What are the estrus induction programs for open (non-pregnant) sows in batch production?

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2 An experienced breeding supervisor carefully observes, touches, stimulates and feels each sow (specifically weaned open sows) from behind, one by one.

A. Observe the sow's expression: dull expression

Changes in the vulva: redness and swelling, mucus.

B. Touch the sow's vulva: warm, moist.

C. Massage the vulva with the hand, press the back, ride the sow, and rub the udder with the foot to stimulate.

D. Sense the sow's estrus signs: standing still and mucus.

VII. Estrus induction program for weaned sows

1. 0-3 days after weaning: put them in large pens; drive a boar in once each morning and afternoon for stimulation.

2. 4-7 days after weaning: move to gestation stalls; drive the boar to walk in front of the sow stalls every day, with artificial stimulation: back pressure, vulva massage, udder massage.

3. 8-10 days after weaning: swap and intermix the sows among the gestation stalls; drive the boar to walk in front of the sow stalls every day, with artificial stimulation: back pressure, vulva massage, udder massage.

4. 11-13 days after weaning: move to gestation stalls in the open-sow area; drive the boar to walk in front of the sow stalls every day, with artificial stimulation: back pressure, vulva massage, udder massage, and at the same time: increase feed (supplementary feeding) or reduce feed (starvation). On day 11, intramuscular injection of D-cloprostenol sodium

5. 14-21 days after weaning: swap and intermix the sows among the gestation stalls in the open-sow area; drive the boar to walk in front of the sow stalls every day, with artificial stimulation: back pressure, vulva massage, udder massage, and at the same time: increase feed (supplementary feeding) or reduce feed (starvation). On day 14 and day 21, intramuscular injection of PG600.

6. 21-30 days after weaning: move to large pens for sows to be culled; drive the boar into the large pen for 5-10 minutes of stimulation every day, with artificial stimulation: back pressure, vulva massage, udder massage, and at the same time: increase feed (supplementary feeding) or reduce feed (starvation), and supplement with green, succulent feed; drive them outdoors for exercise and sunlight.

7. Sows still not in estrus more than 30 days after weaning: cull.

Notes:

1. The required figures differ across the 6 different stages.

2. After stages 2-5, apart from injection of D-cloprostenol sodium, the other measures in the estrus induction program can be used simultaneously.

3. The figures for stage 6 are derived from the normal days to estrus after weaning in sows (5-7 days) and the estrous cycle (18-24 days).

VIII. Specific operations of estrus induction methods for weaned sows

1. Boar patrol for estrus induction

Drive the boar to walk slowly in front of the stalls, pausing for 10-20 seconds in front of each open sow's stall, so that each sow and the boar can make contact; by no means let the boar run around randomly;

2. Artificial stimulation

Massage the vulva with the hand, kneel with both legs behind the sow's hindquarters, press the hindquarters with the knees, and press the back with both hands; mount the sow's back and gently rub the sow's udder with both feet. During artificial stimulation, the effect is best when the sow shows forward and backward movement, jumping around and squealing.

Diagram of the body parts that respond to stimulation during estrus induction

3. Moving/swapping stalls

Move gilts compactly into gestation stalls, as this facilitates estrus checking and estrus induction; frequently swap open sows with each other, and it is best to move estrus sows next to anestrous sows, using the estrus sow's restlessness, bar-biting and biting of neighbouring sows to stimulate the neighbouring sows into estrus; by no means leave open sows forgotten in a corner;

4. Driving into large pens for stimulation

Drive 5-6 open sows into each large pen, drive the boar in twice a day, morning and afternoon, for estrus induction, stimulating for 5-10 minutes in each large pen; the boar stimulates the sows into estrus by mounting, nuzzling their abdomen and licking the vulva, which can also stimulate and maintain the boar's vigorous libido. It is even better to manually press the sow's back at the same time as the boar induces estrus;

Estrus induction in large pens can also stimulate sows into estrus by increasing their exercise and through mutual nuzzling and fighting among the sows;

5. Changing feed intake

Reduce feed appropriately for overly fat sows, increase feed appropriately for thin ones, and supplement with green, succulent feed;

6. Outdoor exercise and sunlight

On sunny mornings or afternoons, when the outdoor temperature is 18-28°C and direct sunlight is best avoided, drive the open sows (more than 10 head) outdoors for exercise; sunlight exposure stimulates hormone secretion in sows to promote estrus, mutual nuzzling, fighting and mounting among sows can stimulate estrus, and sows rooting in the ground and eating miscellaneous feed outdoors can also stimulate estrus;

7. Drug-induced estrus

D-cloprostenol sodium can stimulate the regression and dissolution of persistent corpus luteum in sows and promote estrus in sows;

8. Maintaining the boar's libido

A boar with good libido plays a vital role in inducing estrus in sows; when driven into a large pen for stimulation, the boar can maintain vigorous libido through the stimulation of the sows, and the boar can also be stimulated once a week by natural mating.