14, 15, 16 Flashcards
1
Q
Antinutritional factors (AFNs, antinutrients)
- Def
A
interfere with the utilisation of dietary nutrients in a variety of ways, including reducing protein digestibility, binding to various nutrients or damaging the gut wall and thereby reducing digestive efficiency.
2
Q
Antimetabolite
- def.
A
Antimetabolite similar in structure to the metabolite, so interfere with their formation or utilization, thus inhibiting essential metabolic routes.
- Antivitamines
3
Q
ANFs
- function in plants
A
- protection against microorganisms, herbivores and insects
- protection against autolysis during storage
- prevention of the stored nutrition (sprouting)
4
Q
ANFs
- harmful effects depends on:
A
- state of the crop at harvest
- plant parts used for animal feeding
- quantity entering the body
- animal species and age
5
Q
AFNs
- Classification based on their effects:
A
- depressive effect on PROTEIN digestion and utilisation (trypsin and chymotrypsin inhibitors, lectins or haemagglutinins, polyphenolic compounds, saponins)
- negative effect on the digestion of CARBOHYDRATES (amylase inhibitors, polyphenolic compounds)
- negative effect on the digestion and utilisation of MINERALS (glucosinolates, oxalic acid, phytic acid, gossypol)
- inactivate VITAMINS or cause an increase in the animal’s vitamin requirements (anti-vitamins ).
- stimulate the IMMUNE SYSTEM (antigenic proteins).
6
Q
Protease inhibitors:
A
substances that inhibit the actions of trypsin, pepsin and other proteases in the gut
- Trypsin and chymotrypsin inhibitors
- Source:
- Colostrum: glycopeptides (cow: Kunitz type)
- legume seeds, soybean
- Other feed constituents such as tannins, can inhibit trypsin activity
7
Q
Trypsin and chymotrypsin inhibitors:
A
- Trypsin and chymotrypsin inhibitors:
- peptides that form stable inactive complexes with some of the pancreatic enzymes - activities of trypsin and chymotrypsin are reduced
- Trypsin inhibitors:
- lysin protease inhibitor (Bowman-Birk trypsin inhibitor)
- serin protease inhibitor (Kunitz group)
- aspartate protease inhibitor
8
Q
Protease inhibitors:
- effect
A
Effects:
- growth depression
- pancreatic hypersecretion
- negative feedback
- hypertrophy, hyperplasia, neoplasia
- deterioration of S-containing AS digestion
- endogenous N loss increases
Heat treatment:
- trypsin inhibitor activity (TIA); trypsin inhibitor units (TIU/mg)
- measured by urease activity (destruction of urease is highly correlated with the destruction of trypsin inhibitors)
- PDI: protein dispersibility index (heat has been shown to lower the PDI)
9
Q
Antinutrients:
A
- Lipase inhibitors
- Amylase inhibitors
10
Q
Lipase inhibitors:
A
is a antinutrient
Lipase inhibitors interfere with enzymes, such as pancreatic lipase, that catalyze the hydrolysis of some lipids, including fats.
- eg. the anti-obesity drugs cause a percentage of fat to pass through the digestive tract undigested
11
Q
Amylase inhibitors
A
is a atinutrient
Amylase inhibitors interfere with enzymes that break the glycoside bonds of starches and other complex carbohydrates, preventing the release of simple sugars and absorption by the body
- eg. diet aid and obesity treatment
- present in many types of beans
12
Q
Lectins (haemagglutinins)
A
- glycoproteins (precipitate trypsin-treated red blood cells)
- characterised by an ability to bind to specific sugars
- binding of lectins to intestinal epithelial cells
- decreased glucose absorption and cell renewal –> growth depression and increased risk of pathogen bacterial colonisation
- prerequisite for the antinutritional properties: resistance to proteolysis – act as antigenes
- source:
- leguminous seeds: lectins in common beans are highly toxic, while lectins in peas and faba beans appear to be the least toxic
- bean – fasin: toxic when raw fed
- soybean lectin: pigs, chicken – decreased growth
- castor bean – ricin: toxic
- different animals may respond to the same lectins in different ways
13
Q
Classification of Glycosides
A
1) Saponins
2) Phenolic Glycosides
3) Glycoside or Cyanogenic Glycoside
4) Mustard Oil Glycoside or Glucosinolates
14
Q
Saponins:
A
- steroid or triterpenoid glycosides
- binding protein and decrease surface tension:
- soap-like foaming they produce when shaken in aqueous solutions
- foamy bloat in ruminants???
