J. Anim Sci.
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J. Anim Sci. 1985. 61:367-375.
© 1985 American Society of Animal Science
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Lifetime Parental Productivity in Twenty-Seven Crosses of Mice. II. Weaning Traits Reflecting Reproduction and Lactation1

S. Newman2,3,, D. L. Harris4 and D. P. Doolittle2

Purdue University and U.S. Department of Agriculture, West Lafayette, IN 47907

Abstract

Twenty-seven crosses of mice derived from three random-mating, unselected strains (SWO, J. PGH) with 16 matings/pureline or cross were cohabited continuously and monogamously for a 365-d reproduction period to evaluate lifetime reproductive performance of the parents. Data from 3,249 litters born (2,792 surviving to weaning) were analyzed to study the effects of parity (number of litters) and type of cross (pureline, two-way, backcross, three-way) on certain traits measured at weaning (21 d). The traits evaluated were 1) weaning to weaning interval (WWI), 2) litter size at weaning (LSW), 3) fraction alive at weaning (FAW)—the ratio of LSW to number born alive, 4) total Iitter weight at weaning (LWT), 5) pup weight at weaning (PWT), 6) weaning weight per pup observed alive at birth (WPP), 7) parental feed consumption per day (FPD) and 8) parental costs (PCT). Cost per live weanling animal was estimated as the ratio of cumulative parental costs to cumulative number weaned. Cost per unit of weaning weight was defined as the regression of cumulative parental costs on cumulative Iitter weight. Parity effects were important (P<.01) for all traits measured. Type of cross effects were noted for LSW, LWT, PWT, WPP, FPD (P<.01) and PCT (P<.05). A parity x cross-type interaction was expressed for WWI, LSW, PWT, WPP, FPD (P<.01) and FAW (P<.05). Three-way crosses were more productive than backcrosses, two-way crosses and pureline matings for all traits studied. Three-way crosses displayed the smallest cost per animal weaned and smallest cost per unit of weaning weight. The influence of parity on traits measured at weaning was less than for traits measured at birth. Weight per pup born alive (WPP) was found to be a better indicator of reproduction and lactation ability than LWT because WPP accounts for preweaning mortality.

Footnotes

1 Journal Paper No. 10034, Purdue Agr. Exp. Sta. Joint Contribution from USDA-ARS, Midwest Area and Dept. of Anim. Sci., Purdue Univ.

2 Dept. of Anim. Sci., Purdue Univ.

3 Present Address: Dept. of Meat and. Anim. Sci., Univ. of Wisconsin, Madison 53706.

4 Research Leader, Animal Genetics Research Unit, USDA-ARS.






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Copyright © 1985 by the American Society of Animal Science.