Method for predicting reproductive performance of mutton sheep

Abstract

The invention relates to the technical field of mutton sheep breeding, and discloses a method for predicting mutton sheep reproductive performance, which comprises the following steps: step 1, integrating historical reproduction data of mutton sheep individuals, and analyzing and establishing a mutton sheep reproductive performance judgment model based on an AGD (anal genital distance); 2, the mutton sheep is fixed, and the distance between the anal genitals of the mutton sheep individuals is measured; and step 3, predicting the reproductive performance of the mutton sheep individual by using the judgment model in the step 1. According to the method, the stable parameter AGD conforming to normal distribution serves as an index for judging the breeding performance of the mutton sheep, the breeding performance of the mutton sheep can be more scientifically and accurately predicted, breeding sheep with excellent breeding performance can be bred easily, and the progress of breeding work of the mutton sheep is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of mutton sheep breeding, and in particular to a method for predicting the reproductive performance of mutton sheep. Background Art

[0002] Livestock reproductive traits are important physiological traits of animals and are related to the production efficiency of the breeding industry. Fertility is a key indicator in meat sheep breeding, and breeding ewes with high fertility is an important breeding direction. Conventional fertility evaluation includes sheep multiplication gene (FecB) detection, serum anti-Mullerian hormone (AMH) determination and other methods. These methods are not convenient in production, and finding other convenient physiological indicators will help to quickly evaluate fertility and select offspring.

[0003] Anogenital distance (AGD) is the distance from the midpoint of the anus to the genitals. Studies in humans and rodents have found that AGD is mainly affected by androgens and has a certain relationship with reproductive capacity. Therefore, an efficient and reliable method for predicting reproductive performance of mutton sheep based on anogenital distance (AGD) was proposed. Summary of the invention

[0004] In order to solve the technical problems raised in the background technology, the present invention provides a method for predicting the reproductive performance of mutton sheep.

[0005] The present invention is implemented by the following technical scheme: A method for predicting the reproductive performance of mutton sheep comprises the following steps:

[0006] Step 1, obtaining the historical reproductive data of individual mutton sheep, analyzing and establishing a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance;

[0007] Step 2, fix the mutton sheep and measure the anogenital distance of the individual mutton sheep;

[0008] Step 3: Use the judgment model in step 1 to predict the reproductive performance of individual mutton sheep.

[0009] Furthermore, the parameters of the reproductive performance include but are not limited to: pregnancy rate, pregnancy time, number of lambs born in the first litter, and lamb weight.

[0010] Furthermore, in step 1, the reproductive data includes the AGD data of each ewe and the corresponding pregnancy results and the number of lambs born after pregnancy. After obtaining the reproductive data, the data needs to be eliminated to exclude the data of ewes with vulvar deformities and those that are not pregnant after artificial insemination.

[0011] Furthermore, the analysis method in step 1 is as follows:

[0012] The data were sorted into the form of mean ± standard deviation (SD), and then analyzed using SPSS22.0 statistical software;

[0013] The distribution of AGD was tested for normality using the Shapiro-Wilk test, the independent samples T test was used for the parameters of AGD and reproductive performance, and the chi-square test was used for the nonparametric parts of AGD and reproductive performance;

[0014] The test results were expressed as "mean ± standard deviation", and some statistical graphs were drawn using Graphpadprism software, and upstream and downstream primers of genes were designed using SnapGene software.

[0015] Furthermore, the AGD data of the ewe are collected at the following stages: diestrus, the day of mating, early pregnancy, late pregnancy, early lactation, and late lactation.

[0016] Furthermore, the ewe is a young ewe or a multiparous ewe.

[0017] Furthermore, the pregnancy result is a pregnancy diagnosis performed via the rectum using a B-ultrasound linear probe starting 35 days after artificial insemination.

[0018] Furthermore, in step 2, a vernier caliper is used to measure the anal genital distance.

[0019] Furthermore, the judgment model is shown as follows:

[0020] If the anogenital distance of the tested mutton sheep is greater than L, it is a breeding sheep with low reproductive performance;

[0021] If the distance between the anus and genitals of the tested mutton sheep is ≤ L, it is a breeding sheep with high reproductive performance;

[0022] The reproductive performance of meat sheep is divided into breeding sheep with high reproductive performance and breeding sheep with low reproductive performance, where L is the median of the original AGD data.

