Abstract:One of the biggest characteristics of breeding synthetic line was developing distinctive specialized lines to obtain the maximum and the fastest genetic progress of these specialized lines, and another was selecting those optimal specialized lines with the best combining ability for multi-line hybrids to produce commercial pigs with the maximum economic benefit. In order to support the rapid development of pig industry, Wens Group began to develop a five-way synthetic line for the demand of domestic pig market with the breeding objectives of high litter size, high feed conversion ratio and large body weight for marketing. Breeding objectives and schemes of Wens WS501 swine synthetic line was formulated to promote the development of new five-line hybrid.

Abstract:The goal of this study is to breed a swine synthetic line with the characteristics of high efficiency, high productivity and large body weight for marketing.Guided by the theory of quantitative genetics and molecular genetics, we adopted the method of combining conventional breeding with marker assisted selection to breed a swine synthetic line named WS501, which consisted of five specialized lines with high productivity and large body weight for marketing, from domestic and abroad germplasm resources. High reproductive performance were observed in W352 sows, indicating that the average litter size of first-born and multiparous sows were 12.86 and 13.10 respectively, the number born alive were 11.71 and 12.00 respectively, and the litter birth weight were 14.59 and 15.96 kg respectively. Testing results of WS501 commercial pig showed that the adjusted back fat thickness at 100 kg was 11.0 mm, the time to reach 100 kg body weight was 147 d, the average daily gain from 30 to 100 kg was 1 004 g, feed conversion ratio was 2.12, carcass lean percentage at 100 kg body weight was 65.8%, and the variation coefficient of these traits were below 10%. W501 commercial pig has the characteristics of muscularity, fast growth, high feed conversion ratio, high lean percentage and good meat quality. It is suitable for marketing at large body weight, and good comprehensive economic benefit can be obtained. It can be widely used in large-scale pig production in China.

Abstract:The nucleus herd was maily composed of 53 sows and 7 boars of Pietrain which were imported from Hybrids Company of France in 2001, and 150 sows and 4 unrelated boars of Pietrain which were imported from Nucleus Company of France in 2009. The open systematic breeding method was used with proper introduction of superior boar semen. Growth and development performances were tested during the improvement period. The Best Linear Unbiased Prediction (BLUP) method and Molecule Maker Selection and Genomic Selection technology were integrated and implemented. The specialized line S11 was obtained after 13 years of breeding. This line S11 possessed the characters of muscular fullness, fast growth and high feed converse efficiency, and the stressed halothane gene was lower than 10%. The line S11 was a suitable sire line for producing high weight slaughter pigs.

Abstract:The nucleus base was composed of 281 sows and 35 heritage boars imported from DGI Company of Canada in 2006. The open systematic breeding method was used with proper introduction of superior boar semen. Growth and development performances were tested during the improvement period. The Best Linear Unbiased Prediction (BLUP) method, Molecule Maker Selection and Genomic Selection were integrated and implemented. The specialized line S22 was obtained after eight years of breeding. This line S22 possessed the characters of high and long body, fast growth, high feed converse efficiency and no stressed halothane gene. This line was a suitable sire line for producing high weight slaughter pigs.

Abstract:Landrance HN151 line of Huanong Wens synthetic line was used to the nucleus base, which located at the Shuitai Pig Breeding Farm. The open systematic breeding method was used with introduction of unrelated boars. The Best Linear Unbiased Prediction (BLUP) method, Molecule Maker Selection and Genomic Selection were used in the breeding system. In the selection objections, the body-shape and the reproduction performance were emphasized. The specialized line W51 was obtained after 10 years of breeding. This line W51 possessed the characters of fast growth, high reproduction performance and good shape, and was used as the sire of dam line in Wens pig production.

Abstract:The nucleus herd was composed of 78 sows and 19 boars of Landrace imported from Hybrid Company of France in 2001, and 210 sows and 8 boars of Landrace from Pig Breeding Center of Beijing in 2002. The open systematic breeding and the Best Linear Unbiased Prediction (BLUP) method were used in the breeding system. The specialized line W52 was obtained after 14 years of breeding.The line W52 possessed the characters of fast growth, high and long body and high reproduction performance. This line was a suitable sire dam line in the WS501 Synthetic Line.

