abbasali gheisari*, peyman ghayor department of animal science, isfahan research center for agriculture and natural resources, isfahan,iran   * corresponding author e-mail: [email protected]     received: 15 august 2013 accepted: 21 november 2013       abstract   this experiment was conducted to investigate the effect of feeding 5 experimental diets containing 0, 5, 10, 15 and 20% rapesee...

Tsaiya ducks and Leghorn hens are the two major laying birds raised in Taiwan. They are all excellent egg layers. Tsaiya ducks are small in body size (1.3 kg) with bigger egg weight (65 g) and stronger eggshell breaking strength than eggs from hens. The eggshell consists mainly of calcium carbonate, hence calcium plays an important role in the eggshell formation. Magnesium is also present in eg...

Blue-green and brown-spotted eggshells in birds have been proposed as sexual signals of female physiological condition and egg quality, reflecting maternal investment in the egg. Testing this hypothesis requires linking eggshell coloration to egg content, which is lacking for brown protoporphyrin-based pigmentation. As protoporphyrins can induce oxidative stress, and a large amount in eggshells...

The aim of this study was to investigate the genetic and phenotypic correlations of egg quality traits in Khazak chicken. Albumen height (AH), albumen weight (AW), eggshell color (ESC), yolk color (YC), eggshell index, long length of egg (ELL), short length of egg (ESL), eggshell weight (ESW), egg weight (EW), Haugh units, and yolk weight (YW) were measured in 201 eggs collected 6 d sequentiall...

A study was conducted to determine the influence of different particle size limestone in layer diets on egg production and eggshell quality during the later stages of egg production (>54 weeks of age). Calcitic limestone (360 g Ca/kg), consisting of small (<1.0 mm), medium (1.0 2.0 mm) and large (2.0 3.8 mm) particles were obtained from a specific South African source that is extensively used i...

A 10 wk trial was conducted to investigate the effect of using ground, sterilized eggshell as a calcium source in the diet of laying hens. Egg production, egg and eggshell quality, hatching characteristics and eggshell ultrastructure were evaluated. A total of 144 hens aged 25 wk were housed in floor pens, located in a conventional open-sided layer shed. The birds were randomly divided into thr...

The chicken eggshell proteins have been largely investigated during the last decade. Proteins and associated genes have been identified and characterized. Various experimental evidences suggest a role for eggshell matrix proteins during mineralization. Indeed, novel specific eggshell matrix proteins are only expressed in tissues where eggshell mineralization takes place and some are highly stim...

Avian eggshell quality is an important trait for commercial egg production, as the eggshell is the primary packaging material and antimicrobial barrier for the internal food resource. Strong eggshells are essential to ensure that eggs can reach their final destination without damage. Ovocalyxin-32 (OCX32) is a matrix protein found within the outer layers of the eggshell and in the cuticle. Nume...

This experiment studied the effect of four calcium (3.0, 3.5, 4.0, and 4.5%) and four available phosphorus levels (0.25, 0.30, 0.35, and 0.40%) in the diet of semi-heavy commercial layers after molting. Hisex Brown layers between 90 and 108 weeks of age were distributed in a completely randomized experimental design with a 4x4 factorial arrangement with 16 treatments of five replicates of eight...