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- 28/07/2021
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Soy and its various uses in animal nutrition
Brazil is the largest producer of soybeans in the world, and should reach a new record in the 2020/2021 harvest with a harvest of 133.67 million tons (CONAB). And all this production is to supply different markets, ranging from animal and human nutrition, to cosmetics, paints and pharmaceuticals.
But of all this national production, it is estimated that 80% is destined to animal nutrition, with swine and poultry being the most demanding crops, where soybean meal, one of the main by-products, contributes with a large share of this 80%.
At first, the average soybean is composed of 15% to 20% of lipids, 35% to 40% of crude protein, 30% of carbohydrates, 10% to 13% of moisture and about 5% of ashes, being able to these values vary depending on the cultivar, region, time of harvest and time of year.
Antinutritional Factors
However, soy in natura has several substances that act in the protection of plants and seeds, and that are antinutritional factors for monogastric animals. That is, these factors bring harm, such as malabsorption of iron and zinc minerals, inhibition of trypsin, kidney stones, allergenicity, among others.
Protease inhibitors
They are protein compounds that complex with trypsin, chymotrypsin and carboxypeptidase. Therefore, they decrease the digestibility of proteins, in addition to affecting the pancreas by altering its metabolism and hypertrophy.
Lecithins
They are proteins with toxic effects that, when ingested, cause intense inflammation promoting the destruction of epithelial cells among other adverse reactions.
Phytic Acid
Main phytate found in soy. This complexes with minerals and proteins leading to changes in the solubility and digestibility of nutrients.
Saponins
They are bitter-flavored glycosides capable of forming insoluble complexes that are difficult to digest. It changes the permeability of the intestinal mucosa and causes hemolysis.
Goitrogens
Iodine bioavailability decreases, with consequent alteration in the production of hormones T3 and T4, which leads to hypertrophy of the thyroid gland.
Allergenic proteins
Represented by B-Glycinin and Glycinin. These cause atrophy of the intestinal villi and hypersensitivity, reducing the absorption of nutrients.
Oligosaccharides: Rafinose and Stachyose
They increase the viscosity of the diet, reducing its digestibility. However, they are not found only in raw soy. For example, soybean meal if not treated with alcoholic solution has high levels of these oligosaccharides. Therefore, it is also noteworthy that in addition to reducing digestibility, they can induce desbiosis.
Thus, with the advancement of research and the greater demand for protein, several forms of soy treatment for the inactivation of its antinutritional factors have emerged, which has enabled its use for the nutrition of non-ruminants.
Therefore, the soy protein concentrate, soy bran, soy protein isolate, micronized soy, soy husk and oils are some of the soy derivatives used in animal nutrition. At the same time, it is worth remembering that there is another range of uses as mentioned at the beginning of this article.
Some by-products / co-products
Soybean meal
It is a by-product of the oil industry, being the most used in animal nutrition. Soybean meal can represent up to 79% of the grain based on dry matter. In the oil extraction process, heating occurs which helps to eliminate some anti-nutritional factors. However, conventional brans still have the oligosaccharides raffinose and stachyose. As for the CP content, the most common are 45.46.48%.
Soy bark
The soy husk, as the name implies, is the film that surrounds the grain before the oil is extracted. It has a content of Crude Fiber – FB 32.9%. and FDN 58.1 (ROSTAGNO), in BRCORTE the FDN is 66.45%. Despite these fiber contents, it is considered an energetic food for ruminants, with an NDT of 72.50%, which is due to the low concentration of lignin and silica.
Micronized Soy
The soybean undergoes a cleaning process, enters through a dosing hopper and goes to a vibrating tile floor that is under gas burners that produce infrared rays as a heat source. The grain is swollen and has internal cracks and passes through a cylinder that laminates the product, after having passed through a round tank with agitator where the product cools. This product has 39.7% CP and 2.51% FB (ROSTAGNO).
Extruded Soy
After going through cooking at high temperatures, pressure and humidity in an extruder cannon, it can be dry or wet, with protein denaturation, starch gelatinization and elimination of anti-nutritional factors. This presents 37.3% CP and 5.19% FB.
Soy Protein Concentrate
Products such as fish meal, porcine plasma and dairy by-products have been used commonly in piglet feeding due to their better performance than with FS-based diets. The use of milk proteins with high quality and digestibility as a source of amino acids for newly weaned piglets is well documented. However, these products are expensive, which forces nutritionists to look for alternative ingredients that have positive effects on these animals. One of the existing alternatives is the soy protein concentrate (CPS) that is obtained by removing the husk, oil and oligosaccharides from the soy bean. For this by-product we have an exclusive publication, to read click here.