How to Farm Pigs: Breeding

This guide from the FAO provides small scale or backyard farmers information on how best to breed your pigs.
calendar icon 6 August 2020
clock icon 23 minute read

Editor’s note: The content on this page was written specifically for farmers in Nepal. While much of the information will be applicable elsewhere, please be aware that every country has its own rules regarding feeding animals, e.g. food waste. You must ensure your practices are in line with official regulations in your own region.


Mating purebred individuals of the same breed. The progeny has the same genetic makeup. The major objective of pure-breeding is to identify and propagate superior genes for use in commercial production primarily in crossbreeding programs as well as to propagate and identify superior females for maintaining valuable genetic material. Furthermore crossbreeding will not be worthwhile unless superior pure bred individuals are used.

Out breeding

Mating individuals of the same breed but who are less closely related than the average of the breed. There should not be a common ancestor for at least four generation back in the pedigree of the boar and the females with which he is mated. It is a useful mating system in purebred individuals.

In breeding

Mating between individuals of the same breed but which are more closely related than the average of the breed. This could be between as close individuals as full sibs or sire – daughter, mother - son. Pure breeding is a special kind of in-breeding. The effect of inbreeding is the concentration of common genes in the offspring. This high frequency of homozygous gene pairs applies to both desirable and undesirable traits. Many undesirable traits e.g. hernia and cryptorchidism involve recessive genes thus inbreeding perpetuates their expression phenotypically. In breeding causes decrease in litter size and increases mortality. Inbred sows are
inferior in milking and mothering ability. It delays sexual maturity in gilts and boars. Inbred boars have less sexual libido. Inbred gilts have fewer eggs during oestrus and farrow smaller litters than those out bred.

Effect of In-Breeding

  • Sow with newly borne litters about 12 piglets.
  • Male and Female piglets taken by another farmers to his home.
  • Breeding between the same siblings.
  • Female giving birth about 9 piglets
  • About 25 % less no of smaller and weak piglets are born as compared with first sow and some of them were borne dead
  • Male and Female piglet taken by another farmers to his home
  • Breeding between the same siblings about six piglets.
  • About 50 % less no of vey smaller and weak piglets born as compared with the first sow, some of them were borne dead

Cross breeding

Mating two individuals from different breeds thus introducing into the progeny a gene combination that is different from that existing in either parent or in the breed of either parent. Cross breeding can involve two or more breeds, depending on the desired result. The sole purpose of cross breeding is to take advantage of the observed improvement in performance of the progeny above that of either parent- hybrid vigour or heterosis.

Methods of cross breeding

1. Cross Breeding Between Unidentified Breeds

2. Cross Breeding Between Unidentified Breeds

Effect of Cross Breeding

  • Local sow with her piglets
  • Exotic sow with her piglets
  • Female piglet from local sow and Male piglet from exotic sow are taken by a farmer to his home for breeding propose
  • Breeding between these male and female pig
  • Healthy and bigger body size piglets are born from the local sow
  • All male piglets are sold and few selected crossed bread female are kept for breeding
  • Another exotic male which is not in relation with the herd introduced for breeding.
  • Breeding between them
  • Very healthy, strong, active and fast growing piglets are born

Effect of Negative Selection

  • Sow with newly borne litters about 12 piglets.
  • Stronger and healthy piglets were either sold or castrated for meat purpose
  • Smaller and weak Male and Female piglets kept for breeding purpose.
  • Breeding between the same siblings.
  • Female giving birth about 9 piglets
  • About 25 % less no of smaller and weak piglets are born as compared with first sow and some of them were borne dead
  • Among the piglets stronger and healthy either sold for cash or castrated formeat and smaller and weak are kept for breeding purpose.
  • Breeding between the same siblings about 6 piglets.
  • About 50 % less, smaller and weak piglets born as compared with the first sow, some of them will borne dead.

Best Breeding Practices to be Adopted in the Villages

Best pig breeding pruchees adapted in the villagee. ( Breeding boar exchange
between villages / farmers grops.)

