Níveis de cálcio e granulometrias do calcário para frangas de reposição no período de 3 a 16 semanas de idade

Abstract

The present work was performed with the purpose of evaluating the effects of the nutritional levels o calcium and particle sizes of limestone replacement pullet rations on the body and morphometric development of the digestive tract. 1,400 replacement pullets of the Lohmann LSL strain , employing CRD in a 5 x 2 factorial scheme (calcium levels and particle size of limestone) with five replicates with 28, 18 and 16 birds per plot, respectively over the periods of 3 to 7, 8 to 12 and 13 to 16 weeks of age. The experimental diets were based on corn, soybean meal and wheat meal (wheat only at growing phase) supplemented with minerals, vitamins and phytase (500 FTU/Kg), their being isoprotein, isocaloric and isophosphorus, their having as a phosphorus source monoammonium phosphorus and balanced according to the Lohmann LSL strain Handbook (LOHMANN, 1999), supplemented with limestone in fine (DGM = 0.135 mm) and gross (DGM = 0.899 mm) particle size to meet the levels of 0.60, 0.75, 0.90, 1.05 and 1.20% of total calcium in the diet. The performance in the period of 3 to 16 weeks , morphometry of the digestive tract and contents of ashes and minerals in the birds' tibia of each plot slaughtered on the 16th week of age. Ration consumption in the period presented a linear growth with the rise of calcium levels. There were no significant differences of weight gain, feed conversion and % digestive tract. On the 16th week of age, higher ash and calcium contents were achieved in pullets were fed gross particle size at the levels of 0.90 and 1.05% of calcium. In the initial and growing phases the level of 0.90% Ca proved ideal in gross size particle for the osseous formation.