Dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate

Abstract

The invention discloses a dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate, and relates to the technical field of dairy cow breeding. The problems that follicles on ovaries of postpartum cows are not synchronous in development, ovulation time cannot be accurately regulated and controlled, and embryonic development regulation and control after fertilization are lacked are solved. The method mainly comprises the following steps: three times of gonadotropin releasing hormone injection, two times of cloprostenol sodium injection, gonadotropin releasing hormone injection, luteinizing hormone releasing hormone A3 injection, timed artificial semen deposition, and VADE mixed liquid injection. GnRH is used for actively regulating follicular development, 95% or more of the dairy cows are synchronized after 2-3 rounds of starting, then timing insemination is performed, the conception rate of the postpartum dairy cows can be remarkably increased, compared with the prior art, the pretreatment time is short, the synchronous ovulation rate and conception rate of the dairy cows can be increased, the calving interval is shortened, and the survival rate of the dairy cows is increased. The economic benefit of the pasture is obviously increased, and the breeding management level can be improved on the basis.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of dairy cow reproduction, and particularly relates to a method for controlling ovulation time and improving embryo implantation rate of dairy cows. BACKGROUND

[0002] Reproductive efficiency is the key to affect the production efficiency of dairy cows. With the improvement of domestic intensive and large-scale level, the estrus rate and estrus detection rate of dairy cows are significantly reduced. Therefore, dairy farms generally use timed artificial insemination technology based on synchronization of estrus. The classic timed artificial insemination basic program (Ovsynch program, GnRH-PG-GnRH) was invented by Pursley and Wiltbank in 1995. When the first injection of GnRH is used, the dairy cow is in the 6-8 days of estrus cycle, and more than 90% of the synchronization of estrus ovulation effect can be achieved. However, postpartum dairy cows may be in any day of the estrus cycle at 60-80 days, so in order to improve the synchronization of estrus ovulation effect, pre-synchronization, double synchronization, G6G and other programs have been developed. Through pretreatment, the conception rate is increased from 30-40% to 40-50%, however, the conception rate still has room for further improvement, and the pretreatment program of the prior art requires a long time, which increases the ineffective feeding days of dairy cows and reduces the economic benefits.

[0003] At present, most of the dairy farms in China use the double synchronization (Double-Ovsynch) technical scheme, and the conception rate of dairy cows is improved. However, this technical scheme still has the following problems: 1. The starting time of follicle development on the ovary of postpartum dairy cows is inconsistent, and after injection of hormone treatment, the follicle development and ovulation are not synchronized, which leads to poor batch treatment effect and low conception rate; 2. The ovulation time is dispersed and not accurately controlled, which leads to that the sperm has aged at the time of ovulation, the fertilization rate is reduced, and the embryo quality is poor; 3. The double synchronization program only regulates the development of follicles, and does not regulate the development of embryos after fertilization, uterine receptivity and luteal function, so the problem of early embryo loss is still not solved, and the embryo implantation rate is low. In addition, the current pretreatment program is based on the successful ovulation after pretreatment, and then PGF 2α is used to dissolve the corpus luteum. However, in the actual situation of dairy production, the proportion of unsuccessful ovulation after pretreatment is high, and the ovary is more at rest, which leads to that there is no corpus luteum on the ovary of dairy cows when PGF 2α is used, so that the next program is difficult to produce effect, and finally leads to low conception rate of dairy cows after synchronization of estrus timed artificial insemination.

[0004] Based on this, the application provides a dairy cow synchronization ovulation and timed insemination method for precisely controlling ovulation time and improving embryo implantation efficiency. SUMMARY

[0005] The application aims to solve the problems in the prior art and provides a dairy cow timed insemination method for controlling ovulation time and improving embryo implantation efficiency.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A dairy cow timed insemination method for controlling ovulation time and improving embryo implantation efficiency comprises the following contents:

[0008] S1: First inject all the dairy cows with gonadotropin-releasing hormone to promote follicle development of the dairy cows;

[0009] S2: Second muscle injection of gonadotropin-releasing hormone to promote follicle development and ovulation of the dairy cows whose follicles do not develop in S1, and promote re-follicle development and ovulation of the dairy cows whose follicles develop in S1, and induce new follicle wave start;

[0010] S3: Third muscle injection of gonadotropin-releasing hormone to promote follicle development, ovulation, and luteinization of the dairy cows whose follicles do not develop in S2, and promote re-follicle development, ovulation, and luteinization of the dairy cows whose follicles develop in S2;

