Reproduction In Pig – Swine Reproduction system for Small and Medium Scale
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Sexual Maturity: This is the age that boar and sow can mate and successful fertilization can take place.
Sexual Maturity in Sow: The sexual maturity for young git/sow is about six months of age. Early mating should be discouraged. This is because it may result in reduction of litter size, Inability to carry the pregnancy, Still birth, poor mothering skills, ect. Young gilt-sow could be serviced as from eight months of age.
Sexual Maturity of Boar: Boar could be used for servicing between 8 and 10 months of age. Boar should not be too heavy for the sow. Heavy boar should be used for servicing heavy sow. A boar can service 5 to 15 sow. It is advisable not to use a boar of more then 5 years for breeding purpose. A boar at early stage should be used once or twice in a week while at older age it can be used 3 to 5 times in a week. The boar should be allowed to rest after servicing.
Factor affecting sexual mexual maturity:
- Feeding regime.
- Health status.
- Management practices.
- Environmental factors.
Oestrous Cycle: This is a rhythmic cycle occurring in female mature pig (sow) in the absence of pregnancy. Oestrous cycle in sow is usually around every 20 days or 3 weeks. The cycle can be divided into;
(i) Follicular phase
(ii) Oestrous phase
(iii) Luteal phase and
(iv) Regression phase
Follicular phase: The grafian follicles grow in the ovary which secrectes hormone (Oestradiol) causing the uterine lining (endometrium) to proliferate and thicken.
Oestrous phase: It is otherwise called heat period. The lining of uterus thickens and ovulation occurs during this period. If mating occurs during this period, it will result into pregnancy, the fertilized egg becomes implanted to the uterine well as embryo.
Luteal phase (Metoestrus): A corpus luteum is formed from the follicle and secretes progesterone which stimulates the uterus to prepare for implantation and causes the mammary glands to produce milk after bith of the young and inhibits ovulation.
Regression phase (Dioestrus): The corpus luteum and endometrium diminish, ovarian hormone level falls and a new follicle begins to start the next full cycle.
How to Know when pig (swine) is on Heat Period
Heat Period: This is the period of sexual receptivity that sow is ready to accept the male. It must be noted that the sow will not accept the boar if she is not on heat.
Signs of Heat:
- Redness and swelling of the vulva.
- Mounting of sow by other sows in the pen.
- Ability to accept the boar without stress.
- The sow will stand, ‘immovable’ while the boar mount her.
Lectating Sow do not come on heat while still breast feeding. She will come on heat after one or two weeks after the piglets have been weaned.
Mating: This is the process when the boar mounts the sow during heat period to induce semen through the penis to the ova via the vagina and oviduct. A successful mating takes place when the spermatozoa fertilizes the ova. Mating could be done in the morning or late in the evening.
The Oestrous should be checked after three weeks in order to detect whether the sow is pregnant or not. It must be noted that on no account should heavy boar be used to service young or light gilt.
Mating of Sow/Gilts:
- Begin to mate gilts once they attain an age of 8 to 10 months.
- For the sow, use the dry sows for mating exercise.
- Young boars can be used for mating as from 12 months of age.
- Before mating, ensure that the animal are on heat.
- Signs of heat to watch include: restlessness, nervousness, mucous discharge from the vulva, swollen red vulva, mounting of one another, ect.
- Once the animal are on eat, mate them but ensure that the exercise is carried out during the cool period of the day.
- The mating procedure is taken the sow/gilt to the boar and ensure that the mating takes place.
- Repeat mating exercise 12 hours after the first one.
Reasons for mating during cool period of the day are:
- To preserve the quality of the semen.
- To reduce sperm mortality.
- To maintain good conception rate.
Note that you can use one boar to mate about ten sow. Young boars can be used for 2 to 3 matings in a week. while the older boars can be used for 3 to 5 mating in a week. Keep adequate record e.g. Date of mating, the boar used, ect.
Additional Points to Note:
- Mate only mature sows.
