Analysis on the possible causes of low conception rate in dairy cows

The conception rate of artificial insemination of dairy cows is a problem that every technician and manager attaches great importance to. Say simple also simple, say complex your conception rate is not raised! Some of the ideas in this post are based on data, some on personal experience, and some on conjecture. I have roughly listed an outline, which may have the following reasons: First, the reasons for the operation of artificial insemination technology. Second, the reasons for ovulation and eggs in cows. 3. The reason for semen. 4. Causes of reproductive diseases. 5. Causes of early embryonic death. Before analyzing the above five reasons in detail, three concepts should be clarified: 1. The estrous cycle refers to the interval time from the beginning of one estrus to the beginning of the next estrus. The estrous cycle of cows is 18-24 days, with an average of 21 days. The estrous cycle is generally divided into four stages: proestrous, estrous, anestrous and diestrus. 2, estrus is also called estrus duration, refers to the period of obvious estrus symptoms. Cows are sexually active, vulva hyperemia, gradually strengthened, uterine hyperemia and contraction strengthened, mucus outflow, cervical canal relaxation, follicle development is rapid. 12-30 hours after farrowing and 10-20 hours after breeding. 3. Estrus conception rate refers to the percentage of the number of pregnant cows in the number of mating periods. To some extent, it can better reflect the fertility effect and breeding level. Estrus conception rate can be divided into first estrus conception rate and total estrus conception rate. continued. Continue to post after reviewing the post. Some of the contents still have to be thought about, welcome to shoot bricks!-------------------------------------- 1. Possible causes of artificial insemination 1. Oestrus observation is inaccurate. To understand the concept of estrus duration, we observe estrus and only observe estrus duration. The most important thing is to observe the time when the cow starts to oestrus, i.e. the time when it starts to steadily accept the climb. Because some cattle begin oestrus at night and others appear quiet, it is difficult to accurately determine when oestrus begins, so sometimes one has to judge from the degree of pudendal swelling and the thinness of mucus. 2. Insemination time is too early or too late. The general insemination time is that the cow begins to accept the first insemination after 12 hours and the second insemination after 24 hours. 24 hours is critical for multiparous cattle and 12 hours is critical for some finishing cattle. Because multiparous cattle ovulate 10-12 hours after the end of estrus, breeding cattle are earlier. Sperm 30 minutes to reach the fertilization site, sperm and eggs need to be capacitated time. The optimum time for insemination should be at the beginning of the end of estrus, when the cow has begun to refuse to climb and mucus is absent or very thick. 3. Try to operate aseptically and pay attention to hygiene. In the process of feeding steak feces, feces more or less stick to the vulva. Some people use a coat repeatedly, it is difficult to achieve sterility. Some people take off their coats too early and carry germs in the air. Too many infusions can also infect the uterus. So the dirty work has to be done cleanly. 4. Semen backflow. Sometimes semen backflow occurs because the sperm gun does not match the coat or the coat is not clamped tightly. Check carefully after losing. 5. When injecting semen, the force is too strong, causing the death of sperm. 6. The sperm gun reaches the uterus body, the gun body is tilted upward, and the semen flows to the coat and is brought back with the gun. Think about it. It's only 0.25ml. So the gun should be tilted down as much as possible, and the injection should be slightly withdrawn. 7, the action is too stiff, unskilled, the vagina, cervix, uterine mucosa stabbed bleeding. 8, sperm by low temperature, high temperature, shock, ultraviolet rays and other attacks quickly die. -------------------------------------- 2. The reasons for ovulation and egg fertilization ability of cows 1. Multiparous cows generally occur 10-12 hours after the end of estrus, and breeding cattle are relatively early. Some cattle often ovulate later because of improper breeding management. The estrous cycle of these cattle is often normal, and the eggs also have normal fertilization ability. They cannot be regarded as sick. Adjusting the sperm infusion time can solve the problem. 