How many ways are there to breed sows? Introduction to common breeding methods
What are the methods of breeding sows, and how many breeding methods are there for sows?
(1) Semen collection method: First train the boar to mount a dummy sow. At the beginning, apply sow urine or sow secretions on the dummy sow, and some also smear boar semen, etc. This induces the boar and can make the boar become excited. While sniffing around the dummy sow, the boar circles back and forth and temporarily mounts the dummy sow to perform mating movements. When the boar begins to have mating movements, the semen collector should stand at the left (right) rear side of the dummy sow, hold the artificial vagina with the right hand, and hold the head of the erect penis with the left hand, inserting it into the artificial vagina. After the penis is inserted into the artificial vagina, the front part of the penis is clamped by the narrow part of the artificial vagina. The right thumb, index finger and middle finger grip the first and second folds of the spiral part of the penis and apply forced pressure, and the penis then elongates. The left hand leaves the artificial vagina and holds the semen collection bottle, while the right hand continues to press the front end of the penis as before. The pressure of the hand should not be too great; it should be limited to controlling the boar's penis so that it does not slip out of the artificial vagina, and it should have a rhythm of looseness and tightness to stimulate ejaculation. When the boar is fully excited and the glans twitches repeatedly, it indicates that ejaculation is about to occur. During ejaculation, do not release the hand, otherwise reduced pressure will lead to interruption of ejaculation.
For young boars that have not been trained for artificial insemination, a sow in initial estrus or a sow not in estrus can be restrained and allowed to be mounted by the boar. Collect semen with an artificial vagina 2~3 times, then train again using a dummy sow. After the boar finishes ejaculating, collect the semen well in a 300~500 ml wide-mouth bottle, and take care to keep the inside of the wide-mouth bottle clean and sterilized. When the temperature changes drastically, sperm motility decreases significantly. Therefore, in cold seasons when the temperature drops below 15°C, placing the semen bottle in a container with warm water at about 38°C can prevent the semen temperature from continuing to drop.
(2) Ejaculation state: The average ejaculation time is 6~7 minutes, the shortest is 2 minutes, and the longest is 23 minutes. During the ejaculation process, what is first discharged is almost colorless liquid with a small amount of urine, followed by thick semen, that is, true semen. Semen consists of two parts, liquid and gelatinous material. In the first half of ejaculation, most of the thicker semen is discharged, after which there is a trend of gradual decrease. The sperm count in the semen is highest within 2 minutes after the start of ejaculation, averaging 82% of the total sperm count. The gelatinous material unique to boar semen is secreted by the bulbourethral glands and is discharged during ejaculation. The total number of gelatinous masses discharged in one ejaculation is 382~1833, averaging 909.
(3) Semen preservation: After semen collection, immediately filter out the gelatinous material with clean gauze, and preserve the raw semen. Put the preserved semen into a pre-sterilized narrow-mouth bottle with a stopper, cover it tightly, and suspend it in a thermos bottle at 15~20°C. When collecting semen in warm seasons, if insemination is performed the same day, special heat preservation treatment is not necessary. In summer, when ice is not easy to find, it can be suspended in a suitable well and stored in a cool place. When preserving semen, the temperature should be made to drop slowly, and sudden changes must be avoided. The suitable temperature for preserving semen is 15~20°C. At this temperature, sperm can generally survive 5~7 days, and within two days they have fertilizing ability. Semen preservation should also avoid direct sunlight, and care should be taken not to mix in water when taking it out or putting it in, and to prevent shaking during transport. If semen is collected and used for insemination the same day, raw semen is generally used for insemination. If dilution is needed, usually 5%~6% glucose solution, 10% sucrose solution or 0.9% physiological saline is used. Semen should be diluted before use, and must not be preserved after dilution.
After semen collection, if it is left standing for a period of time, the sperm layer and semen layer will separate. After several hours the sperm appear in a suspended-animation state. Usually after shaking at 38°C for 2 hours they can recover to their original motile state, but the motility of such sperm must be checked under a microscope. Insemination after recovery of motility will not affect conception.
(4) Insemination method: First wash the injector (insemination tube) clean, then draw in semen, point the top upward, expel the air, and fill the injector with semen so that there are no gaps. If the sow is in estrus at the right time but cannot be restrained well, and the operation is affected by the sow's movement, the tip of its nose must be restrained before insemination, and at the same time the sow's vulva should be wiped clean before insemination.
