Abstract
Roosting on elevated perches is a behavioral priority in laying hens, which is well-investigated in both experimental and commercial settings. However, little is known about perching behavior and perch requirements of alternative hybrids, such as dual-purpose hens. The aim of the present study was to gain basic knowledge on linear space requirements and perching patterns of dual-purpose hens (Lohmann Dual, LD) by comparing them to a conventional layer line (Lohmann Brown plus, LB+). About 3,700 hens per genetic strain were housed in two consecutive batches in four compartments of an aviary system with metal perches at different heights above a grid tier. As an indicator for required perching space, the body widths of a sample of individual hens was determined by image analyses. In addition, the use of five differently located perches and one cross-brace (structural element of the aviary system) was assessed by photo-based observations during the light and the dark phase. The LD hens measured an average body width of 15.95 ± 0.08 cm, and thus occupied about 7% more linear space than the LB+ hens (14.77 ± 0.08 cm body width; P < 0.05). Overall perch use was higher during the dark compared to the light phase, both in the LB+ (3.89 ± 0.08 vs. 0.79 ± 0.03 hens/m, P < 0.05) and the LD hens (2.88 ± 0.06 vs. 0.86 ± 0.03 hens/m, P < 0.05). With a maximum of 8.17 hens/m, the LB+ hens preferred to roost on the highest perches available at night. In contrast, the LD hens also rested on the lowest perches, and showed a more even use of all perches provided. During the day, the LD hens seemed to need lower perches for easy access to the feeders, whereas more LB+ hens used the higher perches, presumably to avoid threatening conspecifics. The present results show that preferences for certain perch locations differed between conventional layers and dual-purpose hens, whereas diurnal patterns of perch use were similar in both hybrids. Therefore, perches should be designed and located in an aviary system to meet the specific preferences and behavioral needs of the hybrid housed.
Highlights
The anti-predator response of roosting on elevated structures is still present in domestic laying hens, even if they are housed in indoor systems (1)
The hens’ body widths and the number of birds per meter perch served as indicators
The LD hens had larger body widths’ and showed no clear preference to roost on the highest perch available at night
Summary
The anti-predator response of roosting on elevated structures is still present in domestic laying hens, even if they are housed in indoor systems (1). Commercial layer hybrids and their feral ancestors, the Jungle Fowl (Gallus gallus), show the same resting postures on perches (2). Since laying hens are willing to work to gain access to a perch at night (3), perching can be regarded as a behavioral priority (4). Thwarting access to perches results in frustration (3), and may impair the birds’ welfare. The presence of perches reduces agonistic interactions among hens by increasing total space availability and decreasing bird density on the floor (5). Access to perches has beneficial effects on the prevalence of non-aggressive abnormal behaviors, such as feather pecking and cloacal cannibalism, in later life (6, 7). Feeding from perches was associated with less aggression and jostling at the feeder, longer undisturbed feeding bouts, and reduced mortality resulting from cannibalism (8)
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