Produção e qualidade de ovos de galinhas poedeiras com rações de diferentes relações de granulometrias de calcário

Abstract

The recommendation of coarse limestone in feeding commercial hens aims to improve the bioavailability of calcium. This nutritional management practice aims to improve the quality of the eggshell, considering that the larger particles of limestone influence the residence time of the food along the gastrointestinal tract, providing an improvement in the in vivo solubility rate of calcium. This thesis is subdivided into three chapters. The first chapter approaches general considerations about the theme. In the second chapter, the objective was to evaluate the use of different levels of coarse limestone in the laying hens diet. The treatments were: T1: 100% fine limestone (FL- 0,103 mm); T2: 50% FL and 50% coarse limestone (CL- 2,867 mm); T3: 40% FL and 60% CL; T4: 30% FL and 70% CL; T5: 20% FL and 80% CL. It was evaluated performance, internal quality, eggshell quality and the digestibility of minerals. The different granulometrics of limestone evaluated had no effect on the studied variables of performance and internal egg quality. It was observed a higher percentage of mineral matter in the eggshell in the treatments 60%, 70% and 50% of coarse limestone, showing no improvement in the other variables of eggshell quality. From this study it was not possible to define an optimal relation of the inclusion of limestone in the diets of commercial laying hens in production. In chapter III, the objective of this study was to compare different limestone granulometry in laying hens ration evaluating eggshell quality, as well as internal and productive quality. The treatments were T1: 100% fine limestone (FL-0.103 mm); T2: 50% FL and 50% medium limestone 1 (ML-1 0.555 mm); T3: 50% FL and 50% medium limestone 2 (ML-2 1,836 mm); T4: 50% FL and 50% coarse limestone (CL- 2.877 mm). Under these experimental conditions, the different granulometry and particle size of the limestone did not determine differences in eggshell quality variables. Differences were observed in the amount of minerals retained in the gastrointestinal tract of laying, with the association of fine limestone and average limestone 1, which results in the higher retention rates of mineral matter, calcium and phosphorus. The different inclusions of coarse limestone may have altered the absorption capacity of the minerals in the laying's organism, but from the results found in this study it is not possible to assert a direct relation with the particle size. In general, from this study it was not possible to define an ideal relation of limestone granulometry in laying hens diets.