J. Anim Sci.
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J. Anim Sci. 1967. 26:16-20.
© 1967 American Society of Animal Science
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A Study of Some Genetic Parameters in Purebred and Crossbred Populations of Swine1

C. M. Stanislaw2, I. T. Omtvedt, R. L. Willham and J. A. Whatley, Jr.

Oklahoma Agricultural Experiment Station, Stillwater3

Abstract

Data used in this study included progeny records of 99 purebred boars that sired both purebred and crossbred litters during the 18 seasons from the fall of 1955 through the spring of 1964. The performance traits studied were 56-day weight, postweaning average daily gain and probed backfat thickness at 90.7 kg. live weight. Least-squares constants were used to adjust the data for station, year, season, breed, age of dam, inbreeding of litter, management system, sex and litter size at weaning differences. Analyses of variance were then performed on the adjusted observations to obtain sire component estimates.

Heritability estimates within the purebreds were O.03 ± .06, 0.28 ± .06 and O.55±.12 for 56-day weight, average daily gain and probed backfat, respectively. Corresponding estimates within the crossbreds were 0.19±.09, 0.39±.10 and 0.47 ± .13. Genetic correlations in the purebreds between 56-day weight and average daily gain, 56 day weight and probed backfat, and average daily gain and probed backfat were 0.29 ±.50, –.05 ±.53 and – .07±.18, respectively. Within the crossbreds the corresponding estimates were O.2O±.21, 0.61±.16 and –.39±.18.

Comparison of trait response to indirect selection showed that, within the purebreds, improvement in postweaning growth rate and probed backfat must come almost entirely from selection pressure applied directly to these traits. Within the crossbreds it appeared that selection for less backfat would decrease 56-day weight almost as effectively as direct selection against 56-day weight. Also, average daily gain would be increased by selection for less backfat, but probed backfat would be increased by selection for 56-day weight. Also, average daily gain would be increased by selection for 56-day weight.

Covariance showed that improvement in crossbred performance from intrapopulation mass selection on both sexes within the purebreds would be greater for 56-day weight and probed backfat than that obtained by reciprocal recurrent selection. However, reciprocal recurrent selection appeared to be superior to half-sib family selection within the purebreds for improving crossbred performance for all three traits.

Footnotes

1 Journal Article 1295 of the Oklahoma Agricultural Experiment Station, Stillwater, Oklahoma. Project No. 808.

2 Present Address: Area Swine Specialist, Box 3027, Wilson, North Carolina.

3 Department of Animal Science in cooperation with the Regional Swine Breeding Laboratory, AHRD, ARS, U.S.D.A.






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Copyright © 1967 by the American Society of Animal Science.