UTERINE CAPACITY AND OVULATION RATE IN MICE SELECTED 21 GENERATIONS ON ALTERNATIVE CRITERIA TO INCREASE LITTER SIZE

Citation
Ac. Clutter et al., UTERINE CAPACITY AND OVULATION RATE IN MICE SELECTED 21 GENERATIONS ON ALTERNATIVE CRITERIA TO INCREASE LITTER SIZE, Journal of animal science, 72(3), 1994, pp. 577-583
Citations number
17
Categorie Soggetti
Agriculture Dairy & AnumalScience
Journal title
ISSN journal
00218812
Volume
72
Issue
3
Year of publication
1994
Pages
577 - 583
Database
ISI
SICI code
0021-8812(1994)72:3<577:UCAORI>2.0.ZU;2-J
Abstract
After 21 generations of selection for alternative criteria to change l itter size in mice, responses in uterine capacity and ovulation rate w ere evaluated. Females from Generations 22 and 23 were sampled from 12 lines, representing three replicates of four selection criteria: LS = direct selection on litter size; M = selection on an index of ovulati on rate and the proportion of ova shed that resulted in fully formed o ffspring; UT = selection on uterine capacity measured as litter size,f rom females unilaterally ovariectomized at 4 wk of age; and LC = unsel ected control. All females in the present evaluation (a total of 1,932 ) were unilaterally ovariectomized (either left or right ovary excised ) at 4 wk, mated at 9 wk, and killed at d 17 of gestation. The number of corpora lutea and number of fetuses were counted to measure ovulati on rate and uterine capacity, respectively. Selection in IX, LS, and U T increased (P < .01) ovulation rate from unilaterally ovariectomized females but by a greater amount (P < .01) in M and LS than in UT. Sele ction also increased (P < .01) uterine capacity of IX, LS, and UT (ave rage response relative to LC = 1.76 pups); response was at least as gr eat in LS and M as in UT. Direct selection in UT was successful at imp roving uterine capacity but was no more effective than M or LS selecti on. Cases in which ovulation rate limited expression of uterine capaci ty in UT may have shifted some selection emphasis to ovulation rate an d reduced response in uterine capacity.