What are the commonly used feed additives for cattle?
(1) Vitamins and trace elements (premix). According to the nutritional needs of beef cattle at different growth and production stages and production levels, a certain amount of vitamins and trace element additives need to be added when formulating diets. Vitamin A, vitamin D and vitamin E, as well as trace elements such as iron, zinc, copper, selenium, iodine, and cobalt, are generally added to the diet according to the dosage. Commonly used compounds of trace elements are ferrous sulfate, copper sulfate, zinc oxide, zinc sulfate, manganese sulfate, manganese oxide, sodium selenite, potassium iodide, etc.
The vitamins and trace elements in beef cattle rations require special processing and mixing, and it is difficult for general cattle farms (households) to prepare them by themselves. It is recommended to supply it in the form of premix from a feed manufacturer with complete purchase licenses, and it should be purchased as needed, used within the validity period, and not suitable for long-term storage.
(2)Amino acid additives. Studies in recent years have shown that there is also an imbalance of amino acids in the small intestine compared to production needs in both beef and dairy cattle. Lysine and methionine are often the most limiting amino acids, and by altering the amino acid pattern of the small intestine, the production performance and protein utilization efficiency of ruminants can be improved.
Due to the degradation of amino acids by rumen microorganisms, the amino acid supplementation for beef cattle must be protected. Currently, there are already rumen-protected lysine and methionine products on the market. Methionine hydroxy analogs are chemically identical to methionine but are resistant to degradation by rumen microorganisms. For beef cattle, it can improve the health level and the speed of fat storage.
(3) Rumen buffer. When the proportion of concentrated feed is high and the amount of acidic silage and slag feed is large, the pH value of the rumen of beef cattle is easily lowered, which leads to the inhibition of microbial development and the impact on health. In this case, the addition of a rumen buffer can keep the rumen in a more favorable internal environment for microbial fermentation, so that the production and health of beef cattle can be normal. Commonly used buffers are baking soda and magnesium oxide, and sodium acetate has also been used in recent years.
Baking soda is the first choice as a buffer, and it is generally believed that the addition amount accounts for 1% to 1.5% of the dry matter intake, which has a good effect on improving milk production and milk fat rate. For high-yielding cattle, on the basis of adding baking soda, 0.3% to 0.5% magnesium oxide can be added, and the effect is better than using baking soda alone. For low-yielding cattle, it is not necessary to add magnesium oxide. After entering the rumen, sodium acetate and sodium diacetate can be decomposed to produce acetate ions, which provide precursors for milk fat synthesis, and also have a buffering effect on the rumen. The ideal daily dosage for adult cattle is 50 to 300 grams.
(4) Biologically active preparations. Biologically active preparations include feed cellulase preparations, yeast cultures, live bacteria preparations, and the like.
① Feed cellulase preparations. Feed cellulase preparations are crude enzyme products, mainly from fungi, bacteria and actinomycetes. Rumen microbes secrete sufficient fiber-degrading enzymes to digest the cellulose content of the feed. Therefore, it is not recommended to add cellulase preparations to beef cattle feed.
② yeast culture. A yeast culture is a mixture that includes live yeast cells and the medium used to grow the yeast. After the yeast culture is dried, it is beneficial to preserve the fermentation activity of the yeast. In addition, the yeast product can also be derived from beer or liquor yeast. Aspergillus oryzae and Saccharomyces cerevisiae are commonly used strains for preparing yeast cultures at home and abroad. Adding yeast culture to beef cattle feed has the function and effect of improving the utilization rate and production level of the diet.
③ live bacteria preparations. Live bacteria preparations are directly fed microorganisms, which are a kind of live microbial preparations that can maintain the balance of animal gastrointestinal microflora. Generally, the microorganisms that can be used as live bacteria preparations mainly include Bacillus, Bifidobacterium, Streptococcus, Bacteroides, Lactobacillus, Peptococcus and some other microbial species. Dosage forms of live bacteria preparations include powders, pills, ointments, and liquids. The application effect of live bacteria preparation in beef cattle production is mainly to reduce stress and enhance disease resistance.
(5) Urease inhibitors. The urea circulating in the rumen of cattle and the urea added from exogenous diets are first hydrolyzed into ammonia under the action of urease, and then used for microbial protein synthesis. Because urea is decomposed quickly, and the utilization rate of microorganisms is slow, the utilization rate of ammonia produced by urea decomposition is low. Urease inhibitors can moderately inhibit the activity of ruminal urease, thereby slowing down the rate of ammonia release from urea, making ammonia production and utilization more coordinated, and improving the efficiency of microbial protein synthesis.
At present, the urease inhibitor for ruminants approved for use in my country is acetohydroxamic acid. The addition of 25-30 mg/kg (dry matter) in beef cattle diets can increase the synthesis efficiency of rumen microbial protein by more than 15%. In diets supplemented with non-protein nitrogen, the addition of urease inhibitors is more effective.
(6) Isotopic acid. Isotopic acids, including isobutyric acid, isovaleric acid and 2-methylbutyric acid, are necessary for the growth of rumen cellulolytic bacteria. The amount of ectopic acid produced during rumen fermentation may be insufficient. Therefore, the addition of ectopic acid in beef cattle diets can increase the number of microorganisms in the rumen, including cellulolytic bacteria, improve nitrogen deposition, and improve fiber digestibility, thereby improving the production level of beef cattle.
(7)Zinc methionine. Zinc methionine is a complex of methionine and zinc, which has the effect of resisting the degradation of rumen microorganisms. Compared to zinc oxide, zinc in zinc methionine has a similar rate of absorption, but a different rate of metabolism after absorption, so that excretion from the urine is lower and plasma zinc declines more slowly. The addition of zinc methionine to beef cattle diets can improve the health and production levels of beef cattle. Under production conditions, zinc methionine also has the effect of hardening the hoof surface and reducing hoof disease. The amount of zinc methionine added is generally 5 to 10 grams per head per day, or 0.03% to 0.08% of the dry matter of the diet.
(8) Ionophores. Monensin and lasalimycin are commonly used ionophores to change the type of rumen fermentation. They are used in beef cattle to improve daily weight gain and feed conversion rate. Monensin can increase weight gain by 6% to 14% without any adverse effects on reproductive performance, calving process and calf birth weight. The effect of lasalidomycin is the same as that of monensin, but lasalidin can be used in cattle weighing less than 180 kg and does not affect feed intake at the beginning of feeding.
The effect of ionophores on rumen fermentation must also affect production performance. Reduce the production of acetic acid, propionic acid, and methane, and increase the production of propionic acid. The increased production of propionic acid indicated that the animals were able to synthesize more glucose. The addition of monensin to beef cattle diets can significantly increase the daily weight gain of beef cattle.