Common energy feedstuffs for pigs: cereal grains (Part 1)

Common feeds for pigs include energy feeds, protein feeds, green feeds, silage, roughage, mineral feeds and feed additives, etc.

Energy feeds refer to feeds with a crude fiber content below 18% and a crude protein content below 20%; their nutritional characteristic is that they are rich in easily digestible starch and are the main source of energy required by pigs. However, such feeds are low in protein, minerals and vitamins, and mainly include cereal grains and their processing by-products, starchy root tubers and tubers, etc.

Cereal grains refer to the mature seeds of plants of the grass family, including corn, sorghum, barley, oats, @#@245@#@, paddy rice, millet, etc. These feeds are characterized by being rich in nitrogen-free extractives, accounting for 70%-80% of dry matter, of which the main component is starch, accounting for 80%-90%. Their digestibility is very high, and the digestible energy is mostly above 13 MJ/kg. The disadvantage is a low protein content of 8.5%-12%. Using such feeds alone cannot meet the protein requirements of pigs; the contents of lysine and methionine are also relatively low; they are deficient in calcium and phosphorus, the calcium-to-phosphorus ratio is also unsuitable, and they lack vitamin A (except yellow corn) and vitamin D.

1. Corn. Corn is one of the most commonly used energy feeds in @#@227@#@ production, with very good palatability and digestibility; among all energy feeds, corn has the highest digestible energy content. Its crude fiber content is low, only about 2%, while it contains about 70% nitrogen-free extractives, mainly starch, with a digestibility of about 90%. The fat content of corn is 3.5%-4.5%, twice that of wheat or barley. The linoleic acid content of corn can reach 2%, the highest among all cereal-based feeds. Linoleic acid is an octadecadienoic fatty acid; it cannot be synthesized in the animal body and can only be supplied through feed, and it is an essential fatty acid. However, the protein content of corn is low, about 8.6%, lower than that of wheat and barley grains, but close to that of sorghum, brown rice, broken rice, etc. The amino acid composition of corn is poor, with insufficient lysine, methionine and tryptophan. Therefore, when using corn to feed pigs, it must be combined with animal and plant protein feeds such as soybean meal (cake) and silkworm pupae to supplement the deficiencies in protein and amino acids, so as to obtain good feeding results. Because the tryptophan content of corn is insufficient, in order to make good use of tryptophan, the amount of niacin or nicotinamide in the additive premix should be increased. The riboflavin and pantothenic acid contents of corn are both relatively low, and niacin is also in a bound state, all of which need to be addressed when formulating feed.

2. Sorghum. The metabolizable energy level of sorghum grain varies with variety; grains with few husks have a metabolizable energy level not much lower than that of corn, making them a very good energy feed. Sorghum produced in Northeast China is of relatively good quality. However, the hybrid sorghum promoted in North China for more than twenty years has a low flour yield, contains too much tannin, and has poor palatability; when fed alone, animals refuse to eat it, so it can only be used in limited amounts in the diet, generally not exceeding 20% of the diet. Good-quality sorghum grain contains 13.81 MJ/kg of metabolizable energy, while poor-quality grain contains less than 12.55 MJ/kg.

The crude fat content of sorghum is not high (2.8%-3.3%), and its linoleic acid content is also low, about 1.13%. Its protein content is also low, similar to that of corn. Its amino acid composition is characterized in the same way as corn, also lacking lysine, methionine, tryptophan and threonine. In varieties containing much tannin, protein digestibility is significantly reduced.

3. Barley. There are two kinds of barley grain: the hulled type is called "covered barley", and the hull-less type is called "naked barley". Covered barley, that is, what is usually called barley, has a relatively low metabolizable energy level, about 11.51 MJ/kg. It has good palatability and contains about 5% crude fiber, which can promote intestinal peristalsis in animals and keep digestive function normal. Barley is a feed that pigs relatively like.

The protein content of barley is relatively high, about 11%; the contents of lysine, tryptophan and isoleucine are all higher than those of corn grain, but calculated according to animal requirements, they are still insufficient. The crude fat content is about 2%, and more than half of the fatty acids are linoleic acid.

Barley is not suitable for piglets, but if it is naked barley or has been dehulled, flaked and steam-treated, it can replace part of the corn to feed piglets. When barley is used to feed finishing pigs, the daily weight gain is comparable to that of corn, but the feed conversion rate is not as good as that of corn. In pig diets, it is appropriate for it not to exceed 25%. Because barley is low in fat and high in protein, it is an ideal feed for the late finishing period and can produce pork with white fat, greater hardness, thinner backfat and more lean meat. In the famous "Jinhua ham" production area of China, barley was historically one of the essential concentrates for raising pigs.

4. Wheat. Wheat is the staple food of the Chinese people and is rarely used as feed. However, in some areas, wheat is priced lower than corn, and wheat is also used as feed. In the northern European countries, the energy feeds are mainly wheat-type grains, among which wheat is used in relatively large amounts.

The crude fiber content of wheat in China is comparable to that of corn, and its crude fat content is lower than that of corn, but its protein content is higher than that of corn, at about 14%, making it one of the higher-protein cereals. The energy value of wheat is also relatively high, at 14.36 MJ/kg, second only to corn. However, its essential amino acid content is relatively low, especially its lysine content. Like corn, wheat has little calcium and much phosphorus, and the phosphorus is mainly phytic acid phosphorus (about 1.8%); the trace elements iron, copper, manganese and zinc are also relatively low in content. Wheat contains much B vitamins and vitamin E, while vitamins A, D and C are extremely scarce.

The palatability of wheat for pigs is better than that of corn; whole grain and crushed grain are good, but grinding too finely is not good. When replacing corn with an equal amount to feed finishing pigs, feed utilization may be reduced because the energy value is lower than that of corn, but it can save part of the protein feed and improve carcass quality, preventing the backfat from becoming thicker.