[0011] S4: First muscle injection of sodium cloprostenol to dissolve lutein;

[0012] S5: Second muscle injection of sodium cloprostenol to fully dissolve lutein;

[0013] S6: Fourth muscle injection of gonadotropin-releasing hormone;

[0014] S7: Muscle injection of luteinizing hormone-releasing hormone A3 to precisely control ovulation time and simultaneously perform timed artificial insemination;

[0015] S8: Muscle injection of a mixture of vitamins A, D, and E 5 days after artificial insemination;

[0016] S9: First use of B-ultrasound for pregnancy diagnosis;

[0017] S10: Second use of B-ultrasound for pregnancy diagnosis.

[0018] Preferably, the first time of the muscle injection of the gonadotropin-releasing hormone is 44-50 days after the postpartum of the dairy cow, and the injection dose is 100ug / head.

[0019] Preferably, the second time of the muscle injection of the gonadotropin-releasing hormone is the seventh day after the S1 step, and the injection dose is 100ug / head.

[0020] Preferably, the third time of the muscle injection of the gonadotropin-releasing hormone is the seventh day after the S2 step, and the injection dose is 100ug / head.

[0021] Preferably, the first time of the muscle injection of the sodium prostaglandin is the seventh day after the S3 step, and the injection dose is 0.5mg / head.

[0022] Preferably, the second time of the muscle injection of the sodium prostaglandin is the first day after the S4 step, and the injection dose is 0.5mg / head.

[0023] Preferably, the fourth time of the muscle injection of the gonadotropin-releasing hormone is 32h after the S5 step, and the injection dose is 100ug / head.

[0024] Preferably, the muscle injection time of the luteinizing hormone-releasing hormone A3 is 16h after the S6 step, and the injection dose is 25ug / head.

[0025] Preferably, the injection dose of the mixed solution of vitamins A, D and E is 10ml / head.

[0026] Preferably, the first diagnosis time of the pregnancy is 32-35 days after the artificial insemination.

[0027] The second diagnosis time of the pregnancy is the sixtieth day after the artificial insemination.

[0028] The beneficial effects of the present application are:

[0029] 1. The present application can significantly improve the pregnancy rate of postpartum dairy cows by only focusing on the start of follicle, actively regulating follicular development by GnRH, and then performing timed insemination after 2-3 rounds of start, so that more than 95% of dairy cows are synchronized, and the pre-treatment time is short, which can effectively improve the synchronization of follicular development and ovulation rate of dairy cows, shorten the interval between calving, and significantly increase the economic benefits of the pasture.

[0030] 2. The present application can improve the synchronization of follicular development and ovulation by continuously using GnRH to regulate follicular development, and improve the efficiency of batch processing of cattle; twice using PGF 2α, fully dissolving corpus luteum, improving follicle development efficiency and oocyte quality; injecting LHRH-A3 when insemination, precisely controlling ovulation time, ensuring that the oocytes and sperm with strong activity are fertilized; injecting VADE after insemination, improving uterine receptivity and corpus luteum function, strengthening the implantation effect of dairy cow embryos and reducing early embryo loss.

[0031] 3. The present application can significantly improve the first mating conception rate of dairy cows, and is simple, efficient, low-cost and does not require estrus identification, which is a programmed ovulation and timed insemination scheme, and is easy to popularize and apply. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A flowchart of a dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate according to the embodiment 1 of the present application is shown in the figure.

[0033] Figure 2 A system flowchart of a dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate according to the embodiment 1 of the present application is shown in the figure.

[0034] Figure 3 A flowchart of a dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate according to the embodiment 2 of the present application is shown in the figure. DETAILED DESCRIPTION

[0035] The technical scheme of the present application will be further described in detail below in combination with specific embodiments.

[0036] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0037] Embodiment 1:

[0038] A dairy cow timed insemination method for controlling ovulation time and improving embryo implantation rate, as shown in the figure, comprises the following contents: Figures 1-2

[0039] S1: First injecting gonadotropin-releasing hormone (GnRH) into the muscles of all dairy cows to promote follicle development of dairy cows; and improving the synchronicity of follicle development.

[0040] Preferably, the first muscle injection time of GnRH is 0 days, i.e. 44-50 days after the dairy cow gives birth, and the injection dose is 100 μg per head.

