Resistance to infectious diseases is a heritable trait in rabbits1

Abstract

Selection for disease resistance is a powerful way to improve the health status of herds and to reduce the use of antibiotics. The objectives of this study were to estimate 1) the genetic parameters for simple visually assessed disease syndromes and for a composite trait of resistance to infectious disease including all syndromes and 2) their genetic correlations with production traits in a rabbit population. Disease symptoms were recorded in the selection herds of 2 commercial paternal rabbit lines during weighing at the end of the test (63 and 70 d of age, respectively). Causes of mortality occurring before these dates were also recorded. Seven disease traits were analyzed: 3 elementary traits visually assessed by technicians on farm (diarrhea, various digestive syndromes, and respiratory syndromes), 2 composite traits (all digestive syndromes and all infectious syndromes), and 2 mortality traits (digestive mortality and infectious mortality). Each animal was assigned only 1 disease trait, corresponding to the main syndrome ( = 153,400). Four production traits were also recorded: live weight the day before the end of test on most animals ( = 137,860) and cold carcass weight, carcass yield, and perirenal fat percentage of the carcass on a subset of slaughtered animals ( = 13,765). Records on both lines were analyzed simultaneously using bivariate linear animal models after validation of consistency with threshold models applied to logit-transformed traits. The heritabilities were low for disease traits, from 0.01 ± 0.002 for various digestive syndromes to 0.04 ± 0.004 for infectious mortality, and moderate to high for production traits. The genetic correlations between digestive syndromes were high and positive, whereas digestive and respiratory syndromes were slightly negatively correlated. The genetic correlations between the composite infectious disease trait and digestive or respiratory syndromes were moderate. Genetic correlations between disease and production traits were favorable. Our results indicate that it is possible to select rabbits using visually assessed disease syndromes without the need for a trade-off between health and production traits. Using a composite criterion that includes all infectious syndromes is easy to implement and heritable and is, therefore, a promising way to improve the general disease resistance in livestock species.

Health and welfare of rabbits farmed in different production systems

“…Hazards for rhinitis can be divided into 2 main groups: predisposing hazards were linked with the line or breed of rabbits, and age, whereas enabling hazards were mainly related with the incorrect combination of the ambient temperature, humidity and air speed (Calvet et al, 2011;da Borso et al, 2016). A genetic component to resistance to Pasteurella has been identified (Gunia et al, 2015(Gunia et al, , 2018Shrestha et al, 2019); however, currently commercial lines are not characterised for this trait. Table 33 summarises the information on the main hazards for this welfare consequence and their degree of scientific support.…”

Genetic Parameters for Resistance to Non-specific Diseases and Production Traits Measured in Challenging and Selection Environments; Application to a Rabbit Case

“…To implement such selection, there is still a need for phenotypes that can be easily measured, at a reasonable cost (Merks et al, 2012 ). In rabbits, previous studies have shown that simple health records, measured once on growing animals of the selection nucleus, can be used to improve disease resistance (Eady et al, 2007 ; Garreau et al, 2012 ; Gunia et al, 2015 ). However, it is not known if such selection will be beneficial for maintaining the health and productivity of animals reared in commercial conditions.…”

Quelles performances pour les animaux de demain ? Objectifs et méthodes de sélection

“…Une alternative consiste à sélectionner pour la résistance aux troubles infectieux non spécifiques (Gunia et al, 2015). Mais une approche encore plus globale consiste à améliorer l'immunocompétence générale des animaux, en sélectionnant sur un ensemble de caractères héritables représentatifs des différentes facettes de la réponse immunitaire, comme la production d'anticorps, la réponse cellulaire et l'activité phagocytaire .…”