Sammendrag
Under commercial conditions, environmental enrichments may be provided infrequently and at limited locations in chicken houses, raising questions about the extent to which they are enriching. We hypothesized that broilers in flocks given limited access to peat would nevertheless exhibit more intense use of peat at a later age compared to broilers in flocks never previously given access to peat. We observed 27 commercial broiler flocks (Ross 308), 9 control flocks with no previous experience with peat and 18 flocks given access to peat starting from 7 days of age in limited locations and often not available all the time. During a visit to each flock at approximately 28 days, we placed 10 l of fresh peat in a central location of the house (peat condition) and pretended to do so at another comparable location (sham condition). We observed behaviour in the peat-covered patch (or equivalent sized patch in sham condition) for 20 min. Latencies of the first 5 birds to perform ground pecking, ground scratching, vertical wing shaking, standing and lying in each patch were recorded and averaged per flock and condition. We also recorded the number of birds lying, and total number present, in each patch based on instantaneous scan sampling at 1-min intervals. Data were analysed in generalised linear mixed models incorporating previous flock experience of peat (vs no previous experience), current peat exposure (vs sham) and their interaction, with flock as a random factor. Due to scarcity of ground scratching and vertical wing shakes in sham patches, only the previous experience effect was examined (in peat patches only) for these variables. We found that flocks with previous experience of peat had a tendency for a shorter latency to ground peck (70±28 vs 141±45 s, P=0.055), shorter latencies for ground scratching (308±79 vs 813±123 s, P0.05), a similar number of birds present (P>0.05) and a similar proportion of birds lying (P>0.05), when compared with flocks without previous experience of peat. In peat (vs sham) patches, there was a shorter latency to ground peck (93±24 vs 197±36 s, P=0.012), a longer latency to stand (180±56 vs 37±8 s, P=0.001) and lie (250±49 vs 97±22 s, P=0.001), a lower number of birds present (8.4±0.2 vs 9.1±0.3, P
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