Minimally-Invasive Assessments of the Behavioural and Physiological Effects of Enriched Colony Cages on Laying Hens

Abstract

Abstract:The well-being of laying hens in cages of 5, 10, 20 and 40-birds/cage, and enrichment with perches, nest boxes and scratch pads, was assessed using behavioral and physiological parameters. Laying hens were Lohmann Brown (n = 360) and White Leghorns (n = 360), housed from 17 to 65 weeks of age. Behavioral parameters were; the percentage of birds per cage roosting on perches, claw length (n = 288), and the percentage of eggs laid within nest boxes. Physiological parameters were; the assessment of feather cover from measurements of radiated temperatures by infrared thermography (IRT), bone mineral content of the humerus and femur by quantitative computer tomography (QCT) scans, and adrenocortical function as a marker of chronic stress by measurements of corticosterone concentrations in egg yolk and albumin.The majority of eggs (72.7 %) in furnished cages were laid in nest boxes. Nest use was highest in Brown hens (P < 0.03). Perch use was >80 %, but significantly less in the 10-bird cages (P < 0.0012) due to a shorter perch length. Claws were shorter on birds in cages with scratch pads (P < 0.0001). Feather insulation declined from 35 to 60 weeks of age for breast and back areas (P < 0.0001). White birds exhibited superior breast feather insulation compared to Brown birds. Egg albumin corticosterone levels declined between 35 and 60 weeks of age (P < 0.011). There were no indications of an affect of colony size or cage enrichment on measurements of bone mineral content. The findings indicated a preference for the use of nest boxes, perches and scratch pads. Significant losses in feather insulation occur with time. A reduction in egg albumin corticosterone levels over time may be a marker of chronic stress in caged laying hens.

Perch use by laying hens in a commercial aviary

“…However, there is also evidence that the percentage of hens in the group that will perch simultaneously increases to 99 to 100% when given 22.5 cm/hen versus 71 to 78% of hens perching when they are provided with 15 cm/bird (Duncan et al, 1992 ). Further, the fewest hens were recorded perching when provided only 15 cm/bird compared with treatments providing to up to 26 cm/bird (Cook et al, 2011 ). Thus how hens prefer to use available perch space becomes important if systems are to be developed or improved to accommodate natural perching behavior.…”

Scientific Opinion on welfare aspects of the use of perches for laying hens

“…In furnished cages, Lohmann Selected Leghorn hens used perches more than Lohmann Brown hens at night, and Hy-Line Brown hens showed a tendency for a higher usage of perches than Hy-Line White hens (Wall and Tauson, 2007). However, Cook et al (2011) did not find any differences in perch usage when they compared Lohmann Brown hens with White Leghorn hens kept in enriched cages.…”

“…In a study done with enriched cages, Cook et al (2011) varied group sizes (5, 10, 20 and 40 hens) and lengths of round metal perches per hen (15.0, 17.0, 19.0 or 25.8 cm). Usage of perches at night was significantly lower in the cages with the smallest perch length (15 cm) than in all of the other cages.…”

Impact of light-emitting diode and compact fluorescent light source type and cage tier on layers reared in an enriched cage system Part 1: Production performance and egg quality

“…This difference might be a result of light intensity at these cage tier levels which was higher at these cage levels. Cook et al [26] reported that percentage of eggs laid in toptier nest boxes was higher compared to the bottom-and middle-tier nest boxes. However, they reported that cage tier did not affect egg production in enriched cages.…”