Practical Techniques and Key Operating Points for Artificial Insemination in Pig Farming

Now many farms are raising pigs, as the economic benefits are relatively high and market sales are fairly stable. Breeding first requires mating, so what are the techniques for artificial insemination in pig farming?

1. Identifying estrus is the first hurdle

Based on the sow's behavior and changes in the reproductive organs, estrus symptoms can be divided into 3 stages.

1. Early estrus: The sow appears restless, has reduced appetite, grunts, mounts other sows, the vulva swells, and the vaginal mucosa is light red, but she does not accept mounting by a boar. This stage lasts 12 to 36 hours.

2. Mid-estrus: The sow continues to appear restless, with severely reduced or completely lost appetite, sometimes standing still with both ears quivering, sometimes following and mounting other sows. The vulva is swollen, the vaginal mucosa is dark red, and the mucus is thin and transparent. She is willing to accept mounting and mating by a boar and shows the standing reflex! This stage lasts 6-36 hours and is the best period for insemination.

3. Late estrus: The sow tends to become calm, the vulva begins to contract, the vaginal mucosa is light purple, the mucus is thick, and she is unwilling to accept mounting by a boar. This stage lasts 12-24 hours.

2. Key points of manual operation

Before insemination, the operator should wash their hands and rinse the boiled and sterilized insemination equipment (a 30-50 ml glass syringe and an insemination rubber tube) once with a small amount of diluent. Raise the temperature of the semen to 35-38°C at a rate of 1°C per 2 minutes; disinfect the sow's vulva with a 0.1% potassium permanganate solution.

Then, with one hand open the sow's vulva, and with the other hand hold the insemination tube and insert it into the vagina, first advancing about 10 cm diagonally upward, then advancing about 30 cm horizontally. When you feel it can no longer be advanced, this indicates that the insemination tube has been inserted into the cervix, and the semen can then be slowly injected. If backflow of semen occurs, pause the injection, move the insemination tube a little, and then inject again until finished, then slowly withdraw the insemination rubber tube.

3. Grasp the “heat” to ensure “high yield”

Generally, sows begin ovulation 24-36 hours after estrus, ovulation lasts 10-15 hours, and the eggs released maintain fertility for 8-12 hours. Sperm maintain fertility in the sow's reproductive organs for 10-20 hours, and after mating it takes 2-3 hours for sperm to reach the fertilization site (the ampulla of the fallopian tube).

Based on this calculation, the suitable time for mating or insemination is 20-30 hours after the sow enters estrus. If mating is too early, the sperm will have lost fertility by the time the eggs are released; if mating is too late, the eggs will have lost fertility by the time the sperm enter the sow's reproductive tract. Both will affect the conception rate, and even if fertilization occurs, the zygote may die midway because of weak viability. However, in production practice, it is generally impossible to determine the exact time of estrus and of willingness to accept mounting by a boar.

Therefore, in production practice, as long as the sow can accept mounting by a boar (which can be judged by the back-pressure reflex or by boar teasing), the first mating is carried out. After the first mating, a second mating is carried out 12-20 hours later. Generally, mating twice within one estrus period is sufficient; more matings cannot increase the litter size and may even have side effects. The key is to grasp the suitable time for mating. To accurately determine the suitable mating time, a teaser boar should be used twice a day, morning and evening, to test the sow to be mated (or the back-pressure reflex should be used).

During mating, careful management by the staff is required, and no mistakes should occur, so as not to affect the next generation.