[0023] Furthermore, the following formula is satisfied between AGD and pregnancy rate:

[0024] y=79.57-0.65x, where: x is AGD length, unit is mm; y is pregnancy rate, unit is %, correlation coefficient R2=0.962;

[0025] It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1 mm increase in AGD, the pregnancy rate decreases by 0.65%. The size of AGD is negatively correlated with the pregnancy rate of young sheep.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention verifies that AGD is normally distributed in young Hu sheep and multiparous sheep, and the changes under different physiological states are not significant, so AGD is a stable parameter with normality and repeatability. In addition, the reproductive performance of the sheep in the short AGD group is significantly better than that of the sheep in the long AGD group in terms of lambing number, pregnancy rate, multiple lamb ratio, and pregnancy time, and the weight of female lambs in the short AGD group is significantly less than that of female lambs in the long AGD group. The shorter the AGD, the better the reproductive performance.

[0028] In summary, the present invention uses the stable parameter AGD that conforms to the normal distribution as an indicator for judging breeding performance, which can more scientifically and accurately predict the breeding performance of meat sheep and help to select breeding sheep with excellent breeding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the AGD measurement operation proposed for this scheme;

[0030] Figure 2 (a) is the distribution diagram of AGD of young sheep in each interval; Figure 2 (b) is the normal distribution QQ plot of young sheep;

[0031] Figure 3 (a) is the distribution of AGD of multiparous sheep in each interval; Figure 3 (b) Normal distribution QQ plot of multiparous sheep;

[0032] Figure 4 (a) shows the changes of AGD in young sheep; Figure 4 (b) Changes in AGD in multiparous sheep; Figure 4 (c) Mean values ​​of AGD of sheep of different parities;

[0033] Figure 5 This is the relationship diagram between AGD and pregnancy rate;

[0034] Figure 6 This is the relationship diagram between AGD and gestational time;

[0035] Figure 7 This is a graph showing the relationship between AGD and the number of first-born lambs.

[0036] Figure 8 The relationship between AGD and first-born lamb weight; Figure 8 (a) is the first-born lamb weight; Figure 8 (b) is the weight of the first-born lamb; Figure 8 (c) weight of first litter twin lambs;

[0037] Fig. 9 is the relationship between AGD and the number of lambs born in multiparous sheep, Fig. 9 (a) AGD and the number of lambs born in the first litter; Fig. 9 ((b) AGD and number of lambs born in two parities; Fig. 9 (c) AGD and the number of lambs born in three parities. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0039] Example:

[0040] This scheme proposes a method for predicting the reproductive performance of mutton sheep, including the following steps

[0041] Step 1, obtaining the historical reproductive data of individual mutton sheep, analyzing and establishing a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance;

[0042] Step 2, fix the mutton sheep and measure the anogenital distance of the individual mutton sheep;

[0043] Step 3: Use the judgment model in step 1 to predict the reproductive performance of individual mutton sheep.

[0044] The parameters of reproductive capacity include, but are not limited to, pregnancy rate, pregnancy time, number of lambs born in the first litter, and lamb weight.

[0045] In step 1, the reproductive data includes the AGD data of each ewe and the corresponding pregnancy results and the number of lambs born after pregnancy. After obtaining the reproductive data, the data needs to be eliminated to exclude the data of ewes with vulvar deformities and those that are not pregnant after artificial insemination.

[0046] The analysis method in step 1 is as follows:

[0047] The data were sorted into the form of mean ± standard deviation (SD), and then analyzed using SPSS22.0 statistical software;

[0048] The distribution of AGD was tested for normality using the Shapiro-Wilk test, the independent samples T test was used for the parameters of AGD and reproductive performance, and the chi-square test was used for the nonparametric parts of AGD and reproductive performance;

[0049] The test results were expressed as "mean ± standard deviation", and some statistical graphs were drawn using Graphpadprism software, and upstream and downstream primers of genes were designed using SnapGene software.

[0050] The AGD data of the ewes were collected at the following stages: diestrus, breeding day, early pregnancy, late pregnancy, early lactation, and late lactation.

[0051] The ewe is a young ewe or a multiparous ewe.

[0052] The pregnancy results were diagnosed by transrectal ultrasound linear probe starting 35 days after artificial insemination.

[0053] In step 2, the anogenital distance is measured using a vernier caliper.