2. There are data showing that the eggs discharged by breeding cattle in the first estrus period have no fertilization ability, and the low rate of first estrus conception after calving is also a problem of egg fertilization ability. 3. I suspect that endocrine disorders caused by improper feeding management (nutrition, exercise, ratio of concentrate to coarse, lactation, etc.) will also affect the conception rate. Endocrine disorders cause the egg to fail to gain normal energy, that is, no ability to fertilize. On the other hand, endocrine disorders make the genital tract contract abnormally, the egg cannot normally reach the fertilization site or stay too short in the ampulla of the fallopian tube, and the sperm egg cannot combine. Third, the possible reasons for semen 1, semen vitality and density of low impact on conception rate almost everyone is attached importance to. Sperm motility 0.3, 0.4, effective sperm number may not reach 10 million, in addition to the impact of density, there is also a problem of acrosome integrity. 2. Preservation of semen. After thawing semen, try to keep it at constant temperature, try to protect it from low temperature, high temperature, shock, sunlight and ultraviolet rays. The shorter the preservation time in vitro, the better. No matter how good the external environment is, it can't catch up with the environment of cow reproductive tract. 3. Sperm survival time is affected by conception rate. The survival time of protosperm in cow is more than 72 hours. The thawed semen was stored at 37℃ for more than 4 hours according to the national standard. Because of the influence of diluent preparation, dilution ratio and processing technology, the survival time of thawed semen in vitro and in vivo is very different. Short survival time, low conception rate. -------------------------------------- - --------------------------------------------------------------- Endometritis is a common disease in dairy cows. Mild endometriosis cows oestrus normal, ovulation normal, long-term mating infertility. On the one hand, it blocks the normal operation of sperm, on the other hand, it makes embryos unable to implant. The causes include poor sterilization of midwifery, poor sanitation of livestock houses, poor sterilization of breeding, excessive insemination times, poor feeding management, reduced body resistance, some infectious diseases, etc. In practice, the diagnosis is generally based on the color of mucus. Endometritis should be considered if the cow has pain response, contractile response is not obvious, and cow anger is severe. 2. Follicular cyst Follicular cysts show prolonged estrous duration and irregular estrous cycle in cows. Direct inspection found that the cow tail root tilt, cervical hypertrophy, uterine contraction response is not obvious, ovary as large as eggs. 3. Delayed ovulation or alternate follicular development Cows have normal estrous cycles but prolonged estrous duration. It takes multiple direct inspections to make a judgment. 4. Brucellosis All livestock farmers know about brucellosis. The main symptom is abortion at 5-8 months. The main influence on conception rate is inflammation of reproductive system and infertility caused by long-term mating. Because this disease belongs to a kind of infectious disease shared by human beings and animals, it is widely distributed. If it is found, it must be killed according to the law. The animal husbandry functional department is also very embarrassed. If it is killed, it must compensate others. The government cannot take out so much money and can only hide it. The technical personnel who enter animal husbandry for the first time must pay attention to cloth disease, not only responsible for production, but also responsible for the health of themselves and their families! In practice, I summarized the approximate diagnosis method of brucellosis without laboratory conditions: when cows are in estrus, put on plastic film gloves with both hands, massage the uterus deeply into the rectum of cows with one hand to keep the cows quiet, if the mucus flowing out is gray, open the vulva with the other hand to observe the vaginal mucosa. If there are pink nodules smaller than millet grains, it is most likely brucellosis. Cows that are not in heat can also see pink nodules, sometimes white. 5. Campylobacteriosis The disease presents with temporary infertility and abortion, prolonged estrous duration and clear mucus. I haven't seen any cases of this disease, so I won't say much. 6. Reproductive infectious rhinotracheitis I haven't seen any cases, so I won't say much. 7. Trichomonas bovis According to an old veterinarian, the sick cow showed severe itching. 8. Ovaritis and salpingitis, tubal obstruction