According to the 1985 National Professional Standard for Feeding and Management of High-yield Dairy Cows, ZBB43002.85 stipulates that high-yielding dairy cows refer to cows with a milk yield of 6,000 kg or more within 305 days of lactation, and a milk fat percentage of 3.4% (or a comparable amount of milk fat). Group and individual cows. According to the statistics of 695,154 cattle registered in China in 1994, the average milk yield was 75 if kilograms. In the same year, American Holstein registered cattle with 256,945 heads of milk recorded on average, with an average milk yield of 8,730 kg and a milk fat percentage of 3.66%. It can be seen that the milk production levels of high-yielding dairy cows in different years and different countries are different.
How to choose high-yield cows? It is recommended to choose from the following aspects.
1. According to the current dairy breeds worldwide, there are mainly Holstein cows (also known as black-and-white cows), Jersey cows, more race cows, Altai cattle and Swiss brown cows. More than 95% of dairy cow breeds in China are Chinese Holstein cows (Chinese black-and-white cows), in addition to Xinjiang brown cows, Sanhe cattle and grassland red cows. Holstein is a large dairy cow with the highest milk yield. The herd with an annual output of more than 10,000 kilograms is more common. The highest herd in China has reached 8773.2 kg. The highest milk production in the United States, Lisda, reached 30,833 kg in 365 days and the milk fat percentage was 3.3%. Therefore, in order to obtain a high yield of cows, Holstein should be selected first. In areas with poor feeding conditions, other varieties can also be selected.
2. According to the milk production results, the determination of the milk production and milk fat percentage of cattle (some of which also determine the milk protein rate) is the most important basis for selecting high-yielding cattle. The producer shall measure the milk production rate for one cow per month and one milk fat rate for the milk collection unit. The interval between two measurements shall be no less than 26 days and no longer than 35 days. Under normal circumstances, dairy cows produce calves once a year and stop milking for two months before birth. Therefore, the milk production period for one lactation period is 305 days, and the high-yield cattle can also be 365 days. From a genetic perspective, there is a negative correlation between milk production and milk fat percentage. The higher the milk yield, the lower the milk fat percentage. Therefore, the selection of high-yielding cattle, in addition to the amount of milk produced, should pay more attention to the rate of milk fat. For low-fat rate bulls, don't choose to use them. Secondly, the selection of high-yielding cattle has a unique feature. After the birth, milk production peaks later than the low-yield cows (high-yield cattle generally 56-70 days after delivery; low-yield cattle 20-30 days after childbirth), and the peak duration is longer Long (about 100 days); after the peak period, the milk production of high-yield cattle is decreasing more slowly than that of low-yielding cattle; at the end of lactation, low-yielding cattle usually stop milk production automatically, while high-yield cattle still produce more than one. If you purchase cows, the purchaser must check the milk production record of the cow you wish to purchase or observe live milk production.
3. According to the body appearance, the appearance of dairy cows has a close relationship with their milk production. Practice has repeatedly demonstrated that selecting good body appearance, especially good breasts and limbs, is very important for improving milk production performance. The head high-yielding cattle body type must have such features as high physique, medium torso volume, obvious breast size, firm breast attachment, strong limbs, and moderate nipple size. To be more specific, the requirements are: 1) Weight: The adult American Holstein has a weight of l100 kg and a body height of 160 cm. The adult cows are 650 kg and 140 cm respectively; in China, Holstein cows are soo respectively. - Coo kilograms and 136 centimeters, the southern body height is 130 centimeters. 2) The whole is a triangle, that is, from the front, with armor as the apex, along the shoulders of the two draw down two straight lines, the two lines are more wide down, a triangle; from the side, the hindquarters deep, front The body is shallow, the front line and the ventral line extend forward and intersect to form a triangle. From the top, the front is narrow and the back is wide. The two body lines intersect at the front and also form a triangle. 3) The breast, which is the most important functional body type feature, the base of the breast should be extended and extended and attached well. Four milk areas were evenly weighed, and the rear area was high and wide. The nipples are vertically cylindrical and well-spaced. 4) Legs and feet, especially the hind legs are more important. Cow genital organs and breasts are in the hindquarters and require strong hind limbs. In short, any dairy cow with a large body size, obvious milk characteristics, and developed digestive, reproductive, and lactating organs must be able to eat, drink, and prolific milk.
4. According to the genealogical lineage, the content includes: dairy cow breed, cow number, date of birth, birth weight, adult body size, weight, appearance score, grade, and cow's milk production scores. In the pedigree, there should also be parental and grandparents' body weights, appearance ratings, grades, cow milk production, milk fat percentage, and grades. In addition, disease and quarantine, breeding, and health of cows should also be recorded in detail. It is very important to select high-yielding dairy cows based on the above information and it is important to not overlook it. If dairy cows are purchased, preventive measures must be taken to prevent transmission of diseases, especially tuberculosis, contagious abortion, leptospirosis, trichomoniasis, and mastitis.
5. According to age and parity age and parity have a great impact on milk performance. Under normal circumstances, the initial age is 16-18 months old and the body weight should reach 70% of the annual cattle. Cows born at the first and 2th cows have 15%-20% lower milk production than cows with 3 or more births; milk production from 3 to 5 cows rises gradually, and milk production from 6 to 7 months later decreases gradually. According to the study, the milk fat percentage and milk protein ratio decreased slightly with the increase in the age and parity of dairy cows. Therefore, in order to make cows or dairy herds more productive, producers must pay attention to the choice of age and parity. Most people think that for a high-yielding herd, if the average parity is 4 children, the reasonable parity structure is: l-3 fetuses account for 49%, 4-6 fetuses account for 33%, and 7 or more children account for 18%.
6. The evaluation of feed remuneration based on feed remuneration is an indicator for selecting high-yield cattle, and is also the basis for assessing milk costs. For this purpose, the producer should collect the amount of feed and milk intake per cow and calculate the feed remuneration [total milk production (kg) in the whole lactation period. Total feed dry matter (kg)]. High-yielding dairy cows should have a maximum fruit weight of at least 4% of dry matter. Every kilogram of milk produced should eat at least 1 kilogram of dry matter. Below this standard, it can cause weight loss or cause diseases such as metabolism.
7. Estimating the speed of milk discharge based on milking speed is an important indicator for selecting high-yielding cattle. It has been determined that US Holstein milk 3.61 kilograms per minute and Shanghai black and white flowers 2.28 grams. Therefore, high-yielding dairy cows should select individuals with fast milk discharge.
The above are several methods commonly used to select high-yield cows. In order to achieve both high yield and high efficiency, it is recommended that the 6th and the 7th should be measured repeatedly to continuously seek ways to increase the production efficiency of high-yield cattle, and prevent high yields from being inefficient.
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