Examination of Nesting Behavior of Laying Hens of Different Genotypes Housed in Indoor Alternative Pens Using a Video System

The aim of the research was to examine how the nest selection preference of laying hens with different genotypes differed, the proportion of eggs laid in the litter, eggs laid in the upper and bottom nests, and the number and duration of nest visits. The experiment was conducted with laying hen genotypes provided by Bábolna TETRA Ltd. (Babolna, Hungary) (Commercial hybrid (C); pure-line maternal (Maternal); pure-line paternal offspring group (Paternal)). N = 318; n = 106 hen/genotype; and 53 hens/pen. We placed 53 19-week-old, non-beak-trimmed hens in each of the six 5.52 m2 alternative pens. We provided 14 nests for the hens at two levels per pen (3.8 hens/nest). We recorded the number of eggs laid in the nests on the bottom and upper levels, as well as within the litter. Infrared cameras were installed above the pens, and we conducted recordings on a test day at the beginning of the third production month. In our results, we found a significant difference in the proportion of litter eggs overall during the 12 months of production (C. hybrid: 30.7%; Paternal: 41.1%; Maternal: 10.2%). A significant difference was found between all genotypes in the proportions of eggs laid at the bottom (B) and upper (U) level during the 12 months of production (C. hybrid: B: 72.2%, U: 27.8%; Paternal: B: 88.0%, U: 12.0%; Maternal: B: 71.4%, U: 28.6%). The evaluation of the video recordings revealed that the C. hybrid and Paternal genotypes visited the bottom nests in 97.2% and 96.0% of the cases, respectively, and the Maternal genotype individuals in a significantly lower proportion, 72.5% of the cases; the Paternal genotype spent significantly more time (13.4 min) on average in the bottom nests compared with the C. hybrid (7.9 min) and the Maternal genotypes (8.6 min). Our conclusion is that it is not enough to ensure the desired ratio of egg nests in egg production, as laying hens may not use nests in certain positions at all. This generates a relative shortage of egg nests and can increase the ratio of eggs laid in the litter, which in turn involves human health risks