Timed insemination method for dairy cow pretreated by prostaglandin and hematotrophin

Abstract

The invention discloses a timed insemination method for dairy cows pretreated by prostaglandin and hemotrophin, and relates to the technical field of breeding of dairy cows in animal husbandry. The problems that an existing synchronous ovulation timing insemination technology is tedious in operation, prone to errors and high in cost are solved. The timed semen deposition method for the dairy cow specifically comprises the following steps that the high-yield lactation Holstein dairy cow is selected, the calving time is recorded as the 0th day, and PGF2a is injected for the first time on the 20th day so as to promote discharge of residual uterine lochia; on the thirtieth day, rectum examination of uterus involution is carried out, the uterus recovery condition is examined, and related uterus diseases are eliminated; and injecting PGF2a for the second time on the 35th day. According to the method, the phenomenon that oestrus is asynchronous due to ovary rest or ovary excessive activity is effectively avoided, so that the conception rate of the high-yield lactation Holstein dairy cow is increased, meanwhile, the medicine cost can be effectively reduced, the stress reaction of the dairy cow caused by frequent fixation is avoided, and operation is easy, convenient and efficient.

Description

Technical Field

[0001] The invention relates to the technical field of dairy cow reproduction in animal husbandry, in particular to a timed insemination method for dairy cows pretreated with prostaglandins and blood gonadotropins. Background Art

[0002] Currently, low reproductive rates in dairy cows are one of the major bottlenecks hindering the improvement of dairy production performance and economic benefits in my country. Reproductive performance not only directly determines production levels and economic benefits but is also crucial to the sustainable development of the dairy industry. High-yielding dairy cows often experience estrus abnormalities during peak lactation due to various stressors. These symptoms include lack of noticeable estrus symptoms, absence of estrus, irregular ovulation, silent estrus, delayed ovulation, ovarian inactivity, or follicular cysts. These abnormalities lead to decreased reproductive rates, severely impacting the economic performance of dairy farms.

[0003] Ovulation-synchronized, timed insemination technology is a key reproductive control method used in modern dairy farming. By using different combinations of reproductive hormones to regulate follicular growth and ovulation, precise control of reproduction is achieved. To improve the reproductive efficiency of dairy cows, various estrus-synchronized, timed insemination protocols have been developed to artificially control ovarian activity and ovulation timing. These protocols accurately track ovulation timing without the need for estrus detection and are widely used in dairy cow breeding.

[0004] However, the existing synchronized ovulation and timed insemination technology still has the following shortcomings:

[0005] (1) Many injections and high execution pressure: During the double synchronization process, multiple hormone injections must be performed on time and accurately. If there are injection errors, inaccurate timing, or missed injections, the conception rate will decrease. (2) The double synchronization effect is poor for cows with dormant ovaries: Some high-yielding dairy cows have problems such as postpartum ovarian dormancy, which in turn affects the synchronization rate of double synchronization and leads to unsatisfactory conception results. (3) Increased medication and breeding costs: When cows are in good health after giving birth and their reproductive systems and ovaries are highly active, the use of the double synchronization program will increase medication costs and may cause cows to ovulate prematurely, miss the best time for insemination, waste estrus, and thus prolong the estrus cycle and increase breeding costs.

[0006] Therefore, in order to solve the above problems, the present invention proposes a method for timed insemination of dairy cows pretreated with prostaglandins and blood gonadotropins to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a timed insemination method for dairy cows pretreated with prostaglandins and blood gonadotropins.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins comprises the following steps:

[0010] S1: High-yielding lactating Holstein cows were selected, calving was recorded as day 0, and the first injection of PGF2a was given on day 20 to promote the discharge of residual uterine lochia;

[0011] S2: On the 30th day, a rectal examination of the uterus was performed to check the recovery of the uterus and rule out related uterine diseases;

[0012] S3: The second injection of PGF2a on day 35 eliminates the corpus luteum of the previous pregnancy and restores ovarian function;

[0013] S4: PMSG was injected on day 56 to synchronize estrus and ovulation;

[0014] S5: On the 60th day, gonadotropin-releasing hormone (GnRH) is injected to induce the development and maturation of the dominant follicle and ovulation to form a corpus luteum;

[0015] S6: PGF2a is injected on days 67 and 68 to promote full corpus luteum dissolution;

[0016] S7: The second injection of GnRH was given in the afternoon of day 69 to induce the maturation of the dominant follicle;

[0017] S8: After GnRH injection on the 69th day, insemination is performed 16 hours later, and LHRH-A3 is injected at the same time to control ovulation, prevent delayed ovulation, and enhance corpus luteum function after ovulation.

