Choline chloride

Choline- chemically known as 2-hydroxyethyl-trimethyl ammonium hydroxide andis referred as vitamin B4. It has recently been claimed as a rediscovered vitamin & performance promoter in poultry. The role of choline in the prevention of conditions suchas perosis and liver enlargement in chicks is already well known. Choline wasfirst isolated from ox bile ("chole" in Greek) in 1849. Its nutritional importancehas been recognized since 1930 and it is now a common dietary supplement forlivestock & poultry. The main function of choline is to act as a lipotropic agentand prevents the abnormal fatty infiltration in liver (Fatty Liver Syndrome)thus ensures proper metabolism of the body & effective utilization of the nutrients.Moreover, it helps in the formation of an excitatory neurotransmitter-acetylcholine,which is responsible for proper functioning of the nervous system and maintainsits harmony.

CHEMISTRY OF CHOLINE:

Choline chloride: An Indispensable Performance Promoter in Poultry - Image 1

The structure of choline reveals that it serves as a methyl donor-three methyl groups attached which are provided by Trimethylamine (TMA)-an essential raw material for the production of choline. These methyl groups are then utilized for the biosynthesis of methionine (a sulphur containing & firstlimiting amino acid in poultry). The ethylene oxide (EO) contributes the ethylenepart in the choline structure while the HCl donates the H+ ion attached to oxygenatom.

Why there is a need of exogenous supplementation of choline in Feed?
Since there is no consistency in the choline content in the natural feedstuffsand also their bioavailability is not predictable. However, it may be expectedthat variation in content of choline will occur due to variation in prevailingcrop growth conditions, e. g. climate, cultivar, soil, location, fertilizer and spray regime etc.
Emmert and Baker (1997) have estimated the bioavailability of choline naturally present in soybean, rapeseed and peanut meals at 83, 24 and 76 % respectively, which shows the variation in bioavailability of the native choline in feed ingredients. Rapeseed has a significantly higher choline content than soybean and peanut meals (6198 ppm versus 2218 and 1685 ppm respectively) but the availability is less than a third that of the others.
Their bioavailability ranges from 24-80%. So inorder to meet the physiologicalrequirement of the birds choline has to be additionally in the feed.

Feed Ingredients	Choline Content (mg/kg)
Feedstuffs issue	NRC 1994
Barley, grain	1027	990
Corn, yellow, grain	1100	620
Cotton seed meal 41%	2807	2753
Feather meal, poultry	880	891
Fish meal, AAFCO	3510	3099
Linseed meal flax (expeller)	1672	NA
Oats, grain	1070	946
Peanut meal and hulls (mechanical)	1540	1655
Rapeseed oil meal (solvent)	6700	NA
Rice bran, unextracted	1390	1135
Sorghum	660	668
Soybean meal, expeller	2673	2794
Sunflower meal, solvent	2900	2894
Wheat bran	980	1232
Yeast culture	3711	3984

How choline chloride is produced?

There are three basic raw materials which are required for the production of choline chloride which are as follows:

1-Trimethyl amine (TMA)
2-Ethylene oxide (EO)
3-Hydrochloric acid (HCl)

Choline chloride: An Indispensable Performance Promoter in Poultry - Image 2

Choline chloride: An Indispensable Performance Promoter in Poultry - Image 2

The intermediate product thus produced is treated with ethylene oxide (EO) toneutralize the TMA in the finished product. If it is not neutralized properlythen it would result into a higher level of TMA content in the finished product.Most of the cheaper brands available in the international market have high levelof TMA (Ethylene oxide being the costliest amongst all). The liquid choline thusproduced is then spread over the cereal-based carrier- corncob to make the dryform of choline.

CHOLINE CHLORIDE - DIETARY REQUIREMENTS OF BROILERS

Choline supplementation in broilers shows a linear response in weight gain upto 1115mg/kg from 10-22 days of age. Increasing choline content up to 2000mg/kgfurther increases the weight gain but over and above this value no significantincrease in weight gain was observed. Thus it could be concluded that excesslevel of choline supplementation had no additional benefit.

