Disney":2viv706g said:
Today she is purple and i've heard things and even read in the dutch rabbit breeders article that the eggs start to die off if you wait too long.
MaggieJ":2viv706g said:
how could they be expired
Actually, they could. Eggs develop within a follicle in the ovary. In most animals (horses, people) several follicles will develop at once, but one becomes dominant, causing the others to regress. Each follicle contains an oocyte (egg), and they are a one time use structure... once development begins it can't just go into limbo waiting for the proper time to be fertilized. All of the follicles that regress (whether due to lack of induced ovulation, or dominance by other follicles) result in "lost" eggs.
I see this all the time when we ultrasound mares to determine when to inseminate them. Usually each ovary has one or two follicles developing and sometimes one ovary will have multiple small follicles. We measure the largest ones to determine if one is likely to rupture within the next couple of days so we can time our semen collections and inseminations appropriately. If we check the mare again in a day or two, usually one is clearly dominant. It is always worrisome when two are large enough to rupture since that may result in a twin pregnancy. Twins in horses rarely make it to full term, and if they do, often one or both die soon after. To prevent this, we do a pregnancy check at day 16, and plan to crush one of the embryos at a later date, which usually cause the other to die as well.
I found this article on alpacas (I had no idea they were induced ovulators! I learn something new every day!
) and it explains the process pretty thoroughly. This is the link:
http://www.gatewayalpacas.com/alpacas/h ... lation.htm
This is the text that applies most:
Even though the alpaca does not have an estrous cycle with definite periods of receptivity and non-receptivity, there is still cyclic activity on the ovaries. Several follicles are stimulated to develop and mature together in "waves" on the ovary. The wave of stimulated follicles develop from primordial follicles to primary follicles and then to secondary follicles which contain some fluid and are capable of producing estrogen. Only one single follicle dominates and continues developing to become a tertiary or Graffian follicle which is larger and able to ovulate. This follicle also produces estrogen and is the follicle which will ovulate if the alpaca is bred at the appropriate time. The follicles which do not ovulate will regress and shrink. Each oocyte (egg) can only be stimulated to develop once and then is not used again. Females connot produce more oocytes than what was already present in the ovaries at birth. Despite this and despite the fact that several oocytes are stimulated to develop and then never used with each follicular wave, there is still plenty of oocytes for the lifetime of the female.
A follicular wave is composed of three stages of growth, maturity, and regression. Each stage takes an average of 4 days, while the entire follicular wave takes about 11 to 12 days. This means that while the follicles are at the mature stage the alpaca is more receptive to the male and breeding should result in ovulation. Breeding is much less likely to result in ovulation during the follicular growth stage or regression stage. The female is usually less receptive during this time. The mature stage occurs 3 to 4 out of every 12 days of a follicular wave. Follicular waves will occur on both ovaries and often the waves do not coincide. For example, as one ovary enters the regression stage, the other ovary will begin the growth stage and have a mature follicle ready within a few days. This maintains follicles which are ready to ovulate more often than without the overlap or lack of syncronization between the ovaries.
This overlap of follicular waves keeps estrogen circulating in the female. Estrogen contributes to making her receptive to the male at almost any point during the follicular wave. An open (non-pregnant) female may appear to be receptive all the time. Just because the female will accept the male does not mean that there is a follicle ready to ovulate. There may only be smaller follicles in the growth or regression stage which cannot ovulate and result in a pregnancy. A breeding which does not result in ovulation could easily occur.
Once ovulation occurs and the corpus luteum is formed, it remains for only about 14 days if a pregnancy did not result from the breeding. The corpus luteum remains throughout the entire pregnancy if a pregnancy has resulted. If the female becomes receptive to the male again in 5 to 7 days, then no corpus luteum formed to produce progesterone because the female did not ovulate during breeding. In a female who becomes receptive again 14 to 16 days after breeding, ovulation occurred but did not result in a pregnancy.
