A method for predicting reproductive performance of mutton sheep

Abstract

The present invention relates to the technical field of mutton sheep breeding, and discloses a method for predicting the reproductive performance of mutton sheep, comprising the following steps: Step 1: integrating historical reproductive data of individual mutton sheep, analyzing and establishing a mutton sheep reproductive performance judgment model based on the anogenital distance (AGD); Step 2: immobilizing the mutton sheep and measuring the anogenital distance of the individual mutton sheep; and Step 3: predicting the reproductive performance of the individual mutton sheep using the judgment model in Step 1. The present invention uses the stable parameter AGD, which conforms to a normal distribution, as an indicator for judging the reproductive performance of mutton sheep. This method can more scientifically and accurately predict the reproductive performance of mutton sheep, facilitates the selection of breeding sheep with excellent reproductive performance, and promotes the progress of mutton sheep breeding.

Description

Technical Field

[0001] The present 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 crucial physiological traits that influence the profitability of livestock farming. Fertility is a key indicator in meat sheep farming, and breeding ewes with high fertility is a key breeding strategy. Conventional fertility assessment methods include testing for the fecundity gene (FecB) and measuring serum anti-Mullerian hormone (AMH). These methods are inconvenient in production, and the search for alternative, more convenient physiological indicators is crucial for rapid fertility assessment and offspring selection.

[0003] The anogenital distance (AGD) is the distance from the midpoint of the anus to the genitals. Studies in humans and rodents have shown that AGD is primarily influenced by androgens and is associated with reproductive performance. Therefore, a method for efficiently and reliably predicting reproductive performance in meat sheep based on 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 meat sheep.

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

[0006] Step 1: Obtain historical reproductive data of individual mutton sheep, analyze and establish a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance;

[0007] Step 2: Fix the sheep and measure the anogenital distance of each sheep;

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

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

[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 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 organized into mean ± standard deviation form (SD) and analyzed using SPSS 22.0 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 parametric part of AGD and reproductive performance, and the chi-square test was used for the nonparametric part of AGD and reproductive performance;

[0014] The experimental results were expressed as “mean ± standard deviation”, and some statistical graphs were drawn using Graphpad Prism software.

[0015] Furthermore, the AGD data of the ewe are collected at the following stages: diestrus, breeding day, 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 diagnosed by transrectal ultrasound linear probe starting 35 days after artificial insemination.

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

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

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

[0021] If the anogenital distance of the tested meat 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 relationship between AGD and pregnancy rate satisfies the following formula:

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

[0025] It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1mm 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] This study demonstrates that AGD is normally distributed in both young and multiparous Hu sheep, with no significant changes under different physiological conditions. Therefore, AGD is a stable parameter with normality and repeatability. Furthermore, the reproductive performance of sheep in the short AGD group was significantly better than that of the long AGD group in terms of lambing, pregnancy rate, multi-lamb ratio, and gestation duration. The weight of female lambs in the short AGD group was significantly lower than that 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 breed breeding sheep with excellent breeding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the AGD determination operation proposed in this scheme;

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

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

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

[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 lamb weight; Figure 8 (a) is the weight of the first lamb; Figure 8 (b) Weight of first-born lamb; Figure 8 (c) Weight of first-born twin lambs;

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

[0038] The present invention will be 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 new embodiments.

[0039] Example:

[0040] This study proposes a method for predicting reproductive performance of mutton sheep, which includes the following steps:

[0041] Step 1: Obtain historical reproductive data of individual mutton sheep, analyze and establish a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance;

[0042] Step 2: Fix the sheep and measure the anogenital distance of each sheep;

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

[0044] The parameters of reproductive capacity include, but are not limited to, pregnancy rate, gestation time or first litter size.

[0045] In step 1, the reproductive data includes the AGD data of each ewe, 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 organized into mean ± standard deviation form (SD) and analyzed using SPSS 22.0 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 parametric part of AGD and reproductive performance, and the chi-square test was used for the nonparametric part of AGD and reproductive performance;

[0049] The experimental results were expressed as “mean ± standard deviation”, and some statistical graphs were drawn using Graphpad Prism 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 using a linear B-ultrasound probe starting 35 days after artificial insemination.

