A method for inducing synchronous estrus in sows

Abstract

The present invention provides a method for inducing synchronous estrus in sows. This method uses long-acting sustained-release triptorelin to induce synchronous estrus in sows. At 10 - 18 days after the sows are in estrus, long-acting sustained-release triptorelin is subcutaneously injected. On the 29th day after injection, pregnant mare serum gonadotropin (PMSG) is intramuscularly injected to promote synchronous follicular development. Then, GnRH is injected at an interval of 72 h, and then fixed-time artificial insemination is performed twice at 24 h and 40 h respectively. Through the method of the present invention, the estrus cycle of sows can be synchronized, solving problems such as the large workload, long duration, and impact on the physiological changes of the endometrium in the existing technical solutions for synchronizing the estrus cycle of sows, and improving the efficiency of batch production of fixed-time artificial insemination.

Description

Technical Field

[0001] The present invention relates to the field of mammalian reproduction, and more particularly to a new method for inducing estrus synchronization in sows with long-acting and sustained-release triptorelin. Background Art

[0002] GnRH is gonadotropin-releasing hormone secreted by the hypothalamus, which acts on the anterior pituitary to secrete FSH and LH, thereby enabling follicles to grow, develop, and ovulate. Triptorelin is an analogue of gonadorelin (GnRH). Clinically, triptorelin is mainly used to treat polycystic ovary syndrome, precocious puberty in children, etc. In recent years, some studies have confirmed that intramuscular injection of GnRH or its analogue before sow ovulation can induce sow ovulation.

[0003] Compared with traditional sow insemination techniques, timed insemination techniques can reduce the workload of workers and improve work efficiency. The timed insemination procedure for gilts is as follows: The estrous cycles of the sow herd are synchronized by feeding 5 mg allyltrenbolone continuously for 15 - 18 days. After an interval of 42 h, 1000 IU PMSG is injected to promote synchronous follicular development. After an interval of 80 h, GnRH or its analogue, such as triptorelin, is intramuscularly injected to induce synchronous ovulation. Timed insemination is performed after intervals of 24 h and 16 h respectively.

[0004] The hormone for inducing estrus synchronization in gilts in the veterinary drug market is allyltrenbolone. Allyltrenbolone is a synthetic progestin that acts on the hypothalamus and pituitary gland to inhibit the production of endogenous gonadotropins in the form of negative feedback regulation. Low levels of gonadotropins inhibit follicle growth, hinder follicle development and sow estrus. After stopping feeding allyltrenbolone, gonadotropins start to be secreted, stimulating follicle growth and development and sow estrus. When allyltrenbolone is used in a sow herd, after continuous treatment for 15 - 18 days, when the treatment with allyltrenbolone is stopped synchronously, the follicles in the sow herd develop synchronously, thus achieving estrus synchronization. However, feeding allyltrenbolone continuously for 18 days not only requires a large amount of work and consumes a lot of manpower, but also disrupts the periodic physiological changes of the endometrium. The physiological state of the endometrium does not match egg fertilization and early embryo development, affecting embryo implantation and easily causing sows to be infertile. In addition, research shows that allyltrenbolone has a relatively long retention time in sows, and allyltrenbolone can still be detected 10 days after stopping use, affecting the effect of estrous cycle synchronization. Summary of the Invention

[0005] The purpose of the present invention is to provide a new method for inducing estrus synchronization in pigs to address the problems caused by feeding allyltrenbolone during pig estrus synchronization.

[0006] Research of the present invention shows that treating sows with long-acting and sustained-release triptorelin can replace allyltrenbolone to prevent follicle development. When the efficacy of long-acting and sustained-release triptorelin disappears synchronously, estrus cycle synchronization of sows is achieved.

[0007] Accordingly, the technical solution of the present invention is as follows:

[0008] The present invention first provides the application of long-acting and sustained-release triptorelin in inducing synchronized estrus in sows.

