No health gains from organic farm feed
No positive health effects from organic farm feed were found in chickens. A positive effect was found for a varied diet: a varied diet keeps the immune system alert and is therefore better for the animals' health.
The effect of feed on disease susceptibility was investigated. Each individual reacts differently to stress. What may cause stress in one individual may have no effect on another. Stress reactivity directly influences the responsiveness of the immune system and therefore also one’s health. It appears that diet has an effect on stress reactivity. This was tested in layer hens that have been on the same diet for 25 generations. Two groups of hens were put on a different diet. One group received organic farm feed and another was put on regular food. These two groups were monitored for two generations, with– among other things – blood analyses. The immune system appeared to be more responsive in both groups. The diet change stimulated the immune system. This not only had an effect on the immunity for diseases but also on the hormonal system, which determines stress reactivity. It did not matter whether the feed was organic or not. Therefore, the debate about whether organic farm feed is healthier or not remains undecided.
Title of the dissertation: Individual differences in sensitivity to immunomodulation by feed in layer hens, by Mrs R. Adriaansen-Tennekes, MSc (Wageningen University)