[0018] Preferably, in S1-S8, the injection dose of PGF2a is 0.5 mg / head, the injection dose of PMSG is 1000 IU / head, the injection dose of GnRH is 100 μg / head, and the injection dose of LHRH-A3 is 25 μg / head.

[0019] Furthermore: in S1 and S3, the interval between the two injections of PGF2a is 15 days.

[0020] Further preferably, in said S2, the interval between the uterine involution examination and the first injection of PGF2a is 10 days.

[0021] As a preferred embodiment of the present invention: in S4, the interval between the injection of PMSG and the second injection of PGF2a is 21 days.

[0022] As a further preferred embodiment of the present invention: in S5, GnRH is injected on the 4th day after the injection of PMSG.

[0023] As a further solution of the present invention: in S6, the interval between the two injections of PGF2a and the injection of GnRH is 7 days, and further, the time interval between the two injections of PGF2a is 24 hours.

[0024] On the basis of the above scheme: in S7, the interval between the second injection of GnRH and the two injections of PGF2a was 32 hours.

[0025] Based on the above scheme, preferably, in S8, on the 35th day after the scheduled insemination, pregnancy diagnosis is performed using B-ultrasound to determine the pregnancy status of the dairy cow.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention provides a method for synchronized ovulation and timed insemination of high-yielding Holstein dairy cows. The method uses PGF2a and PMSG to pre-treat the cows, effectively avoiding estrus asynchrony caused by ovarian inactivity or overactive ovaries, thereby improving the conception rate of high-yielding lactating Holstein dairy cows. At the same time, the timed insemination method proposed by the present invention can effectively reduce drug costs, avoid stress reactions in cows caused by frequent restraint, and is simple and efficient to operate.

[0028] 2. The PGF2a used in the research process of the present invention has the effect of efficiently dissolving the corpus luteum. At the same time, it can accelerate the recovery of the cow's uterus and promote follicle development, playing a good pretreatment role for the next step of follicle development regulation.

[0029] 3. PMSG used in the research process of the present invention is a glycoprotein hormone synthesized and secreted by the cup-shaped tissue of the endometrium of pregnant mares. It has the dual activity of follicle-stimulating hormone and luteinizing hormone, can promote the development of follicles and ovulation, and plays a role in improving the synchronization of the next step of follicle development and ovulation regulation. Because its half-life is longer than that of GnRH, it was found in the research process that it has a good therapeutic effect on dairy cows with ovarian inactivity.

[0030] 4. During the research process of the present invention, three different intervals for injection of PMSG and GnRH were designed (the intervals for injection of PMSG and GnRH were 9d, 7d, and 4d, respectively) to screen the optimal PMSG administration time. The experimental results showed that an interval of more than 4 days between the injection of PMSG and GnRH would reduce the conception rate and increase the return of estrus. It was concluded that the preferred interval for the injection of PMSG and GnRH was 4 days, thereby further improving the first-time conception rate of cows. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic flow chart of a method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins proposed by the present invention;

[0032] Figure 2 This is a data table showing the effect of the interval between injections of PMSG and GnRH on the reproductive indicators of dairy cows in a timed insemination method for dairy cows pretreated with prostaglandins and gonadotropins proposed by the present invention;

[0033] Figure 3 A data table comparing the PMSG pretreatment timed insemination procedure and the double simultaneous insemination procedure of a method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins proposed in the present invention;

[0034] Figure 4 A schematic diagram of the injection sequence and intervals of a timed insemination method for dairy cows pretreated with prostaglandins and gonadotropins proposed by the present invention;

[0035] Figure 5 A line graph showing the effect of the injection interval of PMSG and GnRH on the first-mating pregnancy rate of dairy cows in a timed insemination method for dairy cows pretreated with prostaglandins and gonadotropins proposed by the present invention;

[0036] Figure 6 This is a bar chart comparing data between the PMSG pretreatment timed insemination program and the double synchronization program of the timed insemination method for dairy cows pretreated with prostaglandins and blood gonadotropins proposed in the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be further described in detail below in conjunction with specific implementation methods.