Abstract:The nucleus herd was composed by 115 sows and 23 boars imported from Hybrid Company of France in 2001, and 78 sows and 6 boars from Pig Breeding Center of Beijing. The open systematic breeding and the Best Linear Unbiased Prediction (BLUP) method were used in the breeding system. The specialized line W62 was obtained after nearly ten years of breeding. The line W62 possessed the characters of high and long body and high reproduction performance. This line was a suitable dam line in the WS501 Synthetic Line.

Abstract:In order to determinate mating ability of three-line hybrid sows, we compared the growth and development performances of five kinds of hybrid sows,including W211, W212, W362, W351 and W352, and mated the S121 boar with five hybrid sows respectively to produce commercial pigs in Huanggong pig farm of Huanong Wens. The growth performance, carcass performance, body comformation and reproductive performance of different hybrid sows were compared. The results showed that the body comformation of different hybrid sows had certain differences. The body length of W211 pig was short and its teat number was less; The effective teat number of W212 pig was more and its body length was medium; The effective teat number of W362 pig was less and its body length was long; The effective teat number of W351 pig was less and its body length was long; The body length of W352 pig was the longest and its effective teat number was more. The farrowing performance and farrowing rate of W352 sows were better than those of W211 sows. The total number born,number born alive, number born robust of W352 first-born sows was 0.7, 0.6, 0.5 higher than that of W211 respectively. The total number born, number born alive, number born robust of W352 multiparous sows was 0.7, 0.9, 0.8 higher than that of W211. W352 sow had a rapid growth rate and a slightly thicker back fat. There was a certain heterosis in different hybrid sows, but the heterosis of W352 sow in litter size was more obvious (more than 5%). W352 line has the advantages of high body length and reproductive performance. Using three-line hybrid sows because of its heterosis and high yield, the average added profit per head of slaughter pig reachs more than 13.9 yuan.

Abstract:In order to determinate combining ability of three-line hybrid sows, we compared growth performance, carcass performance and body conformation of four kinds of hybrid sows,including W211, W212, W351 and W352 which were produced by W51, W52, W61 and W62 lines, and four kinds of hybrid sows were mated with the S122 boar to produce commercial pigs in Zhagang pig farm of Huaiji branch of Guiyue company. The reproductive performance of different hybrid sows were compared. The results showed that there were some differences among them in terms of body conformation. The body length of W211 pig was short, teat number was less, back fat was thin and growth rate was medium. The effective teat number of W212 pig was more, body length was medium, back fat was thicker and growth rate was faster. The effective teat number of W351 pig was less, body length was longer, back fat was medium and growth rate was slower. The body length of W352 pig was the longest, effective teat number was more, back fat was medium and growth rate was faster. W352 sows had obvious advantages in terms of total litter size, number born alive, number born robust, and litter weight at the age of 21 days, and the heterosis rate of its hybrid combination was higher. Among four kinds of hybrid sows,W352 pig had a longer body length with obvious advantages of reproductive performance.

Abstract:In order to provide references for the selection of terminal sire to produce commercial pigs, performance of different kinds of terminal sires were compared. The traits of Duroc boar and hybrid-boar bred by Wens were determined, including average daily gain, feed/gain ratio, back fat thickness, body length and body height. The performances of different types of terminal sires were compared. The results showed that the hybrid terminal sire was superior to purebred boars in terms of growth performance, body size and semen quality. S122, crossed by S22 Duroc and Pietrain, is an excellent terminal sire for commercial pig production.

Abstract:In order to determine the difference of combining ability between different terminal sires and three line sows, two commonly used terminal sires S121 and S122 from Wens Group were mated to W352 sows, the mating effects of five-line pigs from different terminal sires were compared to select the appropriate terminal sire through two repeated tests of combining ability. WS501 hybrid pig had advantages in body length, growth rate, feed/gain ratio, meat color, marbling and big market weight compared with WS502 hybrid pig. The results showed that WS501 hybrid pig had long and tall body length, small head, wide back, compact muscle, good abdomen and group uniformity. Feeding WS501 hybrid pig has the better economic value.

Abstract:In order to compare growth performance of different commercial pigs of Wens synthetic lines, growth performance and meat quality of WS501, WS401 and SH301 hogs were determined. The results showed that there was no significant difference in growth rate between different groups. WS501 had a better feed conversion ratio (FCR), which was 0.047-0.115 lower than those of two other synthetic lines, especially at last stage. In the large group of pig production, WS501 had the advantages in FCR and feeding days. In slaughter test, WS501 had the advantages in carcass length, rib number, fat thickness and HGP estimated lean meat percentage, and there was no significant difference in meat quality.

