Dual-Purpose Poultry in Organic Egg Production and Effects on Egg Quality Parameters.

Marianne Hammershøj,Sanna Steenfeldt,Gitte Kristiansen

doi:10.3390/foods10040897

Abstract

Egg laying genotypes have been selected for generations due to their high yield and egg quality, resulting in efficient feed utilization and low body weight; hence, they are not suitable for meat production. This imposes an issue for the male layer chicks, which are killed at one day old. Because of ethical and food waste concerns, the search for suitable dual-purpose genotypes in order to avoid euthanasia of male day-old chicks has intensified. The aim of the present study is to evaluate potential dual-purpose genotypes for their egg quality compared to a representative egg laying genotype. Two dual-purpose genotypes with divergent characteristics were evaluated: genotype A represented an experimental crossbreed based on a broiler type male and an egg layer female, and genotype C was a crossbreed of a layer type. These were compared to a rustic genotype B and a control genotype D, which was an egg layer. Eggs were collected six times during the period of 21–54 weeks of hen age, i.e., a total of 990 shell eggs were analyzed. Examined parameters were weights of egg, shell, yolk, and albumen, by calculating their relative proportions. Shell quality was assessed by shell strength, shell stiffness, and shell thickness. Yolk quality was determined as yolk color and inclusions of blood and meat spots, and albumen quality was evaluated in terms of pH and dry matter (DM) content. The egg layer genotype produced the smallest eggs with least blood and meat spot inclusions compared to that produced by the three dual-purpose genotypes. Shell quality was superior for the layer genotype. However, the experimental genotype A laid eggs of comparable shell quality, albumen DM, and yolk weight, but also with the darkest and most red-yellow colored yolk. The two other dual-purpose genotypes produced eggs of low-medium quality. In conclusion, the genotype A could serve as dual-purpose genotype from an egg quality perspective.

Highlights

Ethical and animal welfare concerns of consumers regarding husbandry procedures in poultry meat and egg production have been increased worldwide and especially in Europe [1,2]
The aim of the present study is to examine the effect of using genotype breeding strategies for dual-purpose chickens on egg production and on various retail egg quality parameters
It is not straightforward to draw a simple recommendation on the implementation of dual-purpose genotypes and a range of criteria must be met on the meat quality side when changing from egg layer genotypes into dual-purpose genotypes for egg production

Summary

Introduction

Ethical and animal welfare concerns of consumers regarding husbandry procedures in poultry meat and egg production have been increased worldwide and especially in Europe [1,2]. The Netherlands and Germany are examples of countries where this trend is happening [4] Another animal welfare issue of poultry has arisen as a result of breeding strategies towards much differentiated poultry genotypes for many generations: meat-type broiler chickens with high growth rates and egg-type lean layer hens with low body weight and high egg-laying capacity. Alternative strategies to the euthanasia of male layer chicks have been suggested, namely in ovo sexing, fattening of lay-hen males, and dual-purpose poultry [9] Based on this perspective, it can be expected that there will be a growing interest in the use of dual-purpose genotypes in the future egg production, and that there will be an increased need for knowledge about the potential of these genotypes for both meat and egg production

Objectives

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Results

Conclusion