[0038] Example 1:

[0039] A method for timed insemination of dairy cows pretreated with prostaglandins and blood gonadotropins, such as Figure 1-6 As shown, the following steps are included:

[0040] S1: High-yielding lactating Holstein cows were selected, and calving was recorded as day 0. The first injection of cloprostenol sodium (PGF2a) (hereinafter referred to as PGF2a) was given on day 20 to promote the discharge of residual uterine lochia.

[0041] S2: On the 30th day, a rectal examination is performed to check the uterine recovery and rule out related uterine diseases to avoid affecting the effectiveness of the synchronized ovulation and timed insemination procedure later;

[0042] S3: The second injection of PGF2a on day 35 eliminates the corpus luteum of the previous pregnancy and restores ovarian function;

[0043] S4: injection of plasma gonadotropin (PMSG) on day 56, hereafter referred to as PMSG, to synchronize estrus and ovulation;

[0044] S5: On day 60, gonadotropin-releasing hormone (GnRH) is injected to induce the development and maturation of the dominant follicle and ovulation to form a corpus luteum;

[0045] S6: PGF2a is injected on days 67 and 68 to promote full corpus luteum dissolution;

[0046] S7: The second injection of GnRH was given in the afternoon of day 69 to induce the maturation of the dominant follicle;

[0047] S8: After the injection of GnRH on the 69th day, insemination is performed 16 hours later, and luteinizing hormone-releasing hormone A3 (LHRH-A3) is injected at the same time to control ovulation, prevent delayed ovulation, and enhance corpus luteum function after ovulation.

[0048] In S1-S8, the injection dose of PGF2a is 0.5 mg / head, the injection dose of PMSG is 1000 IU / head, the injection dose of GnRH is 100 μg / head, and the injection dose of LHRH-A3 is 25 μg / head;

[0049] In steps S1 and S3, the interval between the two injections of PGF2a is 15 days;

[0050] In step S2, the interval between the uterine involution examination and the first injection of PGF2a is 10 days;

[0051] In step S4, the interval between the injection of PMSG and the second injection of PGF2a is 21 days;

[0052] In step S5, GnRH is injected on the 4th day after the injection of PMSG;

[0053] In step S6, the interval between the two injections of PGF2a and the injection of GnRH is 7 days, and further, the interval between the two injections of PGF2a is 24 hours;

[0054] In step S7, the second injection of GnRH and the two injections of PGF2a are separated by 32 hours;

[0055] In step S8, on the 35th day after the scheduled insemination, B-ultrasound is used to perform pregnancy diagnosis to determine the pregnancy status of the cow.

[0056] In order to understand the effect of the interval between PMSG and GnRH injection on the first-time conception rate of high-yielding Holstein cows, 73 healthy cows without reproductive tract diseases were selected and three intervals were designed for screening. The intervals between PMSG and GnRH injection were 9 days, 7 days and 4 days, respectively.

[0057] The specific operations are as follows:

[0058] S1: The day when all Holstein cows calved was designated as day 0;

[0059] S2: On days 20 and 35, all cows received intramuscular injections of PGF2a at a dose of 0.5 mg / cow;

[0060] S3: Uterine involution was examined on day 30. 73 healthy lactating Holstein cows were selected and randomly divided into three experimental groups:

[0061] The number of dairy cows in experimental group I was 24, and the experimental steps included the following:

[0062] A1: PMSG was injected intramuscularly on day 51 at a dose of 1000 IU / head;

[0063] A2: GnRH was injected intramuscularly on day 60 at a dose of 100 μg / head;

[0064] A3: Receive intramuscular injection of PGF2a on days 67 and 68, with a dose of 0.5 mg / head;

[0065] A4: GnRH was injected intramuscularly in the afternoon of day 69, with a dose of 100 μg / head;

[0066] A5: Insemination was performed on the morning of the 70th day, and LHRH-A3 was injected intramuscularly at the same time, with a dose of 25 μg / head.

