How are lysine and methionine used in feed? 100 Questions and Answers on Scientific Pig Farming 13

The protein in animal products comes from the protein in feed. The shortage of feed ingredients, especially the shortage of protein feed, is the primary factor restricting the development of the livestock industry. The use of amino acids in feed has opened up protein resources beyond conventional protein, and has opened up a way to resolve the contradiction between the development of the livestock industry and the shortage of protein feed. Amino acids produced by the feed additive industry can easily increase the concentration of essential amino acids in feed, which not only improves the nutritional value of the feed but also achieves many other beneficial effects, which has enabled industrial amino acids to be widely used in the feed industry.
At present, the most widely used industrially produced amino acids in the feed industry are mainly lysine, methionine, and a small amount of tryptophan and threonine, etc.
L-lysine salt is the L-type optical isomer of lysine, with the molecular formula C6H14N2O5·HCI and a relative molecular mass of 182.65; it appears as a white or light brown crystalline powder, odorless or with a slight special odor, easily soluble in water, difficult to dissolve in ethanol and ether, optically active, with a melting point of 263-264℃. China has established the national standard for the feed additive L-lysine hydrochloride (GB8245-87).
DL-methionine, also called methionine, has the molecular formula C5H11N02S and a relative molecular mass of 149.22; it appears as white or light yellow crystals with a slight special sulfide odor; it is easily soluble in water, dilute acids, and dilute alkalis, slightly soluble in ethanol, insoluble in ether, with a melting point of 281℃ (decomposition). The content of commercial methionine is ≥98.5%. At present, China has not yet established a national standard for it as a feed additive.
At present, there are mainly four methods for industrial production of amino acids: ① fermentation method; ② chemical synthesis method; ③ enzymatic and chemical-enzymatic method; ④ protein hydrolysis method. Lysine and methionine are used for all kinds of livestock and poultry, but in poultry feed, the use of methionine is emphasized, while for pigs, the use of lysine is emphasized more. Rational use of both is even more important. How much to use varies according to the raw materials and nutrient content in each region.
　　
Reference for lysine usage:
For pigs weighing below 10 kg, corn 65%, soybean meal 30%, lysine addition amount 0.50%;
For pigs weighing 10-20 kg, corn 65%, soybean meal 30%, lysine addition amount 0.40%;
For pigs weighing 25-50 kg, corn 75%, soybean meal 20%. Lysine addition amount 0.35%;
For pigs weighing 50-100 kg, corn 80%, soybean meal 15%, lysine addition amount 0.20%;
For pregnant sows, corn 85%, soybean meal 10%, lysine addition amount 0.05%;
For lactating sows, corn 85%, soybean meal 10%, lysine addition amount 0.20%.
　　
For broilers, add 0.1-2.5%; for laying hens, 0.1-0.2%; 0.1% in the early laying period, 0.05% in the late laying period. In broiler feed, it is best to add 3-5% fats such as beef tallow, lard, and soybean oil. In pigs, the amount of methionine used is generally 50% of lysine, while in the feed for broilers and laying hens, sufficient methionine must be added. If rapeseed cake or cottonseed cake is used to replace soybean meal, the amount of lysine added must be increased by 20%. If fish meal is used to replace soybean meal, the amount of lysine added can be reduced by 20%. When each pig farm actually designs a formula, it must be handled flexibly according to the different breeds of pigs, different stages, and different feed ingredient varieties, so as to obtain better feeding benefits. (This content is excerpted from "100 Questions and Answers on Scientific Pig Farming", compiled and printed by the Yingtan City Association of Old Science and Technology Workers and authored by Zhang Genkai.)