Floor Laying—a Heritable and Environmentally Influenced Trait of the Domestic Fowl

Floor laying is the tendency for pullets not to lay in conventional nests. If trap nesting is involved, this behavioral trait is responsible for an underestimate of the birds’ egg laying ability. A marked increase in floor layers early accompanied intense inbreeding of lines originating from two random bred control populations (Cornell Controls and Regional Reds) in contrast with other lines from the same stock but not inbred. This suggested a heritable basis for the trait. The results of breeding tests provided evidence for the expression of a genetic basis for differences between floor laying and non-floor laying pullets when maintained under certain environments. Certain management variables studied affected the expression of this trait. One of these concerned method of rearing—confinement, in contrast with free range, was intimately associated with a greater floor layer incidence. Two laying house locations also differed significantly in the proportion of floor layers recognized. More light and aisle nest arrangement may have been responsible for the consistent greater incidence at one location. Significant differences were noted between lines as well as their single crosses with respect to floor laying. No significant interactions were detected between the genotypes and management variables studied.