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Performance and egg quality of semi-heavy layers in the second cycle of production supplemented with limestone and oyster flour


The experiment will have duration of 112 days and it will be accomplished with the objective of evaluating the effect of the levels of calcium and its granulimetric composition sources on the development and eggs quality of 576 semi heavy layers hens in the second cicle of egg production. A randomized blocks design will be used with 12 treatments in a factorial arrangement 3x4, with three levels of calcium in the diet (2,6; 3,2 and 3,8%) and four compositions particle size of sources of calcium (1 - 100% fine limestone, 2 - 50% fine limestone + 50% thick limestone, 3 - 50% fine limestone and 50% oyster shell, 4 - 50% fine limestone + 25% thick limestone + 25 % oyster shell) and six replication of eight birds in each. The mean geometric diameter and the solubility in vitro of the sources of calcium will be determined. At the end of each 28 days period two eggs of each parcel will be taken in three consecutive days per treatment an a total of 36 eggs for evaluation of the specific gravity, yolk percentage, albumen percentage, peel percentage, thickness of the peel, resistance of the peel to the break, weight of the peel for surface area, Haugh units, means index and coloration of the yolk. The following parameters will be used to evaluate the development productivity: eggs weight (g), eggs production (%), eggs mass (%), feed consumption (g), fed conversion (kg/dz and kg/kg), mortality (%) and cracked eggs percentage. At the end of the experiment, one bird of each parcel will be removed, in a total of 72 birds to be slaughtered for subsequent evaluation of calcium and phosphorus teors in the tibias and for resistance of the bones to the break. A statistics analysis of the date will be performed by using and analysis of variance and contrast between treatment means by Tukey’s test at 5% of significance using a SISVAR computational method (Ferreira, 2000). (AU)

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