Selection of Breeding Gilt

It is extremely important to select a good boar since it contributes half the quality of the herd. Areas to be consider while selecting breeding gilts:

  • Gilts selected to have at least 12 teats so as to accommodate a large litter
  • Gilts to be selected from sows, which wean 9 -10 or more piglets per litter and are known to be good mothers and first farrowing at one year of age and farrowing interval of seven month.
  • Select breeding gilts at weaning period, further selection should be done 5-6 months of age.
  • Select fast growing weaners. These will likely consume less feed per unit live weight gain. Thus less costly to keep.
  • Select gilts which have developed hams and comparatively light heads.
  • The selected gilts should have good body confirmation i.e. strong legs, sound feet etc.
  • Gilt should not select for breeding purpose having supernumerary and inverted teats, and fat deposited at the base of the teats
  • Gilt must be at least 8 months old at first service

Heat detection - Common signs of heat

1st stage: Early heat signs

  • General restlessness
  • Vulva turns red and is swollen
  • White mucus discharge

2nd stage: Service period signs

  • Real Oestrus lasts for 40 - 60 hours
  • Vulva becomes less red and swollen
  • Slimy mucus discharge
  • Tendency to mount and be mounted by others.
  • The sow or gilt will stand still when pressure is applied to her back (can accept a man's weight sitting on her. Thus the right stage to send her to the boar).

3rd stage: Post oestrus-period signs

  • The sow/gilt will not stand still when pressure is applied to her back.
  • The swelling of the vulva disappears.

How to induce heat - Recommended practices

After farrowing, a sow may be slow to come into heat. Here are a few methods used by farmers to induce heat:

  • Gently stroke the sow’s vagina with a freshly cut papaya stalk every morning for 3-5 days.
  • Spray the sow’s (or gilt’s) pen with boar urine every morning for 3-5 days.
  • Grind 1 kg of fresh or dried lotus (Semen nelumbinis) seeds. Mix with 20 kg of dry feed. Feed to the sow twice a day for 5-7 days.
  • Bring the sow to the boar, or place the sow in a pen next to the boar.
  • Put the sow with the boar for a short period every day when the heat is expected.
  • Always take the sow to the boar. This is less upsetting for him.
  • Put the sow and boar together just before feeding.
  • During her 24-hour pick heat period allow the boar to serve twice, with an interval of about 12-14 hour intervals between services. Do not mate animals during the hot time of day.
  • If the sow doesn't conceive, she will return on heat again in about 3-week's time.
  • 10 days before service, give the sow/gilt 1 - 2 kg of feed extra per day. Continue this for one week after service.
  • During the last month of pregnancy, give 0.5 kg extra feed per day but decrease this gradually one week before farrowing. Provide plenty of water to help prevent congested gut during farrowing.
  • Each boar should be kept in its own pen to avoid fighting. For mating, the sow is taken to the boar.

Stimulating regular heat

  • Remove the sow from the piglets early (at 4 - 6 weeks of age) and all at once.
  • Take the sow to a house with dry sows.
  • Put the sow close to a boar, in a way that makes direct contact (hear , see, smell) possible.
  • The sow should not be given any feed on the day of weaning.
  • The next day feed about 4 kg/day. This is called flushing and should be done for a maximum of 10 days or until the service takes place.
  • Put the sows in groups (stress stimulates heat)
  • If there are heat problems, change the type of feed for a few days.
  • Maintain a good climate; see to it that there is sufficient light in the house.
  • Sows should not be too fat or too thin when they are served. It is important to keep this in mind when determining the ration during the suckling period.

When sow is in gestation

  • after 21 days of serving she does not show heat signs
  • Echo scan pregnancy detection 23 - 35 days, positive results


  • Sows that are difficult to get in-pig (pregnant) which only manage to rear small litters should be sold off.
  • Boars which are infertile or moderately infertile should be culled


  • Young boars may need assistance in lining up their mate. Make sure your hands and wrists are clean and your fingernails are trimmed.
  • Pigs mate slowly. The boar may take a minute or more to reach the point of ejaculation.
  • To improve conception: Crush 1 kg of Semen nelumbinis (lotus) seed and mix with the sow’s feed. Give 2 times per day for 3-5 days.
  • Fat sows may have difficulty conceiving. Therefore, if a sow is too fat, reduce her feed.

Reasons for not conceiving

  • The sow is too fat.
  • It is the animal’s first heat cycle.
  • The boar is too young.
  • The boar is overworked (used for more than five matings a week).