[0067] In experimental group I, the interval between the injection of PMSG and GnRH was 9 days.

[0068] The number of dairy cows in experimental group II was 24, and the experimental steps included the following:

[0069] B1: PMSG was injected intramuscularly on day 53 at a dose of 1000 IU / head;

[0070] B2: GnRH was injected intramuscularly on day 60 at a dose of 100 μg / head;

[0071] B3: received intramuscular injection of PGF2a on days 67 and 68, with a dose of 0.5 mg / head;

[0072] B4: GnRH was injected intramuscularly in the afternoon of day 69, with a dose of 100 μg / head;

[0073] B5: Insemination was performed on the morning of the 70th day, and LHRH-A3 was injected intramuscularly at the same time, with a dose of 25 μg / head.

[0074] In experimental group II, the interval between injection of PMSG and GnRH was 7 days.

[0075] The number of dairy cows in experimental group III was 25, and the experimental steps included the following:

[0076] C1: PMSG was injected intramuscularly on day 56 at a dose of 1000 IU / head;

[0077] C2: intramuscular injection of GnRH on day 60, dose of 100 μg / head);

[0078] C3: received intramuscular injection of PGF2a on days 67 and 68, with a dose of 0.5 mg / head;

[0079] C4: GnRH was injected intramuscularly in the afternoon of day 69, with a dose of 100 μg / head;

[0080] C5: Insemination was performed on the morning of the 70th day, and LHRH-A3 was injected intramuscularly at the same time, with a dose of 25 μg / head.

[0081] In experimental group III, the interval between injection of PMSG and GnRH was 4 days.

[0082] After insemination, the three experimental groups of cows were observed daily for their return to estrus and relevant records were kept until the 35th day after insemination, when their pregnancy status could be diagnosed by ultrasound. The first-time conception rate, return to estrus rate, and empty pregnancy rate (excluding return to estrus cows) were calculated.

[0083] See the results Figure 2 and Figure 5 The first-time conception rate of dairy cows in Experimental Group III was 56.00%, significantly higher than that in Experimental Groups I and II (P < 0.05). During the present study, three different intervals between PMSG and GnRH injections were designed (9 days, 7 days, and 4 days, respectively) to screen for the optimal PMSG administration time. The results showed that an interval greater than 4 days between PMSG and GnRH injections reduced conception rates and increased estrus relapses. Therefore, a 4-day interval between PMSG and GnRH injections was the preferred interval.

[0084] Example 2:

[0085] In order to further verify the effect of the timed insemination program by pre-treatment with prostaglandins and blood gonadotropins, 76 healthy Holstein cows without reproductive tract diseases were selected for control experiments in this example.

[0086] This controlled experiment optimized the physiological status of dairy cows. On the 40th day after calving, all cows were examined for ovary by B-ultrasound and randomly divided into two groups: an experimental group (43 cows) and a control group (33 cows).

[0087] The experimental group used the procedure of Example 1 with an interval of 4 days between the injection of PMSG and GnRH;

[0088] The control group used the existing synchronized ovulation and timed insemination technology scheme, and the specific steps were as follows:

[0089] S1: GnRH was injected intramuscularly 44 days after delivery, with a dose of 100 μg / head.

[0090] S2: PGF2a was injected intramuscularly on day 51 at a dose of 0.5 mg / head;

[0091] S3: On days 53 and 60, GnRH was injected intramuscularly at a dose of 100 μg / head;

[0092] S4: PGF2a was injected intramuscularly on days 67 and 68, with a dose of 0.5 mg / head;

[0093] S5: GnRH was injected intramuscularly in the afternoon of day 69 at a dose of 100 μg / head;

[0094] S6: Insemination was performed on the morning of the 70th day.

[0095] After insemination, the return of estrus in each group of cows was observed and recorded every day until the 35th day. Their pregnancy status was diagnosed by B-ultrasound, and the first-time conception rate, return of estrus rate, and empty pregnancy rate (excluding return of estrus cows) were calculated.

