Females are induced ovulators meaning that they do not have a “season” like many other animals, but rather they ovulate once they have been mated.  So pregnancy occurs during the week after mating.  The females have a 3-weekly hormonal cycle which prepares an egg, but doesn’t release the egg unless the female is mated.  Females are usually receptive to mating for 2 weeks of the cycle.

There is little point in mating a female that is not receptive. She will be highly unlikely to fall pregnant, as receptivity is related to the presence (or not, as the case may be) of a mature follicle.  Levels of receptivity vary, but ideally the female should sit with little encouragement from the male.

The alpaca mates in the “cush” position.  The male will pursue the female until she sits down (cushes). Then he will sit on top of her for the mating.  Alpacas take between 5 minutes and 30 minutes to mate. Duration has little effect on the possibility of pregnancy. In fact, long matings are not particularly good for the female -  15-20 minutes is plenty. Also it is important to check that the male has in fact fully penetrated the female.  Don’t be afraid to get down and check that this is the case!!

Maidens

Some maidens may panic when put with a male for the first time. If they are put into the pen with other matings at around 11 months of age they will become accustomed to the process without pressure and will invariably sit when ready. There is no specific age or weight guide as to when a maiden is ready for mating. Rather, she should be mated when physically and psychologically ready. Physically she should be at least 2/3 of her adult size and weight, taking into account the size of her sire and dam. Psychologically she should be sitting readily. Some maidens may not be reproductively mature until two years of age.

It is also worth mentioning the hymen. It might not be broken with a maiden and it might be quite persistent and difficult for the male to break. If the male is having difficulty with full penetration you can check the hymen by inserting your small finger (gloved and lubricated) in the vulva. If you feel the hymen (1-2cm in) you can very gently probe to break it.   This is a well documented reason for a maiden not achieving pregnancy.

Maidens are best bred with proven working males, and similarly young unproven males are best tried with proven breeding females, so that if there is a problem the cause is clearer.

Confirming Pregnancy

The easiest way to confirm pregnancy is by doing a ‘behavioural test’, commonly called a “spit off”.

A change in behaviour may be the traditional "spit off" where the female spits at the male or it may be running away or even just planting the feet firmly and flattening the ears. Also look out for the "escape sit". Some females respond to the male's pressure by beginning to sit and then lunging forward and upward at the last moment. They are simply trying to avoid the male's attentions, albeit in a less traditional way. It is therefore important not to remove the male at the first sign of sitting. Wait until you are sure of the outcome. It also pays to be aware of the escape sit, as it can be dangerous for the handler.

In summary, what you are looking for is a change from the female's receptive behaviour as an indication of ovulation and pregnancy.

After the mating check the female with a male at 7 days to see if her behaviour has changed. A change of behaviour at 7 days indicates ovulation and if that change continues to 14 days that indicates a pregnancy.

Some females will "spit off" after a matter of hours; others will take up to 7 or possibly even 8 days to know if they have ovulated.

If the female does not spit off, then she will again cush for the male so that she can be mated.  Generally speaking the female will ovulate within 7 days of mating, so a spit off at 7 days will confirm ovulation but this is no guarantee of pregnancy.  Another spit off at 14 days should confirm pregnancy, then a third spit off at 28 days is fairly conclusive.  If you don’t have a male around to do the spit offs then the breeder who is offering the stud services might bring a male back at least twice for spit offs. It is a good idea to have an ultrasound scan done at around 60 days to confirm pregnancy – especially if you have paid stud service fees.  Most vets have mobile ultrasound equipment.

There are 2 types of ultrasound machines - internal and external - ask your vet to use the external ultrasound equipment as it is less stressful for the alpaca.  However, the external ultrasound machine will only be able to confidently confirm pregnancy after around 60 days.  The internal ultrasound can pick up a pregnancy from about 30 days.

If the female has not ovulated she will continue to be receptive. However, she should not be mated until at least 7 days since her last mating. Repeated mating can make the uterus too disturbed and unhealthy to hold a pregnancy due to factors such as infection or damage.

If a female continues to fail to ovulate she may need an ovulation-inducing drug to assist her. If a female continues to ovulate but fails to fall pregnant often a course of penicillin can help as she may have a uterine infection that may or may not be detectable on ultrasound. Your vet can advise on the specific drugs, dosages and management plan.

If the female is receptive and is not pregnant after three good matings, it is time to try something new. The first thing to consider is changing the male, particularly if he has no confirmed pregnancies or does little work. This simple step often solves the problem.

Occasionally a female will miscarry, or reabsorb the foetus, so it is a good idea to perform spit offs every so often during the pregnancy.  If you observe a discharge down the back legs of your female it could mean a miscarriage, so check the poo pile for any sign of a miscarried foetus.

Pregnancy lasts for between 11 and 12 months. It is rare for them to deliver before 11 months, but is well known for them to go past the 12 months mark.  For working out due dates, most people work on an average of 11.5 months or around 345 - 350 days.

 
"False Pregnancies"

Occasionally a female that has ovulated but is not pregnant will have a retained corpus luteum ("CL"), resulting in a "false pregnancy". The CL has failed to regress, despite the egg not being fertilized. She thinks she is pregnant and behaves accordingly, but is in fact empty.

Such a female may require prostaglandin to facilitate regression of the CL and she should be receptive again anywhere between 24-72 hours afterwards. If she is not receptive then she may have a persistent CL that may require a course of prostaglandin. These are often the result of a retained CL not being detected and being left for some time. This is one reason why it is important to confirm pregnancies to ensure the change in behaviour is consistent with an actual pregnancy and not a false one. Your vet can advise on the use of prostaglandin.

Health, nutrition and stress can have an effect on whether or not a female is ovulating and falling pregnant, so bear these factors in mind. Similarly there are anatomical and hormonal problems that may arise that your vet can assist with.