HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Eisen, E. J. Articles by Durrant, B. S. Search for Related Content PubMed PubMed Citation Articles by Eisen, E. J. Articles by Durrant, B. S.

Genetic and Maternal Environmental Factors Influencing Litter Size and Reproductive Efficiency in Mice^1,2,

North Carolina State University, Raleigh 27650

Abstract

Lines of mice which have been Genetically differentiated in litter size at birth and 6-week body weight by single-trait or index selection were randomly assigned to be reared in postnatal litter sizes (PLS) of N8, N12 or N16. The lines were selected as follows: large litter size (L⁺), large 6-week body weight (W⁺), selection index to decrease litter size and increase 6-week body weight (L^–W⁺), selection index to increase litter size and decrease 6-week weight (L⁺W^–) and random selection (K). Line and PLS differences in female body weight at weaning and 6 weeks were significant (P<.05), with W⁺>L⁺>L^–W⁺>K>L⁺W^– and N8>N12>N16. Although there was a significant interaction between line and PLS, ranking of the lines was the same at each PLS. Females of each line by PLS group were exposed to males of the same group. Line and PLS differences (P<.05) in female body weight at copulatory plug, adjusted for age, exhibited the same rankings as the earlier weights. Litter size at birth (dead plus alive), number born alive and number born alive per female exposed each revealed similar differences (P<.05) in the ranking of lines and PLS. No significant interactions were found. Means for litter size were as follows for each line: L⁺ (17.4)> [W⁺ (14.1), L⁺W^– (14.3)] >K (12.0)>L^-W⁺ (10.8), and for each PLS: [N8 (14.0), N12 (13.9)] >N16 (13.2). The decline in litter size as PLS increased did not differ significantly from linearity. Adjusting litter size for body weight at copulatory plug eliminated the significant effect of PLS [N8 (13.9), N12 (13.7), N16 (13.4)]. The established genetic differences in litter size among lines due to selection were considerably larger than the maternal environmental effect due to postnatal litter size. Because of the negligible interaction between line and PLS, valid inferences concerning genetic differences among lines in litter size may be made at any postnatal litter size between eight and 16.

¹ Paper No. 6040 of the Journal Series of the North Carolina Agr. Res. Service, Raleigh. The use of tradenames in this publication does not imply endorsement by the North Carolina Agr. Res. Service of the products named, nor criticism of similar ones not mention

² The technical assistance of Ms. Billie Jean Edwards is acknowledged.

³ Dept. of Anim. Sci.

⁴ Zoological Soc. of San Diego, San Diego, CA 92112.