My­co­tox­ins and their in­ter­ac­tions

The ob­sta­cles in the road to risk as­sess­ment

The Poultry Bulletin - - POULTRY AND GRAIN -

Typ­i­cally my­co­toxin risk as­sess­ment is very spe­cific in terms of an­i­mal species and pro­duc­tion stage as well as my­co­toxin type; the first two ap­proaches make much sense as my­co­tox­ins af­fect, for ex­am­ple, poul­try in a dif­fer­ent way than cat­tle; and broil­ers in a dif­fer­ent way than lay­ing hens; but in the day to day of farm­ing and feed­ing an­i­mals, hav­ing in­di­vid­ual my­co­toxin chal­lenges is not a re­al­ity. In prac­ti­cal ex­pe­ri­ence, my­co­toxin multi-con­tam­i­na­tion is found very fre­quently. Since 2014, EW Nu­tri­tion has con­ducted more than 15,000 my­co­toxin tests around the globe from both raw ma­te­rial and fin­ished feeds sam­ples. 80% of these sam­ples were con­tam­i­nated with more than one my­co­toxin and al­most one third was pos­i­tive for four or more my­co­tox­ins.

Syn­er­gies, ad­di­tive ef­fects and an­tag­o­nisms

The tox­i­c­ity of com­bi­na­tions of my­co­tox­ins can­not be pre­dicted based upon their in­di­vid­ual tox­i­c­i­ties; in­ter­ac­tions can lead to toxic ef­fects at con­cen­tra­tions at which no ef­fects are ex­pected and can be an­tag­o­nis­tic, ad­di­tive, or syn­er­gis­tic. Syn­er­gis­tic ac­tions may oc­cur when the sin­gle my­co­tox­ins of a mix­ture act at dif­fer­ent steps of the same mech­a­nism; or when the pres­ence of one my­co­toxin in­creases ab­sorp­tion of an­other or de­creases its meta­bolic degra­da­tion. An­tag­o­nism, on the other hand, may oc­cur when my­co­tox­ins com­pete with one an­other for the same tar­get or re­cep­tor site. How­ever the in­ter­ac­tions are com­plex and their ef­fects de­pend on the an­i­mal species, age, sex, nu­tri­tional sta­tus, dose and du­ra­tion on ex­po­sure as well as on en­vi­ron­men­tal fac­tors. For ex­am­ple, the com­bined pres­ence of DON and ZEA, very com­mon, may give ground for ad­di­tive ef­fects. In a feed­ing trial the com­bined ef­fects of DON and ZEA in poul­try were stud­ied, hav­ing a nat­u­ral con­tam­i­na­tion of around 5000 ppb of DON and 300 ppb of ZEA. As it can be seen in fig­ure 1, the my­co­toxin chal­lenged group (T2) had a lower av­er­age body weight than the con­trol groups (Con­trol: no chal­lenge and no anti-my­co­toxin ad­di­tive and T1 a feed with­out my­co­toxin chal­lenge but hav­ing a my­co­toxin binder); the chal­lenge was coun­ter­acted by an anti-my­co­toxin agent (Master­sorb® Gold, pro­duced and com­mer­cial­ized by Ew-nu­tri­tion) (T3 and T4). Sig­nif­i­cant de­creases in villi height in duo­de­num and je­junum of poul­try have been found in sev­eral stud­ies af­ter in­ges­tion of di­ets con­tam­i­nated with DON, as well as apop­to­sis of in­testi­nal and im­mune cells. ZEA has toxic ef­fects on neu­trophils, and de­creases IGG, IGA, IGM and TNF-Υ syn­the­sis, af­fect­ing im­mune func­tion, which can ex­plain the ad­di­tive ef­fect.

More in­ter­ac­tions: the gas­troin­testi­nal tract

Af­ter in­ges­tion of feed its com­po­nents, in­clud­ing my­co­tox­ins, first reach the gas­tro-in­testi­nal ep­ithe­lium. One of the func­tions of the in­testi­nal mu­cosa is to act as a bar­rier to the ex­ter­nal en­vi­ron­ment, pre­vent­ing the pas­sage of virus, micro­organ­isms and tox­ins. The in­testi­nal ep­ithe­lium in its whole ex­ten­sion is in con­tact with my­co­tox­ins of­ten at higher con­cen­tra­tions than other tis­sues. More­over my­co­toxin ex­po­sure can in­crease the an­i­mals’ sus­cep­ti­bil­ity to harm­ful agents present in the gas­troin­testi­nal tract. In that re­gard, the in­take of DON, OTA and fu­mon­isin (FUM) con­tam­i­nated feed (sep­a­rately or in com­bi­na­tions) is a pre­dis­pos­ing fac­tor for the de­vel­op­ment of necrotic en­teri­tis (NE) due to their neg­a­tive in­flu­ence on the ep­ithe­lial bar­rier. Fur­ther­more, my­co­tox­ins can in­flu­ence the com­po­si­tion of the in­testi­nal mi­cro­biota can po­ten­tially be me­di­ated by my­co­tox­ins.

Afla­tox­ins have im­mune-in­hibitory ac­tiv­ity in the in­testi­nal bar­rier and can also dam­age the gut ep­ithe­lium. An in­crease in pop­u­la­tions of E. Coli, Sal­mo­nella, and to­tal gram-neg­a­tive bac­te­ria has been found af­ter the in­ges­tion of afla­toxin con­tam­i­nated feed in poul­try and swine. In broil­ers chal­lenged with AFB1 and AFB2 the E. Coli and co­l­iform bac­te­rial count in ce­cum con­tent was sig­nif­i­cantly lower in a group of an­i­mals re­ceiv­ing the anti-my­co­toxin agent Master­sorb® Gold than in a group chal­lenged but not re­ceiv­ing the ad­di­tive (fig­ure 2), in­di­cat­ing a pos­si­ble re­la­tion­ship be­tween the bac­te­rial count and the my­co­toxin chal­lenge. As shown in sev­eral ex­am­ples and in the prac­tice in an­i­mal pro­duc­tion, my­co­toxin risk as­sess­ment has to be used in thought­ful way, pre­ven­tive mea­sures, like lim­it­ing highly con­tam­i­nated raw ma­te­ri­als and us­ing ef­fec­tive anti-my­co­toxin ad­di­tives, have to be taken se­ri­ously and will be re­flected in bet­ter health, wel­fare and pro­duc­tiv­ity of an­i­mals.

Fig­ure 1: Body weight of broil­ers at 33 days of age fed a DON and ZEA con­tam­i­nated diet with and with­out Master­sorb® Gold

Fig­ure 2: E. coli and to­tal co­l­iform count of ce­cal con­tent of broil­ers at 42 days of age fed an AFB1 and AFB2 con­tam­i­nated diet with (green bars) and with­out (grey bars) Master­sorb® Gold

Newspapers in English

Newspapers from South Africa

© PressReader. All rights reserved.