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Importance of anti-nutritional factors in sorghum and soybean

Published on: 1/17/2023
Author/s : Roberto Q. López Martínez, Médico Veterinario Zootecnista / Gerente Técnico Phytobiotics México y Latinoamérica.
There are several components of grain and plants that can cause detrimental effects on animal production. These components are commonly known as antinutritional factors. According to their mode of action, anti-nutritional factors can be grouped as follows:
  • Substances that limit or decrease the digestion or metabolism of proteins, ex. lectins and saponins.
  • Substances that interfere or decrease the correct utilization of minerals, ex. phytic acid and oxalic acid.
  • Substances that inactive or increase some vitamins requirements, ex. nicotinic acid and pyridoxine.
Some anti-nutritional factors can show more than one mode of action.
A highly important grain used as a basic element in the diet of poultry and pigs is the sorghum, characterized by being resistant to drought, toxic soils and extreme temperatures.
Anti-nutritional factors in sorghum
Tannins are water soluble heterogenic polyphenolic compounds of sorghum which proportion depends on the variety of the grain, in some varieties can reach until 5%; through drying, grinding and pelletizing techniques, its concentration can be reduced. It can be found also in soybean, sunflower seeds, alfalfa and wild plants.
Its main effect on production animals is given when digestibility of proteins decrease, due to the formation of complexes that inhibit the activity of proteolytic enzymes during feed digestion.
When exists a very high concentration of tannins on feed, animals decrease the consume due to the lack of palatability and toxic detrimental effects during metabolism.
On broilers, slight histopathological changes have been observed in kidneys and liver, as well as an increase in the cellular immune response when sorghum contains up to 23 g tannins/kg; legs and wings anomalies have been also reported when the tannins concentration is high.
Ruminants are more tolerant when it ingest these compounds, however some effects like ruminant dysfunction, lack of appetite, poor wool growing and decrease of weight gain have been found in sheep.
Studies have shown that some ruminant bacteria can metabolize tannins or at least remain active under a high concentration, this can help to overcome tannins negative effects at rumen environment.
Dhurrin is a cyanogenic glycoside that changes to cyanide hydrogen due to enzymatic action, it is located mainly on the shoots of sorghum plants.
Ruminants are more susceptible to cyanide hydrogen poisoning in comparison to horses or pigs, although sheep are more resistant than cattle. Cyanide hydrogen causes dysfunctions in central nervous system and cardiac/breathing failures. Just very high levels of cyanide hydrogen (75.96 mg/100 g) could decrease nutrient digestibility on broilers.
The amount of cyanide hydrogen in sorghum varies according to the kind of crop and growing conditions but decreases with the age of the plant.
Importance of anti-nutritional factors in sorghum and soybean - Image 1
Anti-nutritional factors in soybean
Lectins are proteins which are usually in the form of glycoproteins, its main characteristic is the capacity to bind glycose compounds and agglutinate erythrocytes.
Lectins can bind to intestinal mucosa epithelial cellular receptors resulting in weight and growing loses such in poultry, pigs and ruminants; due to the injury on the intestinal tract, permeability increases and therefore the digestive processes and nutrients absorption are interfered, as well as an affectation in the immune system.
Trypsin and protease inhibitors
Trypsin and protease are molecules that inhibit digestive enzymes, its importance in animal nutrition is very wide.
The first trials made to identify these compounds in soybean were applied on rodents, a lack of growing was observed due to the intestinal enzymatic inhibition. The secretion of pancreatic enzymes is mediated by the cholecystokinin-pancreomycin hormone, with the inhibition of trypsin happens a hormonal overproduction resulting in an increase of the circulant enzymes and a possible hyperplasia and hypertrophy of pancreas. This pancreatic hypertrophy has been observed in rodents and poultry, it is not common to occur in larger mammals like pigs or cattle.
Phytic acid
Phytic acid its part of soybean, bean and pea seeds. It shapes anionic complexes that reduces the availability of minerals like calcium, phosphorus, magnesium, zinc, copper and iron. It also can inhibit proteolytic and amminolytic enzymes.
Some bone problems can be related with high concentrations of this antinutritional factor.
The use of a product like SANGROVIT, with the function of modulate intestinal inflammation response, can help to reduce the negative impact that some of these compounds can cause on production animals

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