Techniques for detecting estrus in sows and breeding them.

For all pig breeds, never breed them during their first estrus cycle, because their bodies are not yet fully developed, and the number of eggs released during the first estrus cycle is low... if bred, the number of piglets born will be low.

1. Estrous cycle in pigs

1.1. Age of first estrus in gilts

Different pig breeds have different ages at first estrus.

Native pig breeds like the Mong Cai pig reach estrus for the first time at 4-5 months of age, weighing 30-40 kg.

Crossbred pigs of foreign breeds with domestic breeds have a later age of first estrus compared to purebred domestic pigs. Female crossbred pigs of foreign breeds with domestic breeds such as F1 (Yorkshire x Mong Cai) and F1 (Landrace x Mong Cai) have their first estrus at 6 months of age, weighing 70-75 kg.

Foreign pig breeds typically reach their first estrus at 6-7 months of age, weighing 100-110 kg.

1.2. Estrous cycle in sows

The estrous cycle in sows is typically 21 days (ranging from 17 to 23 days). The estrus period usually lasts 3-4 days.

Sows will come into estrus again approximately 4-6 days after weaning.

2. Techniques for detecting estrus in sows

Detecting estrus in sows is the most important step in the breeding process.

Sows should be checked at least twice daily, with a 12-hour interval between checks. Estrus checks should be performed between 5-6 AM and 5-6 PM, as these are the times when estrus symptoms are most pronounced.

To accurately determine when a sow is in estrus, it is necessary to understand the estrus cycle and carefully observe the sow's behavior.

Signs of estrus in sows:

First day of estrus

The sow paced around, squealed, and tried to jump out of the pen; she ate less or stopped eating, and damaged the trough; if touched, she avoided or ran away. The vulva was swollen, reddish-pink, and shiny. A thin, clear, and non-sticky discharge flowed from the vulva.

Second day of estrus

In the morning, sows are calmer, squealing less, occasionally jumping onto the backs of other sows, but they don't stand still when another sow jumps onto their backs.

By afternoon, the vulva is less swollen, turning pale pink with faint wrinkles. The vaginal discharge has become sticky. To determine if the sow is receptive to the boar: use both hands to massage from the last row of teats up the sow's back, then press on the sow's back (if a boar is present, it's even better). When the sow stands still, with her ears perked up, in a ready position for mating, mating or artificial insemination is most effective at this time.

Third day of estrus

The lethargic state gradually subsides, and towards the end of the day, the sow becomes less inclined to be near the boar. The vulva gradually shrinks back to normal, and the discharge is minimal, cloudy white, and non-sticky.

The tail is tucked under the vulva.

3. Breeding techniques

3.1. First mating (mating gilts)

The necessary and sufficient conditions for breeding gilts are that they must have reached the required age and weight.

The age for first breeding for domestic sows is 7-7.5 months, and for crossbreds (foreign x domestic) and foreign breeds, it is 7.5-8 months. Suitable weight for breeding: Mong Cai pigs are 50-55 kg, crossbreds (Yorkshire/Landrace x Mong Cai) are 75-85 kg, and foreign breeds are 110-130 kg.

For all pig breeds, never breed them during their first estrus cycle, as their bodies are not yet fully developed, and the number of eggs released during the first estrus is low... if bred, the number of piglets born will be low. Breeding should only be done after the gilts have gone through 2 or 3 estrus cycles.

It is necessary to accurately determine the timing of sow incubation in gilts so that they can be inseminated immediately. Then, a second insemination should be performed approximately 12 hours after the first.

The mating date needs to be recorded in order to predict the sow's farrowing date.

3.2. Breeding for sows that have given birth from the second litter onwards

Sows typically return to estrus about 4-6 days after weaning. Careful monitoring and accurate identification of the exact time of estrus are necessary for preparing for breeding.

When lethargy is detected in sows, do not breed them immediately as with gilts, but breed them for the first time within 10-12 hours of detecting lethargy.

To prevent sows from giving birth to the wrong piglets, a second mating should be performed approximately 10-12 hours after the first mating.

It is necessary to record the mating date in order to predict the farrowing date of the sow.

Direct mating

Advantages: Easy to implement, no investment in breeding equipment required.

Disadvantages: It is labor-intensive to transport boars, there is a high risk of direct disease transmission from boars to sows, it is not possible to breed many sows at once, and good quality boars cannot be used due to the significant weight difference between boars and sows.

Artificial insemination

Advantages: Sows will receive semen from selected, high-quality boars, eliminating the need to transport boars, avoiding limitations on pig size differences, and one semen collection can be used to inseminate multiple sows.

Disadvantage: Requires trained personnel and equipment for artificial insemination.

Note: The boar used for artificial insemination must be healthy and have undergone semen quality testing.

Artificial insemination techniques

Intrauterine insemination techniques

Semen must be properly stored in a cool place (around 20°C), protected from light, and should not be shaken or vibrated vigorously. The semen container should be intact, free from cracks, and without bubbles. The steps for performing artificial insemination are as follows:

Prepare the insemination equipment, including: a semen collection device (bottle, bag), a catheter, and a semen ejection device (ball pump or syringe). Boil the insemination equipment in water for 15 minutes, drain, and let cool.

Clean the sow's vulva, gently stroke her back to keep her still. Apply Vaseline to the insemination duct and the sow's vulva.

Warm the semen to 35-37 degrees Celsius by holding the vial in your palm for a while.

According to the National Agricultural Extension Center