CHOLINE CHLORIDE - DIETARY REQUIREMENTS OF LAYERS

Layers, like broilers, have an essential requirement for choline. Choline is required for the formation of a phospholipid lecithin, a component of egg yolk. Current NRC recommendations for choline allowances in laying hens are 105 mg/day for white egg layers and 115 mg/day for those laying brown eggs. On an average for the two groups it can be concluded that required dietary concentration of choline at feed intake levels of 100 and 110 g/day respectively, is approximately 1100 mg/kg.
There are several factors which influence a hen's requirement for choline, like age, feed intake and dietary crude protein or methionine levels. It is generally accepted that dietary requirement declines with age, possibly associated with an increasing feed intake. Methionine is the first limiting amino acid for egg production and, given the common function with choline in methyl group donation, interactions between the two nutrients may be anticipated. Choline requirement in layers also varies according to the methionine and cysteine levels in feed. A diet rich in M+C has low requirement of choline and vice-versa.

SALIENT FEATURES OF AN IDEAL CHOLINE CHLORIDE:

Low Trimethylamine (TMA) content
High Bioavailability
Uniform particle size
Free from any toxin/contaminant

High Trimethylamine content causes toxicity in birds:
The most important & limiting raw material, which decides the quality of the product, is Trimethylamine (TMA), which is highly corrosive in nature. If its level exceeds beyond the permissible limit i.e.>200ppm then it causes toxicity in birds. Due to its corrosive action it causes sloughing of the intestinal mucosa & results into malabsorption (reduced nutrient utilization). Moreover the fumes generated by TMA when enter the respiratory tract of the bird leads to discomfort that restricts the birds from feeding & ultimately it results into reduced production and may cause even death. So the TMA content in the choline chloride should be low to prevent toxicity and better production.

High Bioavailability: Bioavailability is the most important parameter, which should be taken into account while selecting an ideal choline chloride. Each carrier particle (corncob) should contain 60% of choline if analysed for its purity.

Uniform Particle Size: Bioavailability is also attributed to the particle size of the carrier material. The ideal particle size for broilers is 0.3mm while for layers it is 0.5mm. The size should match with the feed in order to prevent selective feeding & toensure uniform mixing.

No bacterial/toxin contamination: Since the carrier materialused for the production of dry choline chloride is corncob-agro byproduct, whichis very much liable to be contaminated with various microorganisms. So it shouldbe thoroughly checked for the presence of any bacterial contamination like E.coli & Salmonella,as poultry is highly susceptible for these pathogenic microorganisms, which leads to reduced production and mortality in flock.

Modern & Global Concept of Dioxin & GMO free choline chloride:
Nowadays apart from mycotoxins another toxin, which has come into picture, is ‘dioxin’-an industrial toxin, after April 25- 2006 – when choline chloride samples from leading manufacturer of choline chloride in China was found positive for dioxin above tolerated European Union levels. Due to this many poultry farmers/feed millers suffered from severe losses.
Dioxin is a general term that describes a group of hundreds of chemicals that are highly persistent in the environment and settle on feed & feed additives. The most toxic compound is 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD. The toxicity of other dioxins and chemicals like PCBs that act like dioxinare measured in relation to TCDD.

Dioxin is fat-soluble which bioaccumulates & climbs up the food chain and is mainly (97.5%) found in meat and dairy products (beef, dairy products, milk, chicken, pork, fish and eggs.
These toxins are then passed on in the poultry products like eggs and chicken & enter the human food chain, where they may lead to following disorders

Malfunction of reproductive and endocrine activity
Carcinogenecity
Immunosuppression
Dermal toxicity

Structure of Dioxin

Choline chloride: An Indispensable Performance Promoter in Poultry - Image 3

Benefits of using GMO free corncob as carrier in choline production:

No introduction of foreign gene in the corn which serves as the carrier material for the production of dry choline chloride (cereal based), thus eliminates the chance of Allergic reactions in humans as poultry birds are the most common link in human food chain
No Biopiracy—foreign exploitation of natural resources
Fulfills the international standards for exports to the countries like United States and Japan.

Global specification of choline chloride:

PARAMETER	REQUIREMENT
Description	Yellowish brown coloured & granular powder
Choline Chloride %(w/w)	NLT 60
Moisture (%w/w)	NMT 03
Particle retention on mesh 20 ASTM /18 BSS (%w/w)	NMT 20
Density (Tapped) g/ml	0.4 to 0.6
Trimethylamine Content (ppm)	NMT 200

How to act when using choline chloride?

Always ask for the original certificate of analysis from the producer.
Ask for a guarantee that no other salts like table salts have been added.
Ask for a guarantee that chloride content has 1:1 relationship with choline.
Do choline specific tests like AgNO3 Titration, Reinecke or Ion Chromatography when you question the quality?