The effect of fat on fat percentage. About 50% of milk fat in milk needs to be supplied by fat in the diet. The high fat energy in feed can directly provide fatty acids for the synthesis of milk fat, but it will affect the rumen fermentation characteristics of dairy cows. Adding a large amount of fat or unsaturated fat can cause a decrease in fat percentage, so it is advisable to add 3% to 6% fat in the diet. To reduce the negative effects of fat on rumen fermentation in dairy cows, whole or crushed oil cakes can be fed, or formaldehyde treatment, calcium saponification and the like can be used.
The effect of protein on fat percentage. When the energy level of the dairy cow's diet increases, the milk protein content also increases, but it may reduce the milk fat percentage. Experiments have shown that an increase in the protein content of a dairy cow's diet does not usually increase the milk protein content, and the protein may also decrease milk protein when it is less than needed. Only when the cow is under very low nutrition or long-term malnutrition can energy and protein have an effect on the fat percentage.
The effect of cellulose on fat percentage. The biggest influence on milk fat in dairy cattle feed is crude fiber content. If the amount of pasture in the diet is less than 50%, or if the ADF (Acid Washing Fiber) is less than 19%, or if the total amount of crude fiber in the diet is limited to 13%, the acetic acid and propionic acid ratio of the diet will be reduced. Reduce milk fat content.
The effect of inorganic salt on milk fat percentage. When the pH of the cow's rumen is kept within the normal range, the formation of acetic acid is easier than propionate, and the intake, milk production and milk fat percentage of the cow will be increased due to the increase of acetic acid. According to research, the addition of an alkalizing agent to highly fermentable feeds such as high-moisture grains and silage corn can achieve ideal results, but the addition of alkalizing agents to feeds containing 20% ​​or more of ADF in hay and silage, etc. Obvious effect. Commonly used alkalizing agents are mostly sodium bicarbonate or sodium sulfate. MgO and sodium bicarbonate have better alkalizing effect in a 1:2 mixture. Zeolite can increase the pH of the rumen, but at the same time it may reduce milk fat and milk protein content. It has been reported that when high-yielding dairy cows or the rumen of dairy cows are propionic acid-type fermented, the addition of sodium acetate or sodium diacetate in feed can promote and improve the electrolyte balance of the body and stimulate the liver, kidneys and intestinal mucosa, thereby increasing Fatty rate. In addition, 450 g of sodium acetate or butyrate may be supplemented daily when the percentage of concentrate increases the milk fat percentage of the cow.
Effect of niacin on milk fat percentage. Niacin can increase cow milk production or milk fat percentage. According to the experiment, the daily feeding of 6 grams of niacin for 120 days postpartum can increase the milk production by 11.9%, but the effect of adding niacin during the mid-lactation period is far less effective than that of early lactation.
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