Effect of the levels of calcium and particle size of limestone on laying hens

José Anchieta De Araujo,Janaína Maria Batista De Sousa,Patrícia Emília Naves Givisiez,José Humberto Vilar Da Silva,Fernando Guilherme Perazzo Costa,Nilva Kazue Sakomura

doi:10.1590/s1516-35982011000500009

José Anchieta De Araujo, Janaína Maria Batista De Sousa + Show 4 more

Open Access

https://doi.org/10.1590/s1516-35982011000500009

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Abstract

This experiment was conducted to evaluate the effect of levels of calcium (Ca) and particle size of limestone (LS) for laying hens. It was used 216 Dekalb White laying hens at 25 to 49 weeks of age in a completely randomized design in a 3 × 2 factorial arrangement, composed of three levels of calcium (3.92, 4.02 and 4.12%) and two particle sizes of limestone (thin - 0.60 mm; and thick - 1.00 mm), resulting in 6 treatments with six replicates of six birds. There was no significant effect of levels of calcium and limestone particle size neither of the interaction calcium × particle size for feed intake, egg weight, specific gravity, shell thickness, shell percentage, Haugh unit, calcium and phosphorus digestibility and percentage of digestive tract. Production, mass, conversion by mass and conversion by egg dozen had their best results with 4.12% of calcium in the diet. Percentage of gizzard and feed intake observed at 3:00 p.m. improved as limestone granulometry improved from 0.60 to 1.00 mm. There was an interaction effect among calcium level and limestone granulometry for breaking strength of tibia, bone density, length of the small intestine and feed intake at 6:00 a.m.; 9:00 a.m., 12:00 p.m., 6:00 p.m. and 9:00 p.m., respectively. It is recommended the addition of 4.12% of calcium and limestone in the thick granulometry (1.00 mm) for a better performance of commercial laying hens. More studies are needed to elucidate the mechanisms involved in the alteration of nutritional behavior of laying hens in response to changes in the levels of calcium and in the granulometry of limestone in the rations.

Highlights

The great genetic development of laying hens in recent years has changed important physiological aspects in these birds, requiring further research to equate them (Geraldo, 2006)
Bone density was not affected (P>0.05) by calcium levels or limestone granulometry, which did not occur (P
Paz et al (2008), evaluating bone density in laying hens, found differences among levels tested for the tibia density and stated that bones of poultry fed 3.8% calcium had higher densities than those fed on 1.8% calcium

Summary

Introduction

The great genetic development of laying hens in recent years has changed important physiological aspects in these birds, requiring further research to equate them (Geraldo, 2006) In this context, the development of body and digestive tract of these birds have been object of concern, with problems related to uniformity of flocks and digestibility of nutrients, affecting their productivity. The calcium requirements by laying hens are considered an ongoing challenge for nutritionists and poultry producers (Roland & Gordon, 1996) The reasons for this fall on the continuous genetic improvement of commercial strains, in addition to the differences in particle size of limestone, which directly influence the availability of this mineral and poultry ability to adjust feed intake to meet their daily needs. This study was conducted to evaluate the effects of calcium levels and particle size of limestone on the growth performance and feeding behavior of light laying hens in the stage of egg production

Material and Methods

Results and Discussion

Conclusions