1.9 ANFs - T2 Flashcards
What do anti-nutritional factors interfere with?
The digestion, absorption, and utilization (metabolism) of dietary nutrients
Are mycotoxins regarded as ANF?
Generally not; they have a toxic effect rather than interfering with nutrition
What are the 4 depressive effects of ANFs?
- Protein digestion and utilization
- trypsin/chymotrypsin inhibitors
- lectins
- tannins - Carbohydrate digestion
- Mineral digestion and utilization (phytase)
- Inactivate vitamins or increase vitamin requirement (anti-vitamins)
What is the stimulative effect of ANFs?
Stimulate immune system (antigenic proteins)
What ingredients are trypsin and chymotrypsin inhibitors found in? What do they do?
Legume seeds, especially soybean
- this is why we don’t feed whole soybeans
Bind irreversibly to the protease
- unable to cleave peptide bonds
- decrease protein digestion and utilization
What are the physiological responses to trypsin and chymotrypsin inhibitors (protease inhibitors) in pigs and poultry?
Protein digestibility decreases
- body recognizes there is undigested protein going farther down the digestive tract
Where are trypsin and chymotrypsin produced?
Pancreas
- as ANFs increase, pancreas has to work harder to produce more
How are protease inhibitors related to protein status?
Harder to digest protein = harder to absorb AA
How are protease inhibitors related to pancreas hypertrophy?
Stimulation of the pancreas to produce more trypsin and chymotrypsin
- can lead to hypertrophy bc it is having to work harder and harder to produce
What are two types of protease inhibitors? How can they destroyed?
- Kuntz
- Bowman-Birk
Can be destroyed using heat (ie heat labile)
How do pigs respond to increasing levels of protease inhibitors? How does this affect total N flow and Endo N flow?
- Respond by consuming more feed
- Total N flow increases (due to increased feed intake)
- Endo N flow increases bc of increase in trypsin and chymotrypsin production
What are lectins also called? Why? What do they bind?
Hemagglutinins; bc they will cause RBC to clump together
Bind specific sugars and oligosaccharides
- on animal cell membranes
- in intestine; bind villi which reduces SA of gut wall
What are 5 effects of lectins?
- Damage of gut wall
- Immunological reactions
- Impaired absorption of nutrients
- Increased synthesis of mucosal protein (endogenous losses)
- Metabolic toxicity
How can lectins be destroyed?
Heat
- heat labile
What feed ingredients are lectins found in?
- Common beans - highly toxic
- Field pea and faba bean - less toxic
In comparison to protease inhibitors, how do lectins relate to DM intake?
- Not as dramatic effect of DM increase
- Overall N flow increases; in part bc of increased feed intake
- Large increase in Endo N flow; due to increase production of mucus (has AA)
What kind of compounds are tannins? What are the 2 categories?
Polyphenolic compounds (aka not proteins)
1. Hydrolyzable
2. Condensed (non-hydrolysable)
What 3 feed ingredients are tannins found in?
- Sorghum
- Cottonseed meal
- Faba bean
What do tannins do?
- Form complex with enzymes or feed proteins
- Reduce protein digestibility
- Bitter taste
What is phytate?
A complex compound that binds P, other minerals, and starch
- P digestibility is low in plant products
- Also other nutrients; minerals, AA, CHOs
What is the major problem that phytate causes?
Phosphorus excretion
1. P intake (available and phytate P) = 100%
2. 30% can be used by the pig/chicken
3. 20% excreted via urine, 50% excreted via feces
4. urine + feces = slurry
- collected and spread on the land
5. Leads to eutrophication = proliferation of algae:
- killing other vegetation
- deoxygenating water
- algal toxins
What 3 characteristics lead non-starch polysaccharides as being considered as ANF?
- Digestibility
- Passage rate
- Viscosity (soluble NSO)
What is a positive, functional property of NSPs?
Hindgut fermentation
- beneficial bacteria = decreased levels of potential pathogens
What are 4 other ANFs?
- Glucosinolates
- cause palatability problems
- impact on thyroid is poorly understood - Sinapine
- rapeseed meal
- no effect on nutrient digestion ; some metabolic effects - Vicine/convicine
- Saponins
- steroid bound to CHO- alfalfa, soy, canola, peas
- bitter, reduced growth performance
- form complexes with sterols
What are a major ANF in canola co-products?
Glucosinolates
- Sulphur-containing secondary plant metabolites
- Present in vegetative and reproductive tissues of plants; serve as defense compounds
- Degraded by myrosinase
- Bitter taste = reduce voluntary feed intake
- Interference with synthesis of thyroid hormones involved in regulation of various metabolic processes = may affect metabolism and growth
Is fibre an ANF?
Yes and no! Depends on your definition. Historically, considered the most common ANF but this is shifting.
YES
- reduces nutrient intake
- increases rate of passage
- physical barrier to nutrients
NO
- physical form encourages gut motility
- fibre fermentation by microbes produces beneficial byproducts
- positive effect on gut microflora
What are mycotoxins?
Toxic compounds produced by fungi
- can be anti-nutritional and/or toxic
- can colonize/grow in the field
- can colonize in the field then grow in storage/transport
- can be difficult to detoxify; often heat stable
- can affect animal physiology
- can also contaminate animal products: meat, milk, eggs
When are mycotoxins generally more of a problem?
In wet years/climates
- Specific mycotoxins need particular growing conditions: hot, cool, cool/warm cycle
What do molds use mycotoxins to do?
Molds use mycotoxins to claim ownership of a resource
- “hey you crappy birds, get off of my lawn”
Almost all field crops (esp. cereal grains) are contaminated to one extent or another with mycotoxins. When does this become a problem?
When specific mycotoxins are present above a particular level
