Anti-nutritional factors in animal feedstuffs are substances that inhibit animal growth; they are also called growth inhibitors. These substances affects nutrient synthesis like protein synthesis and absorption of minerals, some destroy the lining of the digestive tract, leading to low efficiency of feed. The following are the anti-nutritonal factors common in livestock feedstuff;
Aflatoxin is a poisonous chemical formed by common soil-borne moulds of the genus Aspergillus. The fungus (mould) is widespread in the tropics and found on many crops, including maize and groundnuts. It is often exacerbated during drought-affected production years or if high yields surpass local post-harvest infrastructure for drying and storage. Aspergillus can be fairly easily seen as a yellow or green mould, but that is not an adequate indicator of contamination by aflatoxin. The chemical cannot be eliminated through cooking or other simple processing and is toxic to humans and animals even at very low doses. Aflatoxin is highly carcinogenic and leads to liver cancer under chronic exposure. Consumption of highly contaminated crops has led to cases of acute aflatoxicosis and even death. Consumption of products contaminated with aflatoxin is strongly linked with immune suppression and childhood stunting, including reduced birth weight. Aflatoxin also negatively impacts the health of livestock and can even enter the human food system through animal based foods, such as milk and eggs.
Control: It can be controlled through thorough drying of the feedstuff to about 10% moisture content.
This is commonly found in cotton seeds, cotton seed meal is used as a protein source in animal feed. Gossypol is a yellow pigment and a poly phenolic aldehyde which is an antioxidant and polymerization inhibitor. It is toxic to simple stomached animals like poultry.
The general symptoms of gossypol toxicity are depressed appetite, loss in weight, laboured breathing and cardiac irregularity. Post-morten examination usually show extensive oedema in the body cavity indicating an effect on membrane permeability.
Control: the gossypol content of cottonseed meal decreases during processing. The shearing effect of the screw press in the expeller is an efficient gossypol inactivator at temperature that does not reduce protein quality. Also, treatment with ferrous sulphate can ameliorate the effects of gossypol with doses ranging from 1 to 4 parts ferrous to 1 part of gossypol.
3. Protease inhibitors:
These are present in raw soybean or unheated soybean meal. They are partly responsible for the growth-retarding property of raw soybean and unheated soybean meal. Soybean is the most reliable plant protein source for livestock feed. It is rich in protein and the protein contains all the essential amino acids. Soybean also contains toxic like allergenic, goitrogenic and anti coagulant factors.
Control: All these toxics and antinutritional factors can be removed by heating.
These materials should be used in limited quantities as they are capable of causing diarrhoea. Sugar may depress utilization of the ration and results in excessive amount of methane gas.
All these affect the utilization of feed in animal, care must be taken to ensure the material to be used for feed formulate are not adulterated. High quality feed must be given animals to yield high quality product as well, thus, resulting in high profit.