Keel Bone Damage in Laying Hens

Abstract

The use of alternative housing systems is increasing in response to the press of animal rights organisations and animal welfare-sensitive consumers. Pursuant to animal welfare legislation, it has become compulsory in the European Union member states to house laying hens in enriched cages or aviaries. However, one of the main problems associated with these housing systems is the frequent occurrence of skeletal damage, as a result of the reflexive movements of freely roaming animals. Owing to its protrusive anatomical structure, one of the most easily damaged skeletal parts is the sternum. Damage to the sternum is also referred to as keel bone damage. The term "keel bone damage" is used to describe bone deformities or fractures, which have long been named as bone anomalies in laying hens. Keel bone damage is a chronic disorder, which adversely affects the profitability of egg farms. Being a multifactorial disorder, it is difficult to identify the primary cause of keel bone damage, as many underlying reasons could be involved in its aetiology. Skilled and experienced practitioners can readily diagnose keel bone damage by palpating the sternal region. This study reviews the significance of keel bone damage for the egg sector and the welfare of laying hens.