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

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

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

[0056] If the anogenital distance of the tested meat 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] This proposal also proposes:

[0059] The relationship between AGD and pregnancy rate satisfies the following formula:

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

[0061] It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1mm 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 reproductive performance in young and multiparous ewes, 400 31-month-old, three-parous multiparous ewes in good condition were selected from the existing stock at the Woyang Anxin Animal Husbandry Sheep Farm No. 3. AGD was measured, and lamb numbers per parity were collected. 1000 10-month-old, good-condition young sheep were selected from the existing stock at the Woyang Anxin Animal Husbandry Sheep Farm No. 4. AGD was measured at the time of artificial insemination. Pregnancy was diagnosed by rectal ultrasound 35 days after artificial insemination. Postpartum data on pregnancy duration, lamb number, and lamb weight were collected.

[0064] The main steps are as follows:

[0065] 1. Determination of AGD

[0066] like Figure 1 As shown, the ewe is held against a wall or railing. The restrainer holds the ewe's head with their left hand and lifts the ewe's tail with their right hand, making 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 transrectally using a B-ultrasound linear probe, starting 35 days after artificial insemination. After restraining the ewe, the operator, wearing disposable gloves, slowly inserts the linear probe into the ewe's rectum. After the ewe defecates spontaneously in response to the probe, the probe is reinserted. If an embryo is visible on ultrasound, the ewe is marked as pregnant; otherwise, it is marked as not pregnant.

[0069] 3. Record of lambing number

[0070] Enter the foal pen every six hours to observe the sheep for signs of labor (frequent bleating, pacing, udder enlargement, and a sunken tail). If there are signs of labor, observe closely and wait for delivery. If the ewe has a difficult labor, artificial delivery can be performed. After lambing, record the number of lambs born and the time of birth.

[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] During the experiment, AGD and lambing data were recorded. Data were converted to mean ± standard deviation (SD) using Excel 2010 and analyzed using SPSS 22.0 statistical software. AGD distribution was tested for normality using the Shapiro-Wilk test. AGD and reproductive performance parameters were compared using independent sample t-tests, and nonparametric AGD and reproductive performance were compared using chi-square tests. All results are presented as mean ± standard deviation, and some statistical graphs were drawn using Graphpad Prism software.

[0074] Results and Analysis

[0075] 1. Distribution of AGD in young sheep

[0076] AGD was measured on 1000 ewes aged 10 months at the time of artificial insemination. Data from ewes with vulvar deformities and unsuccessful artificial insemination were excluded. After applying these filtering methods, data from 791 ewes were included in the final analysis. Figure 2 As 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 2-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 was used for analysis, which showed 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 ambiguous 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 As shown in Figure 1-a, the AGD data of 332 multiparous sheep were divided into 18 groups with equal spacing 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 -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 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 healthy, 10-month-old young ewes and 24-month-old, second-parous multiparous ewes, housed under identical care and management, were selected for synchronized estrus and artificial insemination. AGD was measured 10 days before breeding, during vaginal plug placement, on the day of breeding, and at gestational days 30, 120, 30, and 60, all before morning feeding. Pregnancy was diagnosed 35 days after artificial insemination, and non-pregnant ewes were excluded because they require a second artificial insemination, which is out of sync with pregnant ewes. After rectal ultrasound confirmed pregnancy on day 35, 21 young ewes and 16 second-parous ewes were included in the study (Table 3-1). The data analysis showed that there was no significant change in AGD from diestrus to estrus, nor from estrus to 30 days of gestation. However, it increased significantly from 30 days of gestation to 120 days of gestation (P=0.045), decreased from 120 days of gestation to 30 days of lactation, and did not change significantly from 30 days after parturition to 60 days after parturition. After one reproductive cycle, AGD showed an insignificant increase ( Figure 4 -a). There is no significant change in AGD from diestrus to estrus, from estrus to 30 days of gestation, but it increases from 30 days of gestation to 120 days of gestation, decreases from 120 days of gestation to 30 days of lactation, and there is no significant change from 30 days of lactation to 60 days of lactation. There is no significant change in AGD after one reproductive cycle ( Figure 4-b). Therefore, AGD is a stable parameter in different physiological states (except late pregnancy) during the ewe's reproductive cycle.

[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 it was found that ( Figure 4 -c): AGD increased significantly with the increase of parity before the second parity, but did not change significantly after the second parity. This indicates that AGD of young ewes increased significantly with the increase of parity (P=0.008).

