Dietary Limestone Versus Extra-Dietary Oyster Shell as Calcium Supplements to Different Layer Diets

Abstract

Hens were given supplementary calcium in the form of 5.7% dietary limestone or oyster shell ad libitum separately from the diet. The two calcium sources were given as supplements to four different diets; wheat-based diets containing soybean meal (SBM) or rapeseed meal (RSM) as the source of supplementary protein and either tallow or corn oil as a fat supplement. Over the 20 weeks of the experiment there were no differences in the rates of production of the birds among the eight experimental treatments. Yolk weight was reduced when the hens fed the diets with tallow as the supplementary fat received their supplementary calcium as oyster shell. When the 5.7% of supplementary limestone was exluded from the weight of feed consumed by the hens given all their calcium mixed into the diet, there was no difference in the amount of feed consumed by the birds on the two systems of calcium feeding. The efficiency of feed conversion to egg meat production was likewise similar for both systems of calcium feeding under the different dietary treatments imposed. Regardless of the composition of the diet, shell weight per unit surface area was greater for the eggs laid by the birds fed oyster shell. (

Use of Particulate Limestone or Oyster Shell in the Dietary Regimen of White Leghorn Hens

“…Brister et al (1981) observed a small drop in egg size when one-third of the pulverized LS in a 3.5% calcium diet was replaced with hen-size OS in a 3.5% calcium diet. The results of March and Amin (1981) indicated interactions between dietary calcium source and fat source influence egg weight. For example, when OS was the source of calcium in diets containing soybean meal and tallow, the eggs produced by molted hens were heavier than when LS was the dietary calcium source (62.0 vs. 61.4 g).…”

“…Roland et al (1974), Muir et al (1975), and Roland (1981) concluded that particulate size had no effect on shell quality if the diet contained sufficient calcium to allow the hens to consume a minimum of 3.75 g calcium per day for young birds and 4.75 g/day for older hens. Results published by March and Amin (1981) indicate that the source of protein and fat in the diet may influence the effect of LS or oyster shell (OS) on shell quality. Scott et al (1971) demonstrated that shell quality could be improved by incorporating a combination of OS and pulverized LS into the diet of laying hens.…”

Efeito do fracionamento de cálcio e granulometria do calcário sobre o desempenho e qualidade de ovos de poedeiras comerciais brancas.

“…Nas tabelas 10, 11, 12, 13 e 14 são apresentados os valores obtidos para peso dos ovos (g), percentagem de albúmen (%), percentagem de A inexistência do efeito do fator fracionamento sobre o peso dos ovos é compartilhada pelos trabalhos de MAGGIONI et al (1996), KESHAVARZ (1998 a e 1998 b ) e WALDROUP e HELLWIG (2000). Quando considerado o fator granulometria das fontes de cálcio, esta mesma situação pôde ser constatada nos trabalhos de BRISTER et al (1981), MARCH e AMIN (1981), CHENG e , GUINOTTE e NYS (1991) e NAKAJIMA et al (1995. Além disso, não são encontradas citações que relacionem a solubilidade das fontes de cálcio e peso dos ovos.…”