[0041] ​S2: the second time of injecting GnRH by muscle, promoting the follicle development and ovulation of the cows whose follicle did not develop in S1, and the second time of follicle development and ovulation of the cows whose follicle developed in S1, inducing the new follicle wave to start; further improving the synchronization of follicle development and ovulation.

[0042] Preferably, the second time of injecting GnRH by muscle is on the 7th day after S1, and the injection dose is 100 μg per head.

[0043] S3: the third time of injecting GnRH by muscle, promoting the follicle development, ovulation and corpus luteum formation of the cows whose follicle did not develop in S2, and the second time of follicle development, ovulation and corpus luteum formation of the cows whose follicle developed in S2; further improving the development rate of corpus luteum.

[0044] Preferably, the third time of injecting GnRH by muscle is on the 14th day after S2, and the injection dose is 100 μg per head.

[0045] S4: the first time of injecting prostaglandin F2a sodium (PGF 2α ) by muscle to dissolve corpus luteum;

[0046] Preferably, the first time of injecting prostaglandin F2a sodium by muscle is on the 21st day after S3, and the injection dose is 0.5 mg per head.

[0047] S5: the second time of injecting prostaglandin F2a sodium by muscle to dissolve corpus luteum completely; promoting the new follicle development.

[0048] Preferably, the second time of injecting prostaglandin F2a sodium by muscle is on the 22nd day after S4, and the injection dose is 0.5 mg per head.

[0049] S6: the fourth time of injecting GnRH by muscle; further promoting the follicle development and maturation.

[0050] Preferably, the fourth time of injecting GnRH by muscle is on the 23rd day after S5, and the injection dose is 100 μg per head.

[0051] S7: injecting luteinizing hormone-releasing hormone A3 (LHRH-A3) by muscle to control the ovulation time accurately, and simultaneously performing timed artificial insemination;

[0052] Preferably, the time of injecting luteinizing hormone-releasing hormone A3 by muscle is on the 24th day after S6, and the injection dose is 25 μg per head.

[0053] S8: injecting the mixed solution of vitamins A, D and E (VADE) by muscle 5 days after artificial insemination; promoting the embryo development and implantation.

[0054] Preferably, the injection dose of the vitamin A, D, E mixed solution is 10ml per head.

[0055] In use, the embodiment improves the synchronization of follicular development and ovulation by continuously regulating follicular development using GnRH, improves the efficiency of batch processing of cow groups, and uses PGF twice 2α , fully dissolves the corpus luteum, improves the efficiency of follicular development and oocyte quality, injects LHRH-A3 during insemination to accurately control the ovulation time and ensure that the oocytes and sperm with strong activity are fertilized, and injects VADE after insemination to improve uterine receptivity and corpus luteum function, strengthen the implantation effect of dairy cow embryos, and reduce early embryo loss.

[0056] The present application can significantly improve the pregnancy rate of postpartum cows by only focusing on the initiation of follicles, actively regulating follicular development using GnRH, and then performing timed insemination after 2-3 rounds of initiation, thereby significantly improving the pregnancy rate of postpartum cows. Compared with the prior art, the pretreatment time is short. The present application not only effectively improves the synchronization of ovulation rate and pregnancy rate of cows, shortens the interval between calving, and significantly increases the economic benefit of the farm, but also improves the level of reproductive management on this basis.

[0057] The present application can significantly improve the pregnancy rate of postpartum cows, and is simple, efficient and low in cost, without the need for estrus identification. It is a programmed synchronization of ovulation and timed insemination scheme, which is easy to popularize and apply.

[0058] Example 2:

[0059] A method for controlling ovulation time and improving embryo implantation rate of dairy cows, as shown in Figure 3 In order to ensure the pregnancy of individual cows, the embodiment is improved on the basis of example 1 and includes the following contents:

[0060] S9: First pregnancy diagnosis by B-ultrasound; determine the pregnancy of the cow.

[0061] Preferably, the first diagnosis time of pregnancy is 32-35 days after artificial insemination.

[0062] S10: Second pregnancy diagnosis by B-ultrasound; determine the pregnancy of the cow.

[0063] Preferably, the second diagnosis time of pregnancy is 60 days after artificial insemination.