- Watch for signs of heat before mating.
- Mate during the cool period of the day.
- Keep proper record.
Fluching: The gilt or sow and boar to be mated are given extra rich proteinous feed of about 16 to 18% crude protein in order to build up strengh for the boar and increase the litter size of the sow.
Advantages of Flushing:
- It gives more strenght to the boar during mating.
- It keeps the boar and sow to be in healthty satge.
- It may increases the potential litter size of the sow.
- Both the boar and sow becomes more active.
- Strong and active spermatoza ere released to fertilize the ova.
- After ejeculation, the boar become strenghened again.
- It gives strengh to the sow to carry the pregnancy at early stage.
Pregnancy: This is the process of development of embroyo. It is the period between fertilization of the eggs to the time the sow farrows (give birth to the young onces or piglets).
How to detect pregnancy in Sow:
- The sow will not come on heat.
- The sow will not accept the boar.
- The sow may not be active as before.
- The teat will be more pronounced.
- There will be increase in weight under normal circumstances.
- There will be protrusion of delly.
Sterility:This is the failure of spermatozoa to fertilize any of the ova shed at one heart period.
Causes of Sterility:
- If the sow fails to come on heat; this could be as a result of averfeeding, under feeding, poor management parctices and disease, ect.
- If the sow come on heat but fail to ovulate.
- Destruction of sperm due to inlammatory changes.
- Insufficient or defective sperm after ejaculation.
- Ineffective service by the boar (insertion of penis to rectum instead of vagina).
- If the boar refuses to serve which could be as a result of inflammation of penis or sheath from disease or accident.
- Inability of sow to produce fertile eggs.
Management of Pregnant Sows and Gilts:
- Remove sows and gilts after successful mating to allow animals to rest and avoid disturbance by boar.
- The gestation period period for sows/gilts is around 112 to 116 days (3 months, 3weeks, 3 days).
- Feed pregnant sows/gilts with balanced ration rich in protein, vitamin, minerals and energy.
- Provide clean water for drinking and wallowing.
- When farrowing period is approaching, disinfect farrowing pen with disinfectant e.g. Lzal, Germicide or moriguade. etc.
- Take sow/gilt to the farrowing pen 2 weeks before farrowing.
- Keep proper record.
Preparation for Farrowing:
- Clean, wash and disinect the farrowing pen 2 weeks before introducing the pregnant sow to the farrowing pen.
- Separate pregnant sow into separate pen, 5 to 7 days to farrowing.
- Disinfect the sow/gilt with antiseptic taking particular interest in the teats.
- Provide water and feed.
- Provide wallow to reduce heat stress.
- Keep farrowing crates to prevent overlaying of sow on the piglets.
- Ensure a draught free farrowing pen.
Gestation Period: It refefers to the time of fertilization to the time of farrowing (delivery) or it could be called ‘Pregnancy Period‘. The gestation period ofor a pig is around 112 to 116 days.
Parturition or Farrowing: It is the act of given dirth to the young once in pig. During the latter part of pregnancy, the mammary glands begin to grow and develop. There is increase in size and development of the udder. During the last twenty-four hours to the parturition, the sow becomes restless, the vulva becomes swollen and red. The teats become turgid and a steam of milk can be drawn from them if they are squeezed. The latest sign to appear is labour pains. The hind legs are drawn up and the sow occasionally grunts. There may be slight discharge from the vulva.
- There is no standard form of parturition.
- The pigs may be expelled head first or tail.
- the membrane in the uterus ruptures and thrown off by the piglets.
- The umbilical cord if not broken should be removed by the attendant.
- Under normal cirumstances farrowing will be completed in 2 to 7 hours.
- After the last piglet has been expelled, the remaining after-birth is also expelled, the sow should not be encouraged to eat this.
Weight of Piglet at birth: The weight of piglet at birth varies between 0.8 – 2kg depending on:
- Breed type.
- Health staus of thr sow.
- Feeding management during pregnancy.
- Environmental factors.