[0082] Table 1 shows the mean change of AGD in each period

[0083] Groups Diestrus Oestrus EarlyPregnancy Late pregnancy Early lactation Late lactation Young Sheep 48.19±7.46 48.20±7.37 48.35±7.38 52.94±7.40 49.81±6.94 49.50±6.75 Second lamb 58.58±6.82 58.74±6.76 59.10±6.63 59.97±6.41 59.44±6.40 59.26±6.69

[0084] 4. AGD and reproductive performance of young sheep

[0085] Among 1,000 10-month-old ewes scheduled for artificial insemination, 791 ewes were successfully artificially inseminated, excluding those with reproductive diseases, vaginal malformations, and failed plug placement. All ewes were inseminated using the same method. Pregnancy was diagnosed by rectal ultrasound on the morning of the 35th day after artificial insemination, before morning feeding. The pregnancy results were recorded: either pregnant or non-pregnant. Angulation Delay (AGD) groups were arranged from low to high and divided into four equally spaced groups: 30 mm group (25 mm < AGD ≤ 35 mm), 40 mm group (335 mm < AGD ≤ 45 mm), 50 mm group (45 mm < AGD ≤ 55 mm), and 60 mm group (55 mm < AGD ≤ 65 mm). The total number of ewes artificially inseminated and the number of pregnancies in each group were recorded, and the pregnancy rate for each group was calculated (Table 3-2). The non-parametric chi-square test analysis of the overall data showed no significant difference (P=0.063), but there was a significant difference between the 30mm group and the 60mm group (P=0.036). In the line graph of AGD and pregnancy rate changes, it can be found that as the AGD of each group increases, the pregnancy rate gradually decreases. The linear fit using the least squares method shows that the pregnancy rate changes as a function of the AGD increase ( Figure 3-4 ), i.e., y = 79.57 - 0.65x (x is AGD length, in mm; y is pregnancy rate, in %), with a correlation coefficient of R² = 0.962. The results showed that for every 1 mm increase in AGD, the pregnancy rate decreased by 0.65%, indicating a negative correlation between AGD size and pregnancy rate in young sheep.

[0086] Table 2: Relationship between AGD and pregnancy rate

[0087] Group Interval Mean value Total No. ofpregnant No. ofunpregnant Pregnancy rate 30mm group 25mm-35mm 32.56±2.36 44 26 18 59.09% 40mm group 35mm-45mm 41.06±2.71 273 148 125 54.21% 50mm group 45mm-55mm 49.44±2.74 393 191 202 48.60% 60mm group 55mm-56mm 57.79±2.21 81 32 49 39.51%

[0088] like Figure 5As shown in the figure, AGD and pregnancy rate are negatively correlated.

[0089] 5. AGD and pregnancy time of young sheep

[0090] The gestation and delivery times of the young ewes were recorded. A total of 397 young ewes successfully delivered in this experiment. The 397 young ewes were arranged in ascending order of AGD, with the median being the dividing point between the AGD length and short AGD length groups.

[0091] 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 age 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 age.

[0092] 6. AGD and number of first-born lambs in young sheep

[0093] 397 young ewes were arranged from small to large AGD, and the median was used as the cutoff point for the AGD length group to analyze the relationship between the number of lambs born and AGD in the long and short AGD groups. 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 in the figure, 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 showed that the smaller the AGD, the more lambs were born.

[0094] 7. AGD and first lamb weight of young sheep

[0095] 397 young sheep were arranged from small to large AGD, and the median was used as the cutoff point for the AGD length group to analyze the relationship between lamb weight and AGD in the long and short AGD groups. The first lamb weight in the short AGD group was 3.08±0.62Kg, and the first lamb weight in the long AGD group was 3.13±0.69Kg ( Figure 8 The independent sample T test showed that there was no significant difference in lamb 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±0.60Kg, while the first litter weight of the long AGD group was 3.42±0.65Kg ( Figure 8 The independent sample T test showed that there was no significant difference in the weight of single lambs between the short AGD group and the long AGD group (P=0.123). The weight of the first litter of multiple lambs in the short AGD group was 3.02±0.56Kg, and the weight of the first litter of multiple lambs in the long AGD group was 3.00±0.59Kg ( Figure 8 (Part c) Independent sample T-tests showed no significant difference in lamb weight between the short AGD group and the long AGD group (P = 0.755). The results showed no significant differences in AGD and weight for either single or twin lambs overall.

