Anti-nutritive factors

Question 1

What increases the chance of mycotoxin contamination of grain feeds?

Answer 1

drought, flooding and temperature extremes

Question 2

What increases the chance that blends of grains will result in combinations of mycotoxins?

Answer 2

increased global trading of feed grains

Question 3

What are the most commonly found mycotoxins?

Answer 3

aflatoxin and fusarium toxins

- DON can be used as a marker

Question 4

What makes the conjugated form so bad?

Answer 4

Its toxic but non-detectable

- conventional analytical techniques are under-estimating the amount of mycotoxins in a feed

Question 5

What species are most sensitive to fusarium mycotoxins?

Answer 5

horses and swine

Question 6

What is the effect of fumonisin?

Answer 6

can inhibit synthesis of membrane lipids –> massive atrophy of the brain

• horses 3 ppm vs. ruminants 200 ppm
• immunosuppressive –> compromised immunity is likely the greatest cause of economic loss in the equine industry arising from feed-borne mycotoxins

Question 7

What are the major sources of fumonisins?

Answer 7

corn and corn screenings

Question 8

Physiological effect of fusaric acid

Answer 8

drop in blood pressure

• low blood pressure –> restricts blood flow to lungs –> restricts ability to exhale CO2
• increases brain concentrations of Trp and serotonin
• fusaric acid and vomitoxin act synergistically to reduce feed consumption and cause loss of muscle coordination and lethargy
• immunosuppressive also

Question 9

Effects of aflatoxins

Answer 9

One of the most potently carcinogenic compounds known

• chronic exposure –> liver cancer
• kidney is secondary target tissue
• can be exposed through ingestion & inhalation –> respiratory disorders

Question 10

What contains ergo peptide alkaloids?

Answer 10

endophyte infected tall fescue

• ergovaline
• vasoconstrictive
• slower recovery after exercise
• increased water consumption and sweating
• reduced concentrations of IgG in milk

Question 11

What makes horses so susceptible to mycotoxin toxicity?

Answer 11

lack rumen detoxification mechanism (largely protects cattle)

Question 12

Strategies for preventing mycotoxicoses

Answer 12

1. dilution with sound grain
2. diversion to less susceptible species
3. processing methods
4. use of mol inhibitors
5. use of enzymes
6. mycotoxin absorbents
7. physical treatment (e.g. heat)

Question 13

What makes the conjugated form of a toxin so bad?

Answer 13

They are toxic but non-detectable using conventional analytical techniques. Therefore, the actual amount of toxin within a feed is being underestimated; further complicating the identification of underlying causes of mortality in a horse that’s been affected.

Question 14

List 3 signs a foal may show when suffering from fescue toxosis.

Answer 14

• hypothyroidism
• incoordination
• poor suckle reflex
• hypothermia
• goiter

Question 15

What is the negative effect of using excessive amounts of mycotoxin adsorbents?

Answer 15

Excess use causes adsorption of other small molecules that are beneficial, like amino acids, vitamins, minerals and bile salts

Question 16

How can Fusaric acid be used in a therapeutic way?

Answer 16

In low doses it can help calm horses by increasing tryptophan in the brain, and lowering blood pressure.

Question 17

True/false: aflatoxins are hepatotoxins, and chronic exposure can cause liver cancer

Answer 17

True