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Evaluation of the uterine capacity - viable embryo model to explain litter size in mice
Abstract
A model including ovulation rate, potential embryonic viability, and uterine capacity was used to study litter size in mice. The selection experiment conducted at the University of Nebraska-Lincoln, based on different criteria to improve litter size, was used as the base for this study. The selection criteria were: LS = litter size, IX = an index including ovulation rate and ova success, UT = uterine capacity, and LC = control. Embryonic survival to 6 d was evaluated in the first study at Generation 36 of this experiment; selection had occurred for 21 generations. Selection for litter size by different criteria increased ovulation rate and embryonic survival to 6 d. Least-squares means for left embryonic survival were.84,.91,.85, and.82, and for right embryonic survival,.91,.90,.86, and.87, respectively for LS, IX, UT and LC. In another study simulation was used to test the model cited above. Comparisons were made to statistics of the base generation and to responses after 13 generations of selection observed in the cited experiment. Parameters for uterine capacity were generated taking into consideration observed means, standard deviations and correlations between left and right litter size, as well as responses in number born. The model was able to generate statistics that agreed with observed ones. Simulated mean and heritability for uterine capacity for the base population were 16.30 and.065, respectively. Although ovulation rate was the more limiting component, uterine capacity was important for explaining litter size. In the last study alternative criteria of selection were compared after 10 generations of simulated selection. Selection indices including ovulation rate and uterine capacity produced greater (23.9 and 14.7%) responses in litter size than direct selection for litter size. Indices including ovulation rate and ova success also produced more response (12.9%) in litter size than direct selection for litter size. Selection for ovulation rate, uterine capacity, or ova success produced responses in litter size that were 4.5, 43.6, and 74.8% smaller than direct selection for litter size. Crossing ovulation rate and uterine capacity lines also produced smaller litter size than direct selection.
Subject Area
Livestock|Genetics|Biostatistics
Recommended Citation
Ribeiro, Edson Luis de Azambuja, "Evaluation of the uterine capacity - viable embryo model to explain litter size in mice" (1995). ETD collection for University of Nebraska-Lincoln. AAI9600752.
https://digitalcommons.unl.edu/dissertations/AAI9600752