This document discusses organic acids in poultry nutrition. It defines organic acids as carboxylic acids containing a carboxyl group that is the source of a donatable hydrogen ion. Organic acids are classified based on carbon chain length as short chain (C1-C6), medium chain (C7-C10), or long chain (C11+). Short chain fatty acids have antimicrobial properties and are the most commonly used in poultry. Organic acids reduce gut pH and disrupt bacterial cell membranes and DNA, inhibiting microbial growth. Their effectiveness depends on concentration in the gastrointestinal tract, with more impact higher in the gut where dissociation is lower. Common organic acids used in poultry include formic,

1. Organic Acids in Poultry Nutrition
More Than Acidifiers

2. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action
– Site of action
– Spectrum
– Using of organic acids in poultry nutrition

3. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

4. When We Can Say:
It is an Acid Produce H+ (as H3O+) ions in water (the hydronium ion is
a hydrogen ion attached to a water molecule)
 Taste sour
 Corrode metals
 React with bases to form a salt and water
 Turns blue litmus paper to red “Blue to Red”

5. 1. Acid dissociation in solution is:
• Complete
• Not reversible
2. Lower pKa value
1. Acid dissociation in solution is:
• Not complete
• May be reversible
2. Higher pKa value
Strong acid Weak acid

6. Dissociated form
50%
Non-dissociated form
50%
If we say that;
pKa for acetic acid = 4.76
It means that;
at pH 4.76
When pH < 4.76, acetic acid ” will accept a proton
(+H) and become “XH”
When pH > 4.76, acetic acid will give up a proton and
exist as “X-”

7. pH and Butyric Acid Dissociation
0.00000%
10.00000%
20.00000%
30.00000%
40.00000%
50.00000%
60.00000%
70.00000%
80.00000%
90.00000%
100.00000%
1.8 2.8 3.8 4.8 5.8 6.8 7.8 8.8
pH and Butyric Acid Dissociation
Undisso Disso2

8. pH and Formic Acid Dissociation
0.00000%
10.00000%
20.00000%
30.00000%
40.00000%
50.00000%
60.00000%
70.00000%
80.00000%
90.00000%
100.00000%
1.8 2.8 3.8 4.8 5.8 6.8 7.8 8.8
pH and Formic Acid Dissociation
Undisso Disso2

9. Organic – Inorganic Acid Combination
› Phosphoric acids lowering the pH which makes the undissociated form organic acid
is more dominant
› When acids will react with other components, the strongest acid in a mix is always
the first one to react.
› So phosphoric acid reacts always before organic acids in the mix, preserving their
efficiency Organic acids can have a more bactericide effect

10. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

11. Organic Acid Definition
› Organic Acid is an organic compound with Acidic
properties associated with their Carboxyl group –COOH
› Organic acids are carboxylic acids with the general formula
of R-COOH, Where;
1. "R" group representing a fatty acid chain of variable
length
2. "COOH" group representing the carboxyl group that
is the source of the donatable H+.

12. Sources of SCFA
1. SCFA are widely distributed in nature as normal constituents of plants or animal
tissues.
2. SCFA are formed through microbial fermentation of carbohydrates mainly in the
large intestine.
3. SCFA are sometimes found as their sodium, potassium or calcium salts.

13. Classification of Organic Acids
› Organic acids may be classified according to side chain length into;
1. Short chain fatty acids (SCFAs) (≤C6)
› Also called volatile short-chain fatty acids (VSCFA).
2. Medium-chain fatty acids (MCFA) (C7 - C10)
3. Long-chain fatty acids (LCFA) (≥C11)

14. Only
Short Chain Fatty Acids
Have antimicrobial activity against gut microflora
3 – 5
Is the pka value for most organic acids
with antimicrobial activity
The antibacterial effect is mainly due to
the un dissociated form
of the carboxylic acid

