Antinutritional factors

1. Antinutritional factors

2. Antinutritional factors
• Substances which either by themselves or through their metabolic
products, interfere with food utilization
• Affect the health and production of animals

3. Characteristics
• Secondary Products of metabolism
• Found in virtually all plants to some degree.
• Common in tropical forages.

4. Charcteristics
• Bitter
• Colored
• Poisonous
• Odor
• Antinutritive
• Immunosuppresive

5. Common Antinutritional factors
• Protease inhibitors
• Lipase Inhibitors
• Glycosides
• Saponins
• Alkaloids
• Phytic acid
• Tannins

6. Protease Inhibitors
Inhibit the actions of
• Trypsin
• Pepsin
• Other proteases

7. Protease Inhibitors
• In the gut,they prevent the
Digestion of protein
Absorption of protein
• For example
Bowman-Birk trypsin inhibitor is found in soybeans.

8. Lipase Inhibitors
• Interfere with enzymes, such as
Pancreatic lipase, that catalyze the hydrolysis of some lipids,
including fats.
• For example,
Anti-obesity drug orlistat causes a percentage of fat to pass
through the digestive tract undigested.

9. Glycosides
• Generally bitter
• Structure
Contain CHO and non-CHO groups(aglycone)
• Mode of action
Toxicity results from aglycone release during enzymatic degradation
• Sources
Linseed, sorghum, soyabean, clover etc

10. Saponins
• Have distinctive foaming characteristics
• Present in
White clover
Alfalfa
Brachiaria decumbens etc.

11. Effects of Saponins
• Bloat
• Haemolysis
• GIT erosion
• Inhibit enzyme action

12. Alkaloids
• Basic in nature
• Toxic
• For example
Cocaine
Nicotine
Caffeine

13. Effects of alkaloids
It can cause
• Kidney damage
• Pulmonary damage
• Liver damage
• Diarrhea

14. Phytic acid
• It has a strong binding affinity to minerals such as calcium,
magnesium, iron, copper, and zinc.
• It makes the minerals unavailable for absorption in the intestine.
• Phytate has direct anti-nutritional effects for poultry causing
reductions in performance by lowering amino acid and mineral
absorption.

15. Tannins
• Compounds that tan leather
• Polyphenolic compounds that can form stable complexes with:
 Proteins
 Carbohydrates
 Minerals
• Have beneficial/harmful effects

16. Selected Forage Plants with Tannins
• Lotus species
• Sainfoin
• Faba beans
• Peas
• Sorghum
• Calliandra calothyrsus
• Leucaena leucocephala
• Sesbania sesban
• Gliricidia sepium
• Acacia species

18. PAs affect forage utilization by:
• Forming strong H bonds with other nutrients.
• Inhibition of digestive enzymes.
• Inhibition of rumen microbial activity.
• Concentrations >7% usually reduce nutrient utilization.

19. Effect of PAs on forage quality
Positive effects
• Increased efficiency of protein utilization.
• Reduction of parasite burden.
• Reduction of proteolysis.
• Bloat prevention.
• Increase quality of animal products.
• Reduction of N emission into the environment.

20. Effect of PAs on forage quality
Negative effects
• Reduction in digestibility
• Erosion of GIT lining
• Toxicity

21. References
• D’Mello,JPF2000.Farm animal metabolism and nutrition. (Ed.).
• CAB, Wallingford. P319. Chapter 18Caygill, J C and Mueller-Harvey
1999. Secondary plant products. Nottingham University press.
• Cheeke, P R and Shull L R 1998. Natural toxicants in feeds and
poisonous plants. AVI Publ. Co.
• Garland T and Barr, C. 1998. Toxic plants and natural toxicants. CAB
International