[0054] As an optional implementation mode of the present invention, the judgment model is as follows:

[0055] If the anogenital distance of the tested mutton sheep is greater than L, it is a breeding sheep with low reproductive performance;

[0056] If the distance between the anus and genitals of the tested mutton sheep is ≤ L, it is a breeding sheep with high reproductive performance;

[0057] The reproductive performance of meat sheep is divided into breeding sheep with high reproductive performance and breeding sheep with low reproductive performance, where L is the median of the original AGD data.

[0058] In this proposal, the following are also proposed:

[0059] The following formula is satisfied between AGD and pregnancy rate:

[0060] y=79.57-0.65x, where: x is AGD length, unit is mm; y is pregnancy rate, unit is %, correlation coefficient R2=0.962;

[0061] It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1 mm increase in AGD, the pregnancy rate decreases by 0.65%. The size of AGD is negatively correlated with the pregnancy rate of young sheep.

[0062] Test example:

[0063] To analyze the relationship between AGD and fertility in young and multiparous ewes. 400 31-month-old, three-parous multiparous ewes in good condition were selected from the existing stock of the third breeding sheep farm of Anxin Animal Husbandry in Woyang. AGD was measured and the number of lambs of each parity of multiparous sheep was collected. 1000 10-month-old young sheep in good condition were selected from the existing stock of the fourth breeding sheep farm of Anxin Animal Husbandry in Woyang. AGD was measured during artificial insemination. Rectal B-ultrasound was used for pregnancy diagnosis 35 days after artificial insemination. After delivery, data on pregnancy time, number of lambs, and lamb weight were collected.

[0064] The main steps are as follows:

[0065] 1. Determination of AGD

[0066] like Figure 1As shown, the ewe is secured against a wall or railing. The person securing the ewe controls the ewe's head with his left hand and lifts the ewe's tail with his right hand to make it 90 degrees to the ground. Aim the top of the vernier caliper at the center of the anus and slowly move the bottom of the vernier caliper to the base of the clitoris. The number displayed on the vernier caliper is the AGD length in mm.

[0067] 2. Diagnosis of pregnancy outcome

[0068] Pregnancy diagnosis is performed through the rectum using a B-ultrasound linear probe starting 35 days after artificial insemination. After restraining the ewe, the operator wears disposable gloves and slowly inserts the linear array probe into the ewe's rectum. After the ewe defecates on its own due to the stimulation of the probe, the probe is reinserted. If the B-ultrasound shows an embryo, it is marked as pregnant, otherwise it is marked as not pregnant.

[0069] 3. Record of lambing number

[0070] Enter the sheep pen every 6 hours to observe whether the sheep have symptoms of delivery (frequent bleating, walking back and forth, udder swelling, and tail concave). If there are signs of delivery, pay attention to observation and wait for delivery. If the ewe has a difficult delivery, artificial delivery can be performed, and the number of lambs and the time of lambing are recorded after lambing.

[0071] 4. Record of lamb weight

[0072] Weigh the lamb within 24 hours of birth. Place the scale on a flat surface and put a plastic weighing frame on it. After the scale is reset to zero, put the lamb in. The weight displayed on the screen is the lamb weight in kg.

[0073] In the experiment, AGD and lambing data were recorded. The data were sorted into mean ± standard deviation form (SD) using Excel 2010, and then analyzed using SPSS22.0 statistical software. The distribution of AGD was tested for normal distribution using the Shapiro-Wilk test method, the independent sample T test was used for AGD and reproductive performance parameters, and the chi-square test was used for AGD and reproductive performance non-parametric parts. The test results were all expressed as "mean ± standard deviation", and some statistical graphs were drawn using Graphpadprism software.

[0074] Results and Analysis

[0075] 1. Distribution of AGD in young sheep

[0076] AGD was measured in 1000 10-month-old ewes at the time of artificial insemination, and data from ewes with vulvar malformations and unsuccessful artificial insemination were excluded. After applying these filtering methods, data from a total of 791 ewes were used for the final analysis. Figure 2As shown in the figure, the AGD data of 791 young sheep were divided into 17 groups from small to large, and the number of sheep in each group was counted. After analyzing the distribution of AGD of young sheep, it was found that the distribution of AGD basically conforms to the normal distribution. Figure 3-1 As shown in b, the normal distribution QQ plot was used to test the fit between the theoretical normal distribution and the actual normal distribution, and the Shapiro-Wilk test method was used for analysis, indicating that the AGD of young sheep conformed to the normal distribution (P=0.2004>0.05).

