Over breeding alpacas can cause not only fertility issues but also difficulties in birthing. In order to understand the risk it is important that alpaca owners understand the breeding anatomy and the breeding process. Unlike most livestock alpacas mate in a recumbent (sitting position). If unchecked mating can last up to 45 minutes, compared to sheep where the mating process takes seconds.
The male penis deposits sperm directly into the female uterus. The penis shape and the fact that it is a strong firm penis means that it may cause internal damage and bleeding in the female during mating.
(This image was taken from an article on fertility by Dr Jane Vaughn Copyright © Jane Vaughn)
The longer the duration of mating the more damage that can be done to the female. Over mating can result in internal scaring, which may result in the females developing internal adhesions. These adhesions can cause a multitude of physical and fertility problems.
Often these adhesions can cause the female to become infertile or at least require the adhesions to be broken before conception can occur. If the female does become pregnant there may also be problems in birthing. If the adhesions form after conception there may be significant trauma and tearing at the time of delivering the cria. Depending on the level of trauma it can result in permanent infertility, significant pain and even death in severe cases.
There is also a psychological impact on over mated females, who associate mating and birth with pain. These females are often reluctant to mate some becoming very aggressive with males.
Leaving entire males in with females for extended periods of time is therefore not recommended, particularly when there are young submissive females in the group. Due to their submissive nature they are the ones most likely to be over mated. More experienced females are likely to be more forceful in their rejection of the male.
Although paddock mating can be used in managing alpacas it is advisable to undertake supervised mating with maiden alpacas to avoid over mating and subsequent internal damage.
We do not recommend paddock mating females with cria at foot as males will attempt to mate young animals if submissive. This could result in serious injury or death of cria. Paddock mating is more suited to large alpaca farms where the male has a large group of females to mate with. Males in this situation are less likely to over mate as they instinctively want to cover as many females as possible. We would not recommend the use of inexperienced males as they are likely to target more submissive females who put up lease resistance.
For more information about managing alpaca mating I recommend the following links.