Care and Management of Breeding Boar

  • High priority should be given to the management of animals newly introduced into the breeding herd to achieve maximum reproductive efficiency. Good reproductive and nutritional management pays dividends through an increased number of pigs farrowed live and weaned. The following boar and gilt management practices will assist in the maximization of fertility and longevity.
  • Upon completion of test, boars should be fed at a level of energy that will prevent excessive fat deposition. This practice should help ensure that they are physically adept and sexually active. Nutrients other than energy should be provided to meet the minimum daily recommended allowance of the National Research Council. See Appendix A for details.
  • Boars tested individually or in small groups in close confinement should be managed upon completion of the test in a manner to develop physical hardening and to stimulate sexual arousal and libido. Where possible, this should be done before delivery to their new owners and might include the following: a) Shifting boars to different locations. b) Providing fence-line contact with cycling females. This may be especially important where the aggressiveness of the boars precludes mixing them together.
  • Although boars tested in large groups and in less confined settings are likely to require less physical conditioning and sexual stimulation before use, they may also benefit from exposure to the management procedures described for boars reared in close confinement.

Care and Management of Breeding Boar

  • To be evaluated for reproductive soundness, boars should be at least 7 1/2 months of age. The evaluation should be completed before the breeding period so problem boars can be identified and culled. Boars should be evaluated on the following criteria.
  • Mating behavior may be evaluated by bringing a gilt in standing heat into the boar's pen and observing the following:
  • Libido: Observe the boar's aggressiveness and desire to mate. Boars may need assistance through at least one mating experience.
  • Mounting: Boars must have the ability to mount correctly. Some boars may be interested in mounting but lameness, arthritis, or injury may prevent success. Boars that mount the front end of gilt should be gently moved to the proper position.
  • Mating: Observe the boar's ability to erect the penis and properly enter the gilt. Examine the boar's penis for normal size and condition. Penis abnormalities encountered occasionally are: (1) adhered or tied penis, (2) limp penis, (3) infantile penis, and (4) coiling of the penis in the diverticulum.
  • These conditions may be heritable, and boars exhibiting these problems should not be used to produce breeding stock.
  • Semen. A few boars fail to produce sperm cells. Hence, semen from young boars should be submitted to a check. The simplest way to collect semen from a boar is to allow the boar to mount a gilt in standing heat. First place a rubber glove (latex) on one hand and after the boar begins to extend his penis, grasp firmly the corkscrew end of his penis and bring the penis gradually forward once extended ejaculation begins. Collect the entire ejaculate into a wide-mouth container covered with a double layer of cheesecloth to separate the gel fraction. The volume of semen obtained is quite variable between boars but averages generally between 200-250 milliliters (about 1 cup). If the sperm concentra ion is high, the semen will be milky in appearance. Boars with watery or bloody semen should be evaluated by a reproduction specialist. Usually 70 to 80 percent of the sperm should be motile immediately after collection. Low sperm motility is not a serious matter unless the condition persists for several months. Boars that produce semen with no sperm or only a few sperm should be rechecked several times at weekly intervals. If the condition persists, the boar should be culled. The first ejaculate of a new boar may not provide an accurate test and should not be used for evaluation.
  • Test Mating. To complete the soundness evaluation, two or three gilts should be bred and carefully checked as to whether they return to estrus within 4 weeks. Exposure to conditions or microorganisms on the new farm may have produced temporary infertility. High environmental temperatures, stress of transportation, illness, lameness, or injuries causing high body temperature can alter sperm motility and reduce fertility for up to 8 weeks.

Care and Management of Breeding Sow

  • At the end of the test, energy intake of selected gilts should be restricted to prevent overweight conditions. Nutrients other than energy should be provided to meet the minimum daily recommended allowances of the National Research Council (Appendix A).
  • Moving gilts to new pens, increased exercise, and daily exposure to boars beginning between 160 and 180 days of age will help stimulate the onset of estrus. Breeding should be delayed until the second or third estrus to increase the probability of large litters and prevent dystocia. Gilts that do not conceive after mating at two estrous periods should be marketed. Likewise, gilts that have not expressed heat by 9 months of age should be culled. During gestation, gilts should be fed to gain about 75 lb and not become overly fat.

Minimum Breeding Ages for Boars and Gilts

In order for the seed stock producer to measure performance to acceptable off test weights, delivery of boars and gilts to the buyer is seldom earlier than 5.5 months of age. Sexual maturity and reproductive performance also are highly age dependent. The minimum age for successful breeding in boars is 7.5 months. Gilts should be bred on the second or third heat to take advantage of the expected increase in ovulation rate that usually occurs following puberty.

Further Reading

You can view the full FAO Farmer's Hand Book on Pig Production by clicking here.

© 2000 - 2023 - Global Ag Media. All Rights Reserved | No part of this site may be reproduced without permission.