Genetic parameter estimates for the use of an aviary with winter garden by laying hens

The behavioral activity of laying hens in an aviary is indicative of their welfare and health. Furthermore, hens' usage of the different locations within an aviary has been shown to influence laying performance and egg quality. For example, hens that spent a longer duration of time in the nest during laying were observed to have lower laying performance. Therefore, understanding genetics of laying hens' usage of the aviary could be important for predicting egg quality, production traits and health and welfare. The objectives of this study were to estimate genetic parameters for duration of time spent at different locations within the aviary and an adjacent winter garden using a multivariate repeatability model and to compare correlations between time spent in these locations. For this study, a total of 1,106 Dekalb white laying hens (Hendrix Genetics) were genotyped using a proprietary 60K SNP array. These hens had access to 5 different zones within the aviary, which included the top level tier, nest box tier, lower level tier, floor littered area and a winter garden. Hens were in the aviary for a total of 290 d and daily records of duration were collected for each hen visit to any location in the aviary, culminating in a total of 937,740 records. Heritability estimates ranged from 0.05 (0.01) to 0.28 (0.03) for the duration of time spent in the different zones. The lowest heritability was estimated for time spent at the lower level tier, while a higher heritability was estimated for time spent in the floor littered area. A moderately high negative genetic correlation of -0.59 (0.08) was observed between time spent in the top level tier and time spent in the floor littered area, while a favorable correlation of 0.37 (0.14) was found between time spent in the lower level tier and time spent in the winter garden. The findings of this study show that the duration of time spent at different zones within an aviary has genetic basis and could be used for selecting animals for better performance and higher welfare.