Abstract
The influence of weight classes (light, medium and heavy) of Ross chicks on performance and carcass yield and main cuts, was studied using a completely randomized design with six replicates of 30 males and 30 females each. The chicks were fed on the same diets during the growing period (1-43 days). The live weight, feed intake, feed:weight gain ratio, viability, carcass yield and main cuts (breast, whole leg, wing and back) and percentages of giblets (gizzard, liver, heart and guts) were analyzed. The heavy weight class chicks were heavier (P<0.05) than the light weight class chicks, during all the growing period and showed higher feed consumption (P<0.05) than the light and medium classes chicks. No differences among weight classes chicks concerning feed:weight gain ratio, viability, carcass yield and percentage of heart, gizzard and liver were observed (P>0.05). The males showed higher carcass yield than the females of medium and heavy weight classes chicks. The whole leg yield of heavy weight class chicks was higher than the medium weight class chicks (P<0.05). Weight class influenced live weight, feed intake, carcass yield and whole leg but had no effect on feed:weight ratio, viability, breast yield and giblets percentage.
Highlights
The influence of weight classes of Ross chicks on performance and carcass yield and main cuts, was studied using a completely randomized design with six replicates of 30 males and 30 females each
Para as análises dos dados de desempenho, cada repetição foi composta por 30 aves e, para os dados de abate, foram utilizadas 12 aves, considerando-se cada ave como uma repetição
Em relação ao peso vivo (Tab. 2), aos 7, 21 e 37 dias de idade, foram observadas diferenças significativas entre os tratamentos (P
Summary
Foram utilizados 1080 pintos da linhagem Ross 308, provenientes de matrizes com 58 semanas de idade, os quais foram alojados em um galpão convencional, dividido em boxes com 15 aves/m2. Definidos pelas categorias de peso dos pintos, foram: leve - de 30. Foram usados 360 pintos, 180 machos e 180 fêmeas. Foram utilizados cinco tipos de ração, de acordo com as fases de criação: pré-inicial (PRE) de 1 a 7, inicial (INI) de 8 a 21, crescimento I (CRE I) de 22 a 29, crescimento II (CRE II) de 30 a e final (FIN) de a 43 dias de idade dos frangos. Para a formulação das rações, foram considerados os valores nutricionais dos ingredientes estabelecidos nas tabelas brasileiras sobre exigências nutricionais de aves e suínos, segundo Rostagno et al (2000). A composição das rações com seus respectivos níveis nutricionais são apresentados na Tab. 1. Composição percentual das rações e respectivos níveis nutricionais calculados
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