Calcium and its Relationship to Excess Feed Consumption, Body Weight, Egg Size, Fat Deposition, Shell Quality, and Fatty Liver Hemorrhagic Syndrome ,

Abstract

In Experiment 1, Hyline W36 caged hens were fed diets containing 1.7, 2.9, 3.5, and 4.1% calcium for 10 and 16 weeks. In Experiments 2 and 4, Dekalb XL and Hyline W36 pullets were fed diets containing 1.0, 1.7, and 3.75% calcium for 3 weeks (Exp. 2) or until 25 pullets from each group laid 7 eggs (Exp. 4). In Experiment 3 and 5, Dekalb and Hyline hens were fed diets containing 1.5 (Dekalb only), 1.75, 2.25, 2.75, and 3.75% calcium for 8 weeks. Criteria were liver, fat pad, egg and shell weights, egg specific gravity, production, feed consumption, liver fat and fatty acid composition, liver hemorrhage score, and body weight. As percent dietary calcium decreased, Hyline birds (Exp. 1, 4, and 5) had increased liver fat, body weight (except Exp. 4), and feed consumption, but egg specific gravity and shell weight decreased. Reduced dietary calcium levels had no effect on egg production in Experiment 1 but significantly reduced production in Experiment 5. Liver hemorrhage score significantly increased as percent dietary calcium decreased (Exp. 1). As dietary calcium decreased, Dekalb pullets (Exp. 2) had increased feed consumption, fat pad weight, and liver hemorrhage score. There was no increase in liver fat. However, in Dekalb hens (Exp. 3), feed consumption and egg production were significantly decreased as dietary calcium decreased. It is concluded that overconsumption caused by feeding pullets or hens inadequate calcium had no beneficial effect on egg size or egg production and, depending on strain, increased liver fat, liver hemorrhage score, body weight, and fat pad weight.

Eggshell Quality as Influenced by Sodium Bicarbonate, Calcium Source, and Photoperiod

“…| Under some circumstances, dietary Ca may |be sufficiently marginal so that shell quality is 8 reduced but production is maintained. The hen 8 may then overconsume energy in an attempt to | meet Ca requirements (Scott et al, 1971; Lentf nards and and Roland, 1985). In § this study, Ca level did not appear to be a pri-| mary problem.…”

“…(1971) found that replacing two-thirds of g limestone in a laying hen diet with oyster shell I produced an increase in feed intake. Ca intake § can be influenced by many factors, depending E on dietary Ca level and production rate of the .2 hen (Roland, 1985). For example, if dietary Ca £ exceeds the hen's nutrient requirement without s reducing palatability, a reduction in energy con-| sumption will result.…”

“…As hens eat to meet energy | requirements (Scott et al, 1982), overconsump-"2 tion may occur. However, a Ca level sufficiently ^ high to influence palatability may result in a « decline in consumption (Roland, 1985). | Under some circumstances, dietary Ca may |be sufficiently marginal so that shell quality is 8 reduced but production is maintained.…”

Changes in egg shell ąuality during the first year of laying in hens

“…Recommendation, 1984) because of the lower Ca availability to older hens. However, if dietary calcium becomes too excessive, feed palatability, and thus feed consumption, is reduced (Roland et al 1985). Moreover, in the experiment of Holder and Huntley (1978) there were no differences in egg shell thickness and Ca percentage in shells between eggs laid by hens given 2.5 or 3.5% Ca in diets.…”

The effect of adding exogenous phytase to nutrient-reduced corn- and wheat-based diets on performance and egg quality of two strains of laying hens

“…Hens given too much Ca in their diets may reduce their feed intake, lowering egg production and egg size (Roland et al 1985). Too little Ca in the diet reduces egg production and shell quality (Abdallah et al 1993).…”