C in ovo. However, chicks that received 4 μg additive showed 2.86% reduction in total mortality when compared with chicks from non-injected eggs. Moreover, tibia area and femur bone mineral density increased in chicks from eggs injected with 2.16 and 6.00 μg of additive, respectively. In ovo feeding with glycosaminoglycans and vitamin C can benefit bone development in embryos and reduce total mortality during the incubation period.

Um experimento foi realizado com o objetivo de estabelecer critérios de avaliação das exigências de isoleucina digestível para frangos de corte de 22 a 42 dias de idade utilizando-se diferentes modelos de regressão (quadrático, exponencial e de retas segmentadas ou Linear Response Plateau) e em caso de significância estatística, as médias foram comparadas pelo teste de Duncan a 5 % de probabilidade. Foram utilizados 1.920 frangos de corte machos com 22 dias de idade, em delineamento inteiramente ao acaso, com seis tratamentos (seis níveis de isoleucina digestível: 0,6118; 0,6655; 0,7192; 0,7729; 0,8265 e 0,8802%) e oito repetições de 40 aves. Utilizou-se como padrão o nível de 0,7192% de isoleucina digestível. O nível de isoleucina digestível recomendado para frangos de corte de 22 a 42 dias de idade é 0,7729%, correspondente à relação isoleucina:lisina digestível de 72%.

Current experiment established different criteria to evaluate the requirements of digestible isoleucine for 22- and 42-day-old broilers by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means by Duncan's test at 5% probability. A total of 1,920 Cobb 500 male broilers were used in an entirely randomized experimental design, with 6 treatments (6 digestible isoleucine levels: 0.6118; 0.6655; 0.7192; 0.7729; 0.8265 and 0.8802%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. Level 0.7192% of digestible isoleucine was considered standard. The digestible isoleucine level recommended for 22- and 42-day-old broilers is 0.7729%, corresponding to a digestible isoleucine:lysine ratio of 72%.

Um experimento foi realizado com o objetivo de estabelecer critérios de avaliação das exigências de valina digestível para frangos de corte de 22 a 42 dias de idade utilizando-se diferentes modelos de regressão (quadrático, exponencial e de retas segmentadas ou Linear Response Plateau). Foram utilizados 1.920 frangos de corte machos com 22 dias de idade, distribuídos em delineamento inteiramente ao acaso, com seis tratamentos (6 níveis de valina digestível: 0,7192; 0,7729; 0,8265; 0,8802; 0,9339 e 0,9876) e oito repetições de 40 aves. Utilizou-se como padrão o nível de 0,8265% de valina digestível. A inclusão dos níveis 0,8160; 0,8484 e 0,9031% de valina digestível proporcionou os melhores resultados de consumo de ração, ganho de peso e conversão alimentar respectivamente.

Current experiment established different criteria to evaluate the requirements of digestible valine for broilers from 22 and 42 days of age, by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means by Duncan test at 5% probability. A total of 1,920 Cobb 500 male broilers were used and distributed in an entirely randomized experimental design, with 6 treatments (6 digestible valine levels: 0.7192, 0.7729, 0.8265, 0.8802, 0.9339 and 0.9876%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. The level of 0.8265% digestible valine was considered standard. The inclusion of 0.816, 0.848 and 0.903% of digestible valine levels, corresponding to digestible valine:lysine ratios of approximately 76.00%, 79.00% and 84.12%, provided best feed intake, weight gain and feed conversion ratio, respectively for broiler from 22 to 42 days of age.