Use of perches and nestboxes by laying hens in relation to social status, based on examination of consistency of ranking orders and frequency of interaction

Abstract

Four groups of 15-19 adult ISA Brown hens were studied in pens to assess the relationship between social status and use of perches and nestboxes. This was to test the hypothesis that subordinate hens use these resources more by day, for avoiding dominants, but that dominants use perches more at night, for roosting. The experiment consisted of a 5-week pre-treatment period, when no perches were present, and a 4-week treatment period, when each group was tested with different perch treatments (No, Low, Medium, High). All groups were observed systematically in each week, when all interactions of three types (aggressive peck, non-aggressive peck, approach/avoidance) in a group were recorded by noting the instigator and recipient (from numbered wing tags) onto a matrix. Proportions of time that each bird spent using perches and nestboxes, by day and at night, were also recorded. The results indicate that social status of individual laying hens is relatively stable across time and can be based reliably on counts of either aggressive pecks or approach/avoidances, but not non-aggressive pecks. Aggressive pecks were the most frequent type of interaction observed, and were reduced by the presence of perches. Use of nestboxes, but not perches, was greater at night than by day. There were weak tendencies for perches, and to a lesser extent nestboxes, to be used more by lower ranking birds by day, but not at night. There was some evidence of increased use of these resources by higher ranking birds at night. It is concluded that provision of perches reduces bird density on the floor (where nearly all interactions occurred), allows subordinates a means of avoiding dominants by day, reduces frequency of agonistic interactions, and should thus benefit laying hen welfare.

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

“…Chickens may also use elevated structures to escape from other hens (Cordiner and Savory, 2001). These authors sequentially provided small groups of 20 adult hens with no perches or combinations of perches in low (17.5 cm above ground), medium (highest perch 35 cm above ground) or high (highest perch 70 cm above ground) configurations.…”

“…Because of the rather low number of papers, this descriptive analysis was not able to account for lack of independence, differences in sample size and other important sources of heterogeneity. Three papers (Struelens et al, 2008b;Tuyttens et al, 2013;Chen et al, 2014) referred to cage systems and the three others (Cordiner and Savory, 2001;Newberry et al, 2001;Brendler et al, 2014) referred to non-cage systems.…”

Systematic review of the effect of perch height on keel bone fractures, deformation and injuries, bone strength, foot lesions and perching behavior

“…The flow chart documents the number of studies identified by the search, the number Data were available from 10 studies to assess the outcomes of interest. The majority of studies (9) assessed perch use (Cordiner and Savory, 2001;Newberry et al, 2001;Riber et al, 2007;Brugesch et al, 2012;Eusebio-Balcazar et al, 2013;Tuyttens et al, 2013;Brendler et al, 2014;Chen et al, 2014). Only 1 assessed keel bone issues (Wilkins et al, 2011).…”

“…This is an overly simplistic representation of the data, as it ignores many aspects that should be considered in a more though metaanalysis i.e., the group sizes to weight the analysis, the inclusion of covariates (including cage height, housing system), differences in metrics (some studies have average proportions of birds with groups o birds as the unit of concern and others have the bird as the unit of concern), differences in central tendency measure (some use median others mean), clustering by study (i.e., some studies contribute multiple data points) and differences in day and night time usage. Data from the only some studies could be extracted and included in the figures (Cordiner and Savory, 2001;Newberry et al, 2001;Tuyttens et al, 2013;Brendler et al, 2014;Chen et al, 2014). These data of course have issues associated with lack of independence between observations, for example, the study by (Tuyttens et al, 2013) includes observations on the same animals over time.…”

“…Stocking density calculated from cage dimension. (Cordiner and Savory, 2001) Daytime: observed on 4 days, for 30 min in the morning and 30 min in the afternoon. In the second 15 min, the identities of all birds using perches and all birds using nestboxes were recorded every 30 s. Nighttime: Each group was video recorded continuously from lights off (21.00 h) to lights on (05.00 h) on one night per week.…”