Fusarium mycotoxins and horses
By Susan L. Raymond, Equine Research Centre, Trevor K. Smith and Swamy
Department of Animal and Poultry Science, University of Guelph
harvest season seems to bring a variety of challenges that horse
owners and farmers need to address. Cool wet climatic conditions
during the harvest season for grain and hay crops increases the
likelihood that fungi such as Fusarium can grow in or on these plants.
Cattle, pig and poultry farmers are well aware of the potential
problems that these fungi and their metabolites can cause in their
livestock. Very little research has been completed in Canada on
the potential impacts of the various fungi and their mycotoxin metabolites
on horse health. In addition, there is a wide range of acceptable
levels for the various mycotoxins.
Two research initiatives at the University of Guelph are ongoing
to better understand fungal mycotoxins and the impact on horse health.
This research update summarizes a project on the effectiveness of
a commercially available mycotoxin binder. Feed manufacturers regularly
monitor mycotoxin levels in grain and commonly add mycotoxin binders
to feed to reduce the potential impact of mycotoxins should they
be present in the grain.
Dr. Bob Wright, Veterinary Scientist, Ontario Ministry of Agriculture
of grain and forage plants usually begins pre-harvest. This is greatly
influenced by weather conditions and is difficult to control. Mould growth
can be compounded by improper storage postharvest, and can alter the nutritional
status of horse feed.
This study looked at the impact of Fusarium moulds on feed consumption.
Fusarium moulds are commonly found in temperate climates like Ontario,
produced by these moulds have a very high economic impact as grain contaminants.
The Fusarium mycotoxins are associated with decreased feed consumption,
disorders and immunosuppression in other livestock species. The horse
industry is questioning the effect Fusarium may be having on their horses
performance or breeding ability and, in particular, the dangers that may
be inherent with the chronic consumption of low levels of these mycotoxins.
In response to these concerns, this study was conducted to measure the
effect of feeding naturally contaminated grains on feed intake and blood
responses in the horse, and to measure the efficacy of a natural nutritional
supplement in preventing the intestinal
absorption of feed-borne mycotoxins.
The feeding of contaminated grains significantly reduced feed intake
compared to controls (please refer to figure 1).
Supplementing with yeast cell wall polymer significantly improved
feed intake compared to the feeding of contaminated grains without supplementation.
Consumption of forage was not affected by diet.
Serum activities of gamma-glutamyltransferase (liver enzyme) were
significantly higher in horses consuming contaminated grains for 7 and
14 days, but not for 21 days.
Serum gamma-glutamyltransferase activities were not affected by
the feeding of contaminated grains containing the yeast cell wall polymer.
Management Methods and Conclusions:
It was concluded that the feeding of grains naturally contaminated with
Fusarium mycotoxins altered serum chemistry in mature horses and significantly
intake. Supplementation of yeast cell wall polymer to contaminated grains
was beneficial in alleviating reduced feed intake in these horses.
Mycotoxins are very
difficult to get rid of once formed and few effective strategies to eliminate
them have been identified. Controlling exposure to mycotoxins begins by
controlling mould growth from point of harvest and maintaining low mould
growth throughout storage up to and including feeding. Forage and grain
should be processed at low moisture content. Grain should be kept intact
until adequately dried. Mould growth is more prevalent in damaged or processed
grains. Mycotoxin adsorbents (yeast cell wall polymer) can be used when
mycotoxin exposure cannot be avoided.
The authors would like to acknowledge the generous support of the Ontario
Horse Racing Industry Association, Rural Job Strategy Fund and Alltech
Inc. The authors would also like to acknowledge the contribution of our