Abstract:VRTN gene is the major gene affecting the number of thoracic vertebra in pigs, which QQ genotype (ins/ins) individuals have one double ribs more than qq (-/-) genotype ones. The molecular marker-assisted selection method of VRTN gene in two landrace pig populations was explored to improve the number of ribs of mating pigs. In the study, PCR were used to detect the distribution of VRTN genes in 420 commercial pigs of Wens Group and 2 specialized landrace pigs (913 W51 Landrace and 240 W52 Landrace),which affected thoracic vertebra number (rib number). It is verified that QQ type had nearly one pair of ribs more than qq type in Wens terminal pigs by effect analysis of commercial pork pigs, which indicated that gene improvement could be carried out through molecular marker-assisted selection. The allele frequencies of VRTN gene in the W51, W52 Landrace populations were not significantly different, and the favorable allele frequencies were 0.844 and 0.905 respectively. Through the correlation analysis between genotype and phenotypes of breeding traits, it was found that among W51 Landrace pigs, the dominant genotype had obvious body length advantage and had no influence on other breeding traits. In W52 line, the dominant allele had a significant negative correlation with the estimated breeding value of age at 100 kg/115 kg body weight, but had no significant correlation with other traits. The effect of VRTN dominant allele type was consistent with the breeding goal. Molecular marker-assisted selection could be carried out for W51 and W52 lines both. Combining with field practice breeding, W51 achieved 100% complete purification of dominant allele frequency after half a year through population renewal and optimization. W52 was basically purified after 2 years while expanding its population.

Abstract:This study was aimed to estimate breed-specific genetic parameters of Large White pigs in Wen's Group and evaluate the accuracy of different methods of genomic selection of the trait of litter birth weight (LBW). Animal model and DMU software were used to estimate variances for the trait of LBW, including additive variance components and permanent environmental effect variance components, as well as heritabilities of the trait. The reproductive reference population for Large White pig genomic selection were built based on genotype-by-sequence (GBS) technology. The accuracy of genomic estimated breeding values (GEBV) were compared using different methods of BLUP, GBLUP and ssGBLUP in the validation group. Estimation of heritability was 0.08 for LBW, which was a trait with low heritability. The genetic correlation coefficients between LBW and some quantitative traits, such as total number born, number born alive, number born robust, number of weak, deformed, stillborn and mummified pigs, were 0.59 0.68, 0.88 and -0.17, respectively. According to the results of the genomic selection, the ssGBLUP had a higher accuracy of 0.38, increased 15.79% compared to the traditional BLUP method. The spearman rank correlation coefficient of GEBV between ssGBLUP and BLUP was 0.63. Selection of LBW has a positive effect on the improvement of litter size. The accuracy of genomic selection can be improved effectively combined with ssGBLUP method.

Abstract:The genetic parameters are important genetic characteristics for livestock. The estimation of genetic parameter is a basis for livestock genetic evaluation. The data of main growth and reproduction traits of each line bred by Wens Group from 2005 to 2014 were collected. The genetic parameters were estimated using the maximum likelihood method, the multiple-trait linear model and DMU software. The results showed that the heritability for growth traits ranged from 0.3 to 0.6, belonging to medium or high heritability. Among them, the heritability of BFT₁₀₀ was the highest above 0.4. There were high positive, high negative and weak negative genetic correlations between DAY₁₀₀ and DAY₃₀, ADG_30-100 and BFT₁₀₀,respectively. The heritability of reproduction traits was low, about 0.1. The heritage of LWB was the highest from 0.12 to 0.18 among reproduction traits. The genetic correlation between TNB and ANB was above 0.90, and the genetic correlation between TNB and HNB was above 0.7.

Abstract:This study was aimed to study the influence of genealogical errors on the reliability of estimated breeding values (EBV) obtained by ssGBLUP. Under the condition of different heritabilities, reference groups and genealogical errors, effects of ssGBLUP, GBLUP and BLUP on the reliability of EBV were evaluated. Data were simulated using QMSim software and analyzed by BLUPf90 software. The results showed that the heritability degree and genealogical error rate had nothing to do with reliability of EBV. The tolerance of ssGBLUP to genealogical errors decreased gradually with the gradual increase of reference group. The reliability of EBV obtained by ssGBLUP decreased linearly with the increase of genealogical error rate.

