Bovine mastitis still causes great loss despite modern treatment, and discussion of this subject is therefore particularly appropriate to the Society of Animal Production. Data obtained before modern treatment became available, in several countries where dairying is intensive, showed that some 3-4 per cent, of dairy animals were culled annually on account of mastitis, that at any given time about 10 per cent, had some obvious abnormality of milk or udder, and that a high percentage of animals—20-40 per cent, in many areas and countries—were infected with one or other of the recognised mastitis bacteria, the majority with Streptococcus agalactiae. Much of this has been overcome by modern treatment, and in some areas Str. agalactiae mastitis has already been eradicated from large numbers of herds. There is no doubt, however, that in many other areas mastitis remains a cause of heavy loss of yield—a loss which could largely be removed by more active measures for its control.

My work during the last few years has been to some extent concerned with attempts at the control of mastitis under ordinary farming conditions, and in speaking to you today I will confine my remarks to what I consider in that particular region of experience is relevant to your tasks and interests. I make no claim to have carried out any fundamental research on the micro-organisms associated with infections of the bovine udder. My aim has been rather to apply the results of primary scientific enquiries carried out at various research centres to practical problems in the field.

It will be appreciated that conditions existing on the average farm differ in many respects from those that pertain on the farms and premises of the field stations and research centres, where a more direct, complete, and constant control can be exercised by the research worker over animal management, milking practices and general hygiene, than is possible on farms scattered over a wide country area and where the investigator must of necessity work from a position somewhat remote. Much in the way of control has to be left in these circumstances to the farmer, his herdsman and the practising veterinary surgeon. The personal element therefore, will always weigh very heavily. The test of any scheme or programme designed to control mastitis is: Can it work under such conditions and produce the desired results ? I am convinced from my own experience that it can.

I agree profoundly with what Dr. Stableforth and Mr. Macpherson have said. There are, however, some points on which I would like to elaborate. The most important is the question of management. The sooner farmers fully realise the great importance of management, the sooner the control of mastitis will be effected. The question of management is inevitably one of personnel and the training of that personnel.

To-day there are fewer people than ever who can milk a cow efficiently by hand. The time has arrived when the veterinary surgeon will tell you that he would rather control mastitis in a machine-milked herd than in a hand-milked herd. That is not entirely due to the fact that you can thus eliminate the handling of the udder. It is simpler to train a man to use a machine efficiently than to hand-milk efficiently. There is no question whatsoever but that the handling of the cow's teats is a most important factor; and in machine milking the elimination of hand stripping is not only practical but is a most important contribution to avoiding transmission of infection. But more can be done.

We have had recommended to us to-day a number of measures than we can take to control and eliminate mastitis. I have not done the things that Dr. Stableforth told us we could do. I had to determine whether in my own particular circumstances, in the state of health or disease in which my herd was at the time and was likely to be in the future, in the light of the degree of supervision I could give to my herd management and with the particular circumstances of labour at my disposal, and all the other relevant factors, I should embark on a policy of eradication or whether I should tolerate the disease.

There is, obviously not one answer for every person. It must depend on each person's circumstances. But I think in regard to these circumstances and considerations that I have mentioned I am more fortunately placed, possibly, than the average farmer, with the single exception of the amount of time I can give to supervision. My labour is above the average in intelligence; my cattle are above the average in health; they are above the average in their state of nutrition. When I weighed up these factors, my decision was, rightly or wrongly, that I should tolerate the disease and not attempt to eradicate it.

I have four dairy farms, two with pedigree Ayrshire herds and two with pedigree Friesian herds. We have a fifth herd we keep at home as a hobby herd, with special heifers and cows, and which my wife specially looks after.

On the four commercial farms we produce Certified milk. We milk about sixty cows; we also occasionally breed a pedigree bull; and we are interested in good records of butterfat. We find that the incidence of mastitis in pedigree cows is extremely important, because if a good-looking cow with a beautiful pedigree and a first-class record is suddenly struck with mastitis her whole history is ruined from the practical farmer's point of view. This is so important that on the four commercial farms we take regular monthly tests from each quarter of each cow. These are reported to me as well as to the veterinarian and to the herdsman who is handling the cows.