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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal AgroParisTech Université Paris-Saclay


GABI : Génétique Animale et Biologie IntégrativeUnité Mixte de Recherche INRA - AgroParisTech

Are there limits to selection : a look at poultry

Poultry selection has led to extreme phenotypes. The evolution of the domestic chicken from the jungle chicken has led to raising questions on the limits of selection.

MOTS-CLES : selection, fitness, ethics, environment, chicken

The analysis of selection theories shows that the number of generations in selection is still inferior to that for which a limit could be attained, according to population size. Other limits exist however: biological (metabolism), reproductive, survival, and ethics level with the refusal by some consumers to buy certain products for reasons related to animal welfare, the environment associated with temperature and the food/feed debate.


Awareness of these challenges by the international scientific community is strong and many different technical or genetic solutions exist to overcome these limitations.

Poultry production is currently growing, with animals with higher and higher performances. This evolution is accompanied by the regular occurrence of severe metabolic diseases (ascites, obesity) in broiler chickens or with abnormally violent behavior in laying hens (cannibalism). Society is shocked and putting pressure on the sectors. The responsibility  of research is to have an independent and critical attitude on this sensitive debate which is at the heart of sustainability. Short-term economic gain must be balanced with preservation of genetic diversity on the middle/long-term but also by respecting the integrity of the animal as an individual and not only as a food product.

Four types of limits were identified through a bibliographic analysis: genetic, biological, ethical and environmental. Technical or genetic solutions exist for the first two limits, even though they seem more and more difficult to find as with some problems of meat quality with broiler chickens which have not been resolved in the last 10 years. Ethical limits are more delicate; they call for greater social responsiblity of the entire sector and not just of breeders. The emblematic example of 'the Chicken of the Future ' in The Netherlands shows how supermarkets have given into the pressure from a welfarist association to commit themselves to a capped growth rate for the chickens they sell. The environmental limits correspond to a greater sensitivity of high-performance animals to high temperatures; genetic solutions exist but have not been adopted due to the cost of developing lines carrying major genes for adaptation. Finally, the food/feed debate has been perceived by the industry and research as moving towards the use of suboptimal foods with dietary supplements.

This research highlight is not so much just this review as it is the echo that was heard during the European Poultry conference in September at Dubrovnik. I was invited to present the same subject at four different international events in 2019: The annual Poultry Science Association meeting in Montreal in July 2019 (1000 participants), an invited seminar at Roslin Institute on October 2, a guest conference at the annual meeting of the Spanish branch of the WPSA association on October 17 (300 participants) and another annual meeting of the Israelian branch of the WPSA on November 17 (200 participants). Clearly the scientific community is concerned.

Two important messages emerge from this study in genetics. 1) Privileging selection for an optimum rather than a maximum, as is already the case with egg weight. The existing methods allow this and this approach would allow a margin of selection on other traits such as behavior or disease resistance. 2) Maintaining a diversity of the lines and reintroducing genetic diversity in the populations like laying hens, whose genetic diversity is decreasing. In addition to genetics, the poultry sector should be reorganized with greater solidarity amongst the links in order to be better attuned to the diversity of consumer expectations. The difficulty for breeders is to manage a diversity of crops by targeting a global clientele, so a diversified genetic offer is needed.


Scientific Contact(s):

Associated Division(s): Animal Genetics

Associated Centre(s): Jouy-en-josas



INRAE guidance document priority

#3Perf-2: Using biology et technology techniques for multiperformance

See also


  • a review article currently under press in the World Poultry Science Journal, 4 invited seminars in 2019


Tixier-Boichard, M., 2019. From the jungle fowl to highly-performing chickens : are we reaching limits ? in revision with minor modifications by the World’s Poultry Science Journal