J. Anim Sci.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J. Anim Sci. 1977. 44:203-212.
© 1977 American Society of Animal Science
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bakker, H.
Right arrow Articles by Eisen, E. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bakker, H.
Right arrow Articles by Eisen, E. J.

Genetic Differences in Age and Weight at Sexual Maturation in Female Mice Selected for Rapid Growth Rate1

H. Bakker2, J. Nagai3 and E. J. Eisen

North Carolina State University, Raleigh 27607

Abstract

Populations of mice selected for large 6-week body weight (H6) and increased 3- to 6-week postweaning gain (Ml6) and their respective controls (C2, ICR) were used to study genetic differences in sexual maturation of female mice. Correlated responses evaluated in the Ml6 and H6 populations were age and body weight at vaginal opening (VOA and VOW) and at first estrus (ESTA and ESTW). Age at first estrus was measured by visual appraisal of the vagina. Reciprocal F1 crosses of the selected populations and of the control populations were used in conjunction with the parental populations to estimate average direct genetic (ADG), average maternal genetic (AMG) and direct heterosis effects in the selected and control populations, respectively. Selection for increased growth in the H6 and in Ml6 populations increased (P<01) VOW and ESTW in both populations and decreased (P<.01) VOA in the M16 population. Contrasts between the selected populations (M16-H6) and between the control populations (ICR-C2) were influenced to a greater extent by ADG than by AMG. ADG contributed to a later (P<.05) VOA and ESTA and a higher VOW and ESTW in the ICR compared with the C2 population. AMG had little influence on VOW and ESTW in ICR relative to C2, but contributed to an earlier (P<.05) VOA and ESTA. In the comparison between Ml6 and H6, ADG contributed to an earlier (P<01) VOA and heavier ESTW in Ml6 but did not significantly affect ESTA and VOW; AMG, although not significant, contributed to an increased VOW, ESTW, VOA and ESTA in M16. Heterosis, resulting in an earlier (P<01) ESTA, was estimated to be 15 and 17% of the mid-parental means of the control and selected crosses, respectively. Percent heterosis was not significant for VOW and VOA. The within-population phenotypic correlation between VOA and ESTA was .23 (P<.05), suggesting that VOA is not a reliable indicator of age at first estrus as measured by visual appearance of the vagina. The among-population correlation between VOA and ESTA was .02, but elimination of the Ml6 population from the analysis yielded a correlation of .85 (P<.01). The within-population phenotypic correlations between VOA or ESTA and 3- or 6-week body weight were negative.

Footnotes

1 Paper No. 4992 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, Animal Research Institute Contribution No. 632 and Agricultural University at Wageningen Contribution No. 654-490-11.

2 On leave from the Department of Animal Husbandry, Agricultural University at Wageningen, The Netherlands.

3 On leave from the Animal Research Institute, Agriculture Canada at Ottawa, Ontario.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1977 by the American Society of Animal Science.