If any one sufficiently curious will take a bound volume of some veterinary periodical of 50 years ago and compare it with a volume of the same publication nowadays, he cannot fail to be struck with the remarkable difference which exists. The dominating subjects in the first would be equine surgery and medicine, chiefly viewed from the standpoint of treatment. A similar place in the second would be occupied by articles on the diseases of all classes of animals and birds, and the emphasis would be on prevention. In the first, references to nutrition would be almost confined to the routine feeding of horses, based on conservative principles; in the second, the outlook has changed and nutrition is envisaged as a subject into which scientific minds are probing very deeply and are yet unsatisfied. The influence of nutrition on disease is seen to have very wide ramifications.
If, similarly, a man's mind casts hack to the problems agitating the mind of the stockowner 50 years ago and compares them with those of today, he will find the same variation. Less dogmatism is visible and there is an appreciation of scientific work and a demand, often rather ill-informed but certainly insistent, for more scientific work.
All this must be very encouraging to those of the community who are engaged in the prevention and treatment of disease in animals. It should be more than an encouragement; it should be a reminder to us that we also must participate in the changing outlook. We are supposed to be, or should consider ourselves to be the leaders in this type of work. If we fail, if we stagnate, what is going to happen? Many things might happen, but one thing would quite certainly happen, and that is that we should he relegated to a back seat. Such an event would be regrettable, but not so much for its effect on ourselves, which would be sufficiently unpleasant although deserved, but it would be a misfortune for the State if it were deprived of the advisings of our own group.
Our national economy is largely based on sound animal husbandry and sound animal husbandry must be based on physiological, chemical and pathological knowledge. The most disastrous errors in animal husbandry are being continually made for want of pathological knowledge.
Recently a very large piggery was visited in which there was unfortunately present a serious disease of pigs, causing heavy mortality. The construction of this piggery was interesting. It was built on the wrong side of a hill in the first place. Along the front of the sties ran a pathway from which one looked down into the sties. Immediately inside the fence was the usual concrete yard, and lower down the slope were the sleeping pens, consisting of railway sleepers fairly well jammed together but not moveable. The main drain of this piggery ran inside the sties. The whole thing seemed to be contrived to spread and perpetuate disease.
As an instance of the changing outlook resulting from scientifie probing, there are some very interesting observations in a recent number of the Journal of the Royal Army Veterinary Corps on Carotene (or Vitamin A) deficiency in horses and the many pathological conditions associated with it. The main result which appears from this very interesting work is to emphasise the high value of even a small ration of fresh green feed. You may say that we knew that before. Some of us did, but judging from the methods of feeding widely adopted in the past there must have been quite a number of people who did not. In any case, whilst we knew the general result we did not know the specific associations between the feed and the pathological conditions. You may ask whether that is a step forward. It undoubtedly is, since now when we meet the pathological condition we have an appropriate line of action as well as being able to prevent the occurrence of these conditions. You see, it works both ways.
We see then that here are the two main subjects of animal husbandry—environment and feeding—brought right into the pathological picture. And so you will find it with every phase of animal husbandry. Take breeding as an instance. We have yet much to learn regarding the factors underlying fertility, but experiment has shown that a diet confined to wheat has very undesirable effects on fertility. But are we to regard every case of sterility in wheat-fed animals as due to that factor? Certainly not. It is only one of the many causes which lead to sterility. The important fact and the one which requires correction is sterility, i.e., the pathological condition. The investigator must start off from that point. His question is, "What is the cause of this sterility?"
Now we come to the heart of this changing outlook. The old problem was the treatment of results; the new problem is the search for the cause. Such a search must he conducted systematically. This animal is sick; these animals are dying. Why? The first thing to do is naturally to look at a what the animal or the carcasses are telling us. Clinically the animal says, "My lungs are in a pathological condition." Why? Infection. Possibly, but what about Verbesina encelioides? A search fails to reveal it, and the animal accommodatingly dying enables a post-mortem examination to be made. A bilateral pneumonia with a copious croupous exudate is revealed. Again you ask yourself—Why? And until you have got down to a reasonable explanation of the final "why?" you have not finished the job.
This simply leads up to what I wanted to say. In an increasing number of instances the answer to the final "why?" is to be found in the realm of nutrition. Now do not run away with the idea that "nutrition" explains everything. Keep a sense of proportion. It is a commonplace of our experience that if a certain disease is in the limelight everything dies from it: if a certain drug is boosted for one thing, it will be found to cure nearly everything—for a little while. Do maintain a healthy scepticism. It is the mark of the quack to be stampeded into error of this sort. But on the question of nutrition it can be frankly said that the tendency has been rather to overlook this factor than to overstress it. The senior man amongst you will realise this most. It is still too often that one sees a judgment given on "feed" based on quantity rather than quality. You cannot over-study this question, or at least you are not likely to. And I would commend to your notice the fairly copious literature on nutrition from various angles which is available to you. In the course of time the stockowner will realise that you can give him just as good advice on feed as you can on medicine, advice which is probably of considerably higher value and which certainly can be more frequently used to advantage.
It is not difficult once the subject of "feed" is dealt with to move on further to hygiene and breeding, and so you cover the gamut of animal husbandry wherein lies much of the future work of our profession.