Is the hen's feed chemical and preservative free?
Yes, in a consumer sense the hen's feed is chemical and preservative free. The best way we can explain this is to state what is in the feed, we would not class any of these as chemicals in that sense. The ingredients include grains, protein concentrates including extra protein building blocks (amino acids), limestone, salt, sodium bicarbonate, enzymes, vitamins and trace minerals. In the technical sense, a chemist will probably argue that all matter is composed of chemical substances, compounds and mixtures - water, sugar, grass, everything ;-) See Wikipedia.
Preservatives are not added to the hens feed. Vitamin E is added to the diet which is a natural anti-oxidant but we would not class this as a preservative.