Timing insemination method for improving pregnancy rate and lambing rate of sheep

Abstract

The invention discloses a timed insemination method for improving the pregnancy rate and the lambing rate of sheep, and belongs to the technical field of livestock breeding. In order to solve the problem that the pregnancy rate of existing sheep is unstable during regular insemination, the method comprises the steps that a progesterone sponge suppository is embedded in the vagina of a healthy and reproductive ewe on the 0th day, and meanwhile 25 g of luteinizing hormone is injected in an intramuscular mode to release hormone A3; removing the thrombus on the 12th day, and performing intramuscular injection of 400IU of pregnant mare serum gonadotropin at the same time; and after the suppository is removed, insemination is carried out on the cervix orifice of the ewe with ram semen diluted at the ratio of 1: (5-8) in 52h and 64h respectively. According to the method, ovarian activities of the ewes are regulated and controlled, the estrus synchronism and the ovulation rate are improved, tests show that the pregnancy rate reaches 81.6%, the lambing rate is 1.14, compared with a conventional method, the pregnancy rate and the lambing rate of the sheep are remarkably improved, and development of the sheep industry is promoted.

Description

Technical Field

[0001] This invention relates to the field of livestock reproduction technology, specifically to a timed insemination method for improving the pregnancy rate and lambing rate of sheep. Background Technology

[0002] Seasonal estrus and low reproductive rates in sheep have become bottlenecks restricting the further development of the sheep industry. Promoting timed insemination technology in sheep is a key measure to solve this bottleneck. Timed insemination technology uses exogenous hormones to control and alter the activity patterns of the ewes' ovaries, thereby synchronizing estrus, ovulation, mating, lambing, and market entry within a predetermined timeframe. This will completely change the traditional indiscriminate mating breeding model of sheep flocks, eliminating the need for estrus detection, reducing labor costs, increasing lambing and reproductive rates, achieving "three births in two years," and also facilitating disease control and maximizing the breeding efficiency of superior rams. The most classic timed insemination technique involves: vaginal implantation of a progesterone sponge plug for 12 days, followed by injection of 250-400 units of pregnant mare serum gonadotropin (PMSG) upon plug removal, with the first insemination 52 hours after plug removal and a second insemination 64 hours later. However, the pregnancy rate of timed insemination in sheep is currently unstable, which seriously affects the promotion and application of this technology.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a timed insemination method, which is an effective and practical way to improve the pregnancy rate and lambing rate of sheep.

[0005] To achieve the above objectives, the present invention provides a timed insemination method for improving the pregnancy rate and lambing rate of sheep, comprising the following steps: Step 1: Select healthy, well-fitting ewes with normal estrous cycles and no reproductive problems. Step 2: Insert a progesterone sponge plug into the vagina of the selected ewe. The day of insertion is marked as day 0. At the same time as insertion, inject luteinizing hormone-releasing hormone A3 into the ewe's muscle. Step 3: On day 12, remove the progesterone sponge plug and simultaneously inject pregnant mare serum gonadotropin into the ewe via intramuscular injection. Step 4: Perform insemination on the ewes 52 hours and 64 hours after tether removal.

[0006] Preferably, the weight of the breeding ewes in step one above is 40-50 kg.

[0007] Preferably, in step two above, the progesterone sponge plug is a vaginal implantable sponge plug with a content of 45mg / plug of fluoroprogesterone acetate, and before implantation, 4 million units of sodium penicillin are evenly coated on the surface of every 50 progesterone sponge plugs.

[0008] Preferably, the injection dose of luteinizing hormone-releasing hormone A3 in step two above is 25µg / animal.

[0009] Preferably, the injection dose of pregnant mare serum gonadotropin in step three above is 400 IU / mare.

[0010] Preferably, in step two above, when implanting the progesterone sponge plug, the young ewe places the plug after feeling the location of the vaginal fornix with her fingers; the multiparous ewe first inserts the plug laterally with an implantation gun, then adjusts it to the front and pushes it along the vaginal wall to the bottom before removing the plug, and the cotton thread outside the plug is cut to be slightly lower than the length of the tail.

[0011] Preferably, during insemination in step four above, the ram semen is diluted with semen diluent at a ratio of 1:5 to 8.

[0012] Preferably, the 0.3 mL diluted semen is inserted into the cervix for slow insemination.

[0013] Preferably, before inserting the progesterone sponge plug in step two above, the vulva of the ewe is cleaned with a topical disinfectant, such as potassium permanganate solution or benzalkonium chloride.