[0064] Test Example 1:

[0065] In order to verify the feasibility of the GG-GPPG basic program, 125 healthy cows without reproductive tract diseases in a certain dairy farm in Heilongjiang Province were selected and randomly divided into two groups for testing, and the specific operation is as follows:

[0066] 1. Test methods

[0067] 1. Herd selection and grouping: Select postpartum Chinese Holstein cows with 1-3 parities, uniform body condition, normal estrous cycle, good health and normal milk production. All cows are injected with PGF on days 14, 28 and 42 after giving birth. 2α The cattle were then randomly divided into two groups: a control group of 78 cattle and an experimental group of 47 cattle.

[0068] 2. Experimental treatment: 1) Control group (double simultaneous procedure): Cows were first injected with GnRH on day 46 after calving and with PGF on day 53 2α , GnRH was injected on the 56th day, GnRH was injected again on the 63rd day, and PGF was injected on the 70th day 2α , PGF injection on day 71 2α , GnRH was injected on the 72nd day, and timed insemination was performed on the 73rd day; 2) Experimental group (GG-GPPG program): Cows were injected with GnRH for the first time 49 days after calving, injected with GnRH on the 56th day, injected with GnRH again on the 63rd day, and injected with PGF on the 70th day 2α , PGF injection on day 71 2α , GnRH was injected on the 72nd day and timed insemination was performed on the 73rd day.

[0069] 3. Pregnancy test: On the 35th day after insemination, B-ultrasound is used to test the cattle for pregnancy.

[0070] 2. Experimental Results

[0071] As shown in Table 1 below, the effects of the two methods on the conception rate of dairy cows: the conception rate of dairy cows in the experimental group was 51.11%, and the conception rate of dairy cows in the control group was 42.31%. The experimental group was significantly higher than the control group. Therefore, the GG-GPPG procedure in the experimental group was more effective.

[0072] Table 1:

[0073] Group Total number (heads) Number of pregnant cows (heads) Pregnancy rate of cows (%) Control group 78 33 42.31 Test group 47 23 48.94

[0074] Test Example 2:

[0075] To verify the efficacy of LHRH-A3 injection during insemination using the GG-GPPG basic procedure, 141 healthy cows without reproductive tract disease from a dairy farm in Heilongjiang Province were randomly divided into three groups based on age, parity, and body condition (the day of calving for all Holstein cows was designated as day 0). Specifically,

[0076] Control group: a double concurrent procedure was used;

[0077] Experimental group I: using the GG-GPPG basic program;

[0078] Test group II: using GG-GPPG+LHRH-A3 program.

[0079] I. Test method

[0080] Control group (n=51): the cows were injected with GnRH (100 μg / head) on the 43rd day after delivery, PGF (0.5 mg / head) on the 50th day, GnRH (100 μg / head) on the 53rd day, GnRH (100 μg / head) on the 60th day, and PGF (0.5 mg / head) on the 67th and 68th days, respectively. 2α 2α PGF (0.5 mg / head) on the 67th and 68th days, GnRH (100 μg / head) on the 69th day in the afternoon, and insemination on the 70th day in the morning.

[0081] Test group I (n=56): the cows were injected with GnRH (100 μg / head) on the 46th day after delivery, GnRH (100 μg / head) on the 53rd day, GnRH (100 μg / head) on the 60th day, and PGF (0.5 mg / head) on the 67th and 68th days, respectively. 2α PGF (0.5 mg / head) on the 67th and 68th days, GnRH (100 μg / head) on the 69th day in the afternoon, and insemination on the 70th day in the morning.

[0082] Test group II (n=34): the cows were injected with GnRH (100 μg / head) on the 46th day after delivery, GnRH (100 μg / head) on the 53rd day, GnRH (100 μg / head) on the 60th day, and PGF (0.5 mg / head) on the 67th and 68th days, respectively. 2α PGF (0.5 mg / head) on the 67th and 68th days, GnRH (100 μg / head) on the 69th day in the afternoon, and insemination on the 70th day in the morning.

[0083] One day after insemination, the synchronization of ovulation in the three groups of cows was detected by B-ultrasound, and pregnancy diagnosis was performed by B-ultrasound 35 days after insemination.

[0084] II. Experimental results

[0085] As shown in Table 2, the ovulation synchronization rate of the cows in the test group II was higher than that in the test group I and the control group, and the ovulation synchronization rate of the cows in the test group I was higher than that in the control group. Therefore, the GG-GPPG program and LHRH-A3 can improve the ovulation synchronization rate of cows.