Abstract:The accuracy and ranking difference of estimated breeding values(EBV) of the same individuals in different time span were evaluated for the major production traits of Duroc pig. Univariate animal model and DMU software were used to estimate the variances and heritabilities of major production traits. The accuracy of EBV and spearman correlation were compared between data from different periods, including two years, three years, four years, five years and all data. The results also showed that the heritabilities of age at 115 kg live weight (AGE), average daily gain between 30-115 kg (ADG), backfat thickness at 115 kg live weight (BF), loin eye area at 115 kg live weight (LEA) and body conformation score (BCS) were 0.22, 0.16, 0.38, 0.30 and 0.08 respectively. Except BCS, the heritabilities of other traits were medium and high. Furthermore, if the variance components were fixed, the accuracy ranges of AGE, ADG, BF, LEA and BCS were 0.62-0.64, 0.56-0.59, 0.72-0.73, 0.67-0.69 and 0.49-0.53 respectively. If the variance components were not fixed and estimated from the specific time span, the accuracy ranges of AGE, ADG, BF, LEA and BCS were 0.64-0.65, 0.51-0.59, 0.61-0.73, 0.67-0.69 and 0.42-0.53 respectively. For another, the spearman correlations were close for conditions of different time span. The results also showed that the prior variance components calculated from the whole data were better than the phase data, while the rank of EBV were close for different periods, so the time span of data could be reduced appropriately.

Abstract:Breeding sows of the synthetic line WS501 in Wens in this study were from the second area of Qingyuan breeding pig farm. In this paper, the breeding data of the pig farm from 2014 to 2017 were analyzed and its reproductive characteristics were discussed. After 10 years of breeding, the breeding sows had characteristics of early oestrus, more estrus cycle, fast growth, early mating age and large litter size;the breeding boars had characteristics of muscular body, fast growth, good semen quantity and quality. The results can provide scientific basis for breeding of fine breeds.

Abstract:This paper was aimed to study the influence of maternal effect on estimation of genetic parameters and breeding values for growth traits in Landrace pigs. Landrace W51-line pigs were used as materials. Three quantitative traits related with growth performances, birth weight, age to reach 30 and 100 kg were chosen. Two models including or ignoring maternal effect were used to estimate genetic parameters and breeding values. Results showed that the model including maternal effect was more reasonable to explain the growth traits. Heritability estimates were inflated obviously and estimated breeding values were deviated more seriously using the model ignoring maternal effect. With increasing ages, the proportion of maternal variances gradually decreased but directive additive genetic variances increased, indicating that the influence of maternal effect became smaller in the later growth stage of pigs. It is necessary to consider the influence of maternal effects on estimating genetic parameters and breeding values for building animal growth trait models.

Abstract:This study was aimed to investigate the relationship between reproductive and genetic properties of cloned pigs and those of donor pigs, and to evaluate the application of somatic cell clone boars in the preservation of excellent genes and production of commercial pigs. Pietrain-Duroc hybrid boars were cloned, and their parameters of semen quality were determined. Reproductive total piglets and live piglets of sows mated with cloned boars and donor boars were compared. Growth performance of offspring of sows mated with cloned boars and donor boars were obtained. The results showed that there was no significant difference between the cloned pigs and the donor boars in various tested indexes as well as their offspring, which indicated that the cloned pigs had normal reproductive properties and retained the excellent genetic properties of the donors and could be applied as excellent boars in production.

Abstract:This paper was aimed to study the effect of timed artificial insemination technology on the reproductive performance of Duroc sows. Reproductive performances of normal estrus gilts, anestrus gilts and weaned sows were determined after using timed artificial insemination technology in a pig farm managed by Guangdong Wens Foodstuffs Group Co., Ltd in East China. The results showed that the estrus rate, fertilization rate, pregnancy rate, reproductive rate and reproductive efficiency of normal estrus gilts and weaned sows was significantly higher than the control group. The timed artificial insemination technology had a certain promoting effect on the reproductive efficiency of anestrus gilts, reaching 4.06 pigs per sow. The timed artificial insemination technology can improve the reproductive performance of Duroc sows to a certain extent.

