Processing Methods for Amelioration of Anti-Nutritional
Meals from many oil seeds often contain undesirable toxic and allergenic compounds that can reduce their nutritive value severely and limit their use in feeds. To remedy these problems a number of processes have been developed to remove the undesirable compounds from the meals through extraction and physical separation or destroy them chemically. Drying, soaking, leaching and fermentation are the techniques generally tried for detoxifying the oil seed cakes and increasing their nutritive value.
Alkali (1.5%, w/w) treatment and urea (2%, w/w) ammoniation are effective in detoxification of neem kernel meal. This processing technology need to be improved to prevent cumulative effect of residual neem bitters in long-term feeding. Defatted rapeseed meal obtained after extraction with aqueous acetone contained very little glucosinolates as compared to those obtained by defatting with hexane only. Some - scientists reported maximum reduction in phytic acid and phenolics in rape seeds boiled for 30 min.
The quality of a protein in a particular oil seed is relatively constant but that the cake or meal derived from it may vary depending upon the conditions employed for the removal of the oil Biochemical effects of extrusion cooking influence the nutritive value of foods including denaturation of proteins, gelatinization of starch and inactivation of anti- nutritional factors and complexing of fatty acids. Care must be taken to ensure that the correct temperature is used. The animals which benefit most from feeding of extrusion cooked feeds are those with low digestive capacity (piglets, chicks, pre-ruminant calves and animals which are deficient in energy), animals sensitive to anti-nutritional factors, those which require a diet rich in fat and cows of high productivity. Extruded soybeans are suitable for use as food and animal feeds.
A number of chemical treatments have been attempted from time to time for the removal of ANFs and toxicants for upgrading the feeds. The chemicals used have been sodium hydroxide, ammonia, hydrogen peroxide and some oxidizing agents. These treatments do degrade the factors under investigation but these often lead to the leaching of nutrients. In addition, chemical treatments are not preferred now due to environmental concern. Biotechnological approach for detoxification of ANFs have two facets: treatment of the feeds with microorganism with specific capacity to elicit degradation or bio-transformation of the factors under investigation, modification of rumen microflora by enrichment techniques and techniques of recombinant DNA technology for imparting them the ‘life-long’ capacity to degrade such factors. This work provides the precedent to exploit the diverse and dynamic population of rumen microorganisms as a solution to the anti-nutritive properties of ruminant feeds.
Differential scanning calorimetry based on measurement of transition energies of chemical changes, seems to be a promising tool, in addition to iso-thermal process research, for the inactivation of anti-nutritional factors in animal feeds.Irrespective of the choice of feed and location, acceptable and successful feeding systems are those that are simple, practical, within the limits of the farmer’s capacity and available resources and consistently reproducible. The approach at the farm level is to seek optimum rather than maximum performance. Plant secondary metabolites (PSM) are thought to have a defensive role that ensures survival of the plant by protecting them against insect predation or by restricting grazing of herbivores. Thus elimination or reduction of PSM by breeding strategies may not be compatible with high production. Adequate processing is essential for the profitable inclusion of some of the by-products of novel oilseeds in livestock diets. Detoxification was often achieved but economical feasibility remains questionable in many circumstances. Processing technologies that are economic and practical are thus urgently required.
The use of biotechnology to improve the nutritive value of feedstuffs is on the verge of delivering practical benefits to ruminant production systems. It is not time to concentrate on solving the technical problems that are limiting its current use rather than further speculate about the potential application of this technology. Beneficial effects of tannins in ruminants include higher retention of N, increased efficiency of N recycling to the rumen and increased microbial N flow to the intestines (increased saliva production, increased rumen turnover rate).
Other studies confirmed the potential benefits of pro-anthocyanidins that include boosting of immune system, protection from arteriosclerosis, enhanced connective tissue health, lower cholesterol level, reduced cancer risk, reduction and repair of UV damage to the cells. Feeding of diets high in CT reduces dependence on anthelmintic drenches and improves reproduction performance. Compounds derived from glucosinolates as a consequence of enzymatic breakdown or metabolism has been shown to activate mechanisms which moderate or reverse carcinogenic processes. The saponins found in oats increase and accelerate the body’s ability to absorb calcium. In ruminants, saponins have been shown to reduce nominal protein degradation and increase microbial protein synthesis. It is time that we take a fresh look at these so called ANFs in view of their positive effects and also reconsider their role in animal systems.