[0086] Table 2:

[0087] Group Total number (heads) Number of cows ovulating (heads) Synchronization ovulation rate (%) Control group 51 40 78.43 Test group I 56 48 85.71 Test group II 34 31 91.18 ​

[0088] The effects of the three methods shown in Table 3 on the conception rate of cows, the conception rate of the cows in Test Group II and Test Group I was higher than that of the control group, and the conception rate of the cows in Test Group II was higher than that of the cows in Test Group I. Therefore, the GG-GPPG program combined with LHRH-A3 can further improve the conception rate of cows.

[0089] Table 3:

[0090] Group Total number (heads) Number of pregnant cows (heads) Pregnancy rate of cows (%) Control group 51 22 43.14 Test group I 56 28 50.00 Test group II 34 18 52.94

[0091] Test Example 3:

[0092] In order to verify the effect of injecting VADE on improving the conception rate, 62 healthy cows (lactating Holstein cows) without reproductive tract diseases in a certain dairy farm in Inner Mongolia were selected, and they were randomly divided into two groups according to their age, parity and body condition (the day when all Holstein cows gave birth to calves was defined as day 0), and the specific conditions were as follows:

[0093] Control group: using GG-GPPG basic program;

[0094] Test group: using GG-GPPG+VADE program.

[0095] I. Test method

[0096] Control group (n=25): cows were injected with GnRH (100 μg / head) intramuscularly on day 46 after delivery, GnRH (100 μg / head) intramuscularly on day 53, GnRH (100 μg / head) intramuscularly on day 60, and PGF 2α intramuscular injection, dose 0.5 mg / head, GnRH (100 μg / head) intramuscular injection in the afternoon of day 69 after delivery, and insemination in the morning of day 70 after delivery and LHRH-A3 (25 μg / head) intramuscular injection at the same time.

[0097] Test Group I (n=37): cows were injected with GnRH (100 μg / head) intramuscularly on day 46 after delivery, GnRH (100 μg / head) intramuscularly on day 53, GnRH (100 μg / head) intramuscularly on day 60, and PGF 2α intramuscular injection, dose 0.5 mg / head, GnRH (100 μg / head) intramuscular injection in the afternoon of day 69 after delivery, and insemination in the morning of day 70 after delivery and LHRH-A3 (25 μg / head) intramuscular injection at the same time, and VADE (10 ml / head) intramuscular injection on day 75 after delivery.

[0098] On the 5th day, 10th day after insemination, blood was collected, and the progesterone content was determined by ELASA kit, and on the 35th day and 60th day after insemination, B-ultrasound was used for pregnancy detection.

[0099] II. Results of the experiment

[0100] As shown in Table 4, the progesterone level of the test group was higher than that of the control group, thus, injection of VADE had certain effect on luteal function and could improve the progesterone level of dairy cows.

[0101] Table 4:

[0102] Group 5th day 10th day 15th day Control group 4.36 ± 1.3 a ]] 6.55 ± 1.2 b ]] 8.28 ± 1.5 b ]] Test group 4.15 ± 1.4 a ]] 8.43 ± 1.3 a ]] 10.51 ± 1.4 a ]]

[0103] Note: For the same column, different superscripts indicate significant difference (P < 0.05).

[0104] As shown in Table 5, the conception rate of the test group was higher than that of the control group, thus, injection of VADE could improve the conception rate of dairy cows.

[0105] Table 5:

[0106] Group Total number (heads) Pregnancy rate (35th day) Pregnancy rate (60th day) Control group 25 44.00(11 / 25) 40.00(10 / 25) Test group 37 51.35(19 / 37) 48.65(18 / 37)

[0107] Test Example 4:

[0108] In order to further verify the effect of the GG-GPPG program on improving the conception rate of dairy cows, 312 healthy cows (lactating Holstein cows) without reproductive tract diseases in a dairy farm in Inner Mongolia were selected, and they were randomly divided into two groups according to their age, parity and body condition (the day when all Holstein cows gave birth was defined as day 0), specifically:

[0109] Control group: using double synchronization basic program;

[0110] Test group: using GG-GPPG+VADE program.

