Organic acids properties associated with their Carboxyl group –COOH groupextensively used for decades in feed preservation, protecting feed from microbial as well as fungal destruction. Thus, it may increase the preservation effect of fermented feed. Withdrawal of antibiotics from poultry feeds has generated the need for alternatives that would affect improvement of healthy production traits of broiler chickens and safety for human consuming poultry products. Organic acids such as formic and propionic acids are particularly effective for this purpose and have been used extensively from past 25 years in swine production mostly for feed preservation.

In General, Organic acids are any carboxylic acid including fatty acid& amino acid. Organic acids categorized as weak acid & do not separate completely in water. The formic acid in breeder diet reduces the contamination of tray liners as well some hatchery waste with S. enteritidis. The diet supplemented with lactic acid was found to increase the body weight. The blend of acids is preferred to individual acid in obtaining the desired antimicrobial effect and acidification of diets with weak organic acids such as formic, fumaric, propionic, lactic and sorbic have been reported to improve digestibility of protein, Ca, P, Mg, Zn and served as substrate in the intermediary metabolism. The blend of formic and propionic acids found to be effective in preventing intestinal colonization with Salmonella spp. from naturally or artificially contaminated feed. Relative studies of organic acids showed that the inhibiting effect of the acids was more evident in stomach contents than in content from the small intestine, probably due to the lower pH in the stomach content.

Organic acids play important role as a feed supplement in poultry has a valuable effect on the overall performance of the broiler as well as layer birds. The individual effect of organic acid variable and depends upon several factors. Likewise, different pathogenic bacteria respond variably to various similar organic acids. Organic acids have direct effect on different GIT parameters that may improve the nutrient absorption and digestibility. Effect of bactericidal organic acids is in the following order:

Benzoic acid (C6H5COOH)>fumaric acid (HO2CCH=CHCO2H)> lactic acid (C3H6O3)> butyric acid (C4H8O2)> formic acid (CH2O2)> propionic acid (C3H6O2).

Feed Acidifiers showed acidic nature comprised in feeds in order to lower the isoelectric point (pI) of the feed, gut, and microbial cytoplasm thereby inhibiting the growth of pathogenic intestinal microflora. Thus, inhibition reduces the micro flora competitively inhibition for the host nutrients and results in better growth performance of the chicken. They also act as mold inhibitors. Organic acids ions showed antimicrobial effect influence bacterial population is in the upper intestinal tract leads to beneficial effects.

Mode of action of Organic acids

Acidifiers with short chain fatty acids, acetate, propionate and butyrate have contributed expressively to the profitability in poultry and provide people with health and nutritious poultry products.

Un-dissociated form of acid RCOOH could penetrate the bacterial cell wall. Once in the bacterial cell, the higher pH of cytoplasm cause dissociation of the acids, and the resulting reduction in pH due to the release of H+ disrupt the enzymatic reactions &nutrient transport system. This influence destruction of the cytoplasm, as well growth of the bacteria is inhibited. Organic acid ions have capability to attacks on bacteria genome results in its death.

Though there are certain challenges like palatability of the feed, corrosion of the equipment, buffering capacity of dietary ingredients, bacterial resistance due to long term exposure etc. which are manageable with certain preventive measures, the acidifiers are being used due to the larger benefits envisaged. Some of the advantages are listed below

Advantages of feed acidifiers

• Role in maintaining an optimum pH in stomach, allowing correct activation and function of proteolytic enzymes.
• Aids in total protein digestion in the stomach
• Stimulates feed consumption.
• Inhibits the growth of pathogenic bacteria.
• Improvement of protein and energy digestibility by reducing microbial competition with host nutrients and endogenous nitrogen losses.
• Depresses the frequency of sub clinical infections and secretions of immune mediators.
• Reduces the production of ammonia and other growth depressing microbial metabolites.
• Increased pancreatic secretion and trophic effects on gastrointestinal mucosa.

Feed Acidifiers feeding in poultry

 

Table: Organic acids impacts in Poultry

 

Sr. No.	Acids	Impacts
1.	Fumaric acid	Improvement in weight gain of broilers. Improved feed efficiency in both broilers and layers.
2.	Propionic acid	Increase in dressing percentage in female broilers & reduction in abdominal fat for males.
3.	Malic acid	Increase in body weight gain.
4.	Sorbic acid	Improves feed efficiency ratio.
5.	Tartaric acid	Increase in weight gain.
6.	Lactic acid	Feed to gain ratio and Body weight gain is improved.
7.	Formic acid	Reduction of caecal pI and bactericidal effect on Salmonella.
8.	Benzoic acid	Positive influence on growth.
9.	Butyric acid	Maintain the beneficial micro flora. Increase the Proliferation and maturation of intestinal cells.