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Anti-nutritional factors
Natural components of feedstuff that interfere with the digestion, absorption or utilization of nutirents or energy
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Toxins
- A poisionous substance produced within living cells
- Organic, inorganic, mycotoxins, agricultural chemicals
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Contaminants
- Material inadvertently included in feed
- toxic plants
- toxic plant components
- microbial (bacteria/fungal) toxins
- drug residues
- pesticides
- pollutants
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General signs of toxicity at low levels
- Growth rate problems
- Reduction in animal vigor
- Reduction in fertility
- Induced abortions
- Birth defects
- Plants often have more than 1 ANF or toxin
- Ruminants can often metabolize many toxins & ANF
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Fibre
- Most common ANF for monogastrics
- -effect on feed passage
- -access of enzymes to substrates in lumen of GI
- -movement of released nutrients from food particles to absorptive substrates
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Pant ANF
- Most poisonous plants unpalatable
- -only consumed in drought, spring, or overgrassed pastures
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Plant ANF physiolocial responses vary with
- Species of plant
- Stage of lifecycle
- Part of plant
- Soil type
- Processing
- Animal species
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Organic ANF - Protein
- Pretease inhibitors (mainly legumes, heat treatment works)
- Lectines (beans & legumes, causes cells to clump, reduces absorption, heat treatment works)
- Anitgenic proteins (allergy, elicit humoral immune response, problem with feeding/withdrawl/feeding)
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Phenolics - Organic Toxins
- Tannins (bitter & stringent: cross-link and become insoluble)
- Gossypol (monogastrics, cardiac irregularity, anemia, infertility: removed by solvent extraction)
- Sinapine (phenyl)(bitter, some chickens back TMA oxidase)
- Cynogenic glyosides (cytochrome oxidase cleaves to form free sugar & HCN)
- Giotrogenic gylcosides (goitrin interferes with thyroid activity and iodine metabolism)
- Coumarin (vit. K antagonist)
- Vicine and convicine (metabolized into toxic product, RBC fragility)
- Saponins (CHO bound to steriod, bubbling in rumin)
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Other Organic Toxins
- Phytoestrogens (plant steriols resemble estrogen)
- Metal-binding agents (phytate: interfere with P availability)(oxylate: binds to Ca)
- Plant alkoloids (nitrogen component: problem for ruminants)
- Blue-grren algae
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Inorganic poisons
- Nitrates; green leaves, heavy N fertilizers
- Uninary calculi; high K or P intake, incorrest Ca:P ratio, silica
- Selenium toxicity; blind staggers, loss of hair, sloughing of hooves. paralysis, respiratory failure
- Grass tetany: hypomagnesemia (too much P), rapidly growing lush pasture, temp or other stresses, organic acid in plants
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Mould growth requirements (5)
- Available nutrients
- Insect damage/disrupted seed coat
- Moisture >14% RH>70%
- Oxygen
- Specific temps.
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Most important species in regards to mycotoxin
- Penicillium spp
- Aspergillus spp
- Fusarium spp
- Claviceps spp (ergot)
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Concern with mycotoxins in livestock feed
Concentration in DDGS
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Aflatoxin
- from Aspergillus flavus
- -typical mold requires 24-40 C
- -greater in tropical areas, shipped worldwide
- Corn, peanuts, cottos=nseed
- Considered storgae mold
- Acute toxicoses, jaundice, cirrhosis of liver
- -lower dose, decreased appetite, weight and unthriftiness
- -reduce by feeding higher protein
- World prominence in 1960s
- Highly potent
- High affinity for nucleic acids
- -interferes with protein synthesis, immunosuppressive & carconiogenic
- Animals metobolize toxins, but metabolites may still be toxic
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Fusarium spp
- Colonizes in field, toxin in storage
- -affects storage, temperate clomates
- zearalenone - causes hyperestrogenism and infertility
- tricothecenes - inhibit translation during protein synthesis
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Ochratoxin
- From aspergillus, Penicllium spp
- Cooler climate
- Serius residue in feed chain
- High affinity for enzymes involved in CHO and protein metabolism
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Alkaloids
- Ergot - fungus develops in seed ovary
- Ergotism - 3 types
- -gangrenous: vasoconstriction due to smooth muscle constriction
- -convulsize: neurotoxic effect
- -hallucinogenic
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Medicinal uses for ergot
- Reduce hemorrhages following childbirth
- Control headaches?
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To use ergot
- Clean it and dilute it
- Don't fed to pregnant animals
- Limit o 0.1% of diet
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