Crop content in nutrient-restricted versus non-restricted organic laying hens with access to different forage vegetations

1. The purpose of this study was to evaluate how feed intake of organic layers varies according to type of forage vegetation available when hens are fed a normal concentrate for organic layers or a nutrient-restricted diet with whole wheat and oyster shells, assuming that the nutrient-restricted diet would reflect the capacity of the hens to forage. 2. Two 23-d experiments were arranged with chicken runs in a 2 x 2 factorial design with two types of complementary feed (concentrate with 184 g/kg dry matter (DM) crude protein vs whole wheat with 120 g/kg DM crude protein) and two types of forage vegetation (grass/clover vs a mixture of forbs in experiment 1 and grass/clover vs chicory in experiment 2): each experiment was carried out in three replications. 3. Twice during each experiment two hens from each run were slaughtered -two in the evening and two the following morning. Subsequently, the birds' crops were removed. Crop content was separated into 8 fractions. 4. For most feed items crop content was found to be significantly higher in the evening than in the morning. 5. Complementary feed significantly influenced the content of several feed items in the crop. In both experiments wheat-fed hens had a significantly higher amount of soil in the crops and a significantly lower amount of weed seeds compared to the concentrate-fed hens. Plant material and grit stone were significantly more abundant in wheat-fed hens only in experiment 2 and numerically more abundant in experiment 1, whereas the amount of oyster shells was significantly higher in wheat-fed hens in experiment 1 and numerically higher in experiment 2. 6. Type of forage itself only significantly influenced the amount of soil in the crops in experiment 1 and amount of seeds in experiment 2, since more soil was found in hens foraging on the mixed forbs and more seeds were found in the hens foraging on the chicory plots, respectively.