Results of pig progeny testing in Great Britain

Abstract

From 1958 to 1962 over 800 boars and 3,000 sows were progeny tested at the national pig progeny testing stations in Great Britain. Their test results for four traits (daily gain, feed efficiency, average backfat and carcass length) have been used to study the amount and effectiveness of selection and to review the use of the test facilities and their effect on pig improvement.The amount of selection on test results was studied by measuring the difference in performance of animals with sons subsequently tested and all contemporary tested animals. The selection differentials found were from 0·05 to 0·30 standard deviation units for the four traits studied which represents a rather mild degree of selection. Thus selection could have had only a small effect in improving the testing population. In fact sons of tested animals showed little advantage over their contemporaries in test performance. Parent-offspring regressions were calculated and these, in agreement with theoretical estimates, indicated that selection would be effective and would lead to genetic changes in any of the four traits studied. Genetic correlations among the four traits were also calculated and indicated genetic compatability in improving the four traits concurrently.Two proposals intended to increase the impact of testing on pig improvement are put forward. These are (1) to restrict the testing facilities to a small nucleus set of breeders who could concentrate on testing and selection and (2) to replace the progeny testing by performance testing which would allow a more intense selection and a greater rate of improvement for the same testing facilities.