The Complexities of Choline Chloride in Animal Nutrition!

Choline is an essential nutrient for animals. Historically animals were able to obtain enough choline from their diets, however this is no longer the case. Modern production systems, focused on maximum production, have pushed the requirement for choline well above what can be supplied by the basal diet. Therefore, supplementation of choline is commonplace in many diets to address this shift in animal requirements. Typically, choline can be supplemented through the inclusion of choline chloride in the diet. While this strategy does provide active choline to the animal, it is not without its risks and considerations that need to be kept in mind.

A vital function in animal diets

Choline plays a critical role in various physiological processes such as fat metabolism, neurotransmitter synthesis, and cell membrane structure. It’s particularly important for:

  • Liver Health: Choline is a key component of phospholipids. They are essential for the structural integrity of cell membranes, aiding in the transport and metabolism of lipids in the liver. It prevents the accumulation of fat and supporting overall liver function.
  • Neurotransmitter Synthesis: Choline is a precursor for acetylcholine which is a neurotransmitter involved in muscle control, memory, and other cognitive functions. Adequate choline levels are necessary for normal nervous system function.
  • Cell Membrane Integrity: As part of its function in phospholipids, it also helps to maintain the integrity and fluidity of cell membranes, which is essential for cellular function and signaling.
  • Methyl Group Donor: Choline is a source of methyl groups in the body, contributing to various methylation reactions involved in DNA synthesis, gene regulation, and protein function.

Inadequate choline intake can lead to health problems such as fatty liver syndrome, reduced growth rates, reproductive disorders, and neurological abnormalities in animals. Therefore, it’s important to ensure that diets are sufficiently supplemented with choline to meet the physiological demands of highly productive farm animals.

Understanding Choline: Sources and Considerations

Choline can be provided in animal diets through various sources, including:

  • Choline Chloride: This is the most common form of supplemental choline used in animal feeds due to its high choline concentration and cost-effectiveness.
  • Choline Bitartrate: A less concentrated substitute for choline chloride.
  • Natural Ingredients: Certain feed ingredients such as soybean meal, fish meal, and distillers’ dried grains with soluble (DDGS) contain choline in lower concentrations.

Choline Chloride is most commonly used in animal nutrition; however, the use of choline chloride has associated considerations that must be made before using this source to supplement choline in the diet.

1. Compatibility

Choline is typically included at premix level in the feed. Supplying choline in this manner is the most practical for the commercial farmer due to its low inclusion rate per ton of final feed (typically 500 – 1000 grams Choline Chloride per ton of feed). This inclusion in a pack has been shown to increase the oxidation of vitamins in a premix significantly. Tavčar-Kalcher (2007) showed the oxidation of vitamin A, E, and K3 with and without Choline Chloride in the premixture. The premixes were stored for 12 months and final active values of the vitamins were measured. This creates a concern when including Choline Chloride with vitamins in a premix.

2. Hygroscopic

Choline is very hygroscopic and absorbs significant amounts of moisture from the surrounding environment, which affects the stability of vitamins included in the premix. Additional to the risk for vitamin stability, moisture in a premix will change the physical characteristics by forming clumps in the mix, further influencing the distribution of vitamins and minerals through a final feed mixture.

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3. Residues

Choline chloride is produced through chemical processes by reaction of hydrochloric acid with trimethylamine (TMA) and concentrated by Ethylene Oxide. Generally, the risk of any undesirable residues being left unreacted in the process is low. However, any failure of quality control may lead to TMA residues exceeding the maximum allowable level. TMA at undesirable concentrations causes a fishy odor in pork that can lead to rejections of the carcass.

What now?

Modern production systems require maximum efficient production in order to remain profitable. Choline requirements of animals are higher in modern breeds than historically required, due to the diets inability to completely meet their needs without supplementation.

Using the Ross 308 requirements of between 1400 and 1700 mg Choline / kg and normal basal diet, the following can be seen. Firstly, intrinsic choline supplied by the basal diet is between 1000 – 1200 ppm representing 80 – 90% of the choline requirement of Ross 308. This leaves a requirement of 225 to 450 ppm of choline going unsatisfied, relating to the diet being unable to meet the requirements for choline and requiring supplementation of choline.

The use of choline chloride to supplement the diet has become ubiquitous through animal feed industry. While this is a suitable supplementation option, newer and better alternatives have come about. These alternatives will help to reduce the oxidation of vitamins and the attraction of moisture, leading to premixes with better stability and reduced hygroscopicity – giving free flowing powders. The time to consider these alternatives is now!

Rhys Sims
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