Slogan of scientific pig raising

1. What kind of sow should pig farmers choose to raise? (1) Evaluate the performance of varieties (strains) and individual traits of sows.

The performance requirements of sow varieties (strains) should pay more attention to their reproductive performance and adaptability to local feeding conditions, except that the lean meat rate reaches the standard of lean pigs and grows fast. In this respect, domestic cultivated varieties have obvious advantages, mainly as follows:

1, multiple nests;

2, sexual maturity is early, and estrus symptoms are obvious, such as making circles, climbing fences, climbing pigs in the same fence, swelling of vulva, etc., which are more obvious than imported varieties, which is very convenient for estrus identification and timely breeding in production. Can reduce mismating and improve reproductive efficiency;

3. For many farmers with poor feeding conditions, it is very important to be resistant to rough feeding and have strong adaptability. Due to the lack of this, the production performance of many imported varieties with excellent performance in China has seriously declined.

(two) comprehensive evaluation and selection from the physical appearance and related traits of sows.

1, sow external genitalia should have no obvious defects, such as vulvar stenosis or vulvar upturn;

2, the number of nipples is generally not less than 7 pairs, the nipple spacing is uniform, the nipple is well developed, and there are no invalid nipples such as blind nipples, inverted nipples and auxiliary nipples;

3, good health, well-developed structure, fast growth, prevention of small old pigs, no limb and hoof disease, easy to walk;

4. Estrus is early, generally not more than 6 months old;

5. gilts with excessive temper should not be used for planting;

6. Conditional people can use family data to genetically evaluate the main production performance of parents and siblings according to their production performance, such as reproductive performance.

Second, the management of sows in different stages. The nutritional requirements and feeding objectives of sows in different growth and production stages are different. Staged feeding method should be adopted to prepare staged sow feed. At the same time, in the continuous production process of sow production, each stage of sow affects each other and needs comprehensive consideration.

1. gilt

Generally speaking, sow selection starts from 25-30kg (of course, some traits such as nipple number at birth can be selected), and selection will be carried out after 60kg. The breeding of reserve sows plays a key and decisive role in the reproductive performance and service life of sows. Raising sows includes the following important objectives:

1. 1 lay a healthy foundation.

In order to make sows have a long service life, the health of sows is very important, which is the guarantee to exert their reproductive potential. Good intestinal development, stable intestinal microbial flora and enhanced immune function are the basis of growing sows.

1.2 Good bone development and body storage

Sows will carry a lot of weight during pregnancy, need strong bones and limbs, and need excessive nutrition during embryo growth and lactation, so it is necessary to create enough body storage for use. If the body storage capacity of reserve sows is small, the service life of sows is short and the elimination rate is high (Young et al., 199 1).

1.3 Reasonable growth rate

Different from growing-finishing pigs, gilts not only need to ensure high body storage of special nutrients, but also need to consider their physiological maturity age. Therefore, when their weight reaches about 100kg, it is generally necessary to limit it to two weeks before mating to improve the service life of sows (Boyd et al., 2000). Feeding with water 2 weeks before mating is beneficial to increase the number of ovulation.

1.4 Breast development is good.

Breast development is very important to sow lactation in the future and to ensure the good growth of suckling piglets. Too much energy intake of gilts will lead to mammary gland dysplasia, and too much fat will penetrate into mammary gland vesicles, limiting blood circulation of mammary gland system and further affecting lactation (Johnston and Trottier, 1999).

2. Pregnant sow

Pregnant sows are raised for pregnancy and farrowing. After sow mating, with the continuation of pregnancy, implantation of fetus, development of embryo and growth of mammary gland, the nutrition and feeding scheme of sow will become more changeable, and feeding should be carried out according to the physical condition and pregnancy stage of each sow.

2. 1 before pregnancy (0-75 days)

The feeding objectives of sows in the first three months include:

2. 1. 1 Maintain normal pregnancy.

After sow fertilization, ensuring the smooth implantation of embryos, maintaining the survival rate of embryos and reducing abortion during pregnancy can improve the number of litters at delivery. Early pregnancy, especially 0-30 days of pregnancy, is an important period for embryo survival and implantation. Too high nutrition level (especially high energy) in early pregnancy will reduce the embryo survival rate (Hughes, 1993), which is not good for the number of babies. Excessive nutrient intake leads to vigorous metabolism, increased secretion of adrenal hormones, which in turn affects the secretion of progesterone, leading to the decrease of plasma progesterone level (Dyck et al., 1980), thus reducing the embryo survival rate (foxcroft et al., 1996).

2. 1.2 Maintain the suitable body condition of sows.

