The aflatoxin molecule. The regulatory action level for aflatoxin B1 is 20 parts per billion. Aflatoxins are potent liver toxins, carcinogens and immune suppressants.
Despite careful ingredient screening for aflatoxin, low
concentrations may get into your petfood undetected. A clay
called HSCAS (Novasil) can provide you with better assurance of
Recent research at Texas A&M University has established
better ways to inactivate aflatoxins. Earlier this year, dozens
of dogs in the US died after eating aflatoxin-contaminated,
commercial petfoods. The use of HSCAS could have prevented
Aflatoxin is a naturally occurring mycotoxin produced by two
types of mold: Aspergillus flavus and Aspergillus parasiticus.
Aspergillus flavus is widespread in nature and is most often
found when certain grains are grown under stressful conditions
such as drought.
Aflatoxins are potent liver toxins and carcinogens.
Suppression of the immune system is also a common effect. Among
the various mycotoxins, aflatoxins have been the subject of the
most intensive research. The losses sustained from companion
animal toxicity and death are incalculable.
Modern control measures
Aflatoxin control measures include using genetically
engineered, resistant crops and ensuring appropriate storage
conditions. These precautionary steps are followed by careful
testing of susceptible commodities for aflatoxins and banning
the lots that, in the US, exceed the regulatory action level of
20 parts per billion for aflatoxin B1. It is the most toxic
type and is regarded as the "sentinel" substance for all other
aflatoxins. HSCAS clay has lately been shown to be a good
Inactivation of aflatoxins
In a presentation at Petfood Forum 2006, Timothy Phillips,
PhD, summarized research in his lab at Texas A&M
University. It has focused on the development of innovative
sorption strategies for the detoxification of aflatoxins. In
particular, the lab has employed isothermal analyses and
molecular modeling techniques to characterize and design
clay-based materials for the enterosorption, and inactivation,
of aflatoxins in the gastrointestinal tract.
Hydrated sodium calcium aluminosilicate (HSCAS) has been
shown to prevent the adverse effects of aflatoxins in various
animals when included in the diet. Studies have also confirmed
that HSCAS can alter the bioavailability of aflatoxin in dogs
(Bingham et al., Food Chem. Toxicol., 2004). Fortunately, HSCAS
does not interfere with the utilization of vitamins and
micronutrients in the diet. However, it is important to note
that it does not protect animals against other mycotoxins.
Clay minerals are structurally and chemically diverse. Many
are ineffective and/or nonselective for aflatoxins. Based on
the Texas research, all aflatoxin sequestering agents should be
rigorously evaluated in vitro and in vivo and should meet the
Efficacy in multiple animal species;
Safety in long-term studies;
Negligible interactions with vitamins and
Favorable thermodynamic characteristics of ligand sorption;
Tolerable levels of priority metals and dioxins/furans.
HSCAS is commonly used as an anti-caking agent in animal
feeds. It tightly and selectively adsorbs aflatoxin. The
following is an abstract from Bingham et al., Food Chem.
In a crossover study, six dogs were randomly fed a
commercial dog food (no-clay control) or the same commercial
dog food coated with HSCAS (0.5% by weight). These dogs were
administered a subclinical dose of aflatoxin B1. Diets were
switched and the process repeated. The HSCAS coated diet
significantly reduced urinary aflatoxin M1 by 48.4%±16.6 SD
versus the control diet.
The conclusion: HSCAS protects dogs fed diets with even
minimal aflatoxin contamination. Despite regular and careful
ingredient screening for aflatoxin, low concentrations may
reach the final product undetected. Therefore, HSCAS may
provide the petfood industry further assurance of canine diet
Aflatoxin management systems ultimately function like an
insurance policy. Not every facility requires the same
insurance plan. It is important to tailor a mycotoxin
management program to fit the needs of individual
John L. Richard, PhD, thinks you
should know which mycotoxins are of concern in your
facility, based on the ingredients you use. Richard is an
independent consultant to several petfood companies, both
domestic and international, in the field of mycotoxin
testing. Richard further counsels that you should
determine your criteria for accepting or rejecting these
incoming ingredients. Next, you should choose a test kit
based on these criteria, and it should perform acceptably
in your hands.
Most of the error in testing for
mycotoxins, says Richard, is in sampling. You should be
cognizant of the appropriate methods of sampling the
various kinds of vessels delivering commodities to your
Rapid test kits
Several commercial firms have marketed rapid test kits
for use in determining the aflatoxin concentration in
corn samples. These test kits are self contained and
provide all the necessary instructions to complete an
analysis on-farm, at the elevator or at the buying
It is important to remember that aflatoxins can be
concentrated in a few kernels that contaminate an entire
load. For this reason, a representative sample is
essential to determine the degree of contamination. A
multi-level probe sampling at several sites and depths
will give the best results. AOAC approved methods
generally agree that an initial sample weight of 10
pounds (5 kilograms) is desirable.
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