The risk factors affecting the development of gentle and severe feather pecking in loose housed laying hens

Injurious pecking remains one of the biggest problems challenging free range egg producers, with both economic implications for the farmer and welfare implications for the birds. The most widespread form of injurious pecking is feather pecking, the most damaging form of which is severe feather pecking (SFP) which has, as yet unclear, links with gentle feather pecking (GFP). The current prospective epidemiological study investigates the development of GFP and SFP oil 61 free range and organic UK farms (111 flocks). Flocks were visited at 25 (20-30) and 40 (35-45) weeks, when rates of GFP and SFP respectively and levels of feather damage were recorded. Environmental and management data were collected for each flock. Factors affecting the development of these behaviours were modelled using the multilevel modelling program, MLwiN (Rasbash et al., 2004). GFP was observed in 89.2% and 73% of flocks at 25 and 40 weeks, respectively, at a mean rate of 0.65 bouts/bird/h. GFP rates decreased with increased percentage range use (coeff.: -0.001 +/- 0.0006, p = 0.025) and temperature inside the laying house (coeff.: -0.005 +/- 0.001, p = 0.001). GFP was higher in flocks with soil or grass litter (chi(2) = 13.16, df = 4, p = 0.012). flocks which had no perch access (0.010 +/- 0.001 vs. 0.007 +/- 0.002 bouts/bird/min, p = 0.047) and flocks which were beak trimmed compared to those non-beak trimmed or retrospectively beak trimmed (0.013 +/- 0.002 vs. 0.003 +/- 0.001 and 0.002 +/- 0.001, p=0.007). SEP was observed in 68.5% and 85.6% of flocks at the 1st and 2nd visits. respectively, at a mean rate of 1.22 bouts/bird/h. SFP rates decreased with range use (coeff.: -0.001 +/- 0.0003. p = 0.003). Mean rates were highest in non-beak trimmed compared to beak trimmed flocks (0.032 +/- 0.003 vs. 0.017 +/- 0.003 bouts/bird/min, p=0.028), flocks observed to be feather pecking when they arrived oil farm compared to those that were not (0.062 +/- 0.018 vs. 0.019 +/- 0.002 bouts/bird/min, p=0.001), and flocks fed pelleted compared to those fed mashed food (0.042 +/- 0.002 vs. 0.016 +/- 0.002 bouts/bird/min, p = 0.005). Plumage damage was lower in beak trimmed compared to non-beak trimmed flocks (plumage score 1.00 +/- 0.0001 vs. 1.15 +/- 0.068, p=0.040), and flocks which were fed mashed feed, and showed a quadratic relationship with severe feather pecking (p = 0.003) which was positive over the observed ranges of the behaviours. In commercial Situations, feeding mashed feed and increasing range use may reduce severe feather pecking and therefore feather damage. (C) 2010 Elsevier B.V. All rights reserved.