Progeny testing in sheep : The inheritance of birth rate, growth rate and carcass quality in Southdowns

Abstract

The application of science to animal breeding requires the measurement of productivity and the measurement of its inheritance. The former is accomplished with relative ease; the latter, because of its nature, only with difficulty. The most accurate method of measuring the inheritance of productivity lies in the assessment of genotype by a study of the effects of random gene samples in a reasonably large number of offspring-a process known as progeny testing. This paper records some of the results of work on the progeny testing of Southdown rams carried out at Lincoln College from 1944 to 1947. The work was designed, first, to find out if heritable differences of an appreciable size could be identified by measurement of productivity and progeny testing. Second, if so, to determine the minimum number of such measurements and progeny necessary to provide a reasonably accurate system for application of the method to commercial animal breeding as it is at present organised; and third, to test the accuracy with which genotype for productivity could be assessed by other methods of selection commonly used by the breeder, such as type, pedigree and performance-in other words, to find out if the farmer who selects and pays high prices for so-called high quality sires, really gets anything better from the point of view of productivity than the farmer who pays low prices.