What are the common feeds and feed additives for pigs?

Feed additives refer to those substances, other than common feeds, that are added in small or trace amounts to compound feed to supplement and meet the nutritional needs of animals in growth, reproduction and production, or for some special purpose. Their purpose is to enhance the nutritional value of the diet or to meet the special needs of breeding production, such as health care, growth promotion, appetite stimulation, prevention of feed spoilage, preservation of the activity of certain substances in feed, destruction of toxic components in feed, improvement of feed and livestock product quality, and improvement of the breeding environment. In a broad sense, feed additives include two major categories: nutritional and non-nutritional additives.

(1) Nutritional feed additives

1. Amino acid additives. Pig feed is mainly plant-based feed, and the most deficient essential amino acids are lysine and methionine. Therefore, amino acid additives for pigs are mainly lysine additives and methionine additives. Both of these amino acid additives have L and D forms; pigs can only utilize L-lysine, but they can utilize both the D and L forms of methionine. Three issues should be noted in actual use: First, add an appropriate amount. Adding synthetic amino acids to reduce the crude protein level in the diet should have a certain limit. Generally, the crude protein level should not be lower than 14% in the early growth stage (before 60 kg), and not lower than 12% in the later stage. Second, it should be economical. If the diet price is too high after adding synthetic amino acids, it is not economical and has no practical significance. Third, synthetic amino acids are mostly sold in the form of salts, such as L-lysine hydrochloride, whose purity is 98.5%, while the amount of L-lysine in it accounts for only 78.8%. When adding, attention should be paid to potency conversion. For example, if 0.1% lysine is to be added to the feed, then the amount of L-lysine hydrochloride added per ton of feed is 1÷0.985÷0.788＝1.288 kg (1228 g).

2. Vitamin additives. With the development of intensification, the year-round and large-scale supply of green feed has become increasingly restricted. Therefore, the addition of vitamin additives to diets has been increasingly widely applied. Currently commonly used vitamin additives include vitamin A, vitamin D3, vitamin E, vitamin K3, B-group vitamins (choline chloride, niacin, pantothenic acid, biotin), etc. In production, compound additive forms are mostly used, with multiple vitamins mixed into the diet; the addition amount is 0.2%-0.3% for piglets and 0.1%-0.2% for finishing pigs. When preparing compound vitamins, attention should be paid to the interactions among vitamins.

3. Trace element additives. Trace element additives are commonly used additives; feed grade purchased from a chemical store is sufficient (it does not necessarily have to be analytically pure or chemically pure). At present, the trace elements mainly added in pig production in China include iron (Fe), copper (Cu), manganese (Mn), zinc (Zn), cobalt (Co), selenium (Se), iodine (I), etc. The trace elements in feed are in the form of mineral salts; what is needed is the amount of a certain element (for example, iron), not the amount of the mineral salt (ferrous sulfate). When used as an additive, the following two points must be noted: First, fully crush and mix evenly. Before being added to a complete feed, it must first be diluted with limestone powder, etc., and then mixed; Second, actual content. Different products have different chemical formulas and different impurity contents, so attention should be paid to the actual content of that element in the product. The content of some elements in different chemical structures differs, and the amount of that salt needed must be calculated according to the element content contained in the mineral salt.

(2) Non-nutritional feed additives. Although non-nutritional feed additives are not inherent nutritional components of feed and have no nutritional value themselves, they have special and obvious effects in maintaining body health, promoting growth and improving feed utilization.

At present, there are many varieties of this type of additive, and their application in practice is also inconsistent. This type of additive should not be understood as essential to compound feed, but in order to obtain a certain specific effect, it is an important means.

1. Antibacterial growth-promoting agents. Antibacterial growth-promoting additives include antibiotics, antibacterial drugs, arsenic preparations, high-copper preparations, etc. The effect of such substances is mainly to inhibit the reproduction of harmful microorganisms in the pig digestive tract, promote the absorptive capacity of the digestive tract, improve the pig's utilization of nutrients, or affect the metabolic rate in the pig body, thereby promoting growth.

Antibiotics have been used as feed additives for more than 50 years. Practice has proved that antibiotics have a certain effect on protecting animal health, promoting growth and improving feed utilization. The effect is especially significant when the breeding environment is poor and the feed level is low. After the 1960s, the use of antibiotics as additives aroused controversy. First is the problem of pathogenic bacteria developing drug resistance. Long-term use of antibiotics can cause some bacteria to develop drug resistance, and these bacteria can pass drug resistance to pathogenic microorganisms, thereby affecting the prevention and treatment of human and animal diseases. Second is the problem of antibiotic residues in livestock products. Meat and other livestock products with antibiotic residues cannot be completely "inactivated" during food cooking, affecting human health. Third, some antibiotics have mutagenic, teratogenic and carcinogenic effects.

Therefore, when using antibiotic feed additives, attention should be paid to the following matters:

First, it is best to choose varieties that are animal-specific, have low absorption and residues, and do not produce drug resistance.