The normal body condition of sows is very important to improve the body storage of sows and maintain the growth and development of fetuses. Whether it is overweight or low-fat storage, it will be unfavorable to the later reproductive cycle. Therefore, the diet of pregnant sows not only needs to control the weight gain, but also needs to provide enough nutrition to meet the needs of embryo development and make up for the weight loss of multiparous sows at the end of lactation and the weight gain of primiparous sows. Because in the early pregnancy (0-30 days), increasing feed intake will lead to the increase of early embryo death, so the ideal time for poor sows to increase body fat is 30-75 days of pregnancy. At this stage, it is the key to control the physical condition of sows through feed intake. The suitable back fat thickness for sows is 16- 18, and the body condition score (BCS) is about 3.

2. 1.3 Maintain sow health.

The health and quietness of sows is the guarantee to maintain normal pregnancy. Parasites and starvation (food restriction) can cause sows to be restless and easily lead to miscarriage. Mycotoxin can lead to decreased immunity, hormone disorder, affect the development of embryos and fetuses, and lead to abortion and stillbirth.

2.2 Late pregnancy (75d- delivery).

The feeding objectives of sows in the late pregnancy include the following aspects:

2.2. 1 Support the rapid growth of fetus and ensure the ideal high birth weight of piglets. After pregnancy 1/3, the fetus grows exponentially. During this period, improving the feeding level and increasing the feed intake of sows can significantly improve the birth weight and survival rate of piglets. However, after 75 days of pregnancy, increasing nutrient intake (especially energy) will reduce the number of breast cells and the ability of milk synthesis. Therefore, the time to attack the fetus with late pregnancy feed (or lactating sow feed) should be appropriately delayed (for example, after 90 days of pregnancy or 100 days) 2.2.2 Ensure that the nutrition is evenly supplied to the fetus. The poor uniformity of newborn piglets and the high proportion of weak piglets are mainly due to the imbalance of fetal nutrition supply. This imbalance of fetal nutrition supply is closely related to sow constipation, slow gastrointestinal peristalsis and uneven placental blood flow distribution.

2.2.3 Make full preparations for sow delivery.

The smooth farrowing of sows is of great significance to the recovery of sows, the reduction of stillbirth, the increase of live farrowing and the reduction of sow elimination rate. The sow's labor process is ideal within 3 hours. Longer labor process will lead to the increase of stillbirth, even postpartum paralysis (more than 5 hours), and affect the time for piglets to eat colostrum, and at the same time increase the reassortment rate of sows. It is very important for sows to increase energy reserves, improve muscle contraction during childbirth and reduce constipation. In addition, the impact on the fetus in the third trimester should be moderate to avoid the fetus being too large and affecting the delivery.

2.2.4 Maintenance of sow health.

The microorganisms of newborn piglets come from the sow's birth canal and feces, so the intestines and birth canal should be cleaned before delivery to avoid the vertical transmission of pathogenic microorganisms from sows to piglets. Good immune status of sows can increase the content of colostrum antibodies, thus improving the disease resistance of piglets.

3. Lactating sows

The feeding objectives during lactation are: to maximize the lactation yield and milk quality of sows to gain weight, to minimize the weight loss during lactation, to shorten the weaning-estrus interval (WEI) as much as possible, and to increase the number of ovulation in the next reproductive cycle. In order to achieve long-term reproductive efficiency, it is necessary to reduce the weight loss of sows during lactation, with emphasis on improving the nutritional concentration of diet and the level and intake of some special nutrients during lactation.

4. Empty pregnant sow (weaning-re-estrus mating)

4. 1 Make sows estrus as soon as possible after weaning, and shorten the interval between weaning and estrus. Can improve the annual litter size of sows. It is reported that improving the feeding level after weaning can shorten the time interval from weaning to estrus of primiparous sows and increase the estrus ratio within 10 days after weaning.

4.2 Increase the number of ovulation of oestrus sows. Can increase the number of fertilized eggs and sow litter size. Short-term optimized feeding before mating is beneficial to improve the ovulation number of sows.

Third, sow reproduction technology first, age-appropriate reproduction

The estrus period of local pig breeds in China is generally 3 months old, weighing about 20 kg, and the sexual maturity is 4-5 months old; Exotic pig breeds are 6 months old in estrus and 7-8 months old in sexual maturity; Hybrid pigs are between the above two. In production, sows that have reached sexual maturity are not bred immediately in order to make their reproductive organs and physiological functions develop more fully and obtain a large number of offspring with good quality. Usually after sexual maturity, after 2-3 times of regular estrus, the body weight reaches 40-50% of the adult body weight. Ovulation number of sows: Young sows are less than adult sows, and their ovulation number increases with the increase of estrus times.

China local maturity early, 7-8 months old, weight 50-60 kg can be bred; 8-9 months old, weighing 90- 100 kg, can be bred into domestic cultivated varieties and hybrids; Exotic pig breeds are 8-9 months old and weigh 100- 120 kg.