- bitter taste
- reduce the palatability
- form complexes with sterols, in particular those in membranes of animal cells
- result in increased permeability of the intestinal mucosa - depress growth performance
- Source:
- significant saponin levels are present in alfalfa, white clover
- saponins found in oats and spinach increase and accelerate the body’s ability to absorb calcium and silicon, thus assisting in digestion
15
Q
Tannins
A
- flavonoids, polyphenolic compounds
- many has antioxidant capacity
- bitter or astringent taste
- reduced absorption of some minerals (Ca, Mg, P)
- form complexes with proteins and carbohydrates in the feeds, and with digestive enzymes - denaturation of proteins – nutrient digestibility is depressed
- ruminants:
- –> increase bypass protein ratio
- –> toxic amount: hemorrhagic gastroenteritis, necrosis of the liver, kidney damage with proximal tubular necrosis
- toxicity to monogastrics: under 5%
- –> depressed growth rates, low protein utilization, damage to the mucosal lining of the digestive tract, alteration in the excretion of certain cations, and increased excretion of proteins and essential amino acids
- Source: shorgum, rapeseed, horsebean
16
Q
Gossypol
A
- polyphenolic compounds
- reduced availability of amino acids, and lysine in particular, in cottonseed meal
- monogastric toxicity: gossypol can cause death if dietary levels exceed 0.015%, respiratory distress, abdominal distension
- ruminant: more resistant, formation of stable complexes with soluble proteins in the rumen by bacterial fermentation, thus preventing absorption (calves not!)
- adverse effects of gossypol can be prevented by providing supplemental iron in the diet
- source: cottonseed
17
Q
Cyanogenic Glycoside
A
- when enzymatically hydrolyzed, release cyanohydric acid (HCN)
- in the intact plant, the enzyme and the cyanogenic glycoside remain separated, but if the plant tissue is damaged both are put in contact and cyanohydric acid is released
- cyanohydric acid is extremely toxic: linking with metals (Fe++, Mn++ and Cu++) that are functional groups of many enzymes, inhibiting processes like the reduction of oxygen in the cytochrome respiratory chain
- Source:
- linseed / flax (linamarin)
- almonds - amygdalin
- Java bean -faseolunasin
- sorghum - durrin
18
Q
Mustard Oil, Glycoside or Glucosinolates
A
- hydrolysis of glucosinolates yields glucose, various goitrogenic compounds and nitriles
- inhibit the uptake of iodine by the thyroid gland for the production of triiodothyronine (T3) and thyroxine (T4) leading to lower plasma levels
- cruciferous seeds and plants: rapeseeds
- use of rapeseed or rapeseed meal in diets for young animals should be avoided
- reducing their content in feedstuffs through plant breeding:
- rapeseed cultivars low in erucic acid and glucosinolate content = double-low cultivars = a direct competitor to soybean meal
19
Q
Phytic acid
A
- principal storage form of phosphorus in many plant tissues, especially bran and seeds
- strong binding affinity to minerals such as calcium, magnesium, iron, copper, and zinc - results in precipitation, making the minerals unavailable for absorption in the intestines
- nonruminant animals: lack the digestive enzyme phytase, so phosphorus and inositol in phytate form is not bioavailable
- ruminants: digest phytate because of the phytase produced by rumen microorganisms
- source: hulls of nuts, seeds and grains
20
Q
Oxalic acid and oxalates
A
- oxalates bind to calcium and prevent its absorption
- secondary hyperparathyroidism is a dietary calcium:phosphorus imbalance
- an equine diet with a 1% oxalate content reduces calcium absorption by 66% and increases faecal calcium excretion
- other species: urolithiasis
- source:
- certain grasses contain a high content of oxalates: „oxalate pastures”
- sugar beet
21
Q
Antinutrients:
- Alkaloids contain:
A
Alkaloids contain nitrogen, generally basic:
- Solanin
- Lupin alkaloids
- Lathyrism
- Colchicin
- Hioscyamine, scopolamine
