1. Factors that affect the thick milk The fat and protein content of milk is the most important two quality indicators of milk. The increase of fat and protein in milk not only increases the consistency of milk, increases the nutritional value, but also raises the acquisition standard for milk, which directly increases the economic benefits of cattle farmers. fenleijieshaohui fang zai na li ne guanjianci Ganzhou Green days Biochemical Technology Co., Ltd. , https://www.tlqcjs.com
The practice of cattle breeding shows that milk cows' milk fat percentage and milk protein rate decrease slightly with age and parity.
Pre-lactating milk volume increased, milk fat percentage and non-fat solid form rate decreased; milk volume decreased during late lactation, and milk fat rate and fat-free solid form rate increased.
2. Feed and Feed Management Factors Dairy cows have too much dietary concentrate, and rough feeds are seriously deficient. In order to pursue a high milk yield, the amount of concentrated feed is increased too much for dairy cows, and insufficient crude feed results in a decrease in ruminal acetic acid production and a decrease in milk fat percentage. Among the volatile fatty acids produced in the rumen of cattle, acetic acid can be used as a raw material for the synthesis of milk fat, in addition to serving as an energy source. The source of acetic acid is cellulose in the roughage, especially hay. In practice, when the hay in the diet is maintained at 1 to 2 kg, the fat rate in the milk will be reduced by 0.3% to 0.5%; the most suitable diet should contain 5 kg of hay. In the diet, if straw is used instead of 40% of hay, milk production and milk fat percentage can be greatly reduced. Therefore, the quantity and quality of roughage are very important for improving milk fat percentage. When the proportion of crude feed in the diet fell below 40%, the milk fat content decreased significantly; when the proportion of crude feed was less than 10%, the milk fat content fell below 2% (normally 4%).
Concentrates are rich in carbohydrates. Feeding too much concentrate will alter the digestion process in the rumen, increase the formation of propionic acid, and reduce the content of acetic acid. Propionic acid cannot be used to synthesize milk fat, resulting in a reduction in milk fat percentage. It is recommended that milk cows produce 1 kilogram of milk per kilogram, and the fine material should not exceed 300 grams. The “material-for-milk†method of production not only results in the waste of concentrate but also raises the cost of raising the cows. It also affects the breeding of dairy cows and can cause ruminal acidosis, rumen retardation, etc., and reduces the benefit of raising cattle.
The type of roughage is single and the quality is poor. According to the survey, farmers implement less than 20% of the whole plant with eared corn silage fed to dairy cows; farmers who feed corn silage silage account for about 30%; farmers who feed corn stalks and wheat straw account for more than 50%. Most dairy farmers do not produce pasture or carrots. The green feed of dairy cows depends on the wild weeds on the roadside of the field. Many dairy farmers give their dairy cows a diet mainly in the form of silage + concentrate or wheat straw + concentrate. Moreover, silage due to poor storage, mold and metamorphism secondary to the phenomenon of widespread, resulting in decreased quality of silage, dairy cow intake decreased, thus affecting milk production and milk quality.
The decrease in the crude protein content of the diet led to a decrease in the milk protein rate. When the crude protein content of diets decreased from 17% to 9%, crude protein decreased by 1% and milk protein decreased by 0.2%.
Dairy cows have poor feeding and management environments. The relative humidity of the cowshed is more than 90%, and the milk fat percentage will decrease by 0.16% to 0.18%. If the ambient temperature is too high, the milk fat percentage will also decrease. When the weather is good in winter, let cows exercise, can promote the milk fat rate increased by 0.17% to 0.24%. Due to poor sanitation conditions, dairy cows suffer from mastitis and the synthesis of milk ingredients is significantly reduced, resulting in a marked reduction in fat and fat-free solids; due to unbalanced feed intake, poor body condition, feeding of deteriorating feed, etc. As a result, the liver function declines, the nutrient supply to the raw materials converted into milk components is insufficient, the milk fat rate decreases, the synthesis of fat-free solids decreases, and the milk thins out.
Heat stimulation. Due to the hot weather, dairy cows have reduced appetite, insufficient feed intake, reduced dairy cows' physical strength, and reduced breast function.
Milking technique is incorrect. Poor preparatory work for milking, incorrect vacuum of the milking machine, and the number of pulsations are not only affecting milk production but also affecting the increase of milk fat percentage.
In addition, the sudden change of the environment, the destruction of the original feeding program, changes in the breeder, the milker, and the disease all have an impact on milk yield and quality.
3. The mistakes in the selection and selection of dairy cows pursued one-sided milk production, ignoring the increase in milk fat percentage. When selecting the species for breeding bulls, only the milk production index was noted, and the milk fat rate index was ignored. Therefore, the bulls with high milk production and low milk fat percentage were selected. As a result, although the milk production of the daughters increased, the milk became thinner.
In order to become cheap, the use of unqualified bull (semen) breeding (even using inferior breeders without a breeding license) ultimately resulted not only in a lack of milk production by the daughter but also in the quality of the milk.