SOURCE ® “Original” and Pelleted “Original” Micronutrients

More than three decades ago SOURCE president and founder, Susan Domizi was competing on her

Got a hard keeper or aging horse who needs three-decades-proven micronutrient support?

Reviewed by Ann Pruitt, InfoHorse.com · Updated April 2026

SOURCE ® “Original” and Pelleted “Original” Micronutrients - Image 2 on InfoHorse.com

SOURCE ® “Original” and Pelleted “Original” Micronutrients
With Source...Hard keepers gain weight, older animals seem to reclaim their lost youth, and many health and breeding problems disappear!

What Makes Our Company Different?

More than three decades ago SOURCE president and founder, Susan Domizi was competing on her eventing horse, Hull, with hopes of being on the US Equestrian Olympic Team. "My horse [Hull] had hoof problems and couldn't maintain his body weight. He received the finest feeding program and veterinary care available. I suspected a nutrient deficiency and set out to find something to help him." She found a great deal of Norwegian and Japanese research on seaweeds that scientists and agriculturists here had been able to duplicate. In addition to using information learned while earning a degree from Columbia University in New York, she studied all available data to determine what the American studies had missed. She used this information as a starting point for developing other approaches..

By trying different kinds of seaweeds, different blends, different methods of processing and constantly analyzing the findings she came up with a finely ground, dry mixture that she put in her horse's food. Her horse began to thrive. And that was the first serving of the product that was later to become SOURCE.

SOURCE ® “Original” and Pelleted “Original” Micronutrients for Horses Is...

NOT a Feed  
NOT a Protein Supplement
NOT a Vitamin Supplement
NOT a major Mineral Supplement

Many thousands of horsemen have provided adequate levels of all of the above in a sound nutritional program, yet still been baffled by horses who express signs of subclinical and clinical disorders to which they can attribute no known nutritional or disease origin. These would include the many problems associated with hoof growth, weight, coat, stamina, conception, attitude and general "bloom".

Increasing the amounts of the above does not result in improvement and indeed may compound the problems.

Thousands of these same horsemen have added SOURCE, the broad spectrum micronutrient supplement, to their horse's diets and experienced dramatic improvement.

"Original" SOURCE Formula
Source contains an extremely broad spectrum of at least 60 elements and their associated micronutrient compounds in a biologically active form. SOURCE contains small amounts of naturally occurring vitamins (14), the 14 currently recognized "essential trace elements", the 21 trace elements now under special consideration with respect to essentiality, plus other unidentified associative factors whose role in nutrition has not yet been established.

SOURCE "Nuggets"
Source Nuggetsconsists of a daily serving of the original SOURCE micronutrients (the concentrated powder) plus all-natural ingredients added to protect our micronutrients during the pelletizing process. They taste so good that you can mix them with feed as usual, or they can even be hand fed. This is especially convenient if you are feeding only pelleted feed, or where the horse is on pasture, or on a restricted diet where he is receiving little or no concentrate feed. Source Nuggets contain the same nutrient power as the original Source, but in a convenient pellet form.

Feeding Instructions

Provide good quality hay and grain, with protein and carbohydrate levels appropriate for the age and demands of the horse; a balanced calcium / phosphorus ratio, an effective parasite control program, fresh water at all times, free access to salt, a good dental care program and feed one heaping measure of SOURCE Original per 1,000 lbs. of body weight (1/2 oz. daily) - use the measuring scoop included in the container. Feed Source Original everyday, including race and competition days for all classes and ages of horses. Average 15.2 hh horse = 1,000 lbs.

The SOURCE Guarantee

We want every person to have the opportunity to see for themselves the effectiveness of the Source micronutrients found in all of our products. If you are not satisfied with any of the products for any reason, your money will be refunded in full - no strings attached. (Simply enclose proof of purchase.)

What Horse Owners Say About SOURCE?