15. Short Chain Fatty Acids
Lipid number
Name Formula Mass
(g/mol)Common Molecular Structural
C1:0 Formic acid CH2O2 HCOOH 46.03
C2:0 Acetic acid C2H4O2 CH3COOH 60.05
C3:0 Propionic acid C3H6O2 CH3CH2COOH 74.08
C4:0 Butyric acid C4H8O2 CH3(CH2)2COOH 88.11
C4:0 Isobutyric acid C4H8O2 (CH3)2CHCOOH 88.11
C5:0 Valeric acid C5H10O2 CH3(CH2)3COOH 102.13
C5:0 Isovaleric acid C5H10O2 (CH3)2CHCH2COOH 102.13

16. Acetic acid
C2
Butyric acid
C4
Formic acid
C1
Isobutyric acid
C4
Isovaleric acid
C5
Propionic acid
C3
Valeric acid
C5
Cont. …

17. Medium Chain Fatty Acid
Lipid number
Name Formula
Mass
(g/mol)
Common Molecular Structural
C6:0 Caproic acid C6H12O2 CH3(CH2)4COOH 116.16
C8:0 Caprylic acid C8H16O2 CH3(CH2)6COOH 144.21
C10:0 Capric acid C10H20O2 CH3(CH2)8COOH 172.26
C12:0 Lauric acid C12H24O2 CH3(CH2)10COOH 200.32

18. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

20. Organic Acids
&
Bacterial Cell Wall
They are short chain fatty acids
such as;
1. Butyric
2. Formic
3. Acetic
4. Propionic
5. Sorbic

21. • Dissociated acid molecules (which cannot
penetrate the cell membrane) cause
damage to the protein structure of the
membrane.
• This alters the permeability of the
membrane for minerals, such as sodium
and potassium.
• The resulting change in the osmotic
pressure of the cell leads to cell death.

22. • The COO- group of the organic acid react
with bacterial DNA and inhibit the activity of
specific enzyme systems, such as those required for
the multiplication of the genetic material DNA.
• As a result, the microorganisms can no longer
propagate.

23. • Dissociated acid molecules (which can
penetrate the cell membrane and release
H+) decrease the pH value in the interior of
the cell
• To get rid of H+, the microorganism induce
energy-consuming compensation
mechanisms, depleting bacterial cell energy
• This weakens the microorganisms

24. Organic Acids
&
Intestinal pH
They are:
Short chain fatty acids such as;
1. Butyric
2. Formic
3. Acetic
4. Propionic
5. Sorbic
Carboxylic acids such as;
1. Lactic
2. Fumaric
3. Citric

25. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

27. • Contains large bacterial community which breaks down indigestible plant material.
• They empty every 24-48 hours and are refilled with contents from the colon
• Lining cells secret HCl
• Low pH environment
• Site of mechanical Grinding of feed
• Low pH environment
• Sets rate of passage through GIT
• Hard pellets or large size require more grinding time which
slows the passage rate
• Fine textured mash or poor quality pellets require less
grinding time which accelerates the passage rate
• Digesta from gizzard is mixed with the bile salts and
digestive enzymes in the small intestine
• Major site of chemical digestion and nutrient
absorption
• High surface area due to villi and microvilli
• Little absorption and digestion occurs
• After leaving the colon, the fecal pellets
passes into the coloaca where it is mixed
with uric acid and expelled via the vent

28. 4.5-5.3
45 Min.
2.0-4.5
70 Min. 5-8 Min.
5.6-7.9
160-200
Min.
5.8-6.8
120 Min.
6.3-7.7
30-50
Min.
pH - Resident Time of Feed - Microbial Population
in GIT of Chicken

29. 5.5-8.5
6-7
Clostridium perfringens
6.8-7.2
Salmonella spp
Optimum pH For Growth of GIT Microorganisms
6.0-8.0
Escherichia coli
6.8-7.2
Camplylobacter jejuni

30. Butyric acid 4.82
Lactic acid 3.83
Sorbic acid 4.76
Formic acid 3.75
Acetic acid 4.76
Propionic acid 4.88
Citric acid 3.13
Fumaric acid 3.02
pKa of Organic Acids Commonly Used as
Dietary Acidifiers
Malic acid 3.40
Tartaric acid 2.93

31. The addition of organic acids to broiler diets results in
pH reduction of digesta in various parts of the GIT.

32. The degree of pH reduction was usually greater in the
upper part of GIT (crop, proventriculus, and gizzard)
as compared to the lower part of the GIT (duodenum,
jejunum, ileum, and cecum).

