Re-mating

When is the best time?

Many people have their own opinions on this, in my own experience, after chasing up a motorway and trying to make sure we mated at the optimum time as theorised by one or two more experienced keepers, which by all accounts was to no avail – one year later!! More research was needed, henceforth:

I have based the following calculations on the paper by P.Walter Bravo et al. full reference is given below.

This study looked at a number of parameters including repeated mating to stimulate ovulation and subsequently conception.

The table 1 below summarises the results.

Clearly ten days postpartum re-mate yields unacceptable results. Re-mating 20 days and beyond is more likely to have a promising outcome.

The study uses a number of stud males (11) but does not indicate which males have been used over which females – this must be taken into account as an overall picture of the success rates achieved.

The study also uses serum progesterone levels to determine the potential for pregnancy, progesterone has its own inherent levels of variability. This variability is apparent throughout pregnancy. I make an assumption that the final pregnancy analysis is confirmed by ultrasound scan at 40 days.

Although the study has one or two minor inconsistencies the results are significant and at very high levels of probability – so variability aside, the results, which are based on a good number of test subjects, 176 animals, are evidently quite robust.

Repeated mating – up to three times once every 24h does not yield any better results than a once only attempt.

It is widely accepted that there is a reproductive cycle in alpacas that simulates a wave pattern. Receptal may be given at the time of mating to alter the pattern of this cycle to coincide with the mating that has taken place, results may be much improved with the addition of a receptal injection. However little research for alpacas exists in this area.


Reference;

Walter Bravo, P., Pezo, D. and Alarcon, V. (1994). Evaluation of early reproductive performance in the postpartum alpaca by progesterone concentrations. Animal Reproduction Science, 39, 71-77.