Níveis de cálcio e relação cálcio: fósforo disponível em rações para galinhas poedeiras leves no segundo ciclo de produção

• Autor(a) principal: Almeida, Rodrigo Lopes de
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5684
• topic: Exigência; Minerais; Cálcio; Fósforo; Poedeira; Requirement; Minerals; Calcium; Phosphorus; Laying hens; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

In order to determine calcium nutritional requirement and the best calcium: available phosphorus ratio for commercial laying hens in second production cycle (71 weeks old), was conducted an experiment with four periods of twenty-eight days each one. Three hundred seventy-eight Hy-Line W36 forced molting laying hens were used, distributed in a randomized experimental block design in a 3 x 3 factorial arrangement, composed of three levels of calcium (3.7; 4.0; and 4.3%) and three calcium: available phosphorus ratios (9,76:1; 10,81:1 and 12.12:1), totaling nine treatments with seven 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) Shell quality: percentage, weight and thickness of egg shell; egg specific gravity; contents of ash, and calcium and phosphorus in the egg shell; 3) bone characteristics (tibia weight, contents of ash, calcium and phosphorus in the tibia); 4) calcium and phosphorus balance (calcium and phosphorus intake, contents of ash, calcium and phosphorus in excretion and retained by the birds) and 5) mortality. There was interaction (P<0.05) between calcium levels and calcium: phosphorus ratio for feed conversion (egg dozen and egg mass). The levels of calcium affected linearly (p<0,05) the posture, which also was affected (P<0.05) by calcium: available phosphorus ratios. Calcium levels also influenced linearly (P <0.05) feed intake, and the greater the amount of calcium in the diet, the lower feed intake by laying hens. Regarding the quality parameters of shell, found that increased levels of calcium promoted a linear increase (P <0.05) in weight and percentage of shell, specific gravity and percentage and content of ash in the shell. Calcium: phosphorus ratio did not affect (P>0,05) the quality parameters of shell. Was found that increased levels of calcium caused a linear increase(P <0.05) on the weight of the tibia, on the absolute value of mineral matter in the tibia, the percentage and absolute amount of calcium in the tibia and on the absolute value of phosphorus in the tibia. Calcium: phosphorus ratio did not affect (P>0,05) the bone characteristics. Regarded to calcium and 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 and 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 and 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. The requirement of calcium for commercial laying hens in second production cycle was estimated in the minimum of 4.3% in the diet that correspond an intake of 3.9 mg of calcium / hen/day. The better calcium: available phosphorus ration was 12.12:1, corresponding to a phosphorus intake of 325 mg/hen/day.