Choline in animal nutrition: Its role, sources and new approaches
by Carlos Lopez, Liptosa, Spain
Although the first references to choline date from back in the nineteenth century, choline's role in animal nutrition was not well known until 1930s. In 1850, Theodore Gobley already discovered lecithin, which was followed by the discovery of choline in 1862, when Mr Adolph Strecker heated lecithin from bile, which produced a new nitrogenous chemical.
Since then, several researches have established choline to be an essential nutrient, which has four main functions (Zeissel 2006, Garrow 2007, Rajalekshmy 2010):
- As a required constituent of phospholipids, choline is essential for building and maintaining cell structures, as well as to ensure the normal maturation of the cartilage matrix of the bone and prevent perosis in broilers
- Choline plays an essential role in regulating fat metabolism in the liver, preventing abnormal accumulation of fat within hepatocytes (fatty liver) by increasing the utilisation of fatty acids in the liver
- Choline is a precursor of acetyl choline synthesis, which makes possible the transmission of nerve impulses
- Choline furnishes labile methyl groups for formation of methionine from homocysteine and of creatine from guanidoacetic acid.
Also, since choline contains biologically active methyl groups, methionine can serve as a partial alternative to choline.
Although, in contrast with most vitamins, choline can be synthetised by most species, this synthesis is often insufficient to satisfy the animal´s needs, making choline an essential component of the diet.
Choline is present in several feed ingredients traditionally used for feed formulation – 7374 mg/ kg DM rapeseed meal oil; 2899-3182 mg/kg DM soybean meal oil; 1743 mg/kg DM wheat meal; 1162 mg/kg DM barley; 617 mg/kg DM maize (INRA-CIRAD-AFZ tables), but little is known about its bioavailability and differences are expected based in crop growth conditions, treatment, season of the year etc.
Therefore, to overcome the variation in raw material concentration and the uncertainty of bioavailability, an adequate choline supplementation is required, supplying both the essential and non-essential needs of different animal species.
The most common choline source is choline chloride (CC), produced by chemical synthesis, by reaction of methanol and ammonia, which gives rise to trimethylamine (TMA) and subsequent reaction of this with ethylene oxide gives choline. CC is obtained by reacting choline with HCl.
Commercially, CC is available in both, liquid and powder form, with differences regarding choline chloride content and equivalent choline activity studied extensively.
However, despite being widely used, chemical choline chloride has some disadvantages:
- Corrosivity: Liquid choline chloride is very corrosive, requiring special storage, transport and handling procedures. Additionally, choline chloride is highly destructive to vitamins, decreasing its stability in the premixes containing it (Coelho et al. reported Vitamin K retention in six months period was 57 percent lower in a vitamin premix containing CC than in a premix without it, and 50 percent, 40 percent and 37 percent lower retention for Vitamin C, B1 and A respectively)
- Higroscopicity: Chemical choline chloride is highly hygroscopic, attracting moisture to preparations containing it, which makes uniform mixing difficult, leading into fluidity problems in the final product
- TMA content: Trimethylamine content should be less than 200-300mg/Kg. Even if within the permitted levels, up to two-thirds of the choline can be transformed into TMA during the digestion process, limiting the CC inclusion rate
- Inclusion rate: Only approximately one-third of the choline is absorbed, requiring a higher inclusion rate in the diet.
Considering the problems faced by feed/premix manufacturers due to the above-mentioned disadvantages, new choline sources have emerged in the market as an alternative to the chemical choline chloride.
Liptosa, a company specialising in the manufacturing of phytobiotics and nutraceutical solutions have launched recently Natur Colin, a product that serves as an effective replacement to chemical choline chloride, overcoming its technological disadvantages, and, at the same time, providing a more competitive choline source and a positive effect for zootechnical parameters.
Natur Colin is a powdered nutraceutical product based on a selected combination of botanicals and plant extracts as a source of phosphatidyl choline, phospholipids, methyl group donors and other phytogenic compounds which are intimately related with the choline functions.
The different active components of Natur Colin work in synergy in order to completely fulfil the choline functions, representing an alternative choline vegetal source, which pays special attention to the activity over the fat metabolism.
The use of a vegetal choline source will allow not only an improvement in the zootechnical performance of the animals but also counteracts the disadvantages of chemical CC:
- Unlike CC, Natur Colin is not corrosive and it is not destructive towards vitamins present in the feed/premixes, allowing to extend its shelf life and its direct inclusion in vitamin premixes (Tavcar-Kalcher and Vengu reported that the concentration of vitamins in premixes containing CC and stored for 12 months could be up to 88 percent lower than premixes without CC)
- Furthermore, Natur Colin solves the hygroscopicity problem related to the use of CC, for markets facing high temperatures and humidity
- As mentioned before, just one-third of the choline in CC is absorbed, while the other two-thirds are transformed into TMA, which limits its inclusion rate. Natur Colin shows a much higher safety margin, with no limits in its dosages
- Natur Colin, at a low inclusion rate, replaces 100 percent CC, leaving more available space in the feed formula for other ingredients. Various studies have shown that 100gr Natur Colin effectively replace 156gr pure choline (300gr CC 60 percent) with the guarantee to reach at least the same production performance.
- Higher inclusion rates of Natur Colin (+20%) are also recommended in those cases where we want not just to replace CC, but to also provide extra support to the animals, which will be reflected in improved animal performance, due largely to its activity as regulator of the liver metabolism.
In a study conducted at the Service of Pathological Anatomy from the Complutense University in Madrid, livers from a group of 69-weeks old hens fed with CC (Group A) were compared with livers from the same group of hens fed with Natur Colin for the following 12 weeks-until they reached 80 weeks old.
The histological sections show a diffuse cytoplasm vacuolisation in group A. However, after 12 weeks of taking Natur Colin, the liver histological section shows a liver with a normal aspect, wherein the cellular damage has been reversed. If it were not for Natur Colin, an irreversible liver degeneration would have had a high chance of occuring.
The use of Natur Colin represents an effective and safe alternative to the use of chemical choline chloride, allowing not only a 100 percent replacement which also overcomes technological disadvantages, but at the same time, provides a tool to optimise production performance.