1. Varieties: Different breeds of cows or cows of the same variety have different performances in the early and late stages of puberty and estrus. For example, the initial age of a small-scale dairy cow, Juanjuan, is 8 months of age, and that of racing cows and Holstein cattle is 11 months. The age of the veterinary cattle breed is often later than that of the dairy breed; The period is later, generally about 13-18 months; the maternal yak has an average period of 24 months. 2. Natural factors: The duration of estrus in cows is also affected by climatic factors. During the hot season, the duration of estrus in cows is shorter than in other seasons. In the hot summer months, progesterone is secreted from the adrenal cortex of the cow, in addition to the normal secretion of progesterone by the corpus luteum, resulting in a shortened estrus duration. 3. Nutritional level: It is a very important factor affecting the animal's prepuberal and estrus performance. The influence of the natural environment on the cow's estrus is also due to changes in the nutritional level to a certain extent. Under normal circumstances, a good feeding level can increase the growth rate of the cow, promote the sexual maturity of the early cow, and can also strengthen the estrus performance of the cow. The change in body weight of cattle is directly related to the puberty period. Therefore, under the conditions of good husbandry and management, the healthy growth of cattle is beneficial to the sexual maturity of cattle. In the feed naturally consumed by cattle, there may be some substances that affect the puberty of the cow and the recurrence of the calf. 4. Production level and management methods: The estrus performance of cows is related to production performance. Beef performance in cattle is often not as obvious as milk cows. Individual dairy cows with high milk yield have sometimes no obvious estrus performance. The reason may be related to the strong metabolic function of milk production of high-yielding dairy cows, which is partly due to the inhibition of the reproductive endocrine effects associated with estrus. Obese cows often have indistinct estrus characteristics and may be related to hormone secretion. Therefore, in production, it should be avoided that the time interval for the recovery of cows after childbirth is related to the feeding and management measures of cattle. For example, high-yielding dairy cows can produce milk for about 9 days before the lower cows produce milk. The more milking or breastfeeding times per day, the longer the interval. Stainless Steel Powder Fire Extinguisher Stainless Steel Powder Fire Extinguisher,Sus Powder Fire Extinguisher,9Kg Powder Fire Extinguisher,Sus 1Kg Powder Fire Extinguisher JIANGSU NEW FIRE FIGHTING TECHNOLOGY CO.,LTD , https://www.newayfire.com