Breeding Boars

Breeding Boars

Kunekune boars are relatively late maturing compared to most pig breeds. They will try and mate sometimes at a relatively young age but don’t start to sexually mature until at least 8 months of age. Generally a young boar won’t be very fertile until about 12 months of age and won’t reach full adult maturity until about 2 years of age.

Once boars reach about 18 months of age they start to develop the strong male characteristic of a shield over the shoulders. This is a very thickened layer of skin and fat plus connective tissue that acts as a protective shield that helps lessen the chance of injuries if they get in a fight. At about 18 months of age their tusks have usually grown enough to start protruding from the mouth. The upper tusks are usually ground short by the action of the lower tusks, which curve upward and outward over a period of time. Once a boar has his tusks starting to grow he has an effective weapon for dominating other pigs. A young boar will sometimes be bullied by sows and be reluctant to mate them until he is old enough to have developed his tusks and so be able to stand up for himself. Occasionally a boar will become a bit of a bully and will learn to plant himself in the middle of the food pile or in the favourite wallow, and by doing so the sows will keep their distance having learnt by experience to keep out of his way!

If using a young boar to mate a larger or older sow it is advisable to take the sow to the boar. The main reason is that a larger or older sow will naturally be dominant, but if put into a new or different paddock are less likely to ‘beat up’ the boar within the first day. A boar can also be ‘put off’ by new surroundings and put more effort into checking out his new territory than into any mating activity.

Older boars will sometimes be quite large and heavy relative to a young sow, so avoid using a large boar with a small sow in case the sow becomes injured by the weight of the boar.

Boars are stimulated particularly by the smell of a sow in season, and can become relatively single minded until the sow goes out of season. During this time the boar may isolate and protect the sow, ‘keeping all challengers at bay’ whether they be other pigs, other animals, or even people. Some boars can become aggressive while a sow is in season, and attack if anyone or anything gets too close. This usually only lasts for the time the sow is in season, but it is not a good idea to keep a boar that does this as someone may inadvertently be hurt by not realising he is ‘protecting’ his mate.

When 2 boars get near to each other they will show challenging behaviour. This includes stropping (stomping with the front feet), chomping (opening and closing the mouth quickly and frothing at the mouth), and threatening behaviour (turning sideways and raising the hair along their back to increase their body profile). If the boars can get at each other they will try to slash sideways with their tusks, injuring the other boar around the neck, shoulders and chest area. If 2 boars know each other, it is unlikely that they will fight much as they usually already know who the dominant one is and the less dominant boar will soon run away. The main risk of a serious fight is when 2 boars meet who don’t know each other or else they are equivalent in dominance terms.

Most boars on their own at home are very placid and rarely get worked up. Often more than 1 Kunekune boar can be run with a group of sows without any real problems.

In an unusual environment such as a show or saleyards where boars may suddenly feel threatened, they can get themselves quite worked up or aggressive. This is why it is important to make sure all boars going to shows are detusked – they are suddenly in a small area and where there are other sexually mature boars and are on the alert for a good fight. A boar that gets worked up may try to break out of a pen or yard or to lift gates off their hinges.

It is very difficult to break up a fight between 2 boars. The simplest way is by putting a barrier between them such as a ‘boar board’, but this can be a difficult and dangerous thing to do and should only be attempted by an experienced pig handler as a boar can often flick a ‘boar board’ upwards very quickly. The safest way to deal with 2 boars fighting is to wait until they ‘take a breather’ and then intervene with much noise and use of a strong stick and ‘boar board’.

Libido is a term used for the sex drive of an animal. Kunekunes are relatively placid and most boars don’t have a strong libido like other pig breeds. Don’t be fooled though – they still get the job done. Occasionally a Kunekune boar may have a strong libido, which can cause problems as he literally won’t leave the sow alone – he may have to be physically separated for the sake of the sow.

Some boars tend to show more enthusiasm than skill, mounting the head end or mounting the side of the sow rather than mounting correctly. Don’t intervene – you will merely put him off if you try to assist. A pragmatic approach is that he only has to get it right once to sire a litter! And don’t rely on a size difference for assuming a small boar can’t get a large sow in pig – there are plenty of examples of a sow that unexpectedly got in pig.

During mating the boar will often stay on top of the sow for a period of time once the ejaculation of semen has taken place. During this time the boar’s penis is still inserted in the sow’s vagina so that the tip of the penis (which is shaped like a corkscrew to fit into the spiral shaped cervix of the sow) is ‘holding’ the semen in to increase the chances of some of the semen travelling up the uterine horns to fuse with any eggs that have been ovulated. Because the boar will tend to stay on top of the sow for a little while this can cause the sow to collapse if the weight of the boar is too heavy for her. A sow that is unsound in the back or hindquarters may find mating too painful and so will refuse to stand for a mating. Likewise, a boar that has problems with his hindquarters or is lame in a hind leg will have difficulty performing a mating.

Infertility can occur in boars through a variety of reasons. The testicles are placed on the outside of the body so that they are maintained at a temperature that is lower than the normal body temperature. Thus any condition that increases the temperature that the testicles are at will reduce the fertility of the semen produced. A generalised illness can cause a boar to be temporarily infertile for 6 weeks or more. Excessive hot weather can also raise the temperature of the testicles and so cause a temporary ‘summer infertility’. An infection in a testicle or epididymis (collecting area for the sperm) can cause a permanent infertility. Boars also reduce in fertility as they get older, and once past 8 to10 years of age may not be reliably fertile.