33. Organic acids effect on bacteria is related to their
concentration
in different compartments of the GIT

34. Most organic acids will
dissociate
before reaching the lower GIT and thus having
little to no effect
on the GIT

35. Optimum pH for growth
Clostridium
perfringens
5.5 - 8.5
(optimum 6-7)

36. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

37. Spectrum of Organic Acids
Acid Effective Less Effective Not Effective
Formic acid Yeasts& Bacteria - (E. coli & Salmonella)
LA-bacteria&
Molds
Acetic acid Many species of bacteria Yeasts & Molds
Propionic acid Molds Bacteria Yeasts
Butyric acid Bacteria (E. coli & Salmonella)
Lactic acid Bacteria Yeasts & Molds
Citric acid Bacteria
Malic acid Some bacteria & Yeasts
Sorbic acid Yeasts, Molds & some Bacteria

38. Cont. …
Acid Yeast Fungi G-ve bacteria G+ve bacteria
Staphlo/Streptoc
occus
Formic acid +++ 0 ++++ 0 0
Acetic acid + - +++ 0 0
Propionic acid ++ ++++ 0 0 0
Sorbic acid ++++ +++ +++++ 0 0
Benzoic acid +++ +++ +++++ 0 0
Lactic acid - - ++ 0 0
Caprylic - Caprinic acid ++ ++ +++ +++++ ++++
Lauric acid GML90 +++ ++ ++ +++++ ++++++

39. Cont. …
Acid G-ve pH lowering Taste Corrosivity
Formic acid +++ +++ -- ---
Acetic acid +++ ++ ++ --
Propionic acid ++++ + -+ -
Lactic acid ++ ++++ ++ +
Fumaric acid -- ++ -+ -+
Sorbic acid +++++
Benzoic acid +++++

40. › Introduction about organic acids
– When we say it is an acid?
– Definition and classification of organic acids
– Mechanism of action of organic acids
– Site of action
– Spectrum
– Using acids in poultry nutrition

41. Free acids
Free acids
15
%
Coated acids
Free acidsLipid coat
85%
Tributerin
Free acidsLipid coat

42. Acids Are Used in 3 Ways in Poultry
1. Added to the poultry feed in a solid form
– This fights mold development in the feed and reduces the pH in the birds’ crops.
2. Sprayed onto the poultry litter.
– This attacks the bacteria that facilitate the breakdown of uric acid, limiting the amount of
ammonia releases.
3. Injected into the water to kill bacteria, facilitate chlorine in killing bacteria and
lowering the pH in the birds’ crops.
– The effect on gram-negative bacteria is increased if the organic acid is not dissociated.
– Because of this mode of action acidifier need to contain organic acids which are undissociated
at different pH-values, so that the anti microbial action is prolonged over a wider pH range.

43. Factors Influencing Efficiency of Dietary Organic Acid
Supplementation
1. pKa value of the organic acid
2. Chemical form (acid, salt, coated or not)
3. Molecular weight
4. MIC value of the acid
5. Kind of micro-organism
6. Animal species
7. Site and location in the gastro-intestinal tract
8. Buffering capacity of the feed

44. Limitations of Using Organic Acids in Poultry Nutrition
1. Palatability may be decreased, leading to feed refusal.
2. Organic acids are corrosive to metallic poultry equipment.
3. Bacteria are known to develop acid resistance when exposed to acidic
environments for over long term.
4. Presence of other antimicrobial compounds can reduce its efficiency.
5. Cleanliness of the production environment.
6. Buffering capacity of dietary ingredients.

45. Contact us on;
ossama.motawae@eurekaeg.com
+201023985680