Effect of untreated and hydrothermally treated rapeseed in feeding of laying hens

Untreated and hydrothermally treated rapeseed were included in laying hen diets at rates of 0 % (control group), 7.5 %, 15 %, 22.5 % and 30 %, respectively. The experimental diets were fed to laying hens (Lohmann Brown) from age 27 weeks to age 62 weeks. Performance data and the trimethylamine content of the egg yolks were recorded. Hydrothermal treatment significantly increased live weight. However, egg production performance parameters were not influenced by hydrothermal treatment. Increasing the rapeseed content of the diets to more than 7.5 % significantly decreased laying intensity and egg mass produced and significantly increased both feed consumption and the feed conversion ratio. The trimethylamine (TMA) content of the egg yolks was significantly reduced, by about 40 %, by feeding hydrothermally treated rapeseed. There were higher reductions at the higher levels of rapeseed inclusion. A reduction down to the level of the control group (0.43 mu g/g egg yolk) was not achieved. However, feeding a diet which contained 7.5 % hydrothermally treated rapeseed gave a TMA content of 0.64 mu g/g yolk. This level did not affect the sensory quality of the eggs. In conclusion, up to 7.5 % hydrothermally treated rapeseed can be used in laying hen diets without any adverse effect on bird performance or egg quality.