When injecting, first open the labia with the left hand, and hold the injector with the right hand to insert it directly into the vagina. When inserting 15~20 cm, tilt the top of the injector slightly upward to prevent the front end of the glass tube from injuring the external urethral opening. Then, return the injector to the horizontal direction and insert it while gently rotating it. When inserted 25~30 cm, resistance can be felt at the top of the injector. At this time, move it further left and right and push the injector; when the small glass tube at the front enters the fold of the uterus, sensitivity is obtained.
At this time it can be considered that the position of the two hard folds has been reached, then connect the syringe containing semen and slowly inject the semen. If the front end of the injector is blocked by mucous membrane, the semen may flow back. At this time, rotate the injector left and right and try slightly changing the position, and then all the semen can be injected. In addition, when the feeling in the boar uterus cervix is not obvious, as long as the injected semen does not flow out, insemination can generally be considered successful.
(5) Semen input and conception rate: In order to achieve conception, a sufficient amount of semen must be input. Usually about 50 ml. When the preservation time is short (within 24 hours) and the sperm count is high, using 30 ml can also achieve good results. In semen preserved within 24 hours, the sperm count is about 5 billion, and above 24 hours about 7 billion gives a good conception rate. Sperm motility is required to be above 70 points, and the semen dilution ratio is 2~3 times. The suitable period for insemination in pigs is 10~26 hours after the boar is allowed to mount. Compared with natural mating, artificial insemination with semen preserved within 24 hours shows little difference in conception rate. However, under usual conditions, it is not necessarily always superior to natural mating, so it is necessary to improvetechnologylevel; if thetechnologyis proficient, the conception rate can reach more than 90%.
(6) Preservation and utilization of frozen semen: For artificial insemination, the ideal semen should be semen with high sperm concentration, vigorous motility, and high survival rate and conception rate. When boar semen is frozen in liquid nitrogen at -196°C, the sperm survival rate and motility after long-term preservation for 500~600 days show almost no change, and semen preserved for 154 days can produce conception.
Frozen semen has the following advantages:
① It can improve the utilization efficiency of boars of superior breeds;
② It can make long-term preservation of semen, long-distance transport and international semen exchange relatively easy;
③ It can adjust the estrous period of sows and be effectively applied to piglet production adjustment, etc.;
④ It can make the establishment of a sperm bank possible.
(7) Semen diluents: Semen diluents have the functions of preventing changes in temperature and pH value, increasing semen volume, providing nutrients for sperm and inhibiting bacterial growth. Most diluents are composed of glucose, electrolytes, buffers and antibiotics.
There are many preparation methods for boar semen diluents, and the formulas include the following:
A. Milk powder diluent: milk powder 9 g, distilled water 100 ml.
B. Glucose-citrate diluent: glucose 5 g, sodium citrate 0.5 g, distilled water 100 ml.
C. "Kafu" diluent: glucose 6 g, sodium citrate 0.35 g, sodium bicarbonate 0.12 g, sodium ethylenediaminetetraacetate 0.37 g, penicillin 30,000 international units, streptomycin 100,000 international units, distilled water 100 ml.
D. Amino yolk solution: aminoacetic acid 3 g, distilled water 100 ml, prepared as a base solution; 70 ml of the base solution plus 30 ml of egg yolk.
E. Glucose-citrate-EDTA solution: glucose 5 g, sodium citrate 0.3 g, ethylenediaminetetraacetic acid 0.1 g, distilled water 100 ml.
F. Glucose-citrate-bicarbonate-EDTA-yolk solution: glucose 5.1 g, sodium citrate 0.18 g, sodium bicarbonate 0.05 g, ethylenediaminetetraacetic acid 0.16 g, distilled water 100 ml, prepared as a base solution; 97 ml of the base solution plus 3 ml of egg yolk.
For the above several diluents, except for "Kafu", the antibiotic dosage is 1,000 international units of penicillin per ml and 1,000 micrograms of streptomycin.
Preparation of 3 commonly used diluents abroad:
A. BL-1 solution (United States): glucose 2.9%, sodium citrate 1%, sodium bicarbonate 0.2%, potassium chloride 0.03%, penicillin 1,000 international units/ml, dihydrostreptomycin 0.01%.
B. IVT solution (United Kingdom): glucose 0.3 g, sodium citrate 2 g, sodium bicarbonate 0.21 g, potassium chloride 0.04 g, sulfanilic acid 0.3 g, distilled water 100 ml. After mixing, heat to dissolve fully; after cooling, pass in carbon dioxide for about 20 minutes to bring the pH value to 6.5.
C. Milk powder-glucose solution (Japan): skim milk powder 3.0 g, glucose 9 g, sodium bicarbonate 0.24 g, a-amino-p-toluenesulfonamide hydrochloride 0.2 g, sulfamerazine sodium 0.4 g, sterilized distilled water 200 ml.