Floor eggs, which are defined as eggs that hens lay off-nest, are a major issue in cage-free layer poultry systems. They create additional work for farmers because they must be collected by hand. They are also usually soiled or broken, which results in economic losses. Nonetheless, knowledge about the genetics of nesting behavior is limited. The aim of this study was to estimate genetic parameters for traits related to nest preference for laying and to time spent in the nests used for laying (laying duration). Two pure lines of laying hens were studied: 927 Rhode Island Red and 980 White Leghorn. Electronic nests were used to record the nesting behavior of these hens in floor pens from 24 to 64 weeks of age. Nest preference was studied based on the mean distance between nests used for laying and the percentage of nests used for laying. Laying duration was studied based on mean laying duration, mean duration in the nest before laying, and mean duration in the nest after laying. Genetic parameters were estimated for each line using a restricted maximum-likelihood method applied to a pedigree-based multi-trait animal model. Estimates of genetic parameters were similar for the two lines. Estimates of heritability ranged from 0.18 to 0.37 for nest preference traits and from 0.54 to 0.70 for laying duration traits. Estimates of genetic correlations of these traits with clutch number or mean oviposition time were favorable. Positive genetic correlations were estimated between nest preference and laying rate in the nests or nest acceptance for laying (+ 0.06 to + 0.37). These results show that genetics influences traits related to nest preference and laying duration. Selecting hens that have no preference for particular nests and spend little time laying in the nests could help optimize nest use, reduce their occupation rate, and thus decrease the incidence of floor eggs in cage-free systems. Genetic correlations of these traits with other traits of interest related to hen welfare and egg quality have yet to be estimated.

中文翻译：

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在蛋鸡中选择地板蛋的巢偏好和产蛋持续时间特征

地板蛋定义为母鸡在巢外产下的蛋，是散养蛋鸡系统中的一个主要问题。他们为农民创造了额外的工作，因为他们必须手工收集。它们通常也被弄脏或损坏，从而导致经济损失。尽管如此，有关筑巢行为遗传学的知识还是有限的。本研究的目的是估计与产蛋巢偏好和产蛋时间（产蛋持续时间）相关的性状遗传参数。研究了两个纯系的蛋鸡：927 Rhode Island Red 和 980 White Leghorn。电子巢用于记录这些母鸡在 24 至 64 周龄期间在地板围栏中的筑巢行为。基于用于铺设的巢之间的平均距离和用于铺设的巢的百分比来研究巢偏好。产蛋持续时间的研究基于平均产蛋持续时间、产蛋前在巢中的平均持续时间以及产蛋后在巢中的平均持续时间。使用应用于基于谱系的多性状动物模型的受限最大似然法估计每个品系的遗传参数。两条品系的遗传参数估计值相似。巢偏好性状的遗传力估计范围为 0.18 至 0.37，产蛋持续时间性状的遗传力估计范围为 0.54 至 0.70。这些性状与离合器数或平均产卵时间的遗传相关性估计是有利的。巢偏好与巢中产蛋率或巢对产蛋的接受度之间估计存在正遗传相关性（+ 0.06 至 + 0.37）。这些结果表明，遗传学会影响与巢偏好和产蛋持续时间相关的性状。选择对特定巢穴没有偏好并且很少在巢穴中下蛋的母鸡可以帮助优化巢穴使用，降低它们的占用率，从而减少无笼系统中地板鸡蛋的发生率。这些性状与其他与母鸡福利和鸡蛋质量相关的感兴趣性状的遗传相关性尚未得到估计。