Alpacas
Trouble-free pregnancies - Claire Waring looks at the breeding behaviour of alpacas and llamas
 |
| Most pregancies are trouble free and the cria is born safely |
CAMELIDS, which include alpacas and llamas, are known as induced ovulators. This means that they do not come into season and ovulate at a regular point in their breeding cycle, regardless of whether or not they have mated. They only actually ovulate as a response to mating.
Females do have follicular waves which generally occur over 10-12 days. Here an egg follicle matures gradually and reaches the point where it could be released as an egg if mating occurs. If there is no mating, the follicle simply regresses.
Maturing follicles produce the hormone oestrogen and this causes the female to be receptive to the male. After ovulation, which takes place 24-48 hours after mating, they change to the production of progesterone. This both inhibits the development of more follicles and causes the female to reject a male's advances. If the egg is not fertilised and the female is not pregnant, the ovaries receive a signal and switch back to producing oestrogen, thus allowing a new follicle to develop.
The follicular waves overlap and a female will still be receptive and "sit" for a male even if the follicle is not sufficiently mature for it to ovulate. This makes it very unreliable to use behaviour alone to determine the best time for mating.
If a female rejects and "spits off" a male after she has been mated, it is a first indication that she is pregnant. However, this is not an infallible sign and some females may continue to reject the male even when they have not conceived.
The most reliable way to confirm a pregnancy is to use ultrasound which will give an image of the developing foetus, if present. A rectal probe can be used within a few days of mating but many females resent this and it is better to leave it until about 28 days after mating when an abdominal probe can be used. This is simply placed on the hairless part of the abdomen, near the udder.
If the female fails to become pregnant, she should be checked to ensure that she is fertile. There are many causes of infertility, ranging through bad management, congenital deformity, infection and nutritional deficiency. However, if infertility has been ruled out, there are other reasons why conception fails.
If mating occurs when the female is not in the fertile part of her cycle, ie, there are not follicles ready for ovulation and fertilization, she will not conceive. Sometimes mating is incomplete, particularly with young inexperienced males. It is always worth checking during mating that everything is connected. In order for fertilization to take place, the semen must be deposited right into the uterus. If a maiden female has a tough hymen membrane which the male cannot penetrate, this will not happen and there will be no pregnancy. In this case, the hymen should be broken manual using a sterile gloved finger.
Even when the female has conceived, she can still lose the cria and this is thought to occur in about 10 per cent of cases. Most commonly, pregnancies fail early on and this may occur before the female has been diagnosed as pregnant. In this case, she will become receptive again. Only if pregnancy has been confirmed by ultrasound will you know if the embryo has been lost. Otherwise it may just be a failure to conceive.
Abortion or early death of the embryo can be the result of infection which debilitates the female. Various bacteria, including Chlamydia, Toxoplasma, Leptospora and Brucella can result in abortion storms within the herd. An aborted foetus should be cooled (not frozen) and sent, together with the placenta, to the laboratory for a post-mortem diagnosis.
This will confirm whether or not it is an isolated incident or one which could affect the other females. If a female consistently fails to hold a pregnancy, she should be checked to ensure she has no infection.
A female may lost her pregnancy if she is short of selenium, vitamin A or iodine. Younger females appear to be more affected by shortage of vitamin A or iodine. Obesity is also associated with loss of pregnancy because of hepatic lipidosis. Pregnant females should be body-scored regularly to ensure that they are not becoming obese.
Stress is the greatest environmental factor associated with abortion. This includes handling, particularly in the early and late stages of pregnancy, heat and transport. The animals seem to be more greatly affected by prolonged periods of stress although they appear to handle short stressful periods fairly well.
Vaccination with prostaglandins will definitely cause abortion and corticosteroids can have the same effect. Other causes of abortion can include low production levels of progesterone, scarring of the uterus from a previous difficult birth, genetic abnormalities and twins. Twins are not the norm and both have been known to survive.
However, this is unusual. Often twin conceptions are reduced to one early on in gestation. If this does not happen, it is highly likely that the female will lose both foetuses late in the pregnancy and termination should be considered.
All this apart, most pregnancies are trouble free and the cria is born safely after about 11 months and is welcomed into the herd.
Claire Waring is the secretary of the British Alpaca Society (www.bas-uk.com).
Print 
Email this 
Comment
What are these links for?
If you liked this article and would like to share it with others on the web who might be searching for good content we've made it easy for you to do it.
At the bottom of all articles, you'll see links to six sites. These sites - commonly called 'social bookmark' or 'social news' sites - have large communities of web users who share and rate interesting, useful and fun things on the web.
Clicking the links will automatically add the address of the story you are reading to one of these sites, letting you share it with others. Each site will ask you to register to share stories. Registration is free and once a member, you can store, recommend and search for stories that interest you.
More on Digg
More on del.icio.us
More on Furl
More on reddit
More on NowPublic/
More on Yahoo!
