The breeding of purebred Duroc in China continues unabated. The breeding population of 300 sows and 10 pedigrees is almost equal to the national agricultural areas, and is continuously introduced from the United States, Canada, Denmark, and other countries. Duroc pigs are the most widely used hybrid parents in China today, and their quality directly affects the production performance and economic benefits of the commodity generation. The quality of a parental boar at least has to affect the quality of (per year) 500 commercial bred pigs. The influence of Duroc over the ancestors is increasing geometrically. Since the country has not yet formed a unified breeding system, the advantages of various breeding software (such as GBS, Herdsman) can hardly be fully realized. Waldo Company of the United States and seven joint venture breeding farms in Anhui, Chongqing, Fujian, Heilongjiang, Guangdong, and Guizhou in China will incorporate China's Duroc breeder breeding technology into the Herdsman breeding program. However, from all Duroc breeding farms across the country, The overall level is still in a primary stage of individual choice. The current individual choice is not only of great importance for small group sports. Furthermore, the relevant parameters can be incorporated into future joint breeding GBS or Herdsman software. This requires the breeding technician to accurately determine and determine the genetic quality of the reserve public and sow to be selected. The early selection of traditional Chinese breeding ideas (before the age of 70 days) was often negligent, resulting in the elimination of a large number of small boars for economic reasons at the age of 70 days. The few boars left are often misjudged but do not have top breeding values. Therefore, the author proposes to conduct a primary election at the age of 28 days, similar to the election of film and television stars. The 28-day-old barrows must not be eliminated at the age of 70 days without significant damage. The 100-114 kg live weight should be measured and then determined to ensure the accuracy of selection. This approach is consistent with the most advanced international breeding farms today. Combining with China’s national conditions, the number and quality of the 28-days entry are the key to the primary election. The key issues of the current specific varieties of Duroc breeding are described below: 1. Birth weight The birth weight of Duroc pigs is the highest among all breeds. The modern version of the imported Duroc has a birth weight of approximately 1.7 kg (preliminary) and 1.8 kg (after production). U.S. counterparts like the 4-pound pig born (about 1.8 kg). The latest version of Duroc pigs weighing 2.0 to 2.5 kg is not rare. The major birth is the inevitable result of breeding in the direction of large and fast growth. The birth weight of offspring of excellent boars often falls between 1.8 and 2.5 kg. Many of their peers are concerned about the selection and retention of important new-born figurines. Future generations will accumulate such large fetal traits and result in difficult labor for future generations of sows. The current production of sows in Duluofan: There are reports on the problem of the prospective birth, but the analysis of the causes is extremely inconsistent. Between the large fetus and dystocia can not form an inevitable causal relationship. There are not a few big fetus pigs that are born. In order to reduce the loss of dystocia, the rational rearing of gilts for Duroc is an important means of preventing dystocia. The new version of the Duroc sow had its first estrus around the age of 7 months. When the second estrus was bred, its weight should be over 150 kg, which is much larger than that of the traditional Duroc sows (125 kg). And the skeleton is also much larger, so the new version of the Durrow sow should not be limited to the pre-publishment period. It must not be restricted before 120 kg live weight, and the grazing movement must be strengthened (this is the key technology) to promote The skeleton of the body, especially the pelvis, is stretched and strengthened to ensure delivery. Some late-maturing dorso gilts need to have their first love after 8 months of age. At this time, the body weight has approached or even exceeded 200 kg. It is highly probable that such individuals produce large fetuses with a weight of more than 2 kg. In the current introduction of excellent strains, the best figurines are often selected among the head sows of these large sows. 2.28 days old body weight and primary election Traditional Duroc piglets weigh between 7.5 and 8.5 kg at 28 days, while modern Duroc pigs have improved this trait to 8.0 to 11.0 kg. The best (individual) performance of Anhui Antai Breeding Company in 2008 reached 14.6 kg. 1) Four-week-old piglets that