[0077] 2. Distribution of AGD in multiparous sheep

[0078] AGD was measured in 400 24-month-old, second-parous multiparous ewes at the time of artificial insemination. Data from ewes with unclear ear numbers, missing birth data, vulvar malformations, and birth trauma were excluded. After applying these filtering methods, data from a total of 332 multiparous ewes were used for the final analysis. Figure 3-2 As shown in a, the AGD data of 332 multiparous sheep were divided into 18 groups in an equidistant manner from small to large. The number of sheep in each group was counted. After analyzing the distribution of AGD of multiparous sheep, it was found that the distribution of AGD basically conforms to the normal distribution. Figure 3-2 As shown in b, the normal distribution QQ plot was used to test the fit between the theoretical normal distribution and the actual normal distribution. The Shapiro-Wilk test method showed that the AGD of multiparous sheep also conformed to the normal distribution (P=0.1136>0.05).

[0079] 3. Changes in AGD during the sheep breeding cycle

[0080] Thirty 10-month-old young ewes and 24-month-old second-parity multiparous ewes in good physical condition were selected under the same feeding and management conditions for synchronous estrus-artificial insemination. AGD was measured when the vaginal plug was placed 10 days before mating, and AGD was measured on the day of mating, 30 days of pregnancy, 120 days of pregnancy, 30 days of lactation, and 60 days of lactation. All measurements were performed before morning feeding. After pregnancy diagnosis was performed 35 days after artificial insemination, non-pregnant ewes were excluded because non-pregnant ewes need to undergo secondary artificial insemination, which is not synchronized with the pregnant ewes. After rectal ultrasound pregnancy diagnosis on day 35, 21 young sheep and 16 second-parity sheep were included in the study (as shown in Table 3-1). The data analysis showed that there was no significant change in AGD from diestrus to estrus, and from estrus to 30 days of pregnancy, but it increased significantly from 30 days of pregnancy to 120 days of pregnancy (P=0.045), decreased from 120 days of pregnancy to 30 days of lactation, and had no significant change from 30 days after parturition to 60 days after parturition. After one breeding cycle, AGD had an insignificant increase ( Figure 3-3a). There is no significant change in AGD from diestrus to estrus, from estrus to 30 days of pregnancy, from 30 days of pregnancy to 120 days of pregnancy, from 120 days of pregnancy to 30 days of lactation, from 30 days of lactation to 60 days of lactation, and there is no significant change in AGD after one reproductive cycle ( Figure 3-3 b). Therefore, during the reproductive cycle of ewes, AGD is a stable parameter under different physiological conditions (except in late pregnancy).

[0081] The AGD data of 791 10-month-old young ewes and 332 multiparous ewes that were about to undergo artificial insemination were analyzed and found that ( Figure 3-3 c): AGD increased significantly with the increase of parity before the second parity, but there was no significant change after the second parity, indicating that with the increase of parity, the AGD of young ewes increased significantly (P=0.008).

[0082] Table 1 shows the mean changes of AGD in different periods

[0083]

[0084]

[0085] 4. AGD and reproductive performance of young sheep

[0086] Among 1000 10-month-old young ewes that were about to undergo artificial insemination, ewes with reproductive diseases, vaginal malformations, and failed plugging were excluded. A total of 791 young ewes were successfully artificially inseminated, and all ewes were artificially inseminated in the same way. Before morning feeding on the 35th day after artificial insemination, rectal B-ultrasound was used for pregnancy diagnosis, and the pregnancy results were recorded after diagnosis: pregnancy and non-pregnancy. The AGD groups were arranged from low to high, and divided into 4 groups with equal intervals. The grouping is as follows: 30mm group (25mm<AGD≤35mm), 40mm group (335mm<AGD≤45mm), 50mm group (45mm<AGD≤55mm), 60mm group (55mm<AGD≤65mm). The total number of young ewes artificially inseminated and the number of pregnancies in each group were recorded, and the pregnancy rate of each group was calculated (Table 3-2). The nonparametric chi-square test showed no significant difference in the overall data (P = 0.063), but there was a significant difference between the 30 mm group and the 60 mm group (P = 0.036). In the line graph of AGD and pregnancy rate, it can be found that as the AGD of each group increases, the pregnancy rate gradually decreases. The straight line fitted by the least squares method shows that the pregnancy rate changes as a function of the AGD increases ( Figure 3-4), that is, y = 79.57-0.65x (x is AGD length, unit: mm; y is pregnancy rate, unit: %), and the correlation coefficient R2 = 0.962. The results showed that for every 1 mm increase in AGD, the pregnancy rate decreased by 0.65%, that is, the size of AGD was negatively correlated with the pregnancy rate of young sheep.