Note: Month age is more important than weight, and estrus cycle (sexual maturity) is more important than month age.

Second, timely breeding.

Timely mating is the key to improve the conception rate and litter size, and its basic basis is the law of estrus and ovulation of sows. The first estrus is 3-6 months old; The estrus time of lactation is 27-32 days; Estrus cycle is 2 1( 16-24) days; Estrus lasts for 5(2-7) days; The time from estrus to ovulation is 24-36 hours; The ovulation process of sows is one after another, and the duration of ovulation is 5(4-7) hours. The time to maintain the fertilization ability of eggs is 8- 10 hour; Ovulation number is15-25; The time for sperm to reach fallopian tube is 2 hours (1-3); The survival time of sperm in fallopian tube is 10-20 hours.

1. Estrus symptoms

At the beginning, excitement and anxiety, sometimes called snoring, slight congestion and swelling of genitals, and a slight loss of appetite are indications of the beginning of estrus. After that, the vulva swelling is more harmful, slightly wet, hurdling, and likes to climb over other pigs. At the same time, I am willing to accept other pigs crawling over, especially boars. This is the beginning of mating desire. Since then, the sow's sexual desire gradually tends to be strong, the vulva is congested and swollen, gradually tends to peak, the vagina is moist, and the desire for males is getting stronger and stronger. When you see it, the sow will climb over it frequently, or stand quietly and thoughtfully. At this time, if you try it with the boar, you can see that it likes to be close to the boar. The wild boar is stable when it climbs on its back. If someone is around, its ass tends to be close to the side of the person, so it can't be pushed away. After that, sexual desire gradually decreased, vulva congestion and swelling gradually subsided, male desire gradually weakened, vulva turned red, slightly wrinkled, occasionally purple, vulva dry, often stuck to straw mats, dull expression, and liked to stay still. This is the breeding season. The estrus symptoms of foreign pig breeds and their hybrids are not as obvious as those of domestic pig breeds, which often leads to difficulties in judgment, so special attention should be paid. Sows in estrus should be observed regularly from the beginning in order to understand its changing process.

Note: Postpartum estrus (3-6 days postpartum, but no ovulation).

2. Ovulation time

The ovulation time of sows is mostly in the middle and late estrus, about 24-36 hours after estrus, so mating is generally not earlier than 24 hours after estrus. It is generally believed that 24-36 hours after estrus has entered the stage of effective fertilization. In order to let more eggs have fertilization opportunities, it is often necessary to reproduce again after 8- 12 hours. Different breeds, ages and individuals have different ovulation times. Therefore, when determining the breeding time, we should be flexible.

In terms of breeds, local pig breeds in China have short estrus duration (mostly 4-5 days) and early ovulation, so they can be bred on the second day of estrus. Exotic pig breeds have long estrus duration (mostly 5-6 days) and late ovulation, so they can be bred in 3-4 days of estrus. Hybrid pigs can mate in the afternoon or the third day after estrus.

In terms of age, the estrus duration of young sows of foreign pig breeds is shorter than that of old sows. The local pig breeds in China are the opposite. The estrus duration of the old sow is 3-4 days, that of the young sow is 6-7 days, and breeding can be carried out 40-50 hours after estrus. It can be seen that the mating experience of "early mating, late mating and middle mating" conforms to the estrus and ovulation law of China pig breeds.

From the performance of estrus, the mental state of sow changed from anxiety to daze, her hands pressed on her hips, her vulva changed from redness to reddish and wrinkled, and her mucus changed from watery to sticky, indicating that she had achieved timely mating. Estrous sows and boars are allowed to cross-breed, accounting for 60% and 38% of the total respectively, and the escapees must be guaranteed (2%) before mating. The mating performance of boars is good within 25.5 hours after being allowed to cross, especially after 10-25.5 hours, it can reach 100% (Japan). Make an oestrus prediction table for each sow, and often observe the oestrus symptoms of sows. If you are close to estrus sows, you can know the allowable time for boars to climb and check the timely breeding period.

Note: Ovulation is earlier and longer for those with short estrus duration.

3. Breeding method

Repeated mating: sows are mated with the same boar twice in one estrus. Generally, mating is carried out 20-30 hours after the beginning of estrus, and mating is carried out again at an interval of 8- 12 hours.

Double mating: During a estrus, sows are mated with two boars of different breeds or two boars of the same breed every 10- 15 minutes.

Multiple mating: sows regularly mate multiple times in one estrus; Or in the estrus of a sow, it is bred three times continuously, the first time is 12 hour after estrus, the second time is 24 hours, and the third time is 36 hours.

Practice has proved that the litter size of sows increased by 10-40% compared with that of single breeding by using the above three breeding methods in one estrus.

4. Breeding method

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