Feeding layers of different genotypes in organic feed environments

1. Two experiments were carried out to evaluate the suitability of an experimental laying hen genotype (SH) in organic egg production. SH had been selected over 25 generations on a low protein diet (130 g/kg) based on home grown feedstuffs. SH hens were compared with LSL (Experiment 1) and Hyline (Experiment 2) hens. The birds were kept in 12 aviary pens with access to outdoor runs. 2. Four diets, which were different in each experiment, were used. A control diet was compared with diets based on feedstuffs supposed to be able to be grown and produced according to organic standards. The diets differed in the content of sulphur amino acids. 3. There were no significant differences in mortality caused by diets or genotypes but an incidence of cannibalism occurred in one Hyline group fed on the diet with the lowest methionine content. 4. Severe feather pecking of LSL birds occurred and was worst on the low protein diet. In Experiment 2, signs of feather pecking of birds on the low protein diet occurred at the end of the experiment, but there was no difference between the genotypes. There was no significant difference in number of eggs produced between diets. Egg weight was influenced by diets in both experiments and by genotype in Experiment 2. Number of misplaced eggs was higher in SH hens in both experiments. There were few significant diet x genotype interactions. 5. The use of the outdoor area was influenced by diets and genotype in both experiments. 6. In conclusion, diets low in methionine content influenced predominantly plumage condition and egg weight, although production of eggs by number was unaffected. The SH hen adapted well to organic conditions, as did the Hyline genotype.