[0111] I. Test method

[0112] Control group (n = 107): dairy cows were injected with GnRH (100 μg / head) intramuscularly on day 43 after delivery, PGF 2α (0.5 mg / head) intramuscularly on day 50, GnRH (100 μg / head) intramuscularly on day 53, GnRH (100 μg / head) intramuscularly on day 60, and PGF 2α intramuscularly on days 67 and 68, respectively, GnRH (100 μg / head) intramuscularly in the afternoon on day 69 after delivery, and insemination in the morning on day 70 after delivery.

[0113] Test group I (n = 205): dairy cows were injected with GnRH (100 μg / head) intramuscularly on day 46 after delivery, GnRH (100 μg / head) intramuscularly on day 53, GnRH (100 μg / head) intramuscularly on day 60, and PGF 2αThe dose is 0.5 mg per head, GnRH (100 μg per head) is injected intramuscularly in the afternoon of the 69th day after delivery, insemination is performed in the morning of the 70th day after delivery, and LHRH-A3 (25 μg per head) is injected intramuscularly at the same time, VADE (10 ml per head) is injected intramuscularly in the 75th day after delivery.

[0114] On the 35th day after insemination, the cows are detected for pregnancy by using B-ultrasound.

[0115] II. Experimental results

[0116] As shown in Table 6, the pregnancy rate of the test group is higher than that of the control group, therefore, the GG-GPPG+VADE program can improve the pregnancy rate of dairy cows, and can be applied in large groups of dairy cows.

[0117] Table 6:

[0118]

[0119]

[0120] Conclusion, the method of the present application can significantly improve the pregnancy rate of dairy cows, and is simple, efficient, low in cost, and does not need to identify estrus, is a programmed ovulation and timed insemination program, and is convenient for popularization and application.

[0121] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate, characterized in that: Includes the following: S1: All cows were given an intramuscular injection of gonadotropin-releasing hormone for the first time to promote follicular development; S2: A second intramuscular injection of gonadotropin-releasing hormone promotes follicular development and ovulation in cows whose follicles did not develop and ovulate in S1, as well as follicular development and ovulation in cows whose follicles developed and ovulated in S1, thereby inducing the initiation of a new follicular wave. S3: The third intramuscular injection of gonadotropin-releasing hormone promotes follicular development, ovulation, and corpus luteum formation in cows whose follicles did not develop and ovulate in S2, and promotes follicular development, ovulation, and corpus luteum formation in cows whose follicles developed and ovulated in S2; S4: First intramuscular injection of cloprostenol sodium to dissolve the corpus luteum; S5: Inject cloprostenol sodium intramuscularly again to fully dissolve the corpus luteum; S6: fourth intramuscular injection of gonadotropin-releasing hormone; S7: Intramuscular injection of luteinizing hormone-releasing hormone A3 to precisely control ovulation time and perform timed artificial insemination at the same time; S8: 5 days after artificial insemination, intramuscular injection of a mixture of vitamins A, D, and E; S9: First diagnosis of pregnancy by ultrasound; S10: Secondary diagnosis of pregnancy using B-ultrasound.

2. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 1, characterized in that: The first intramuscular injection time of the gonadotropin-releasing hormone is 44-50 days after the cow gives birth, and the injection dose is 100 μg / head.

3. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 2, characterized in that: The second intramuscular injection of gonadotropin-releasing hormone is on the 7th day after step S1, and the injection dose is 100 μg / head.

4. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 3, characterized in that: The third intramuscular injection of gonadotropin-releasing hormone is on the 7th day after step S2, and the injection dose is 100 μg / head.

5. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 4, characterized in that: The first intramuscular injection of cloprostenol sodium is on the 7th day after step S3, and the injection dose is 0.5 mg / head.

6. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 5, characterized in that: The time for the second intramuscular injection of cloprostenol sodium is the first day after step S4, and the injection dose is 0.5 mg / head.

7. A method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 6, characterized in that: The fourth intramuscular injection of gonadotropin-releasing hormone is 32 hours after step S5, and the injection dose is 100 μg / head.

8. The method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 7, characterized in that: The intramuscular injection time of the luteinizing hormone-releasing hormone A3 is 16 hours after step S6, and the injection dose is 25 μg / head.

9. The method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 1, characterized in that: The injection dosage of the vitamin A, D, and E mixed solution is 10 ml / head.

10. The method for timed insemination of dairy cows for controlling ovulation time and improving embryo implantation rate according to claim 1, characterized in that: The first diagnosis time of the pregnancy is 32-35 days after artificial insemination; The second diagnosis time of the pregnancy is 60 days after artificial insemination.

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