Níveis de cálcio e relação cálcio/fósforo disponível em rações para poedeiras leves no período de 42 a 58 semanas de idade

• Autor(a) principal: Pastore, Silvana Marques
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5648
• topic: Minerais; Cálcio; Fósforo; Poedeira; Minerals; Calcium; Phosphorus; Hen; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

In order to determine calcium nutritional requirement and the best calcium/available phosphorus ratio for light-weight laying hens from 42 to 58 weeks of age, it was conducted an experiment in the Setor de Avicultura in Departamento de Zootecnia at Unversidade Federal de Viçosa for 112 days. Three hundred and twenty-four light-weight laying hens were used, distributed in a completely randomized design in a 3 x 3 factorial scheme, composed of three levels of calcium (3.9; 4.2; and 4.5%) and three calcium/available phosphorus ratios (12.12:1; 10.53:1 and 9.30:1), totaling nine treatments with six replicates with six birds each. The following parameters were evaluated: 1) performance: posture, feed intake, egg weight, egg mass, feed conversion (egg dozen and egg mass) and weight gain; 2) egg quality: percentage of albumen and yolk, weight and thickness of egg shell; egg specific gravity; contents of ash, calcium and phosphorus in the egg shell, and lost eggs; 3) bone characteristics (tibia weight, contents of ash, calcium and phosphorus in the tibia); 4) calcium/phosphorus balance (calcium and phosphorus intake, contents of ash, calcium and phosphorus in excretion and retained by the birds) and 5) mortality. There was no interaction (P>0.05) between calcium levels and calcium/phosphorus ratio for the studied variables. Levels of calcium and calcium/phosphorus ratio did not affect performance, egg quality and bone characteristics. Regarded to calcium/phosphorus balance, dietary calcium levels promoted a linear effect (P<0.05) on percentage and on the absolute value of the mineral matter in excreta, on consumption of calcium and phosphorus by the birds, on the levels of calcium in excreta, in percentage and in absolute value as well, and on retention of calcium determined as a percentage. When calcium retention was determined in absolute value, there was no significant effect (P<0.05). There was no effect (P>0.05) of levels of calcium on retention and excretion of phosphorus by birds, both in percentage and in absolute value, either. The calcium/phosphorus ratios did not influence (P>0.05) calcium intake by the birds, contents of mineral matter and calcium in the excreta in percentage and in absolute terms as well, retention of calcium by birds, in percentage and in absolute value as well, the percentage of phosphorus in feces and the percentage of phosphorus retained by the birds. However, when the retention of phosphorus was determined in absolute terms, the calcium/phosphorus ratios promoted a linear effect (P<0.05). There was also a linear effect (P<0.05) in the calcium/phosphorus ratios on phosphorus intake and on phosphorus excretion in absolute value. Diets containing 3.9% calcium and calcium/available phosphorus ration of 12.12:1, corresponding to a calcium and available phosphorous intake of 3.51 g/bird/day and 289 mg/bird/day, respectively, guarantee a satisfactory performance for light-weight laying hens from 42 to 58 weeks of age.