There are many factors affecting the milk production performance of dairy cows, which can be divided into genetic, physiological and environmental factors.
First, genetic factors
Different breeds of dairy cows have significant differences in milk production and milk composition. Individuals of the same variety, due to different genetic basis, have significant differences in lactation performance and milk fat percentage among individuals, such as Holstein cattle and low-yielding cattle. Only about 3,000 kilograms, high-yielding cattle can reach 30,833 kilograms, milk fat rate of 2.6% to 6%.
Second, physiological factors
1. Age and parity. Due to inadequate mammary gland development, young cows generally have a low milk production, which is equivalent to 70% to 80% of adult cows. After 7 to 8 months of age, the cows are also affected by the aging of the body and the amount of milk produced. decreasing gradually. Chinese Holstein cows have the highest milk production from 5 to 6 births.
2. Initial calving age and calving interval. When the age of the first calving of the cow is too early or too late, the milk production will be affected. Under normal circumstances, when the weight of the bred cow reaches 70% of the annual cow, it can be bred. The Chinese Holstein cows are bred under 13 to 16 months of age under reasonable breeding conditions. The first calving age is 22-25 months. The calving interval refers to the number of days between consecutive calving sessions. The ideal calving interval is 365 days, ie 305 days of milk production, 60 days of dry milk, and 1 child of 1 year.
3. During lactation. In the lactation period, the milk production of dairy cows showed a low, high, and then gradually decreasing curve. The low-yield cows produced 20 to 30 days after calving, and the high-yielding cows peaked at 40 to 50 days after calving. The general peak period is maintained for 20 to 60 days and gradually decreases. High-yielding cattle generally decline by 4% to 6% per month, and low-yield cattle reach 9% to 10%.
4. Weight. Cows of the same species and age, cows with large body size, relatively large volume of digestive organs, high feed intake, and high milk production, but cows with excessive weight do not necessarily produce more milk, and Holstein cows weigh more. To 650 to 700 kilograms is more appropriate.
5. Disease. After the cow is ill, the physiological condition is abnormal, the milk production is decreased, the composition of the milk is irregular, and it is generally related to the severity of illness and the length of illness, as well as the different stages of the constitution and lactation of the cow.
Third, environmental factors
1. Feeding management. Dairy cows have inadequate dietary nutrient levels, which will affect the amount of milk produced and shorten the lactation period. Poor environment conditions will destroy the metabolic processes of dairy cows, and milk production will decline. At the same time, the content of milk components is closely related to the feeding and management conditions. For example, if there are many concentrates in the diet and the coarse material is insufficient, the milk fat percentage will decrease. If the proportion of coarse material is increased and the energy level of the diet is reduced, the milk protein content will be affected. In addition, non-fat solids also decreased when dietary energy was low.
2. Milking. Milking is a very important technical task for dairy cows. Properly mastering the milking technology can give full play to the milk production potential of dairy cows and prevent the occurrence of mastitis.
3. Calving season and outside temperature. The suitable temperature for dairy cows is 10°C～16°C. When the temperature reaches 26.7°C, the number of cows' respiration and pulse increases, the feed intake decreases, and the milk yield decreases, especially for high-yielding cows and dairy cows during prolific lactation. Particularly sensitive. In order to maintain the health of cattle and increase milk production, summer cows must take measures to prevent heatstroke, and adjust the calving season so as to avoid the hot summer season of June to August.
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