[0009] According to the above application, long-acting and sustained-release triptorelin is subcutaneously injected on the 10th - 18th day after the sow is in estrus. Further, it is preferably injected on the 14th day.

[0010] According to the above application, the injection dose of the long-acting and sustained-release triptorelin is 1.875 - 5.625 mg. Further, the injection dose is preferably 3.75 mg.

[0011] Further, the present invention provides a method for inducing synchronized estrus in sows, which method comprises subcutaneously injecting long-acting and sustained-release triptorelin on the 10th - 18th day after the sow is in estrus.

[0012] Further, it is preferably injected on the 14th day.

[0013] According to the above method, the injection dose of the long-acting and sustained-release triptorelin is 1.875 - 5.625 mg.

[0014] Further, the injection dose is preferably 3.75 mg.

[0015] Further, the present invention provides a method for inducing timed artificial insemination during synchronized estrus in sows, which method comprises inducing synchronized estrus in sows by the above method, intramuscularly injecting PMSG on the 29th day after injecting long-acting and sustained-release triptorelin to promote synchronous follicular development, then injecting GnRH at an interval of 72 h, and then performing timed artificial insemination twice at 24 h and 40 h respectively.

[0016] Among them, the injection dose of PMSG each time is 800 - 1200 units. It is preferably 1000 units.

[0017] Among them, the injection dose of GnRH is 80 - 120 μg, preferably 100 μg.

[0018] The long-acting triptorelin used in the present invention is a highly effective analogue of GnRH, which has a higher affinity for GnRH receptors. When administered continuously, it can down-regulate pituitary GnRH receptors, thereby significantly reducing the levels of FSH and LH, causing follicle growth and development to stagnate, but not affecting the endometrium and subsequent embryo implantation. In addition, its half-life in the blood is only 2.8 ± 1.2 h. Therefore, in the present invention, treating sows with long-acting sustained-release triptorelin can replace allylgestin to prevent follicle development. When the efficacy of long-acting sustained-release triptorelin disappears synchronously, the estrus cycle of sows can be synchronized, solving problems such as the large workload, long duration, and impact on endometrial physiological changes in the existing technical solutions for synchronizing the estrus cycle of sows, and improving the efficiency of timed insemination batch production. For the long-acting triptorelin used in aquaculture production, it greatly saves labor and workload in management. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the technical solution for optimizing the long-acting sustained-release triptorelin of the present invention.

[0020] Figure 2 is the content of long-acting sustained-release triptorelin at different concentrations in the blood in vivo. The injection volume of Series 1 is 3.75 mg, and the injection volume of Series 2 is 5.625 mg. The X-axis is time, and the Y-axis is the content in vivo (ng / ml). DETAILED DESCRIPTION OF THE INVENTION

[0021] The following examples are used to further illustrate the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, any modification or replacement made to the present invention belongs to the scope of the present invention.

[0022] Unless otherwise specified, the technical means used in the examples are conventional means well-known to those skilled in the art. Unless otherwise specified, the reagents used in the present invention are all of analytical pure or above specifications. The long-acting sustained-release triptorelin used in the present invention can be a commercially available product, and the one used in the examples can be purchased from IPSEN.

[0023] Example 1 Effect of Long-acting Sustained-release Triptorelin on Synchronizing Estrus in Sows

