Níveis de cálcio e relações cálcio: fósforo em rações para galinhas poedeiras leves

• Autor(a) principal: Silva, Eliane Aparecida da
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1882
• topic: Galinhas poedeiras - Alimentação e rações; Nutrição - Controle; Cálcio; Fósforo; Laying hens - Food and feed; Nutrition - Control; Calcium; Match; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL::EXIGENCIAS NUTRICIONAIS DOS ANIMAIS

Two experiments were conducted in the Poultry Sector, Department of Animal Science, Federal University of Viçosa, in order to determine calcium nutritional requirement and the best calcium: available phosphorus ratio for commercial laying hens in the periods 24-40 and 42-58 weeks of age. Five hundred seventy-six Hy-Line W36 laying hens were used in both experiments, distributed in a completely randomized experimental design in a 4 x3 factorial arrangement, composed of for levels of calcium (3.4, 3.8, 4.2 and 4.6%) and three calcium: available phosphorus ratios (9:1, 13:1 and 17:1), totaling twelve treatments with eight replicates with six birds each. The first experiment was conducted during the period from 24 to 40 weeks of age and the second experiment during the period from 42 to 58 weeks of age. both experiments, the following parameters were evaluated: 1) performance: posture, weight gain, feed conversion (egg dozen and egg mass); 2) Egg quality: percentage and weight of yolk; percentage and weight of albumen; percentage, weight and thickness of egg shell and gravity specific; 3) composition of the egg shell: contents of ash, calcium and phosphorus; 4) bone characteristics: tibia weight, contents of ash, calcium and phosphorus in the tibia; 5) calcium and phosphorus balance: calcium and phosphorus intake, contents of ash, calcium and phosphorus in excretion and retained by the birds. Concerning the first experiment, from 24 to 40 weeks of age, effect (P<0.05) was observed of calcium levels on feed conversion (egg dozen and egg mass). Calcium levels and calcium /phosphorus ratios did not affect (P>0.05) feed intake and egg production. Regarding the parameters related to egg quality, increased levels of calcium caused (P<0.05) a reduction in weight and percentage yolk; increased levels of calcium caused (P<0.01) increase in weight and percentage shell and also specific gravity of eggs. For to parameters for the composition of the egg shell, there was a significant interaction between calcium and the calcium/phosphorus ratios on the mineral matter and phosphorus contents, in percentage and in grams, and the calcium content in grams. Considering bone parameters, it was observed that increased levels of calcium caused a linear (P<0.01) increase in the percentage of ash in the tibia; was observed effect (P<0.01) of interaction levels of calcium and calcium/phosphorus ratios on the percentage of phosphorus in the tibia. With respect to the balance of calcium and phosphorus, calcium levels affected linearly (P<0.01) calcium intake, which was not affected (P>0.05) by calcium/ phosphorus ratios; except for calcium intake, there was interaction effect (P<0.01) between levels of calcium and calcium/phosphorus ratios for all parameters. The requirement of calcium for commercial laying hens from 24 to 40 weeks of age is 4.27% in the diet that correspond an intake of 4.0 g of calcium/hen/day. The better calcium: available phosphorus ratio is 17:1, corresponding to an available phosphorus intake of 235 mg/hen/day. With respect to the second experiment 42 to 58 weeks of age, it has been found a significant effect of calcium on feed intake and feed conversion (egg dozen and egg mass). The calcium/phosphorus ratios did not affect (P>0.05) the parameters related to the productive performance. With regard to the quality of the egg, calcium levels significantly affected the percentage, the weight and thickness of the egg shell and also the specific gravity of the eggs. Parameters related to egg quality were not affected (P>0.05), by calcium/phosphorus ratios. Considering the composition of the egg shell, a linear increase was observed in the calcium content in grams, with increasing levels of dietary calcium; the calcium/phosphorus ratios did not affect (P>0.05) the parameters related to the composition of the egg shell; there was interaction effect (P<0.01) between calcium levels and calcium /phosphorus ratios on contents of mineral matter and phosphorus, in grams and the percentage of calcium in the egg shell. The calcium/phosphorus ratios did not affect (P>0.05) the parameters related to the bone characteristics; calcium levels significantly affected the contents of calcium and phosphorus of the tibia, in grams. The contents of mineral matter, in percentage and in grams, of calcium and phosphorus, in percentage, were significantly affected by the interaction between calcium levels and calcium/phosphorus ratios. Considering the balance of calcium and phosphorus, it was observed effect (P<0.01) of calcium levels to calcium intake, calcium excreted and retained, in percentage and grams/bird/day, and also, for the phosphorus excreted in grams/bird/day; the content of phosphorus in excreta, in grams/bird/day, was affected by the calcium/phosphorus ratios, the lower excretion of phosphorus was obtained with the calcium/ phosphorus ratio 17:1; the percentage of mineral matter in excreta, consumption of phosphorus, phosphorus excreted in percentage, and phosphorus retained in percentage and gram /bird/day, were significantly influenced by the interaction between calcium levels and the calcium/phosphorus ratio. The requirement of calcium for commercial laying hens from 42 to 58 weeks of age is 4.43% in the diet that correspond an intake of 4.27 g of calcium/hen/day. The better calcium: available phosphorus ratio is 17:1, corresponding to an available phosphorus intake of 251 mg/hen/day.