Níveis de cálcio e granulometrias do calcário para frangas de reposição no período de 3 a 5 semanas de idade

Abstract

The present work had the objective of to evaluate the effects of the nutritional levels of calcium and particle sizes of limestone replacement pullet rations on the performance and morphometric development of the digestive tract. A total of 1.400 replacement pullets of the Lohmann LSL strain, by using the CRD design in a 5 x 2 factorial scheme (calcium levels and particle size of limestone) with five replicates with 28 pullets per plot for the period of 3 to 5 weeks of age. The experimental diets were based on corn and soybean meal supplemented with minerals, vitamins and phytase (500 FTU/Kg). The rations were formulated to be a isoprotein, isocaloric and isophosphorus, being the phosphorus source supplied by monoammonium phosphorus and balanced according to the Lohmann (1999) strain Handbook, 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 5 weeks, morphometry of the digestive tract and contents of ash and minerals in the pullet tibia of each plot were taken after slaughtered pullet on the 5th week old. Feed conversion shown interaction to calcium levels and particle size of limenstone, occurring quadract effect of calcium levels in the gross particle size, with better feed conversion in the level of 0,96% of Ca. Inside of level 0,90% Ca the gross particle size shown better feed conversion. The pullets fed rations with limestone particle size of 0,899 mm had minus length of small intestine (cm/kg) and percentage of digestory tract. The better level of ash in the tíbia was obtained with the calcium level of 0,93% Ca. The gross particle size provided a higher level of P in tibia and any differences on levels of calcium levels were observed.