1. Causes
Feed Nutrition Level:
Dairy cows consume too much or too little energy during the perinatal period, which will cause postpartum estrus but also lead to a reduction in the fertility rate. When dairy cows are fed a diet containing low levels of protein, their fecundity will decline, while higher levels of protein, i.e. more than 19%, will lead to postpartum estrus delay, resulting in lower fertility rate. When dairy cattle absorb too much protein, the excess part will eventually enter the blood in the form of urea nitrogen, resulting in a higher level of urea nitrogen in blood and milk, thus causing a significant decrease in the pH value of the uterus, causing the occurrence of the disease in its liquid composition, and also poisoning the eggs, sperm and embryos. Besides, when the ratio of calcium to phosphorus is unbalanced, vitamin A and some trace elements are deficient in the diet of dairy cows, it will lead to postpartum estrus, unable to maintain regular estrus cycle, resulting in a significant decrease in the fertility rate.
Various diseases:
Female cows suffer from certain diseases during the perinatal period, which can also cause long-term estrus deficiency after delivery. Besides, cows suffering from uterine inflammation can also lead to estrus. When they are in an unsanitary environment during childbirth and use midwifery without strict disinfection, they are prone to uterine inflammation. At this time, the endometrium can not normally release prostaglandins, inhibit luteolysis in vivo, thus postponing postpartum. The first estrus time causes irregular estrus. Besides, when dairy cows suffer from foot disease, it often causes estrus. Because foot disease usually causes pain in dairy cows, they often limp and refuse to move. Instead, they lie down for a long time, resulting in little contact with other cows, resulting in no obvious estrus, recessive estrus or estrus. At the same time, the pain will also lead to a reduction in feed intake, resulting in a reduction in milk production, weight loss, increasing negative energy balance, it often causes estrus. Because foot disease usually causes pain in dairy cows, they often limp and refuse to move. Instead, they lie down for a long time, resulting in little contact with other cows, resulting in no obvious estrus, recessive estrus or estrus. At the same time, the pain will also lead to a reduction in feed intake, resulting in a reduction in milk production, weight loss, increasing negative energy balance.
Seasonal factors:
Dairy cows can oestrus all year round, but there are significant differences in ovarian activity in different seasons. The sensitivity of the pituitary to gonadotropin-releasing hormone was weaker in spring than in autumn, which resulted in delayed first ovulation, but the number of follicles on the ovaries of spring cow babies was more than that of autumn cow babies, and the volume of follicles also increased significantly. Besides, the dairy cow oestrus must also be within the appropriate range of sunshine, beyond this range, will not be conducive to oestrus.
Other factors:
Dairy cows'estrus is related to their age. For example, the first ovulation time of the parturient cows is earlier than that of the primiparous cows, and the estrus period of the parturient cows is usually shorter by 1-4 weeks than that of the primiparous cows. Besides, dairy cows of different genotypes and breeds also have different anesthetic periods after delivery. Often, the anesthetic period of hybrid dairy cows is shorter than that of pure dairy cows.
2. Treatment
The bull induction method is to release human bulls in dairy farms, stimulate them to produce luteinizing hormone secretion pulses, make them appear luteinizing hormone peak before ovulation, and stimulate ovulation. Besides, if dairy cows are exposed to bulls after parturition, it can shorten the period of postpartum estrus and stimulate ovulation, but attention should be paid to the proportion of bulls, season, delivery condition and which stage of postpartum exposure in bulls.
Dairy cows suffering from estrus caused by ovarian motility or atrophy must first improve the level of feeding management and cooperate with hormone therapy. The diseased cattle can be injected with 50 Um2 per muscle once a day for 3 consecutive days, or 10 ml vitamin AD3 injection (containing 50 000 01U vitamin A and 50 000 1U vitamin D3 per milliliter), and then 20 ml type (the main component is vitamin E) after 3 days. If the ovarian function of diseased cattle is still due to lactation, 100 mg progesterone can be injected intramuscularly once a day for a week.
Dairy cows after hormone treatment, if estrus occurs within 10 days, can not be mating, to wait until the next estrus. After hormone treatment, if no cow has oestrus, the cow should be examined again on the tenth day. If the corpus luteum is found, it is effective; otherwise, it is ineffective, and the treatment should be continued.
In addition, the diseased cattle can also cooperate with the use of traditional Chinese medicine Aphrodisiac Powder, that is, 40 g Angelica Sinensis, 30 g Morinda Officinalis, 30 g Cistanche Deserticola, 50 g actinolite, 1 Ogg Epimedium, 45 g Codonopsis Pilosula, 50 g yam, 15 g licorice, 30 g horse placenta, 120 g Leonurus Japonicus, after boiling, continuous use of three agents to promote oestrus, pay attention to the first occurrence of oestrus can not be. Formating, the second oestrus occurs before mating.
If dairy cows suffer from estrus due to persistent corpus luteum, cattle farmers can inject 20 ml of estradiol benzoate into their muscles or 200 um of cloprostenol into their uterus to accelerate corpus luteum lysis and promote follicular development.
When dairy cows suffer from estrus caused by an ovarian cyst, proper vitamin A, D3 and E can be added to concentrate to improve feeding management. At the same time, 20 mL of type I and type II can be injected into their muscles respectively. It should be noted that when estrus occurs for the first time after medication, they cannot be mated, and when estrus occurs for the second time, they can be mated. Intramuscular injection of 0.6 mg cloprostenol was given once, once again after 5 days without estrus, and intramuscular injection of 15 mg dexamethasone. Besides, 100 mg progesterone was injected into the muscles of diseased cattle every time, and another injection was given every other day for two consecutive times to treat ovarian cysts.
When a cow suffers from cervicitis, endometritis, and salpingitis, if the inflammation is mild, it can be given 6.4 million IU penicillin and 2 million IU streptomycin per muscle intramuscularly. Use it for 3 days. When the diseased cow has estrus, inject 30mL of 5% glucose injection with 1.6 million IU of penicillin and 1 million IU of streptomycin into the uterus; if the inflammation is severe or purulent, the uterus can be washed, using 500mL The mixture was washed with 10 g of oxytetracycline and 10% saline at a temperature of 30 to 40 °C, once a day for 3 consecutive days.