[0087] Table 2: Relationship between AGD and pregnancy rate

[0088]

[0089] like Figure 5 As shown, AGD and pregnancy rate are negatively correlated.

[0090] 5. AGD and pregnancy time of young sheep

[0091] The gestation time and delivery time of young ewes were recorded. A total of 397 young ewes successfully delivered in this experiment. The 397 young ewes were arranged from small to large in AGD, and the median was used as the dividing point of the AGD length group.

[0092] The gestational time in the short AGD group was 151.22±3.02 days, and that in the long AGD group was 152.66±3.88 days. Figure 6 The gestational time in the short AGD group was significantly shorter than that in the long AGD group (P=0.002<0.05). The results showed that the smaller the AGD, the shorter the gestational time.

[0093] 6. AGD and the number of first-born lambs in young sheep

[0094] The 397 young ewes were arranged from small to large AGD, and the median was used as the dividing point for the AGD length group to analyze the relationship between the number of lambs born in the long and short AGD groups and AGD. The number of first-born lambs in the short AGD group was 1.63±0.53, and the number of first-born lambs in the long AGD group was 1.52±0.53. Figure 7 As shown, the number of lambs born in the short AGD group was significantly greater than that in the long AGD group (P = 0.034 < 0.05). The results show that the smaller the AGD, the more lambs are born.

[0095] 7. AGD and first-born lamb weight of young sheep

[0096] The AGD of 397 young sheep were arranged from small to large, and the median was used as the dividing point for the AGD length group to analyze the relationship between the lamb weight and AGD of the long and short AGD groups. The first lamb weight of the short AGD group was 3.08±0.62Kg, and the first lamb weight of the long AGD group was 3.13±0.69Kg ( Figure 8The independent sample T test showed that there was no significant difference in the birth weight between the short AGD group and the long AGD group (P = 0.353). The first litter weight of the short AGD group was 3.31 ± 0.60 kg, and the first litter weight of the long AGD group was 3.42 ± 0.65 kg ( Figure 8 The independent sample T test showed that the weight of single lambs in the short AGD group was not significantly different from that in the long AGD group (P = 0.123). The weight of the first litter of multiple lambs in the short AGD group was 3.02 ± 0.56 kg, and the weight of the first litter of multiple lambs in the long AGD group was 3.00 ± 0.59 kg ( Figure 8 In the c part of the study, the independent sample T test showed that there was no significant difference in the weight of multiple lambs between the short AGD group and the long AGD group (P=0.755). The results showed that there was no significant difference in AGD and weight of single lambs or twin lambs.

[0097] 8. AGD and reproductive performance of multiparous sheep

[0098] The AGD of 332 parous sheep was measured and the number of lambs born in three parities was collected and analyzed. It was found that the number of lambs born in each group increased significantly with the increase of parity. Fig. 9 As shown, the number of lambs born in the short AGD group of the first and second parities was significantly higher than that of the long AGD group (P1=0.018<0.05, P2=0.010<0.05), and the number of lambs born in the short AGD group and the long AGD group in the third parity was not significantly different (P3=0.137). At the same parity, the short AGD group was larger than the long AGD group, and the number of lambs born in the short AGD group was larger than that in the long AGD group in each parity and the total parity. The results showed that the number of lambs born in the short AGD group in the first and second parities was significantly higher than that in the long AGD group, and the number of lambs born in the long AGD group and the short AGD group in the third parity was not significantly different.

[0099] In summary, we can conclude that:

[0100] 791 young ewes were arranged from small to large AGD and divided into 4 groups with equal distances. The pregnancy rate linear regression graph was made based on the pregnancy rates of the four groups. For every 1mm increase in AGD, the pregnancy rate decreased by 0.65%. Therefore, it is believed that AGD and pregnancy rate are negatively correlated.

[0101] 791 young ewes were excluded from non-pregnant ewes, and a total of 397 young ewes were pregnant. The AGD of the 397 ewes was arranged from low to high, and the median was used as the dividing point between long and short AGD. The pregnancy time of the short AGD group was significantly shorter than that of the long AGD group. Among the 397 young ewes that gave birth, the number of lambs born in the short AGD group was significantly greater than that in the long AGD group, and the proportion of multiple lambs in the short AGD group was significantly greater than that in the long AGD group. Comparing the male-female ratio, it was found that there was no significant difference between the male-female ratio of the short AGD group and the male-female ratio of the long AGD group, which preliminarily indicates that the length of the ewe's AGD has nothing to do with the male-female ratio of newborn lambs. Based on the analysis of the above indicators, this experiment preliminarily proves that the reproductive performance of the short AGD group of young ewes is significantly better than that of the long AGD group.

