The Effect Of Different Environmental Factors And Early Experience On Feather Pecking In Laying Hens

Feather pecking means hens peck the feather of conspecifics, which is a non-combative abnormal behaviour. In laying hens feather pecking damages feathers and raises mortality, so it causes not only welfare problems but also economic losses. The researches have shown that many factors could effect the occurrence of feather pecking, such as light intensity, stocking density, food consumption, and stress, but the internal causes of feather pecking were not clear known. There were two widely accepted hypotheses which explained the mechanism of feather pecking. One hypothesis regarded feather pecking as foraging-oriented behaviour while the other one regarded as dust-bathing oriented. Two experiments were carried out in this research. Through behavior observations the regulation and character of feather pecking of laying hens was studied in different stocking density, early experience, fiber level and systematically analyzed in their relations to the feather pecking in order to further understand the mechanism of feather pecking. Materials and methods In EXP I, 320 non-beak-trimmed hy-line white laying chicks were used. In first three weeks, they were reared on deep litter floor but reared in cage from the fourth week. In these two periods, both two environmental treatments were set for rich environment(polystyrene blocks and dust)and poor environment. The experimental treatments were allocated in random plot design. Each of four environment treatments was ER-LP, ER-LR, EP-LP and EP-LR(E=early, L=late, R=rich, P=poor)and the stocking densities with the four treatments were 30 chicks/m2 ,40 chicks/m2,50 chicks/m2 and 60 chicks/m2 and each treatment contained four replicates. Behavioural observation was conducted in the fifth week, behaviours were recorded by direct observation using time sampling method. The time interval for each observation was 20s. Observation started at 9:00 in the morning and constantly for continues 160 min. In EXP II, 300 7-week-old hy-line white laying chicks were used. The experimental treatments were allocated in random plot design, there were three treatment factors: D means stocking density, each of two density treatments was 15 chicks/m2 and 30 chicks/m2; F means fiber levels, fiber levels were set for 2%, 5% and 8%; E means environmental conditions, two kinds of environmental enrichment were provided for the dust-bathing environment and the foraging environment. In the dust-bathing environment, sand was provided to chicks on 60% area of each cage. In the foraging environment, polystyrene blocks and polystyrene cord with five colors of yellow, pink, green, white-blue and white-red were provided. Behaviour observation started from the eighth week, behaviours were recorded by direct observation with time sampling method and time interval for each observation was 30s. Results The result of EXP.1 indicated that early experience effected the occurrence of feather pecking in laying hens. The occurrence of Feather pecking in ER-LR and ER-LP group was lower than EP-LR and EP-LP group respectively. Environmental factor also affected the occurrence of feather pecking which was lower in ER-LR and EP-LR group than in ER-LP and EP-LP group. Feather pecking was increased with the increase of stocking density. In EXP.2, the occurrence of feather pecking in the foraging environment was lower in the dust-bathing environment. But in foraging environment, the occurrence of foraging behaviour was higher than that in dust-bathing environment. The occurrence of feather pecking showed the tendency to reduce with the enhancement of the fiber level. The occurrence of feather pecking increased with the increase of stocking density. Conclusions ①Early experience effected feather pecking significantly and determined the intensity of feather pecking in later life. ②Stocking density significantly effected the feather pecking. The occurrence of feather pecking showed the tendency of increase with the enhancement of stocking density. ③Fiber level effected the feather pecking significantly. The occurrence of feather pecking reduced with the increase of fiber level. ④Environmental factor effected the feather pecking significantly. The rich environment could reduce the occurrence of feather pecking efficiently. ⑤The mechanism of feather pecking was a redirected foraging behaviour.