[0014] The timed insemination method provided by this invention is simple to operate and low in cost. Insemination using the method provided by this invention can significantly improve the pregnancy rate and lambing rate of sheep through timed insemination, and has application potential in the sheep breeding field. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the timed insemination method provided in this invention. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Note: Unless otherwise specified, the experimental methods in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0018] Example 1: A timed insemination method to improve pregnancy and lambing rates in sheep 1. Test conditions 1.1 Experimental Animals Select 1360 healthy, well-fitting, and normal-cycle breeding ewes with no reproductive problems, weighing (40-50) kg.

[0019] 1.2 Test Drugs and Materials Vaginal implantable sponge plugs (MAP, manufactured in Australia), specifications: fluprogesterone acetate 45mg / plug; pregnant mare serum gonadotropin (PMSG, Ningbo Sansheng Biotechnology Co., Ltd.), specifications: 1000IU / vial; luteinizing hormone-releasing hormone A3 (Ningbo Sansheng Biotechnology Co., Ltd.), specifications: 25µg / vial. Plug gun; physiological saline; external disinfectant (potassium permanganate solution or benzalkonium chloride), syringe.

[0020] 1.3 Processing Method The experiment will run from September 2021 to March 2025. For every 50 sponge plugs, 4 million units of sodium penicillin will be evenly coated on the surface before being placed into the vagina of the ewe to prevent vaginitis. Luteinizing hormone-releasing hormone A3 and PMSG will be administered via intramuscular injection. The specific steps are as follows:

[0021] A progesterone sponge plug is implanted into the vagina of the breeding ewes mentioned above. The day of implantation is recorded as day 0. Before implantation, the ewes are restrained, and their vulvas are cleaned with disinfectant. For young ewes, before implantation, the location of the vaginal fornix is ​​felt by inserting a finger into the vagina. The tail is lifted with one hand, and the sponge plug is slowly placed into the fornix with the other hand. For multiparous ewes, the tail is lifted with one hand, and the implantation gun is first inserted laterally with the other hand. Then, the gun is slowly adjusted to the front and pushed along the vaginal wall to the bottom. The handle is then pushed to remove the progesterone sponge plug, and the implantation gun is gently pulled to complete the implantation. To prevent the ewes from biting each other and pulling out the sponge plug, the cotton thread can be cut short, ideally slightly shorter than the tail.

[0022] On day 0, luteinizing hormone-releasing hormone A3 was injected intramuscularly into breeding ewes with implanted progesterone sponge plugs at a dose of 25µg / ewes. On day 12, the progesterone sponge plugs were removed from the breeding ewes, and PMSG was injected intramuscularly at a dose of 400 IU per ewe.

[0023] 1.4 Identification of Thrombosis and Inflammation When a sponge thrombus falls off during thrombectomy, it is called thrombus dislodgement; when bleeding, foul odor, or purulent discharge occurs during thrombectomy, it is called inflammation.

[0024] 1.5 Ewe insemination Insemination was performed 52 hours and 64 hours after thrombectomy. The collected ram semen was diluted with semen diluent at a ratio of 1:(5-8). During insemination, the ewe's vagina was opened with a vaginal speculum, the cervix was located, and 0.3 mL of semen was drawn up using an insemination device. The device was then inserted into the cervix and slowly inseminated. A schematic diagram of the timed insemination method provided by this invention is available for reference. Figure 1 As shown.

[0025] 1.6 Data Statistics Experimental data were compiled using Excel 2016 and analyzed for differences using SPSS 26.0 statistical software. Pregnancy rate = number of lambs giving birth / number of lambs giving birth × 100%; lambing rate = number of lambs born / number of lambs giving birth × 100%.

[0026] 2. Test Results 2.1 Effects of short-cycle estrus synchronization in sheep Table 1 shows that the control group did not receive luteinizing hormone-releasing hormone A3 injection at the time of tether implantation, while the treatment group received 25 µg of luteinizing hormone-releasing hormone A3 per sheep at the time of tether implantation. The results indicated that the pregnancy rate and lambing rate in the treatment group were significantly higher than those in the control group, suggesting that injection of 25 µg of luteinizing hormone-releasing hormone A3 at the time of tether implantation significantly improved sheep reproductive rate.

[0027] Table 1. Effects of timed insemination on sheep in Example 1 Note: Different lowercase letters in the superscript of the same data indicate significant differences (P < 0.05).