are 2 times the standard deviation of the mean should be more concerned about the gradual adjustment of the human pig affinity in order to do a good job tracking investigation and observe their fellow compatriots, the higher the uniformity The more reliable the estimated breeding value of the boar. 2) Variety characteristics: Requirements are basically in line with Duroc's size and coat color. The color of the coat is golden - red - brown - brown - dark brown (close to black, this stripe is stripped at birth) is normal. There is also a small group of White Duroc in the United States that is considered purebred. A closer look at the Duroc pigs will reveal that there is a fair portion of Duroc's nose that has white spots, small ones such as green beans, and grown up like pecans. This is a feature inherited from its ancestors, Hong Mao Baksha. It is a pity that some domestic players have eliminated a lot of excellent “white nose†and “Durok†crimes with impure crimes. 3) Preliminary identification of reproductive-related traits: whether the arrangement of the nipples is tidy, whether there are more than 14 or not, whether there is any single testicles or scrotal fistulas, etc., and individuals with reproductive lesions must be eliminated. 4) Preliminary identification of congenital limb disease: The two hooves that land on each foot are the recessive genetic defects of Duroc. This type of abnormal hooves is more common in individuals with particularly well-developed muscles and special hind dogs. This abnormal hoof has been apparent at the age of 28 days. When the body weight exceeds 90 kg, it begins to show that the dog is paralyzed and limp after sitting in the hind limbs and loses its ability to self-cultivation. It should be eliminated as soon as possible. 3.70 days old body weight and seed selection Nursery pigs should have a weight of 31 to 33 kg (seasonal difference of 2 kg) when they are getting out of bed at 70 days of age. In 2008 Anhui Antai Company's best Duroc boars amounted to 49 kg, indicating that the long-range grade of pigs has been opened at this stage and there is ample room for choice. This is the key moment for choosing the inheritors of the boar lineage. 1) Weight: Generally reserved pigs choose to keep more than 35 kg, so as to ensure the long speed of 114 kg live weight between 153 and 156 d. This is the level that the original version of the original Duroc excellent breeder pig should reach in 2008. 2) Body type: At this time, the appearance characteristics of the pigs with good long speed and good health are mostly tall skeletons, slender bodies without heavy feelings (much less in size, plump pigs), and at first glance they are somewhat thin. If you do not look at the weight measurement records, and no practice by Ma Jin, it is easy to miss a good pig. 3) The external genitalia must be strictly controlled: At this stage, there is no obvious exposure of the external genitalia of the boar. The most common flaw is the prepuce. Duroc pigs have a much higher probability of being overwhelmed than Landrace, Great White, and Hampshire. The boar's hernia and sow's abnormal super-small cunt (upturned vulva) have begun to be clearly exposed at this age and should be eliminated. 4) Variations in the erect ears occur in about 0.1% of individuals in purebred Duroc and should be eliminated. Whether the mutation in the erect ear is due to a gene mutation or the homozygous relapse of recessive genes in its ancestor Red Barkshire remains to be further studied. 4. Growth period selection (70 days of age) Modern Duroc tends to be large late-maturing, but gains weight very quickly. Long speed is the preferred target for reserve pigs. At present, the excellent terminal brood level of Duroc pigs is 114 kg live weight at 153 days and the best international level is 114 kg live weight at 132 days. The best individual in 2008 was 114 kg at 123 days (equivalent to 100 kg live weight at 108 days of age). The corresponding maximum adult boar body length is 214 cm (about 630 kg live weight). The current average growth rate of China Duroc pigs is approximately 114 kg live weight at 179 days, which is 24 days compared with the United States. The cost of raising a large pig for 24 days is about 100 to 150 yuan. It can be seen that the selection quality of the Duroc species boar can result in a profit of 100 to 1.5 million yuan per year for a 10,000 pig farm. The reason why U.S. origin places emphasis on the choice of daily growth weight during growth period is because the growth rate is the most effective trait for improving the ratio of feed to weight, turnover, and economic efficiency. It is also the main technical lever in the strategy of raising pigs for raising pigs. Whether the selection of the growing season is in place is the most critical and final step in