The Ethics of Laying Hen Genetics

Abstract

Despite societal concerns about the welfare of commercial laying hens, little attention has been paid to the welfare implications of the choices made by the genetics companies involved with their breeding. These choices regarding trait selection and other aspects of breeding significantly affect living conditions for the more than 7 billion laying hens in the world. However, these companies must consider a number of different commercial and societal interests, beyond animal welfare concerns. In this article we map some of the relevant dilemmas faced by genetics companies in order to outline the scope of opportunities to improve welfare under current market conditions. This includes identifying cases where different animal welfare concerns conflict. We discuss the moral responsibility of laying hen genetics companies and the welfare implications that derive from the choices they make and the policies they follow. In addition to evaluating a selection of predominant current practices and breeding goals, we outline different angles from where to assess the moral legitimacy of various industry practices and policies. We discuss specific issues such as injurious pecking, bone health, induced moulting, chick culling and the circumstances of breeding stock.

Impact of Eimeria tenella Oocyst Dose on Parasite Replication, Lesion Score and Cytokine Transcription in the Caeca in Three Breeds of Commercial Layer Chickens

“…Layer chickens are primarily produced by a small number of large companies, crossing three or more highly selected pedigree lines to produce the hybrid chickens used in many production systems. While these companies commonly produce different commercial layer “lines,” selection for performance traits is often very similar and one or more pedigree lines may be represented in the grandparental crosses used to produce multiple hybrid layer populations, possibly explaining the lack of variability observed ( 34 ). Evidence of resistance or susceptibility to Eimeria infection is apparent in some inbred chicken lines ( 35 , 36 ) and native breeds such as the Egyptian Fayoumi chicken also appear more resistant compared with White Leghorns ( 37 ).…”

Albumen Quality of Fresh and Stored Table Eggs: Hen Genotype as a Further Chance for Consumer Choice

“…As reported, the Hy Line hens complete the muscle growth earlier than the purebreds, at about 30 weeks of age [ 24 ]. Furthermore, a more variable laying rate, throughout the productive period, as generally shown by purebreds, allows the hens to have a healthy condition of their bones: such a skeletal mineral status is an important issue for the welfare of laying hens [ 25 ]. As far as the 41- to 42-week period is concerned, Figure 1 shows a light decrease of values of RM, HB and HW; such a decrease may be due to the low environmental temperature and higher body thermal regulation requirements, but also an age effect could be considered.…”

“…Recently, other authors [ 33 ] stated that relevant phenotypic differences exist among local chicken breeds, commercial layers and their crosses in terms of bone traits; furthermore, for the genetic groups a rather weak relationship between laying performance, especially in terms of total eggshell production, and bone stability, were found [ 34 ]. The aim to improve the impaired bird welfare due to skeletal disorders in highly productive hens [ 25 ] needs more knowledge on bone traits of purebred genotypes for their further use in crosses also with hybrid lines.…”

Effects of feeding ISA brown and Shaver white layer breeders with sources of n-3 fatty acids on hatching egg profiles, apparent embryonic uptake of egg components, and body composition of day-old chicks

“…However, the persistency in lay requires consideration of how to maintain birds' health and welfare in longer laying cycles. Therefore, genetic companies should not only focus on extending the laying cycle but also on improving bird resilience and coping with longer productive life (Fernyhough et al 2020). The potential of breeder nutrition on hatchling quality can play an important role in the bird's health and further production.…”