Ecological conditions: The distribution areas of Qingping Pig are the corner of northwest of Jianghan Plain, which extends from Jianghan Plain to the northwest of Hubei province of China. It lies in East longitude 114A1E349A1E4-112A1E32A1E4and North latitude 30A1E344A1E4-31A1E34A1E4. it is also the intersection point of three types of pigs of North, Central and Southwest China. The central production areas of Qingping Pig are mainly Yuqi, Longquan and Guandang around the coastwise of Qingping River, Hubei province. It is also distributed in the neighborhood counties of Zhijiang, Jiangling, Jinmen,Yichang and Yuan'an (See the Figure below, yellow color area). In these areas, the topography is flat, the climate is warm and the soil is fertile; the area has an average altitude of 50 meters, mean air temperature of 16.4A1E6, annual precipitation of 980 millimeters, annually 268 non-frost days, relative humidity of 75% and annual total sunlight of about 1905.9 hours. Given the unique ecological conditions of these intersection areas and several year of artificial selection, Qingping pig has gradually developed characteristics of Southwest type, North China type and Central China pig types. The number of teats and litter size are inclined to North China type while the maturity age and the meat quality are inclined to Central China type. It also has a shorter gestation. Qingping was classfied as Central China type (Editorial Committee of the "Breeds of domestic animal and poultry in Hubei province", 1985; Zhang et al., 1986).
Appearance characteristics: It has a medium body size, a shapely frame, and straight posture. their foreheads are narrow and relatively pretty; thin and shallow burrow, with no obvious wrinkles. The ears are big and drooping, the mouth is long, the back and waist are flat and straight, the abdomen is relatively big and the thighs are plump, they have slender bone, straight front leg, slightly low-pitched hind legs. The body is covered with pure black hair, with usually 7-9 pairs of teats.
From records of 1059 young pigs, these pigs have an average of 15.74 teats and with up to 92.78% of the pigs having 14-17 teats (Zhang et al., 1986).
Production performance: Qingping Pig has a characteristic short gestation. The average gestation period of sows in Dangyang Qinping Pig breeding farm is 111.51 days, which is 2.49 days shorter than the others. The sows in the first parity have even shorter gestation period of about 110.69 days. Sexual behaviors in the boars appear at 21-30 days after birth. In the countryside, they are used to mate from about 4 months of age, but the optimal mating age is 5-7 months. The first oestrus in sows occur at 73-99 days of age with an average of 86.98 days, but the best time of mating is when they are 6-7 months old. They furrow 9.42, 10.73 and 12.12 piglets in the first, second and third parities, respectively. The average birth weight is 0.79 kg and litter weight at 21 days is about 30.91 kg, weaning and survival rate is 11.27 is 97.74%, respectively. Litter weight at weaning is 107.15 kg. The average daily gain can reach 500g on high plane of energy supply, but this could decline to 349.5g under a low energy supply. The dressing and lean meat percentage is 69.71% and 41.04%, respectively (Editorial Committee of the "Breeds of domestic animal and poultry in Hubei province", 1985).
1. Crossbreeding Qingping pig used as dam line on commercial breed sires (such as large whiteA1C1Qingping), produce the Waiqing crossbred sows. When Qingping is used as a dam, on another different exotic breed as sire line (eg landraceA1C1large whiteA1C1qingping), three breed crossbred offspring Waiwaiqing is produced. The three breed crossbred offspring have more advantages over those of exotic breeds. They grow quickly, have a high resistance, and produce pork of a good tasty flavor, hence they are accepted in the domestic markets. The crossbred sow of Large white A1C1 Qingping pig is well adapted to the farmer feeding environment in different ecology conditions such as a mountainous area, hill, plain and lake areas, and has considerably good reproductive characteristics. According to the statistics of Qingping breeding farm in Dangyang City recorded since 1995, the crossbred sow of large white and Qingping Pig reaches oestrus at 105-115 days and are used for mating at 125-130 days of age with 40- 50kg body weight. The optimal age for breeding is about 7 months of age with 80-90kg body weight. Post-partum oestrus occur after 45 days. The litter sizes in first, second and third parity and above are 10.45, 10.53 and 12.5 piglets, with litter weight at weaning of 125.19kg, 137.98kg and 152.13kg, respectively.
Towards the end of the 20th century, the Qingping breeding farm in Dangyang city initiated a new female parents breeding project "Chinese Qingping lean meat type of the new female parent line breeding" (QLL) under the support of Agricultural Ministry of China and Animal Husbandry Bureau of Hubei province. Four years of efforts have seen the completion of three generation of QLL line which has good productivity: the average litter size of first parity is about 10.61, the live number is 9.93, litter weight at birth and 60 days is 10.11kg and 107.61kg, respectively. In addition, the average daily gain of QLL line pigs is 650g and lean meat percentage is 56% (Guo et al, 2003).
Evaluation of the genetic diversity Lin et al.(2001) studied the genetic variation of the Qinping breed with eight of the serum protein loci Ab, Pi-I, Pi-II, Po-I, Po-II, Cp, Amy-I and CA by the vertical polyacrylamide gel electrophoresis. The result showed polymorphism in all the markers expect for the locus of Cp and the mean heterozygosity was 0.2416. Clustered with other four studied breeds, the genetic distance was smallest (0.0086) between Qinping and Nancheng breeds, than when clustered with the Yanxing breed.
Li et al. (2001) analyzed the genetic variation of the Qinping breed with four microsatellite markers, the results showed polymorphism in all these markers, the observed heterozygosity and polymorphic information content were 0.6114 and 0.5642. Li K.et al (2001) studied the genetic variation of Qinping breed with a set of 27 microsatellite markers recommended by the Food and Agriculture Organization of the United Nations and International Society of Animal Genetics (FAO-ISGA), all of these markers were polymorphic. The result of clustering with other four original breeds studied implied that Qinping had closest genetic relationship with the Tongcheng breed. Yang et al(2003) presented the genetic diversity with the near-complete mtDNA genome of 17 breeds of indigenous Chinese pigs and there were 267 polymorphic loci in the tested regions.
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