[0102] After weighing the newborn lambs, the analysis found that there was no significant difference in the lamb weight between the short AGD group and the long AGD group; combined analysis of single and multiple lamb data found that there was no significant difference in the lamb weight between the short AGD group and the long AGD group, whether it was a single lamb or multiple lambs. Adding gender analysis on the basis of lamb weight, it was found that the weight of male lambs in the short AGD group was significantly greater than that of female lambs, which is the same as the current situation of most animals, that is, the weight of male animals is greater than that of female animals, but there was no significant difference in the weight of male and female lambs in the long AGD group. For male lambs, the weight of male lambs in the short AGD group was greater than that of male lambs in the long AGD group, but the difference was not significant; for female lambs, the weight of female lambs in the short AGD group was significantly less than that of female lambs in the long AGD group. The results showed that different AGD lengths significantly increased the increase in female lamb weight, but had no effect on male lamb weight. After subdividing single and multiple lambs, the increase in AGD had no effect on both female and male single lambs. The increase in AGD will lead to an increase in the lamb weight of female twin lambs, but has no effect on male twin lambs. The lamb birth weight of males in the short AGD group was significantly greater than that of females in the short AGD group. There was no significant difference in the lamb birth weight of males and females in the long AGD group. However, the results of single lambs were not obvious, which may be due to the small number of single lambs, resulting in reduced sample accuracy.

[0103] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for predicting the reproductive performance of mutton sheep, characterized in that: The following steps are included Step 1, obtaining the historical reproductive data of individual mutton sheep, analyzing and establishing a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance; Step 2, fix the mutton sheep and measure the anogenital distance of the individual mutton sheep; Step 3: Use the judgment model in step 1 to predict the reproductive performance of individual mutton sheep.

2. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The parameters of the reproductive performance include, but are not limited to, pregnancy rate, pregnancy time, number of lambs born in the first litter, and lamb weight.

3. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: In step 1, the reproductive data includes the AGD data of individual ewes and the corresponding pregnancy results and the number of lambs born after pregnancy. After obtaining the reproductive data, the data needs to be eliminated to exclude the data of ewes with vulvar deformities and those that are not pregnant after artificial insemination.

4. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The analysis method in step 1 is as follows: The data were sorted into the form of mean ± standard deviation (SD), and then analyzed using SPSS22.0 statistical software; The distribution of AGD was tested for normality using the Shapiro-Wilk test, the independent samples T test was used for the parameters of AGD and reproductive performance, and the chi-square test was used for the nonparametric parts of AGD and reproductive performance; The experimental results were expressed as "mean ± standard deviation", and some statistical graphs were drawn using Graphpad prism software, and SnapGene software was used to design upstream and downstream primers of genes.

5. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The AGD data of the ewes were collected at the following stages: diestrus, breeding day, early pregnancy, late pregnancy, early lactation, and late lactation.

6. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The ewe is a young ewe or a multiparous ewe.

7. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The pregnancy results were obtained by transrectal pregnancy diagnosis using a B-ultrasound linear probe starting 35 days after artificial insemination.

8. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: In step 2, the anogenital distance is measured using a vernier caliper.

9. A method for predicting reproductive performance of mutton sheep as claimed in claim 1, characterized in that: The judgment model shown is as follows: If the anogenital distance of the tested mutton sheep is greater than L, it is a breeding sheep with low reproductive performance; If the distance between the anus and genitals of the tested mutton sheep is ≤ L, it is a breeding sheep with high reproductive performance; The reproductive performance of meat sheep is divided into breeding sheep with high reproductive performance and breeding sheep with low reproductive performance, where L is the median of the original AGD data.

10. The method according to claim 1, wherein: The following formula is satisfied between AGD and pregnancy rate: y=79.57-0.65x, where: x is AGD length, unit is mm; y is pregnancy rate, unit is %, correlation coefficient R2=0.962; It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1 mm increase in AGD, the pregnancy rate decreases by 0.65%. The size of AGD is negatively correlated with the pregnancy rate of young sheep.

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