Effect of the calcium level and limestone particle size on the performance of semi-heavy layers in the second cycle of egg production

Cc Pizzolante,C Laganá,Ap Deodato,Ea Garcia,L Batista,Mr Scherer,Espb Saldanha,Abg Faitarone

doi:10.1590/s1516-635x2006000300006

Cc Pizzolante, C Laganá + Show 6 more

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https://doi.org/10.1590/s1516-635x2006000300006

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Abstract

An experiment was carried out at the Research and Development Unit of Brotas aiming at evaluating dietary calcium level and limestone particle size on the production performance of commercial (Hy-Line Brown) layers in the second lay cycle. Experiment duration was 112 days. A total number of 288 hens, with 83 weeks of age in the beginning of the experiment, were used in a completely randomized experimental design in a factorial arrangement of 2x3, with two calcium levels (3.5 and 4.0%) and three limestone particle size compositions: 100% fine limestone (FL), 30% coarse limestone (CL) + 70% fine limestone (FL), and 50% (CL) + 50% (FL), with six replicates of eight birds each. Egg weight (g), egg production (%), egg mass (%), feed intake (g), feed conversion ratio (kg/dz and kg/kg), mortality (%), and egg loss (%) were evaluated. The analysis of variance did not detect significant differences (p>0.05) among treatments on any of the evaluated performance parameters. It was concluded that the tested calcium levels and limestone particle composition did not influence the performance of semi-heavy layers in second production cycle.

Highlights

Second cycle layers produce larger eggs, with consequent increase in eggshell quality problems, causing expressive losses
There is a great interest in calcium metabolism because as the hens age, eggshell quality decreases
The intake of inadequate calcium amounts may promote skeleton abnormalities, increased mortality, reduction in the size and in the number of eggs produced, and poor eggshell quality leading to high rates of cracked eggs (Maynard et al, 1984)

Summary

Introduction

Second cycle layers produce larger eggs, with consequent increase in eggshell quality problems, causing expressive losses. There is a great interest in calcium metabolism because as the hens age, eggshell quality decreases. There is a decrease in 1-α-hydroxylase – the enzyme responsible for the activation of vitamin D metabolite in the kidneys –, and a reduction in the efficiency of calcium absorption. This causes poorer eggshell quality, and increase in egg loss. Older layers have diminished capacity of replacing the calcium lost during hypocalcemia periods as compared to young layers (Elaroussi et al, 1994)

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