Non-beaked laying hens housed in aviaries. II: Behaviour of cockerels and their effects on hen performance.

摘要

Non-beak-trimmed white layers (Norbrid41) were housed in a 3-tiered battery cage system (C), or in Marielund (M) or Laco-Voletage (V) aviaries for 4 laying cycles. About 1500 hens were included per system. Cockerels (Nordbrid41 or Jaerhons) were introduced to the systems in the 4th egg-laying cycle at densities of 1 cockerel per 30 hens or 1 cockerel per 130 hens. In the 4th cycle the average egg production per hen per day was 51.9 g (V), 51.8 g (M) and 51.3 g (C) compared with 48.07, 48.67 and 50.20 g in cycles 1-3. The mortality rate was reduced from an overall mean of 12.3% in the first 3 cycles to 10.5% in the 4th cycle; no cannibalism was recorded in the 4th cycle. The cumulative percentages of mislaid eggs were slightly reduced in the 4th cycle (3.5 and 8.4 vs. 3.7 and 10.3 for M and V, respectively). Pens with the high density of cockerels had a lower frequency of mislaid eggs than pens with few cockerels (16.3 vs. 18.6%). Few differences in cockerels' behaviour related to cockerel type ordensity were observed. However, cockerels with high social rank crowed more, received more pecks from the hens, and had more interrupted mating than cockerels with low social rank.[For Pt. II see pp. 413-424 of the same number of the journal].