The size of a litter is determined first by the number of eggs that are ovulated. Then secondly, on the number of those eggs that are fertilized, so the max number of puppies possible is determined by the female. The optimum time for breeding is 2 days after ovulation. It only takes once for her to become pregnant, but if you are not doing progestrone testing you will not know exactly when she will ovulate. This is the reason why most will breed once a day or once every other day until she stops standing. We do not breed on certain days of a heat cycle since some females will ovulate on day 8 (or earlier) or day 18 (or later) and any day inbetween.
All eggs are believed to be fertilized within a 24 hour time period.
__________________ Jackie JaLa Yorkshire Terriers |