Effet chez le porcelet d'une exposition à un régime co-contaminé en ...

INTRODUCTIONIn studies of the potential of bentonites to reduce the carry-over of aflatoxins into milk of dairycows variable reductions have been observed (Veldman, 1992). Petterson (2004) thus concluded thatit will be hazardous to trust the efficiency of these adsorbents at the low EU tolerance limits foraflatoxins in feed and milk. However, significant reduction of milk aflatoxin M 1 content was verifiedby Pietri et al. (2009) using a blend of bentonites. Regarding trichothecenes, in 1983 Carson andSmith observed general improvements in performance parameters and an increase in the toxinexcretion in rats fed a diet with T-2 toxin and bentonite incorporation. However, these results couldonly be achieved when the incorporation level in the diet was about 10-20 times higher (10%) thanthe efficient level for aflatoxins.Contradictory, bentonites have shown low or no effect against zearalenone and although theymay be useful in situations where moulds cause non-specific unpalatability, bentonites appearineffective where feed refusal is due to direct effects on appetite as appears to be the case withtrichothecenes such as nivalenol (Williams et al. 1994; Guerre, 2000).c) ZeoliteZeolites, other aluminosilicate clays, are similar to molecular sieves as well as to ion exchangeresins and are suitable for the distinction of different molecules by size, shape and charge.Depending on dosage, physical structure, type of zeolite and respective concentration of aflatoxins inthe contaminated feed, the ability of zeolites in reducing their toxicity can differ widely.Zeolites have been studied as adsorbents for aflatoxins. They normally have less capacity thanHSCAS or bentonites to adsorb aflatoxins in vitro, but showed some in vivo efficacy under practicalconditions (Pettersson, 2004). Natural zeolite (1% in the diet) given to broilers consuming 2.5 ppmAFB 1 has alleviated the growth depression and reduced the increase in liver lipid concentrationcaused by aflatoxins (Scheideler, 1993). Indeed, several studies with natural zeolite, the clinoptilolite,which is frequently added to animal feed, confirmed improvement on performance, decline of liverand kidney lesions, heterophilia and lymphopenia reduction and improvements on humoralimmunity (Sova et al., 1991, Parlat et al., 1999; Oguz and Kurtoglu, 2000; Oguz et al., 2000; Oguz etal., 2003; Ortatatli et al., 2001; Ortatatli et al., 2005).However, other studies reported contradictory results being ineffective and causing organ lesions(Mayrua et al., 1998; Harvey et al., 1993). Incorporation of a synthetic anion-exchange zeolite into ratdiets at 5% completely eliminated the deleterious effect of zearalenone on body weight, feedconsumption and feed efficiency. In opposite, the use of a synthetic cation-exchange zeolite was notable to protect rats against ZEA toxicosis (Smith, 1980), presenting higher uterus weight in piglets fed76