The recent increase of some 40 per cent, in the country’s pig population has been instrumental in bringing about one of those periodic renaissances in pig housing which appear to be not uncommon in the history of agriculture. The importance of good pig housing as an essential factor to efficient pig production and subsequent pig profitability is probably more widely recognised today than ever before. We must have more home-produced food, therefore we must keep more pigs, and if we are to do so profitably we must have good pig housing.

The two fundamental methods for genetical improvement of livestock are selection on die basis of performance and mating according to relationship. The most familiar forms of the latter are crossbreeding and inbreeding according as mates are chosen which are less closely or more closely related than the average of the breed.

The possibilities of inbreeding, followed by crossing, were exploited in the production of ‘ hybrid corn’ in U.S.A. and the success achieved led to the hope that similar methods might be successful in livestock breeding. Accordingly the Regional Swinebreeding Laboratory organised a programme of producing inbred lines of pigs and then crossing them. During the 12 years of this programme, about 90 inbred lines have been started and about 50 still survive. Inbreeding degeneration is greatest in those characters, such as fertility and viability, which have been subject to intense natural or artificial selection. The inbreeding decline in growth rate and economy of food utilisation is considerably less. When the lines are crossed in pairs the average performance of the first cross pigs is the same as that of the initial population.

I am very glad to have this opportunity of discussing litter testing, although I imagine tliat most of you are familiar with the work which we are carrying on at Stoke Mandeville. To recapitulate the set-up as briefly as possible, we receive half-litters of three hogs and one gilt (from litters of not less than eight weaned), aged 65-70 days so that the first test weighing can be carried out at exactly ten weeks of age. Environmental conditions have been arranged so that each team of pigs receives as near standard treatment as possible. Each lot has its own 8 foot x 7 foot wooden pig hut facing south, with a 9 foot x 8 foot enclosed concrete run. The pigs are kept bedded down on a good depth of long straw litter and a Fordham automatic drinking bowl (fitted with a soft spring) is available to each house. Feeding is simplified by means of three-compartment Seaford self-feeders which are kept fully supplied with dry Sow & Weaner Meal (No. 1) until the pigs reach 110-120 lbs. liveweight (17 weeks).

The credit for the discovery that antibiotics in stable form added to feedstuffs (in amounts so small that they resemble vitamins) have growth-promoting properties, goes to Lederle Laboratories, a subsidiary of the American Cyanamid Company. This was in 1948 and was revealed during studies with residues following the manufacture of aureomycin. It was found that these were a rich source of vitamin B12 which had been discovered to have growth-promoting properties when added to all-vegetable diets. But the aureomycin residues contained a further stimulus to growth which was later found to be related to the antibiotic itself.

The first move to establish an international society for animal breeding was made during the Fourth International Congress of Animal Husbandry held at Zürich in 1939. The idea was revived in 1946 when the Swiss Society of Animal Husbandry again took up the matter, with the result that a meeting was held in Zürich in October 1947, attended by Mr. Alec Hobson and Mr. I. L. Mason representing the British Society of Animal Production. At this meeting it was agreed that an international organisation composed of private societies directly concerned with animal production was highly desirable and a preparatory committee was elected to prepare draft statutes. The United Kingdom was a member of this committee. The secretarial work was entrusted to the FAO Temporary Bureau in Europe, and was in fact mainly carried out by Dr. I. Moskovits of the Animal Production Branch.

There is set up under the name “ European Association for Animal Production,” in French “Fédération Européenne de Zootechnie “; in Italian “ Federazione Europea di Zootecnia“; in German “ Europäische Vereinigung fur Tierzucht “ an international organization, whose object is to promote the improvement of the technical and economic conditions of animal production by all means contributing to its better adaptation to the needs of mankind.

As a provisional measure, animal production organizations in non-European countries economically related to the Mediterranean zone may be admitted to the European Association for Animal Production in the same way and under the same conditions as those in the European countries.

The Sixth International Congress of Animal Husbandry held in July, 1952, at Copenhagen was valuable from more than one point of view. While the cynical may say that we suffer from too many conferences the fact remains that we have now entered a period where co-operation of one kind or another between European countries will almost certainly increase. This being the case it is as important that we should find the best way to make international conferences more efficient as it is to listen to papers and discussions arranged at them.

The progress in animal improvement depends on the accuracy with which the breeding value of each individual in the breed, or herd, is estimated, and how the animals chosen on the basis of our estimates are combined in matings. We are concerned here only with the first part of the problem, i.e. the estimation of breeding values. The estimates are made in regard to certain characters, or traits, which are of particular interest from an economic point of view, and they may be based on the phenotypic merit of the individual, or on the merits of its ancestors or collateral relatives, or on the merits of its progeny, in regard to the character in question. Often a combination of two, or three, or all four methods may be used. Their relative importance depends on the heritability of the character, as will be discussed later.

During the last decade or more we have heard a great deal about progeny testing. Discussion has centred round three chief points. Under what conditions can selection by progeny testing lead to an increase in the rate of genetic improvement ? What method of testing and interpretation of results is most efficient and most practical ? How should the results be applied—that is in what way should the tested animals be used ?

In their paper reprinted herein (page 79) Johansson and Robertson have shown to what extent modern genetical theory can answer the second of these questions. It now remains for the executive agencies of livestock improvement to demonstrate the practical utility of the schemes they outline. We must wait some time, especially for slow-breeding animals like cattle, before the results of such a demonstration are available.