The books say that alpaca gestation is between 335 and 342 days, but in reality this is only a guide and a numbers of factors will affect gestation.
Over the years we have noticed that this may vary according to environmental and nutritional conditions. In the early years when we had less numbers of animals and paddocks sown down to lucerne it wasn’t uncommon for a full term cria to be born at 10.5 months gestation, but as numbers increased and there was more competition for feed gestation terms normalized.
Generally speaking we have noticed that maidens will have longer gestations than proven breeders and will have smaller cria, but this can change depending on nutrition and the time of year. We have found that Spring births generally have larger birth weights and longer gestation, which can be problematic for maidens as overly large cria can be more difficult to deliver so we attempt to be on hand to assist if required.
Particular females seem to have their own normal gestation which does not conform to the information in the books. It is quite normal for one of our females to go up to 12 months gestation. If you keep accurate records on the gestation periods of your alpacas it is easy to see what is normal for particular animals and you can then work on a average for specific animals.
Cria can also be delivered prematurely, so vigilance is required in monitoring pregnant females. In the case of premature cria we tend to focus on the well being of the cria first and foremost, but it is also important to check the health of the dam. Illness or infection may have triggered the premature delivery or significant stress may have also been the cause. Stress in alpaca can cause serious health concerns in alpaca and veterinary advice should be sought.
The main thing to note is that gestation guides are just that, unfortunately alpacas can’t read the books so it it up to alpaca owners to monitor pregnant females and be aware of the signs of impending birth.