Floor laying by Pekin ducks: effects of nest box ratio and design.

The laying of eggs outside nest boxes is a common problem in poultry production systems. Factors potentially contributing to floor laying by Pekin ducks were investigated. In a 2 × 2 factorial design, 16 groups of 18-wk-old ducks (8/group) were provided access to either 2 (4 ducks/box) or 8 (1 duck/box) closed-topped or open-topped nest boxes. Egg locations were recorded daily for 16 wk. Video analyses were used to determine the time of day eggs were laid on the floor when the ducks were 18 to 22, 26, 30, and 34 wk of age. An analysis of nontoxic dye deposition in the egg yolk was conducted on wk 30, 32, and 36 to determine the contribution of each duck to floor laying. The proportion of floor eggs was especially high early in the laying cycle, reaching 84 and 44% of eggs laid in pens offering ratios of 4 ducks/box and 1 duck/box, respectively, when ducks were 22 wk of age. Repeated measures ANOVA revealed that although the proportion of floor eggs decreased over time (F(3,9) = 29.29, P < 0.0001), it remained greater in the groups housed with 4 ducks/box vs. 1 duck/box (F(1,11) = 24.09, P = 0.0005). The proportion of floor eggs was not affected by box design (F(1,11) = 0.08, P = 0.8). Not all available nest boxes contained eggs on a given day, and the distribution of eggs within the pen was clumped. However, it was unlikely that this reflected nest box location preferences because the locations of the eggs laid within the nest boxes changed over time. Taken together, these results suggest that floor laying by Pekin ducks may be caused in part by insufficient nest box availability. However, the clumped distribution of eggs suggests that other social factors, such as conspecific attraction, may also be important.