[0096] 8. AGD and reproductive performance of multiparous sheep

[0097] The AGD of 332 multiparous sheep with three parities 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. Figure 9 As shown, the number of lambs born in the short AGD group was significantly higher than that in the long AGD group for both the first and second parities (P1=0.018<0.05, P2=0.010<0.05). There was no significant difference in the number of lambs born in the short AGD group compared to the long AGD group for the third parity (P3=0.137). At the same parity, the short AGD group was larger than the long AGD group, and the short AGD group had a higher number of lambs than the long AGD group at each parity and for all parities. The results showed that the short AGD group had significantly higher numbers of lambs born in the first and second parities than the long AGD group, but there was no significant difference in the number of lambs born in the third parity between the long and short AGD groups.

[0098] In summary, we can conclude that:

[0099] A total of 791 young ewes were divided into four equally spaced groups, arranged from smallest to largest AGD. A linear regression graph of pregnancy rates was constructed using the pregnancy rates in the four groups. For every 1 mm increase in AGD, the pregnancy rate decreased by 0.65%. Therefore, it is concluded that AGD and pregnancy rate are negatively correlated.

[0100] After excluding non-pregnant ewes from 791 young ewes, a total of 397 young ewes were pregnant. The AGD of the 397 ewes was arranged from low to high, with the median 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 in the male-female ratio between the short AGD group and 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.

[0101] Analysis of lamb birth weights revealed no significant difference between the short and long AGD groups. Combined analysis of single and multi-lamb data revealed no significant differences in lamb weight between the short and long AGD groups, regardless of whether they were single or multi-lamb. Incorporating sex into lamb weight analysis revealed that male lambs in the short AGD group were significantly heavier than female lambs, consistent with the prevalence of males over females in most animal species. However, no significant difference in lamb weight was observed between male and female lambs in the long AGD group. Male lambs in the short AGD group were heavier than those in the long AGD group, but the difference was not significant. Female lambs in the short AGD group were significantly lighter than those in the long AGD group. These results indicate that varying AGD length significantly increases female lamb weight, while having no effect on male lamb weight. When categorizing single and multi-lamb lambs, increasing AGD had no effect on either male or female single lambs. Increasing AGD increased female lamb weight in twin lambs, but had 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.

[0102] The above 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 replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A method for predicting reproductive performance of mutton sheep, characterized in that: Includes the following steps Step 1: Obtain historical reproductive data of individual mutton sheep, analyze and establish a mutton sheep reproductive performance judgment model based on AGD, where AGD represents anogenital distance; Step 2: Fix the sheep and measure the anogenital distance of each sheep; Step 3: predicting the reproductive performance of individual mutton sheep using the judgment model in step 1; The parameters of reproductive performance include but are not limited to: pregnancy rate, gestation time or number of first-born lambs; The judgment model shown is as follows: If the anogenital distance of the tested sheep is greater than L, it is a breeding sheep with low reproductive performance; If the anogenital distance of the tested meat 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.

2. A method for predicting reproductive performance of mutton sheep according to claim 1, characterized in that: In step 1, the reproductive data includes the AGD data of the individual ewe and the corresponding pregnancy results and the number of lambs 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.

3. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: The analysis method in step 1 is as follows: The data were organized into mean ± standard deviation form and analyzed using SPSS 22.0 statistical software; The distribution of AGD was tested for normality using the Shapiro-Wilk test, the independent samples T test was used for the parametric part of AGD and reproductive performance, and the chi-square test was used for the nonparametric part of AGD and reproductive performance; The experimental results were expressed as "mean ± standard deviation", and some statistical graphs were drawn using Graphpad Prism software.

4. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: AGD data of ewes were collected at the following stages: diestrus, day of breeding, early pregnancy, late pregnancy, early lactation, and late lactation.

5. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: The ewe is a young ewe or a multiparous ewe.

6. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: Pregnancy results were obtained by transrectal ultrasound with a linear B-ultrasound probe starting 35 days after artificial insemination.

7. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: In step 2, the anogenital distance is measured using a vernier caliper.

8. The method for predicting reproductive performance of mutton sheep according to claim 1, wherein: The relationship between AGD and pregnancy rate satisfies the following formula: y=79.57-0.65x, where x is the AGD length, in mm; y is the pregnancy rate, in %, and the correlation coefficient R2=0.962; It can be seen that with the increase of AGD, the pregnancy rate gradually decreases. For every 1mm 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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