Dogs and cats, like many other species, require choline.
It's the "Intel inside" kind of molecule that allows others to
function to their full potential. Almost all commercial
petfoods contain supplemental choline, predominantly from
choline chloride. However, putting choline chloride into the
formula can have profound effects on the way the ingredients
are combined and processed during production due to the
molecule's hygroscopic (water-loving) nature.
Studies with dogs in the 1930s first led researchers to
identify choline as a necessary nutrient. Since that time it
has been recognized as a:
The choline oxidation product betaine also acts as an
osmolyte in the kidney. In its absence, choline deficiency can
result and cause weight loss, vomiting, fatty liver and even
death in dogs and cats.
While often grouped with theB-vitamins, choline is actually
a closer fit, structurally and functionally, with the amino
acids and fatty acids. Its similarity to B-vitamins is
associated with the way it moves through the body.
Specifically, choline is soluble in polar solvents like water
and alcohol, has no bodily storage depots and is metabolized
and excreted in proportion to the amount consumed. Thus, it
must be replenished daily. Because of this constant efflux and
the fact that dogs and cats are unable to produce adequate
quantities themselves, dietary sources are required.
Meeting the needs naturally
Much of the required choline can be found in common petfood
ingredients. Choline occurs naturally in plant and animal
tissues. In ingredients, free choline is found only in small
amounts with the greatest proportions appearing as the
phospholipids phosphatidylcholine (lecithin),
phosphatidylethanolamine and sphingomyelin.
The richest natural source of choline in the ingredient
market is the emulsifier lecithin, which contains approximately
2 to 3.5% choline; most is derived from soybeans. Eggs
(especially the yolk), liver, fish, meats, rendered protein
meals, soybeans, soybean meal, peas and wheat germ are rich
sources with levels ranging from 1,500 to as high as 3,000
mg/kg. Grains, fruits, vegetables, fats and oils contain only
marginal levels of choline with concentrations of 500 to 1,000
Considering that the requirements for dogs and cats on a
bioavailability adjusted, 4,000-kcal diet basis are 1,700 and
2,550 mg/kg, respectively, there can be a gap in the amount
provided by the diet and that needed by the animal. There are
provisions for methionine as a methyl group substitute for
choline in feline diets (3.75 parts methionine for one choline
when methionine exceeds 0.62%). Betaine (hydrochloride or
anhydrous) can also be used to replace supplemental
However, the more common approach for petfood manufacturers
is to make up the shortfall and provide some insurance to cover
the variability of the base diet ingredients by supplementing
with synthetic choline sources. Several choices are allowed in
feed and petfood, such as choline chloride, choline bitartrate,
choline pantothenate and choline xanthate. The most common in
petfood is choline chloride; it's found in almost every petfood
product labeled as complete and balanced. Its popularity is due
to a combination of cost, choline content and availability.
The problem child
The pencil and paper exercise of putting choline chloride in
a petfood formula is pretty straightforward, but using it in
production can be a real headache. Choline is chemically
synthesized from trimethylamine and ethylene chlorohydrin or
ethylene oxide. In free form,
2-hydroxy-N,N,N-trimethylethanaminium (also known as
2-hydroxyethyl trimethylammonium) is a very hygroscopic organic
base (alkaline). The chloride salt popular in the livestock and
petfood market is more hygroscopic than the bitartrate salt
used more commonly in the human foods and supplements
Because of its hygroscopic nature and solubility in water,
an aqueous solution (approximately 75% choline) causes the
least number of plant sanitation issues. However, it requires
capital investment in liquid holding tanks and plumbing.
Further, because the application rate is relatively small, with
supplemental levels at 0.05 to 0.25% of the diet, sophisticated
systems are required for uniform dispersion and mixing. Not
every petfood company is willing or able to take such
An alternative is choline chloride enrobed onto a dry
carriermost commonly ground corn cobs. The resulting powder can
be handled in bulk or in bags and is more consistent in form
and handling to other dry ingredients. However, using corn cobs
as a carrier dilutes the amount of choline delivered per pound
to levels of 50% and 60%.
The cost-benefit to the liquid form is often enough to
justify the capital improvement, with a payback in one to three
years, especially when the cost of plant cleanup is taken into
account. The choline powder is very hygroscopic. It pulls
moisture from the surrounding air and quickly becomes a sticky
mess that clings to equipment and personnel and creates zones
of cross-contamination. Its challenge is compounded in
facilities lacking humidity controls.
A logical approach is to use the vitamin premix to carry
choline into the formula. However, because of its affinity for
moisture, choline chloride is also the culprit in vitamin
losses in premixes. As it draws water into a vitamin premix,
the increase in water activity creates an environment more
conducive to oxidation.
For this reason, vitamin suppliers vehemently discourage
customers from including choline chloride as part of their
premix because of the reduced vitamin retention during storage.
Most affected are vitamins A, K3 (menadione sodium bisulfite
complex), thiamine mononitrate and niacinamide. Inclusion can
result in spotting and discoloration in the premix. This can
extend into product appearance, especially for wet foods.
However, once in the product, choline chloride itself is very
stable through extrusion, drying and enrobing.
Addressing the issue
There are options for meeting the choline needs in dog and
cat formulas but no quick and inexpensive ways around the use
of choline chloride. Regardless of form used, there will be
complications and cost due to its hygroscopic nature. The most
prudent management approach is to fortify to meet choline needs
with the route that causes the least pain and overall cost.
What is this quiet, unassuming ingredient, and should it be there?
It's the finishing touch that can meet both owner and pet needs.
The question is whether they provide additional benefit to the dog or cat
To be effective, probiotics must be live and viable
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