Nest acceptance, clutch, and oviposition traits are promising selection criteria to improve egg production in cage-free system.

Lorry Becot,Pascale Le Roy,Thierry Burlot,Jenna Coton,Nicolas Bedere,Ewa Tomaszewska

doi:10.1371/journal.pone.0251037

Abstract

In cage-free systems, laying hens must lay their eggs in the nests. Selecting layers based on nesting behavior would be a good strategy for improving egg production in these breeding systems. However, little is known about the genetic determinism of nest-related traits. Laying rate in the nests (LRN), clutch number (CN), oviposition traits (OT), and nest acceptance for laying (NAL) of 1,430 Rhode Island Red (RIR) hens and 1,008 White Leghorn (WL) hens were recorded in floor pens provided with individual electronic nests. Heritability and genetic and phenotypic correlations of all traits were estimated over two recording periods–the peak (24–43 weeks of age) and the middle (44–64 weeks of age) of production–by applying the restricted maximum likelihood method to an animal model. The mean oviposition time (MOT) ranged from 2 h 5 min to 3 h and from 3 h 35 min to 3 h 44 min after turning on the lights for RIR and WL hens, respectively. The mean oviposition interval ranged from 24 h 3 min to 24 h 16 min. All heritability and correlation estimates were similar for RIR and WL. Low to moderate heritability coefficients were estimated for LRN (0.04–0.25) and moderate to high heritability coefficients for CN and OT (0.27–0.68). CN and OT were negatively genetically correlated with LRN (-0.92 to -0.39) except during peak production for RIR (-0.30 to +0.43). NAL was weakly to moderately heritable (0.13–0.26). Genetic correlations between NAL and other traits were low to moderate (-0.41 to +0.44). In conclusion, CN and OT are promising selection criteria to improve egg production in cage-free systems. NAL can be also used to reduce the number of eggs laid off-nest in these breeding systems. However, variability in MOT must be maintained to limit competition for the nests.

Highlights

To provide animals with living conditions that consider their sensitivities better [1], cage-free farming systems were developed for laying hens
Phenotypic distributions of Laying rate in the nests (LRN), clutch number (CN), mean oviposition time (MOT), logarithm of the variance of oviposition time (LVOT), mean oviposition interval (MOI), logarithm of the variance of oviposition interval (LVOI), nest acceptance for laying (NAL) were calculated for both lines and breeding periods (Table 2)
Four Rhode Island Red (RIR) hens laid their eggs in the nests 1–7 min before the lights were turned on during peak production, which resulted in some negative MOT values (Table 2)

Summary

Introduction

To provide animals with living conditions that consider their sensitivities better [1], cage-free farming systems were developed for laying hens (barn, free-range, and organic). In the European Union, 50% of laying hens were raised in cage-free systems in 2018 vs 30% in 2009 and 8% in 1996 [2]. These housing systems provide special breeding conditions, such as social interactions in a large group, and require the hens to lay in the nests so the eggs can be collected. Novogen provided support in the form of salaries for authors TB and JC, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section

Methods

Results

Conclusion