[0024] As Figure 1As shown in the figure, 48 nine-month-old replacement sows of the same breed, in good health condition and with clear estrus records, were divided into 4 groups. Starting from the 14th day after estrus, the first three groups of sows were subcutaneously injected with 0 mg (recorded as natural estrus), 3.75 mg, and 5.625 mg of long-acting sustained-release triptorelin respectively. At 8:00 am every day after injecting the drug, 5 ml of blood samples were collected from each sow, centrifuged to separate the serum and stored frozen for measuring the changes in triptorelin levels, and the hormone levels of FSH, LH, E2, P2, etc. in sows. And a boar was used to check the estrus of sows once a day to count and observe the estrus situation of sows. It was continuously measured for 28 days. On the 29th day after injecting the long-acting sustained-release triptorelin, each sow was intramuscularly injected with 1000 units of PMSG, and 100 μg / head of GnRH was injected again after 72 h, and then timed (artificial) insemination was carried out twice at 24 h and 40 h respectively. The last group (experimental group 4) was fed 20 mg of allyl trenbolone per sow per day for 18 consecutive days. 42 h after the last feeding, each sow was intramuscularly injected with 1000 units of PMSG, and 100 μg / head of GnRH was injected again after 72 h, and then timed (artificial) insemination was carried out twice at 24 h and 40 h respectively. The sows in experimental group 4 were checked for estrus by a boar once a day to count and observe the estrus situation of sows. After the sows showed standing estrus, timed (artificial) insemination was carried out twice at 24 h and 40 h respectively.

[0025] Experimental results

[0026] For the content of triptorelin measured in the blood every day, a line graph with the date on the abscissa and the content of triptorelin in the body (ng / ml) on the ordinate is as Figure 2 shown. Among them, series 1 is the injection of 3.75 mg of long-acting sustained-release triptorelin, and series 2 is the injection of 5.625 mg of long-acting sustained-release triptorelin. The results show that a transient peak is formed in the blood on the day of injecting the long-acting sustained-release triptorelin, and it maintains a stable release within the subsequent 28 days. The average content of triptorelin in the blood is 0.63 ng / ml. As shown in Table 1, when the injection dose of the long-acting sustained-release triptorelin is 3.75 mg, a stable inhibitory effect on sow estrus can be achieved, and 100% of the sows do not show estrus during the duration of the drug effect.

[0027] Table 1 Effects of long-acting sustained-release triptorelin on inhibiting sow estrus and timed insemination and ovulation

[0028]

[0029]

[0030] During the suppression period, the ovaries of sows were mainly in the luteal phase and small follicle phase, and the average level of follicle-stimulating hormone (FSH) in the blood was comparable to that of the natural estrus and altrenogest groups. After the suppression ended, pregnant mare serum gonadotropin (PMSG) was injected into the sows to induce follicle development. The follicle diameters in the long-acting sustained-release triptorelin group were comparable to those in the natural estrus and ovulation group, and the ovulation rate was 75-100%.

[0031] The results of the present invention indicate that treating sows with long-acting sustained-release triptorelin can replace altrenogest to prevent follicle development. When the efficacy of long-acting sustained-release triptorelin disappears synchronously, the estrus cycles of sows can be synchronized, solving problems such as the large workload, long duration, and impact on the physiological changes of the endometrium in the existing technical solutions for synchronizing the estrus cycles of sows, improving the efficiency of timed artificial insemination batch production, and greatly saving labor and workload in production management.

Claims

1. Application of long-acting sustained-release triptorelin in inducing estrus synchronization in sows to replace allylgestin to prevent follicular development, characterized in that, Inject long-acting sustained-release triptorelin subcutaneously on the 10th to 18th day after the sow is in heat, and the injection dose of the long-acting sustained-release triptorelin is 1.875 to 5.625 mg.

2. A method for inducing synchronous estrus in sows, characterized in that, This method injects long-acting sustained-release triptorelin subcutaneously on the 10th to 18th day after the sow is in heat to replace allyltrenbolone to prevent follicle development, and the injection dose of the long-acting sustained-release triptorelin is 1.875 to 5.625 mg.

3. A method for inducing synchronous estrus and timed artificial insemination in sows, which includes inducing synchronous estrus in sows by using the method described in claim 2. After 29 days of injection, inject PMSG intramuscularly to promote synchronous follicle development, then inject GnRH after an interval of 72 h, and then perform timed artificial insemination twice at 24 h and 40 h respectively.

4. The method according to claim 3, wherein The dose of each injection of PMSG is 1000 units.

5. The method according to claim 3, wherein The injection dose of GnRH is 100 μg.

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