From: Fertility Farming by Newman Turner (Written over 50 years ago!)

My experience of Johnes Disease started when I was a boy on my father's farm in Yorkshire, between twenty and thirty years ago. It was the first disease of dairy cows of any significance to us and certainly the first in my experience -- and before I farmed on my own I had lived with and studied scores of Johnes Disease cases, both alive and dead. Apart from occasional difficult calvings, we had no troubles with our cattle at all. We had certainly never had any trouble which resulted in the death of the cow, as it did inevitably with every Johnes-diseased cow. We had heard of animals dying of tuberculosis, but even T.B. losses had not touched us and were apparent only on farms where cattle were seriously underfed. My father had always fed his cattle well -- as everything else on the farm, including his own family, though we were never allowed to eat until every animal on the farm had been given a meal.

And here, of course, was my clue. For at that time manufactured cattle cakes were becoming increasingly popular and we were using a lot more than the cow's stomach was designed to digest. It is generally accepted that diarrhoea in human beings is a dietary matter, resulting in fermentation in some part of the alimentary canal. May not the same be true of cattle, I thought. And around this thought I have studied the subject of Johnes Disease ever since.

The widespread incidence of Johnes Disease coincided with the general use of manufactured cattle foods and the consequent deteriorating digestion of the animal. Far from being caused by a mysterious virus, which is the usual explanation of a trouble for which there is no obvious cause, and for which there is no orthodox cure, Johnes Disease starts with incompletely digested food remaining in the intestines and setting up fermentation which, if not eliminated quickly, breaks down the mucous membrane of the intestines, and eventually even the walls themselves.

The simple prevention of Johnes Disease is a diet of natural foods, and if there is no alternative to the limited feeding of concentrated prepared foods, then occasional fasting is necessary to enable the system to eliminate the residues of unnatural food which are never completely digested or absorbed by the body.

It is essential that the diet should contain a high proportion of fresh organically grown foods rich in vitamins, trace elements, and plant hormones, all of which are essential to complete digestion. It is probably the absence of these pre-requisites of good digestion from the food ingested, rather than the concentrated nature of the manufactured food itself, which is the real cause of the trouble. For it is not until the animal has had many months of unnatural food that she starts to scour -- the first sign that the digestion is impaired.

Source: http://journeytoforever.org/farm_library/turner/turner21.html