[0028] This invention, based on conventional timed insemination, injects luteinizing hormone-releasing hormone A3 simultaneously with the implantation of the embolus, significantly improving the pregnancy rate and lambing rate of sheep.

[0029] One possible explanation for this difference is: Luteinizing hormone-releasing hormone (LH-A3) effectively induces follicular turnover in ewes at any stage of the estrous cycle and promotes the loss of dominant follicles. The loss of dominant follicles promotes the recruitment and growth of smaller follicles, directly inducing higher ovulation rates and embryo numbers. LH-A3 promotes ovulation without affecting sperm transport or fertilization, and it also promotes preimplantation embryo development, which is beneficial for improving pregnancy rates. LH-A3 likely triggers a series of cascade reactions in vivo and regulates embryo implantation by modulating corpus luteum function and endometrial receptivity. Simultaneous injection of LH-A3 with follicular implantation induces ovulation or follicular atresia in ewes, leading to the loss of dominant follicles, a significant decrease in serum estrogen levels, the emergence of a new follicular wave, and the accelerated recruitment and development of numerous smaller follicles into ovulatory follicles.

[0030] The method of this invention differs from conventional timed insemination techniques for sheep in that luteinizing hormone-releasing hormone A3 is injected simultaneously with the implantation of the embolus, resulting in the following effects: In this experiment, luteinizing hormone-releasing hormone A3 was injected simultaneously with the implantation of the progesterone sponge plug. The progesterone concentration released from the progesterone sponge plug remained at a high level, negatively inhibiting the secretion of follicle-stimulating hormone and progesterone. The high-dose injection of luteinizing hormone-releasing hormone A3 during implantation further enhanced the negative feedback effect, significantly inhibiting the development of dominant follicles, promoting the recruitment of small follicles, and inhibiting estrogen secretion. This resulted in concentrated and delayed estrus in ewes and increased estrus synchronization. Luteinizing hormone-releasing hormone A3 did not affect sperm transport or egg fertilization, and it could even promote the development of preimplantation embryos, which would help improve the pregnancy rate.

[0031] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A timed insemination method for improving pregnancy and lambing rates in sheep, characterized in that, Includes the following steps: Step 1: Select healthy, well-fitting ewes with normal estrous cycles and no reproductive problems. Step 2: Insert a progesterone sponge plug into the vagina of the selected ewe. The day of insertion is marked as day 0. At the same time as insertion, inject luteinizing hormone-releasing hormone A3 into the ewe's muscle. Step 3: On day 12, remove the progesterone sponge plug and simultaneously inject pregnant mare serum gonadotropin into the ewe via intramuscular injection. Step 4: Perform insemination on the ewes 52 hours and 64 hours after tether removal.

2. The method according to claim 1, characterized in that, In step one, the breeding ewe should weigh 40-50kg.

3. The method according to claim 1, characterized in that, In step two, the progesterone sponge plugs are vaginal implantable sponge plugs with a content of 45mg of fluoroprogesterone acetate per plug, and before implantation, 4 million units of sodium penicillin are evenly applied to the surface of every 50 progesterone sponge plugs.

4. The method according to claim 1, characterized in that, In step two, the injection dose of luteinizing hormone-releasing hormone A3 is 25µg / animal.

5. The method according to claim 1, characterized in that, Step 2: When inserting the progesterone sponge plug, young ewes should place the plug after feeling the location of the vaginal fornix with their fingers; multiparous ewes should first insert the plug laterally with an implantation gun, then adjust it to the front and push it along the vaginal wall to the bottom before removing the plug, and the cotton thread outside the plug should be cut to a length slightly lower than the tail.

6. The method according to claim 1, characterized in that, In step three, the injection dose of pregnant mare serum gonadotropin is 400 IU / mare.

7. The method according to claim 1, characterized in that, In step four, during insemination, the ram's semen is diluted with semen diluent at a ratio of 1:5 to 8.

8. The method according to claim 1, characterized in that, In step four, during the insemination procedure, the ewe's vagina is opened using a vaginal speculum, the cervix is ​​located, and the insemination device is inserted into the cervix after drawing 0.3 mL of diluted semen and then slowly inseminated.

9. The method according to claim 1, characterized in that, Before inserting the progesterone sponge plug in step two, clean the ewe's vulva with a topical disinfectant, such as potassium permanganate solution or benzalkonium chloride.

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