Abstract:The reproductive performance of sows is one of the main production indicators for pig farms. There is a significant correlation between back fat thickness and reproductive performance of the sow. To study effects of back fat thickness on reproductive performances of sows at different stages of gestation period by regulating, the new French Large White pig from Wens breeding pig company were chosed as subjects. The back fat thickness and reproductive performances were measured at different stages of gestation period. The best reproductive performance of sows appeared in early pregnancy and mid-pregnancy with back fat thickness regulation range of -2 to 3 mm. The best reproductive performance of sows appeared in late pregnancy with back fat thickness regulation range of -2 to 0 mm. Back fat thickness of sow keep in a appropriate range, which can improve its reproductive performance and increase benefits of pig farm.

Abstract:This study was aimed to explore the effects of different feeding mode for sows on the reproductive performance. In this study, 434 head of gilts were divided into A and B group according to the feeding regimes. Group A were fed in a mode of gradually increased feed intake while group B were fed in mode of high-low-high feed intake under the same environmental conditions. The back fat thickness at P2 point and number born of the first farrowing sows were recorded. The results showed that the reproductive performances of group B were better than those of group A. Total number born, number born alive, number born robust were 14.2, 12.4 and 10.7 respectively. The reproductive performances of sows with back fat thickness of 16-20 mm were the best. In addition, the ratio of sows with back fat thickness of 16-20 mm in the group B were 6.8% higher than that in the group A, and there were fewer fatty sows in the group B. It was indicated that better reproductive performance and comprehensive benefit could be achieved by feeding first farrowing sows in a mode of high-low-high feed intake during gestation period.

Abstract:This study was aimed to evaluate the effect of backfat loss on reproductive performance of sows from the first parity to the second parity. The backfat loss were determined and reproductive performance differences were analyzed. The results showed that the total litter size of sows decreased significantly when the loss of backfat was more than 2 mm from the first parity to the second parity. Linear regression analysis showed that the backfat of first parity parturition sows should not exceed 18 mm.

Abstract:This study was aimed to obtain the effects of measuring back fat and adjusting feed intake on breeding sows. Back fat were measured, feed intake were adjusted for one year and reproductive performance changes were compared in the same period. The results showed that after measuring back fat and adjusting feed intake, accurate feeding could be achieved, sows body condition could be controlled reasonably, and reproductive performance of sows could be improved, so as to improve the efficiency of pig farm.

Abstract:To meet the neeeds of rapid development of pig industry of Wens Group, we carried out the production, application and extension research on five-breed hybrid pig WS501. Preliminary extension area covered seven branch companies in Guangdong, Guangxi, Fujian, Jiangsu, Hubei, Anhui and other provinces(regions). The farrowing results showed that W352 sows had the characteristics of long and tall body, small head, moderate muscle, good abdomen, more teats and good reproductive performance. Compared with two-line hybrid sows at the same period, teats of W352 sows were 0.3-0.8 more,total number born were 0.3-0.9 more, number born alive were 0.3-0.8 more,number born robust were 0.2-0.7 more,and piglets per sow per year (PSY) were 0.8-1.8 higher. More than 2.6 million head of five-line hybrid pigs(WS501) were on the market. From the reaction of farmer and market, WS501 pigs were popular in the market because of their fast growth, high lean meat percentage, large market weight and good consistency.

Abstract:To explore the application methods of molecular markers in pig breeding,we reviewed the research progress of major effect genes and causal mutation sites for important economic traits,classified the available molecular markers and tracked the application effect of some molecular markers assisted breeding in Wens Group. The application methods of molecular markers in pig breeding were summarized. Molecular marker assisted selection would be widely used in pig breeding.

Abstract:The reproductive performance of sow is an important factor affecting the economic benefits of pig industry, and improvement of reproductive performance is one of the goals for breeders and pork-producers. The reproductive trait of sow is not only a low-heritability trait, but also a sex-limited trait. So the selection effect is not obvious when the traditional selection methods are used. The characteristics, influencing factors, selection methods of porcine reproductive traits were summarized by consulting the relevant literatures and researches. And the advantages and disadvantages of these selection methods were discussed. Genomic selection is the potential selection method to improve porcine reproductive performance.

Abstract:The selective mating is the critical step of modern pig breeding and genetic selection workflow, which can ensure the genetic response of pig performance test and improve the breeding effect. Based on the different economically important traits of pig genetics and the experiences from Wens Foodstuff Co. Ltd., the standard operation procedures for pig selective matings were analyzed and compiled. The SOP will provide theoretical guidance and scientific basis for pig breeding of contemporary farms.

