1. Cow Breeding Technology

1-Sexual maturity

Calf growth and development to a certain time, the reproductive organs have matured, with reproductive capacity, called sexual maturity. The age of sexual maturity of cattle varies with breed, feeding management, climatic conditions, nutritional status and growth and development. In general, cows reach sexual maturity at 8-12 months of age. Generally, the initial mating age of cows is 18-24 months old, and its weight should reach 65%-70% of the adult weight, which will affect its own development too early. However, it should not be too late, otherwise it will reduce the number of calves in a cow's life and damage production.

2. Estrus cycle (also called sexual cycle)

Cows undergo periodic estrus in the absence of pregnancy from sexual maturity until sexual function declines in old age. The time between the start of this estrus and the start of the next estrus is called the estrus cycle. The estrous cycle of cows is 21 days on average, ranging from 18 to 24 days, and young cows are generally shorter than midlife cows.

When a cow is in estrus, a series of physiological changes occur inside and outside the body. According to these changes, estrus can be divided into four periods: one is the early stage of estrus, when the activity of the reproductive gland of the cow is strengthened and the secretion increases, but there is no mucus discharge in the vagina, and there is no expression of sexual desire. The second is the estrus period, during which the cow shows strong sexual excitement, the reproductive tract is obviously congested, the labia are swollen, the cervix is opened, the gland activity is enhanced, and mucus is discharged from the vagina. If the egg is fertilized, I .e. after the cow is pregnant, the estrous cycle stops until it reappears after delivery. If the egg is not fertilized, it moves into late estrus. Third, in the late stage of estrus, the corpus luteum is formed in the ovary after ovulation, and the performance of estrus disappears and returns to its original state. The fourth is the rest period, also called the inter-love period. From a period of time after the last estrus to the beginning of the next estrus, the sexual organs have not changed, there is no sexual activity, and the body is in a relatively static state.

3. Estrus duration

The period of time from the beginning of the external estrus performance of the cow to the end of the external estrus performance is called the estrus duration. The duration of estrus in cows varies with age, nutritional status and seasonal changes, generally 18 hours, ranging from 6 to 36 hours. The ovulation time of the cow is 12-15 hours after the end of the estrus. These basics are key to choosing the timing of insemination. The breeding personnel shall be informed in time to ensure the success of breeding.

4, cow estrus identification

Estrus identification is to use comprehensive technology to judge the estrus stage of cows and determine the best mating time, so as to carry out artificial insemination in time and achieve the purpose of maximizing the mating conception rate.

There are many methods of estrus identification, such as external observation, test, vaginal examination, rectal examination and bionic method, etc. In my opinion, in the absence of advanced equipment, the most important is the external observation method, which I will focus on:

Cows show excitement and restlessness when in estrus, are sensitive to changes in the external environment, look in all directions, lose appetite or do not eat, sometimes chirp, chase bulls, climb across other cattle, and accept other cattle to climb across. When other cows climb across, the cow's hind limbs open, raise its tail arching its back, and urinate frequently. Vulva swelling, mucus outflow from the vagina; estrus climax when the amount of mucus, thin and transparent, with the extension of estrus time, the amount of mucus gradually decreased, thickened and turbid. At this time, the cow lies down and the slime sticks to the tail, making the tail stained with a lot of mud and sand. At the end of estrus, sometimes there is a small amount of blood in the mucus, which is more common in young cattle. There are a few cows in estrus, lying down from the vulva shed a small amount of dark red liquid, called "cow menstruation". There are a few cattle estrus when there is no obvious external changes, that is, estrus symptoms are not obvious, called "dark estrus" or "quiet estrus". There are several ways to identify dark estrus: carefully observe the cow herd, because estrus cows always have vulva swelling, but each cow has different degrees of swelling and more or less mucus will flow out; According to the breeding records, the cow estrus can be predicted; Cows in dark estrus can also be traced by "cow menstruation". Put castrated bulls in the cow herd to find cows in dark estrus to prevent leakage. In addition, a few cows still have estrus after pregnancy, which is called "wig estrus". 3%-5% of the cows in the herd show a wig. Attention should be paid to identification and mismatching should not cause miscarriage. Identification method: general wig estrus cattle, estrus symptoms are not strong, short duration, vulva swelling is not obvious, the amount of mucus is not much or no mucus. The vulva of the cow is swollen and has mucus. Climbing across other cows and accepting other cows to climb across is an obvious sign of the cow's estrus. The swelling of the vulva of the cow disappears, wrinkles appear again, and the acceptance of the climbing cross returns to the refusal of the climbing cross, which is the sign of the end of the external performance of the estrus. The difference between the two is very obvious. Technicians should go deep into the cows to observe them twice a day in the morning and evening, and work closely with the breeders to identify the estrus.

5. Infusion time

The ovulation time of the cow is 12-15 hours after the end of the external manifestation. After the ovum is discharged, the fertilization ability in the fallopian tube is maintained for 8-12 hours. Therefore, the insemination time is arranged 6-8 hours before ovulation, and the conception rate is the highest. However, ovulation time is not easy to accurately grasp, and according to the time of estrus to grasp the time of insemination is relatively easy, with estrus late insemination is better.

2. variety improvement and establishment of hybrid pedigree

The establishment of hybrid pedigree is to avoid inbreeding, resulting in the loss of good traits and the degeneration of varieties. At present, the 16 breeding cows in our farm are all frozen semen provided by the county's first livestock improvement station, and a hybrid pedigree is being established. 16 breeding cows were numbered, and the father and mother of the previous three generations and their offspring were recorded. The 16 cows in our farm can reproduce, of which 12 cows can reproduce Charolais use Simmental frozen semen, and 4 cows can reproduce Simmental all use Charolais frozen semen, which greatly avoids inbreeding and promotes the breeding of excellent varieties.

Feeding Technique of 3. Calves

When calves are born, the rumen volume is very small, the structure is not perfect, and the microflora has not been established. At this time, the rumen has no digestive function, and the digestive function is similar to that of monogastric animals. 2-3 weeks old calves began to feed grass, this time began to supplement fine grass concentrate feed, to 3 months old, the volume of the rumen increased significantly, 10 times more than the first birth, has established a more complete microflora. At this time, high-quality plant feed should be fully supplied to promote the good development of calves digestive organs. At the age of 4 months, digestion is close to adulthood. Excessive milk intake of calves will delay the development of intestines and stomach. Forage should be supplemented in advance, and the amount and frequency of milk intake of calves should be controlled to force calves to eat forage, promote the development of rumen, etc. Early weaning can be achieved. According to the information: each gram of rumen content contains 15 billion -25 billion bacteria and 600000-1.8 million protozoa, these bacteria and protozoa are very beneficial to cattle. Under anaerobic and weak acid conditions, the rumen is a huge fermentation tank, so when feeding, feeding silage should be added with soda powder, which can neutralize the acidity of the feed and create a weak acid environment, which is conducive to digestion, otherwise it will cause acidosis.

Selection of the next best mating period after 4. cow breeding

Mastering timely breeding is an important technical measure to prevent leakage and improve conception rate. It is also an important measure to improve economic efficiency.

In order to improve economic efficiency and shorten the interval of the first estrus after delivery, measures such as strengthening feeding and early weaning can be taken to make the cows have early estrus and early mating. According to my observation, Charolais and Simmental do the best estrus mating 40-60 days after delivery. Because less than 40 days, cows can not fully recover after delivery, poor resistance, prone to disease, more than 60 days, due to calves eat a lot, cows consume more, prone to low conception rate.