Characterization and Safety of Uniform Particle Size NovaSil Clay as a Potential Aflatoxin Enterosorbent

NovaSil (NS) clay, a common anti-caking agent in animal feeds, has been shown to adsorb aflatoxins and diminish their bioavailability in multiple animal models. The safety of long-term dietary exposure to NS has also been demonstrated in a 6-month sub-chronic study in rats and in a 3-month intervention in humans highly exposed to aflatoxins. Uniform particle size NovaSil (UPSN) is a refined material derived from parent NS; it contains lower levels of dioxins/furans, and has been selected for a more consistent uniform particle size. Nevertheless, the efficacy and potential safety/toxicity of UPSN for long term-use has not yet been determined. In this research, 4-week-old male and female Sprague Dawley rats were fed rations free of clay (control) and containing UPSN at low dose (0.25%) and high dose (2%) for 13 weeks. AFB(1) sorption characteristics remained the same for both clays. When compared to the control, total body weight gain was unaffected in either sex at the doses tested. No UPSN-dependent differences in relative organ weights or gross appearance were observed. Isolated differences between UPSN groups and the control were observed for some biochemical parameters and selected vitamins and minerals. None of these differences were dose-dependent, and all parameters fell between ranges reported as normal for rats less than 6 month old. The Na/K ratio, Na and vitamin E concentrations were the only parameters that were increased in both males and females in the low dose and high dose UPSN groups. Serum Zn levels in males from the 2% UPSN treatment were lower compared to the control. Serum K levels were lower in the males of UPSN groups than in the control. However, neither Na/K ratio, K, nor Zn values were dose dependent and fell outside ranges reported as normal. These results suggest that dietary inclusion of UPSN at levels as high as 2% (w/w) does not result in overt toxicity. Nevertheless, further research on the effects of clays on Na, Zn, K and vitamin E is warranted.

In vitro and in vivo characterization of mycotoxin-binding additives used for animal feeds in Mexico

The study was conducted to characterize and compare twelve different additives distributed in Mexico as mycotoxin binders utilizing: (1) equilibrium isothermal analysis for aflatoxin B(1) (AFB(1)) adsorption, (2) a variety of mineralogical probes, and (3) Hydra toxicity bioassay. The test additives Milbond-TX (MLB), Mycoad (MCA), Volclay FD181 (VOL), Fixat (FXT), Toxinor (TOX), Mexsil (MEX), Mycosil (MYC), Klinsil (KLS), Zeotek (ZEO), Duotek (DUO), Mycosorb (MSB), and Mycofix Plus 3.0 (MIX) were compared with NovaSil Plus (NSP). Isotherms for AFB(1) adsorption were conducted at pH 2 and pH 6.5, mimicking pH conditions in the stomach and small intestine. Mineralogical analysis included determination of swelling volume, X-ray diffraction analysis, and fractionation procedures. A Hydra vulgaris toxicity study was performed to evaluate the potential safety of the additives. Computer-generated isotherm data were fit using the Langmuir model, and parameters of Q(max) and K(d) were estimated. The most effective additives for AFB(1) at both pH conditions were NSP, MLB, MCA and VOL, while the least effective was MSB. The amounts of sand, silt and clay fractions varied among the additives. Nine of the additives showed the presence of smectite. Most of the additives were found to be non-toxic to Hydra except for the organoclays (ZEO, DUO) and MSB. In general, NSP demonstrated the highest sorption capacity in the bulk material and the different fractions. Studies to characterize these binding additives further and to evaluate their multiple mycotoxin sorption claims are ongoing.