PROGENY TESTS AT LINCOLN

Press, Volume LXXXIII, Issue 25086, 18 January 1947, Page 7

PROGENY TESTS AT LINCOLN

USE OF STUD AND CULL SIRES INTERESTING FINDINGS Indications that differences in \ the breeding worth of sires occur irrespective or the apparent individual merit of the sires are among interesting preliminary findings from progeny tests which are in their third year at Canterbury Agricultural College. A progress report was obtained this week from Mr J. W. McLean, of the college staff, who has been in charge of the work. Tfundreds of years ago, animal breeders used the simple principles of “mating the best to the best” because “like tends to beget like,” to produce new and. improved breeds of stock. They have done so, slowly if surely, however, because like does not always beget like, and the best-looking are not always the best breeding. With little modification, animal breeders today use these same principles. Their disappointments are more frequent, however, because as improvement continues it becomes increasingly difficult to make further improvements. A stationary state is soon reached unless more refined selection methods are employed—increased accuracy in the identification of superior breeding animals. The most certain way to test the sire (though not the simplest) is to breed from it and if possible measure, not estimate, the quality of progeny under known* environmental conditions.

This progeny testing work at Lincoln has been with Southdown rams. The purpose is partly to demonstrate the limitations of present selection methods; but ‘mainly to find more accurate and certain methods, which would be of use to the stud breeder, of identifying superior breeding animals for economically-important characters.

Since Southdowns are single-purpos e sheep used solely for the production of high quality fat lambs by crossing with commercial flock ewes, the most direct way of determining their breeding worth is to measure ( the average quality of their progeny out of such ewes. If some rams jire better than others they will be so to the extent that their progeny are better as fat lambs.

Selection for? Trials The design of the trials has been therefore to mate Southdown rams of various grades and from various registered flocks —ranging from high-priced studs to culls—to random groups of 30 .Corriedale flock ewes. Since the ewe groups are random, any difference in; average merit of progeny can be attributed to the sires.

In the first year, five “stud” rams and five medium to low grade “flock” rams from one registered flock were tested. The next jjear, high-grade flock rams from two flocks were compared with what would be classed as culls. This season some of last year's rams were retained for a further year as a repeatability test, and further high-grade and cull rams were introduced. Last year the ewes were slaughtered after two seasons’ production and a fresh lot of aged ewes were brought in. Lambing percentages have been high, about 140 per cent, in, tne last two seasons, with the great majority of the lambs being sold fat off the mother.

The ewes are individually identified,, and after mating are all run together. At lambing the lambs are ear-tagged, and weighed at birth and afterwards at monthly intervals. As the progeny reach marketable weights they are slaughtered at the freezing works and the carcase quality is determined by measurement on the hooks. The two chief criteria of fat lamb quality—rate of growth and carcase conformation and composition—are thus measured accurately. Many other measurements are made, and the data collected and recorded. Last season, for example, with the testing of 12 rams on 360 ewes, some 30,000 single observatiohs were recorded after the lambs and -ewes had been slaughtered and measured. An enormous amount of work remains to be done in the correlation and analysis of this data. , Tentative Results

At this stage, only .results of a general and tentative nature can be given. According to the report obtained by “The Press” this week,, however, it seems* fairly clear that although rams may differ greatly in their appearance at the shearling stage, some looking very good and some very bad, the differences in their breeding worth as as fat lamb sires are very’tnuch smaller, and their merit is not necessarily in the order in which they would be placed on their appearance. Each year, before the first drafts are taken out for slaughter, all the lambs are divided into the various sire groups and an inspection is made for any characteristic which would not perhaps be noticeable when they are running together. This inspection gives at least some indication of the average merit of the progeny groups and an opportunity to compare, rather crudely, the progeny o’f the various sires.

When this is done it is not possible to detect any differences, or to observe which are the progeny of the good and which of the bad rams. Preliminary examination of the recorded data, however, shows that small differences in characters of economic importance do exist between sires (irrespective of the sires’ apparent individual merit), and it is these differences that make- possible the resumption of slow but sure progress. Other related problems are being studied at the same time. For example, to provide information on the influence of the size and conformation of the ewe on fat lamb quality, the ewes are also slaughtered and measured after grading on the hoof. It is possible, also, to measure the repeatability with which ewes produce good or bad lambs from year to year. Additional work of interest is the counting of worm parasites in the stomachs of all lambs at slaughter in an attempt to find whether or not re sistance or susceptibility to worm parasites is inherited. Features of conformation predisposing to blowfly strike are studied also. Such avenues of work may make it possible to breed for more healthy stock.