Genetics of behavior: selection for mating ability in chickens.

MATING behavior in animals is complex and determined by diverse genetic and environmental factors. As one aspect of this behavior, mating frequency in chickens has received considerable attention ( UPP 1928; WOOD-GUSH 1956; MCDANIEL and CRAIG 1959; SIEGEL 1959; CARBAUGH, SCHEIN and HALE 1962; JUSTICE, MCDANIEL and CRAIG 1962). These reports, while not in agreement on the best procedures for the study of this component of sexual behavior, were consistent in showing that it was highly variable. Although phenotypic variation is large, data are available to suggest a genetic basis for mating frequency and sex-drive in chickens. For example, GUHL (1951 ) found significant differences among males for mating frequency. Differences have been noted among sire families (WOOD-GUSH and OSE~QRNE 1959) and inbred lines (SIEGEL 1959). A repeatability estimate of .31 was obtained by SIEGEL (1960a) for the number of completed matings made in 10-minute observation periods. Further, some progress in the separation of lines by selection for sex-drive has been reported by WOOD-GUSH (1958, 1960) and TINDELL and ARZE (1965). The present study was designed to measure the effects of mass selection in divergent directions for mating frequency at 31 to 34 weeks of age. Information was sought on the inheritance of this trait and its relationship with unselected characteristics.