Abstract:The annual repcacement rate of the sow population is actually a problem of "lifespan of the sow" as well a bioeconomic problem of the appropriate parity structure needed to achieve the targeted PSY level. The impact factors that affect the renewal rate or the longevity of sows have genetic factors, and more are non-genetic factors. The main reason is that the lifespan of sows cannot be measured within nucleus herd, nor can it be directly included in the complex selection index, along with the low heritability from 0.05 to 0.25. Therefore, the major measures for improving sow longevity or reducing the replacement rate are gilt development and selection standards, feeding management on body condition, reproductive management, which are recognized by developed countries with high level pig production. Genetic selection and selection of sows with integrity of legs and hooves are important indirect selection methods for improving the longevity of sows.

Abstract:Artificial insemination (AI) can effectively improve the utilization rate of boar, reduce the cost of feeding boars and the biological risk. This paper is aimd to increase the success rate of AI by analyzing the influencing factors and key operation. The importance of AI, the condition to be satisfied, the factors influencing AI to apply successfully, and the key processes were discussed in this paper. The key factors of AI were summarized,which included the quality of semen, accurate estrus identification, clean and hygienic insemination conditions,correct conception device and insemination techniques.

Abstract:With the large-scale development of pig industry, the pork market chain effect has been formed and gradually tightened in China, which reflected in multiple demands of market pigs including large body weight, high carcass lean ratio and better meat quality. One of the goals of current commercial pork production is the big market weight, but the problem is backfat thickness increasing subsequently, the excess fat is resisted by more and more urban and rural residents. The meat quality performance, both the gene level (halothane heterozygous individuals in large weight are closer to the homozygous positive pigs) and delay in the slaughter process innovation (large eye muscle area and thick eye muscle depth cause central temperature to be harder to cool),are not conducive to guarantee and improve meat quality. This paper expounds the measuring of back fat, loin eye muscle area and eye muscle depth of live breeding pig according to the carcass lean ratio of market requirement, and for selecting scientific instrument to meet the needs of pricing the carcass.

Abstract:The carcass composition traits such as lean meat percentage and intramuscular fat content in breeding swine have different economic values in different social development periods and have always been important performance indexes for animal breeding. CT can be used to estimate the carcass composition of live animals. In this paper, the technique and application of CT in swine live performance test were reviewed.

Abstract:Swine selective breeding is the process of selecting superior genetic pigs into nuclear herd, selective mating and offspring production, and delivery of the genetic merit to next generation. The selection traits include quality traits and quantitative traits. Quality traits are more stable and not easily influenced by environmental condition. Quality traits are distributed in the herd discontinuously, therefore the hybrid progenies can be grouped by genotypes and the frequencies of different individuals of genotypes can be calculated. Quantitative traits are prone to be influenced by environment and distributed in the herd continuously, which are controlled by minor multiple genes, perhaps major effect gene. Most of selected traits are quantitative traits with economical value. Selective breeding is a process including accumulation of additive effects and purification of advantageous genes with economical values. This article would like to make an introduction of techniques of performance test for breeding swine, in order to provide references for pig breeding.

Abstract:Besides the common one-week system, batch management also allows the interval between adjacent batches to be multiple weeks in pig farms. Compared with the one-week system, multiple-week system can reduce pressures of disease control and increase production efficiency. However, some problems such as facility utilization and sow re-service need to be considered. This paper discussed some details for batch management in pig farms.

Abstract:This study was aimed to verify fetus protection effects of altrenogest and delivery induction effects of 2 needles of half dose of cloprostenol on sows, in order to shorten their delivery interval. The abnormal parturient sows were treated with altrenogest orally for several consecutive days. Postponed delivery sows were injected by 2 needles of half dose of cloprostenol (2 needles interval 6 h) to induce parturition. The results showed that the proportion of deliveries was 0% in the test group treated with altrenogest orally and 0.2% in the control group. The proportion of births in the test group was 74% after the first injection of cloprostenol with half dose during 22 to 32 h, while 57% in the control group. The proportion of births in the test group was 2% with the first injection of cloprostenol after 56 h, while 9% in the control group. The altrenogest can effectively inhibit early delivery in sows, and injection of 2 needles of half dose of cloprostenol can effectively improve induced delivery and reduce the proportion of delayed delivery.