Lecture 7 - Anti nutritional factors in feeds Flashcards
Example of global climate change
2012 North American drought
Drought, flooding and temp changes can
increase chance of mycotoxin contamination of feed grains
Increase chances of mycotoxin combinations in feed
global trading of feed grains
Most common found mycotoxins
aflatoxin
fusarium toxins
Fusarium toxins more difficult to analyze
- large number of compounds
- widely varying chemical structures
What is necessary to analyze fusarium toxins
DON as a marker compound
Found in naturally contaminated corn and wheat from slovakia?
biologically active
non detectable
glucose conjugates of DON
- fraction of total DON represented by glucose conjugate is up to 30%
Chemical hydrolysis of feed samples before DON measurements resulted in
up to 88% increase in detectable DON in barely
- north dakota
Glucose conjugates of what compound have been reported?>
zearalenone fumonisin nivalenol fusarenon-X T-2 toxin HT-2 toxin
Use what in lab to optimize hydrolysis conditions for corn and wheat
TFMSA
-trifluoromethanesulfonic acid
Avg increase in Canadian wheat with acid hydrolysis treatment
36.8%
7%-64%
Avg DON increase in corn with acid hydrolysis treatment
35.5%
17%-70%
2012 US corn crop (alfatoxin)
some alfatoxin but within legal limit
Fumomosin incidence
Significant amounts reported in 2012 in U.S corn
- formed from strain of fusaium fungi
- same strain forms fusaric acid
- crops not typically analyzed for this
Most sensitive species to fusarium toxins
swine and horses
- poultry more resistant but have altered metabolism and specific legions
- ruminant animals most resistant, but effect reproduction and milk production
Fumonisins effects
inhibit synthesis of membrane lipids
- result “equine leucoencephalomalacia”
- ataxia and sudden death
- massive atrophy of the brain
Fumonisins required to produce syndrome
3ppm
Major source of fumonisins
corn and corn screening
Trichothecenes
family of 100+ structurally related toxins
- feed refusal toxins
- most common deoxynivalenol (DON)
Trichothecenes effects
- alter brain neurochemistry by increasing tryptophan and serotonin levels
- dermal necrotic agents and inhibit cellular protein synthesis
- cause hemorrhaging of intestinal tract, ulcers and nutrient malabsorption (bloody feces)
- immunosuppressive, make susceptible to 2nd mycotoxic disease (inhibit immunoglobulin synthesis)
Zearalenone
Estrogenic fusarium mycotoxin
Zearalenone effects
bind estrogen binding sites
- enlargement of uterus and rectal and vaginal prolapse
Fusaric Acid
inhibits enzyme dopamine-beta-hydroxylase
- catalyzes dopamine to norepinephrine
- causes lowering blood pressure
increases brain conc of tryptophan and seritonin
- acts with vomitoxin (DON) synergistically
- reduce feed consumption, muscle contraction and lethargy
Fusaric acid content of cereal grains
whole foods - 35.8mg/kg high moisture corn - 26.4 barely - 12.2 dry corn - 11.8 wheat - 11.6
Alfatoxins produced mainly by?
- what are they
aspergillus flavus
aspergilus parasiticus
- tropical / semitropical fungi
- thrive in warm moist climates
Naturally occurring aflatoxins
Aflatoxins B1, B2, G1, G2
What are Alfatoxins
hepatotoxins
- cause fatty infiltration and fibrosis of the liver
- following acute exposure
- due to inhibition of helpatic protein synthesis
- one of the most carcinogenic compounds known
chronic exposure causes liver cancer
Aflatoxicosis in ponies
increase serum enzyme activities of gamma glutamyl transferase (GGT)
- confirms liver is key target
- kidney secondary target
Aflatoxins exposure other than feed?
Inhalation from bedding material covered with mold and mycotoxins
- respiratory disorders in horses and agricultural workers
Activation of aflatoxin B1
- where is it highest
Converted to AFB1 epoxide
- by cytochrome P-450
Activation higher in nasal olfactory mucosa than liver
- predisposes equines to respiratory disease
Low level aflatoxin contamination
respiratory problems and immunosuppression
Fescue
important pasture forage crop in humid regions
- especially eastern US
Equine Fescue Toxicosis cause
Endophytic fungi grow symbiotically on tall fescue and ryegrass
Endophyte infected tallgrass contains
ergopeptide alkaloids (ergovaline) - tall fescue toxicosis
Endophyte infected ryegrass contains
lolitrem alkaloids (lolitrem B) - ryegrass staggers
Equine fescue toxicosis exist because
equines lack rumen detoxification of compounds
- protects grazing cattle
Equine fascue toxicosis signs / symptoms
characterized by reduced concentrations of IgC in milk
- predispose foals to septicemia and death
also prone to:
- hypothyroidism
- incoordination
- poor suckle reflex
- hypothermia
- goitre
Alkaloids are vasoconstrictive
- predispose to laminitis from increased edema and vascular collapse
Endophyte infected fescue cardiorespiratory and thermoragulatory effects
exercising horses
- slower recovery post exercise
- recovery to pre-exercise levels was prolonged for heart rate and skin temp
- increase water consumption and sweating
Equine fescue toxicosis effects on reproduction
vasconstriction of peripheral blood flow, leads to
- increased gestation lengths
- early embryonic mortality
- agalactia
- weak and immature foals
Equine Ergot Toxicosis initiation
fungus claviceps purpurea
- produces alkaloid indolics (erotamine)
- when invading wheat, rye and oats
Equine Ergot signs/symptoms
reduced udder development
weak foals lacking suckle reflex
Ergot contamination detection
visual examination for sclerotia (ergot bodies)
Equine Tremorgenic Mycotoxins (tremorgens)
Lolitrem B (neurotoxin)
- produced by acremonium lolli
- cause ryegrass staggers
Equine Tremorgenic Mycotoxins (tremorgens) common problem in
Australia
New Zealand
Western North America
Lolitrem B signs/symptoms
trembling
hypersensitivity to stimuli
abdominal muscle spasms
disorientation of horse
(Tremorgens)
Lolitrem B (tremorgens) proposed mechanism of action
inhibition of gamma-aminobutyric acid in the nervous system
- inhibits chloride flux
- prolongs nerve depolarization causing tremors
Equine Slaframine Toxicosis initiation
fungus ‘rhizoctonia leguminicola
- grows on red clover
- others include soybeans, cow peas, alfalfa, white clover
Equine Slaframine Toxicosis signs/symptoms
Salivary syndrome or slobbers
- due to slaframine - parasympathetic alkaloid
- salivation
- diarrhea
- piloerection
- respiratory failure
- feed refusal
stratagies to prevent mycotoxicities
dilution with sound grain diversion to less susceptible species processing methods such as cleaning use of mold inhibitors (ex. propionic acid) use of enzymes mycotoxin adsorbents physical treatment (heat)