determining the effect of breeding. The biggest difference between China Duroc breeder breeding and American Duroc breeder breeding is in this step. Mainly in two aspects: First, China's Duroc breeding pigs are basically set for 70 days, and many potential seedlings have not been sold yet. Staying to be planted is a good option for a 1.3:1 reserve pig. In the United States, the ratio can be 5:1, and it is the performance of the entire group of compatriots. Second, measure differences in ideas. China's Duroc breeders have adopted different degrees of restricted feeding due to traditional concepts. The reason is to prevent sows from becoming over-fat and to reduce limb and foot disease. As everyone knows, the modern version of the lean pigs are turning to late-maturing, and the reserve period is for fear that they are not fat and lead to lack of love. For limb and foot disease, the author visited 11 typical reserve core populations in the United States in three different seasons (5 to 10°C in early spring, 20 to 32°C in early summer, and 5 to 25°C in late autumn), east to Ohio, and west to Nebraska, south to Kansas, north to Minnesota. The author's breeding grounds basically belonged to the unlimited feeding, but did not find limb and foot disease and dystocia. Why is it that the domestic breeding farms are prone to leg and foot disease if they are not fed on their own? Combined with the comparison of breeding pigs in European breeding farms, the author found that the key lies in the structure of the pig house. The Western-style reserve pig house has a 6 to 20m playground. It is the spare pig's free movement that improves the limbs and promotes growth. There are basically no playgrounds in domestic reserve pigs. Pigs are raised like fattened pigs. They grow fast and have a large weight. Their limbs and hoofs come sick. In order to prevent hooves disease, it is corrected with limited feeding. The disease has been prevented, and it has become increasingly heavy. Individuals with the best genetic potential and fast individuals have not been shown to be eliminated. This is the crux of the failure of Chinese-style selection. How can China's existing breeding farms solve this problem? The author once tested in the breeding farm of Anhui Antai Company that all the reserve pigs were rushed to the 133,000 m2 (20 mu) sports grounds 2 times in the early morning and late afternoon, and they were always feeding as much as possible from small to large. In this way, the pig's limb and foot disease was eliminated, and a reserve boar with 123 kg of age and 100 kg of limbs was developed. A 6-month-old reserve pig should have the following reference records: primary birth weight, 28-day-old weight, 70-day-old weight, 114 kg age, body length (at this time should reach 135-145 cm), father's paternal or Maternal index, mother's paternal or maternal index, sibling fattening performance (weight to weight ratio), sibling corpus callosum measurement results, sibling meat quality measurement results, single nucleotide polymorphism analysis results, and Herdsman software required registration of measured data. The more detailed the reference records, the more accurate the selection of breeding pigs when the sexual maturity can basically confirm the qualifications for retained seed. At this time, the external characteristics of the reserve boar should be: large eyes, wide nose, straight mouth wide mouth, a pair of lop ears relatively small, early tooth decay, such as bamboo shoots sprout, foam mouth like a beer to open the bottle, the ridge is full and magnificent comparable Spanish bullfighting. The shoulders are thick and thick like drapes. The deep-breasted ribs and the front shoulders form a triangular body. The tiger's back bears a round bulge and arches. The shaft is under the circumcision, and the tail loop is behind the testicles. The pig's testicles are much larger than other breeds. The limbs are stout and powerful. They are sturdy, athletic, ferocious, sexy and handsome. At this time, the corresponding gilt eyes have a great deal of diligence, beautiful nose and mouth, beautiful face, smooth and dignified face, clear neck and not thin. The shoulders are plump, not swollen, and the back is wide and wide. Circular ribs deep chest, large abdomen without falling (sister bogey slender waist), long waist does not fall down, slender lined nipples 7 aligned without confusion. The oval is full and open, the vulva is large and sagging, the limbs are strong, the gait is graceful, the overall curve is mellow, no one gets up, and at a glance it is known as a genius. Smart Nucleic Acid Diagnoostic Cloud Service Nucleic Acid Diagnoostic,Multiplex Quantitative Pcr,Quantitative Pcr Instruments,Real Time Pcr Machine Thermal Cycler Jiangsu Dinai Bioengineering Co.,ltd. , https://www.dinaipcr.com