Important antinutrients in plant feedstuffs for aquaculture: an update on recent findings regarding responses in salmonids

TLDR: Anoverview ofantinutritivefac-tors (ANFs) relevant for ¢sh nutrition is presented and strengthening of the knowledge base is urgently needed to understand the eiects and to overcome or modify these eiECTs.

Abstract: Thisreviewpresentsanoverviewofantinutritivefac-tors (ANFs) relevant for ¢sh nutrition.The sources ofANFs and the possibilities of reducing the impact ofANFs are brie£y mentioned. Proteinase inhibitors,lectins, saponins and oligosaccharides are given amore thorough presentation regarding mechanismsofactionandthestateof knowledgeregardingeiectson gut function in ¢sh and upper safe dietary levels.Thereafter, selected results from recent works ad-dressing the involvement of T cells and proteinase-activated receptors in soybean-induced enteritis aresummarized. Our conclusions are as follows: we areonlybeginning tounderstandeiects of ANFs in ¢sh;strengthening of the knowledge base is urgentlyneeded to understand the eiects and to ¢nd themeans to overcome or modify these eiects; interac-tions between the eiects of ANFs appear to be veryimportant; the microbiota may modify the eiects ofANFs; not only salmonids are aiected; not only soy-beans contain ANFs of biological importance in ¢sh;andwithincreasedknowledge,wecandevelopbetterdiets for optimal nutrition, health and economy inaquaculture.Keywords: ¢sh,antinutrients,digestivephysiology,immunology,guthealthIntroductionNature has equipped many plants with the ability tosynthesize avarietyof chemical substances withtheapparentfunctionofprotectingthemfrombecomingfood for microbes, insects and higher animals. Con-sequently, many of these compounds may exertharmful eiects when ingested by humans and ani-mals. Such substances are often called antinutritivefactors (ANFs), although they may also have bene¢-cial eiects, such as being antioxidative, immunosti-mulatory or prebiotic, depending on the amountingested.Possibleharmfuleiectsincludereducedpa-latability,lesse⁄cientutilizationoffeednutrientsforgrowth,alterednutrientbalancesofthediets,inhibi-tion of growth, intestinal dysfunction, altered gutmicro£ora, immune modulation, goitrogenesis, pan-creatic hypertrophy, hypoglycaemia or liver damage.The species of animal, its age, size, gender, state ofhealth and plane of nutrition and any stress factorsmaymodifytheseresponses.Inhistextbookontoxicconstituentsofplantfoods,Liener (1980) wrote the following:‘What has only re-cently been realized is that althoughthere might notbe an immediate violent reaction to a certain foodcomponentthere might still beaslowcumulativead-verse eiect resulting in overt disease or less thanop-timal health. This poses a great challenge, sinceknowledge of these eiects is gained slowlyand withdi⁄culty, particularly if the causative principles re-main unidenti¢ed’. Liener’s statement is still validand relevant. During the last10^15 years, inclusionofplantfeedstuisin¢shfeedhasincreasedmarkedlyand consequently so has exposure toANFs. Antinu-tritivefactorsarenoveltomostcultivated¢shspecies,particularly carnivorous species. Fish nutritionistsshould keep in mind Liener’s warning that ‘there