Different breeds of cattle or cows of the same breed have different performances in the early stage of puberty and estrus. Under normal circumstances, the initial age of large breeds is later than that of small breeds. 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.
Natural factors Due to the influence of natural geographical factors, different breeds or breeds of cattle have formed their own estrus characteristics through long-term natural and artificial selection. Although this characteristic has changed greatly with the changes in feeding methods, natural The influence can sometimes be seen.
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. Cows grazing in the grasslands have a shorter duration of estrus than cows in the farming area when there is insufficient feed.
Nutritional level Nutritional level is a very important factor affecting the animal's estrus period and estrus performance. The influence of the natural environment on the estrus of cows is also partly due to changes in nutritional levels. 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. Experiments have shown that compared with the low nutritional level of cows with high nutrient levels, the former can make cattle's puberty early 6-9 months. Qinchuan cows enter sexual maturity at an average of 9.3 months (280 days) under better husbandry conditions, and may have 3-6 months later at the time of their lower feeding level.
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. For example, phytoestrogens present in legumes (such as clover) may affect the estrus profile of cattle. Traditionally in China, the use of certain plants in the early spring to aphrodisiac animals is an example of the use of phytoestrogen.
After long-term intake of clover, the abortion rate of cows increased, and the virgin cows had breast and breast hair. North American madder is believed to contain estrogen-like substances and other "toxins" that can affect sperm and egg production. Experimental studies have shown that the estrogen-like substances present in some plants can inhibit the development and maturation of bovine follicles, leading to changes in the fertility of cattle.
Production level and management methods The estrus performance of cows is related to production performance. Beef cattle performance is often not as obvious as milk cows, and dairy cows with high milk production have sometimes no other cows. 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.
Poor nutrition and weak cows also have longer intervals. Feeding low- and high-energy feeds to pre- and post-natal calves of beef cattle can shorten the first estrus interval. For example, prenatal feeding with sufficient energy and low-energy postpartum feeding, the first estrus interval is prolonged, and some cattle are not in the mating season. In case of estrus, if this part of the cattle is to be bred in advance, it must take measures (early weaning, etc.) as far as possible to allow the cow to heat in advance.
Disposable Face Mask,3-layer Disposable Face cover,Anti Dust Face Cover,Kid Disposable Face Mask
Dongguan Keyutai Mask Co., Ltd. , https://www.maskkytai.com