A genetic correlation near unity between ovulation rate in heifers and later twinning frequency led to consideration of using measures of ovulation rate in heifers for each estrous cycle, beginning at puberty, to increase accuracy of selection for twinning rate. An initial evaluation with a multiple trait animal model for predicting breeding values included six genetic groups: 1) selected Scand...

Genetic differences in natural vs hormone-induced ovulation rates were compared in immature female mice from five lines that had undergone long-term single-trait and antagonistic index selection for litter size and(or) 6-wk BW. Lines used were control (K); high litter size (L+); high BW (W+); low litter size and high BW (L-W+); and high litter size and low BW (L+W-). Natural ovulation rate at a...

Background To evaluate the effect of metformin on ovulation and pregnancy rate in clomiphene citrate resistant women with polycystic ovary syndrome (PCOS). MaterialsAndMethods In this clinical trial each patient, regarding her previous resistance to Clomiphene, served as her own control. A total of 35 clomiphene citrate resistant PCOS patients, referring to Royan institute were studied. Clomiph...

BACKGROUND A recent meta-analysis has proven that metformin (M) is highly effective for ovulation induction in the clomiphene citrate (CC)-resistant patient. There is uncertainty whether M should be introduced as a primary ovulation induction agent in polycystic ovarian syndrome (PCOS). METHODS We conducted a systematic review and meta-analysis to establish if M is better when given alone or ...

After 21 generations of selection for alternative criteria to change litter size in mice, responses in uterine capacity and ovulation rate were 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; IX = selection on an index of ovulation rate and the proportion of ova shed that re...

Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning pr...

Our knowledge of ovulation rate is still very rudimentary, but that is not to say that little information is available. The literature contains a vast body of data on the subject (Cumming, 1977) but a general model, such as those that are now widely accepted for the control of the oestrous cycle (Baird & McNeilly, 1981) or of seasonal reproduction (Goodman & Karsch, 1981), is not available. The...