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Items
Details
Title
Specific and general combining ability
Author
Contributor
Gowen, J.W. Book author
Imprint
Iowa Ames: Iowa State College Press United States
Publication Date
1952
Description
p.352-370
Call Number
REP.G2132
Summary
By general combining ability we mean the average merit with respect to some trait or weighted combination of traits of an indefinitely large number of progeny of an individual or line when mated with a random samp]e from some specified popuLation. The merit of the progeny is measured in some specified set of environmental circumstances. If maternal effects are present, we must specify that the tested individuals are males. If the tested individu\-als are females, the merit of the progeny is a function of both general com: bining ability and maternal ability. General combining ability has no meaning unless its vaLue is considered in relationship to at lea$t one other individual or line and unless the tester population and the environment are specified. For example, suppose two dairy bulls used concurrently in an artificial breeding ring each have 500 tested daughters, and that it can be assumed that the cows to which the two bulls were mated were a random sample of cows from herds using artificial breeding. Suppose that the mean of the butterfat records of the daughters of the first sire is 410 pounds and f the second sire is 400 pounds. Five hun\-dred tested daughters are sufficient to reduce the sampling variance of the progeny mean to a negligible amount. Consequently the general combining. ability of the first sire is 410 - 400 = 10 pounds better than that of the second in this particular population and in this set of environmental circum\-stances. The general combining abilities of the two sires might differ by more. or by less than 10 pounds if they were used in some other region where both the genotypes of the cows to which they were mated as well as the environment could be quite different from those of the test.
Book Title
Heterosis: a record of researches directed toward explaining and utilizing the vigor of hybrids
Contact Information
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