Abstract
Effects of nine generations of 450r per generation of ancestral spermatogonial X irradiation of inbred rats on genetic parameters of body weight at 3, 6 and 10 weeks of age and of weight gains between these periods were studied. Covariances among relatives were estimated by mixed model and regression techniques in randomly selected lines with (R) and without (C) radiation history. Analyses of the data were based on five linear genetic models combining additive direct, additive indirect (maternal), dominance and environmental effects. Parameters in these models were estimated by generalized least-squares. A model including direct and indirect genetic effects fit more closely to the data in both R and C lines. Overdominance of induced mutations did not seem to be present. Ancestral irradiation increased maternal additive genetic variances of body weights and gains but not direct genetic variances. Theoretically, due to a negative direct-maternal genetic correlation, within full-sib family selection would be ineffective in increasing body weight at six weeks in both R and C lines. However, progress from mass selection would be expected to be faster in the R lines.
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Selected References
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- Havenstein G. B., Taylor B. A., Hansen J. C., Morton N. E., Chapman A. B. Genetic effects of cumulative x irradiation on the secondary sex ratio of the laboratory rat. Genetics. 1968 Jun;59(2):255–274. doi: 10.1093/genetics/59.2.255. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koch R. M. The role of maternal effects in animal breeding. VI. Maternal effects in beef cattle. J Anim Sci. 1972 Dec;35(6):1316–1323. doi: 10.2527/jas1972.3561316x. [DOI] [PubMed] [Google Scholar]
- Kyle W H, Chapman A B. Experimental Check of the Effectiveness of Selection for a Quantitative Character. Genetics. 1953 Sep;38(5):421–443. doi: 10.1093/genetics/38.5.421. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Robison O. W. The role of maternal effects in animal breeding. V. Maternal effects in swine. J Anim Sci. 1972 Dec;35(6):1303–1315. doi: 10.2527/jas1972.3561303x. [DOI] [PubMed] [Google Scholar]
- Rutledge J. J., Chapman A. B. Systematic crossfostering within control lines. J Anim Sci. 1975 Jan;40(1):70–74. doi: 10.2527/jas1975.40170x. [DOI] [PubMed] [Google Scholar]
- Rutledge J. J., Robison O. W., Eisen E. J., Legates J. E. Dynamics of genetic and maternal effects in mice. J Anim Sci. 1972 Nov;35(5):911–918. doi: 10.2527/jas1972.355911x. [DOI] [PubMed] [Google Scholar]
- el-Oksh H. A., Sutherland T. M., Williams J. S. Prenatal and postnatal maternal influence on growth in mice. Genetics. 1967 Sep;57(1):79–94. doi: 10.1093/genetics/57.1.79. [DOI] [PMC free article] [PubMed] [Google Scholar]