[0096] See the results Figure 3 and Figure 6 The first conception rate of the experimental group was 51.16%, which was higher than that of the control group, but the difference was not significant. Therefore, the control experiment results show that the timed insemination program with prostaglandin and gonadotropin pretreatment can replace the double synchronization program and be applied in production practice.

[0097] The above-mentioned timed insemination protocol, using the present invention, showed the best results in high-yielding lactating cows, with intramuscular injections of PMSG on postpartum day 56, followed by injections of GnRH at 4-day intervals. This method significantly improves first-time conception rates in dairy cows. Furthermore, the present invention is simple, efficient, and cost-effective, requiring no estrus identification. It represents a programmed, synchronized ovulation and timed insemination protocol, making it readily available for widespread application.

[0098] The present invention provides a method for synchronized ovulation and timed insemination of high-yielding Holstein dairy cows. PGF2a and PMSG are used to pre-treat the cows, effectively avoiding estrus asynchrony caused by ovarian inactivity or overactive ovaries, thereby improving the conception rate of high-yielding lactating Holstein dairy cows. At the same time, the timed insemination method proposed by the present invention can effectively reduce drug costs, avoid stress reactions in cows caused by frequent restraint, and is simple and efficient to operate.

[0099] The PGF2a used in the research process of the present invention has the effect of efficiently dissolving the corpus luteum, and at the same time, can accelerate the recovery of the cow's uterus and promote follicle development, playing a good pretreatment role for the next step of follicle development regulation.

[0100] The PMSG used in the research process of the present invention is a glycoprotein hormone synthesized and secreted by the cup-shaped tissue of the endometrium of pregnant mares. It has the dual activity of follicle-stimulating hormone and luteinizing hormone, can promote the development of follicles and ovulation, and plays a role in improving the synchronization of the next step of follicle development and ovulation regulation. Because its half-life is longer than that of GnRH, it was found in the research process that it has a good therapeutic effect on dairy cows with ovarian inactivity.

[0101] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins, characterized in that: The steps include: S1: High-yielding lactating Holstein cows were selected, calving was recorded as day 0, and the first injection of PGF2a was given on day 20 to promote the discharge of residual uterine lochia; S2: On the 30th day, a rectal examination of the uterus was performed to check the recovery of the uterus and rule out related uterine diseases; S3: The second injection of PGF2a on day 35 eliminates the corpus luteum of the previous pregnancy and restores ovarian function; S4: PMSG was injected on day 56 to synchronize estrus and ovulation; S5: On the 60th day, gonadotropin-releasing hormone (GnRH) is injected to induce the development and maturation of the dominant follicle and ovulation to form a corpus luteum; S6: PGF2a is injected on days 67 and 68 to promote full corpus luteum dissolution; S7: The second injection of GnRH was given in the afternoon of day 69 to induce the maturation of the dominant follicle; S8: After GnRH injection on the 69th day, insemination is performed 16 hours later, and LHRH-A3 is injected at the same time to control ovulation, prevent delayed ovulation, and enhance corpus luteum function after ovulation.

2. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S1-S8, the injection dose of PGF2a is 0.5 mg / head, the injection dose of PMSG is 1000 IU / head, the injection dose of GnRH is 100 μg / head, and the injection dose of LHRH-A3 is 25 μg / head.

3. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S1 and S3, the interval between the two injections of PGF2a was 15 days.

4. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S2, the interval between the uterine involution examination and the first PGF2a injection is 10 days.

5. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S4, the interval between the injection of PMSG and the second injection of PGF2a was 21 days.

6. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S5, GnRH was injected on day 4 after the injection of PMSG.

7. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S6, the interval between the two injections of PGF2a and the injection of GnRH is 7 days, and further, the time interval between the two injections of PGF2a is 24 hours.

8. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S7, the interval between the second injection of GnRH and the two injections of PGF2a was 32 hours.

9. The method for timed insemination of dairy cows pretreated with prostaglandins and gonadotropins according to claim 1, characterized in that: In S8, on the 35th day after the scheduled insemination, B-ultrasound is used to perform pregnancy diagnosis to determine the pregnancy status of the dairy cow.

Images