Says America's Most Trusted Horseman John Lyons…
" Susan, Thank you for Source. Our horses have better coats, improved weights, and better hoof walls. Wherever I travel, horsemen share their stories with me about how Source has helped their own horses. Thank you for helping bring quality products at reasonable prices to horses everywhere."
-John and Jody Lyons & all of our horses"

Says Ann Pruitt- Director at InfoHorse.com

"My husband's horse Dream started to Pant in the heat and really struggle in the heat-- even when we had him in his stall with high powered fans. In desperation, I learned that the Thyroid can cause horses to loose the ability to sweat and that Seaweed can Help restore a healthy thyroid. In total desperation, I tried SOURCE and in 4 days he was Sweating-- after 6 months of NO sweating! He shed out his thick coat, he quit panting, his coat when from a dull yellow to a Brilliant "Gold"-- this product is a Miracle and I'll never be without it"

Order SOURCE Today!

Source actually Does what it says it will do! SOURCE products are widely available at your local feed and tack stores, through online catalogs or web stores, or directly from SOURCE-- just visit our Shop area at 4Source.com for a complete listing.

<br/> -<strong>John and Jody Lyons</strong> & all of our horses

More than three decades ago SOURCE president and founder, Susan Domizi was competing on her

Open container of SOURCE Original powdered seaweed micronutrient supplement for horses

What exactly is SOURCE Micronutrients?

SOURCE is a broad-spectrum micronutrient supplement, not just a "hoof product" or a "coat product." A single half-ounce daily measure delivers approximately 60 elements and their associated compounds in a biologically active form — including 14 naturally occurring vitamins, 14 essential trace elements, and 21 trace elements still under study for essentiality. Because these micronutrients are involved in virtually every physiological process, owners report wide-ranging gains in hoof growth, weight, coat, stamina, conception, and attitude. The company's tagline says it best: "Essentials to thrive."

30 lb sealed container of SOURCE Original micronutrient supplement

Who makes SOURCE and how did it begin?

SOURCE was introduced in 1975 by founder and president Susan Domizi, after a seaweed-based blend transformed her own eventing horse, Hull. SOURCE micronutrients LLC operates from North Branford, Connecticut, with its seaweed processing plant in Brunswick, Maine. The company is a founding member of the NASC (National Animal Supplement Council) and carries the NASC Quality Seal — and Domizi has personally taken the product for more than three decades.

SOURCE Original product label showing guaranteed analysis and seaweed ingredients

What's actually in the bag?

The label answer is refreshingly short: "Our proprietary blend of Pure Dehydrated Seaweed Meals...and nothing else!" There are no artificial colors, flavors, preservatives, synthetics, or drugs. Marine plants carry a far broader spectrum of micronutrients than land-based plants, and the exact species and formula remain closely guarded proprietary information developed and refined over more than 35 years specifically for horses.

Open container of SOURCE Nuggets pelleted micronutrient supplement for horses

How the seaweed is harvested and processed

SOURCE's harvesting grounds are in cold, northern North Atlantic waters, where seaweed is hand-cut at species-specific points in its growth cycle, bundled into thousand-pound loads, and delivered to the Maine plant — never dumped in bulk, which would cause heating and composting. From ocean to finished meal takes under 24 hours: bundles hang in overhead racks under strict dehydration controls to minimize nutrient loss, then are ground to a fine meal and packaged. Every component is independently lab-tested for pesticide and heavy-metal residue plus microbiological safety, exceeding human-food standards.

Powder or pellet — Original versus Nuggets

SOURCE Original is the concentrated powder: feed one heaping 1/2-oz measure per 1,000 lbs of body weight daily, and a 5 lb container lasts roughly five months. It is offered in 5 lb and 30 lb sizes, priced $41.53 – $204.58. SOURCE Nuggets is the pelleted form — a daily serving of the same micronutrients plus all-natural ingredients added to protect them through pelletizing — ideal for horses on pasture, on restricted diets, or fed only pelleted concentrates. Feed one level 1.5-oz measure per 1,000 lbs daily; Nuggets come in 3.5 lb and 25 lb sizes, priced $24.45 – $133.65.

Who it's for and how to order

SOURCE costs only pennies a day per animal and suits hard keepers, older horses, sun-burning light-faced horses, and even insulin-resistant horses (it contains no molasses or rapidly metabolized carbohydrates). It should be mixed into one daily feeding rather than offered free-choice, since seaweed's salty taste can lead to overconsumption. To order or ask questions, call, 9 AM–5 PM ET Monday–Friday, or visit www.4source.com.

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The Solution Section (FAQ)

How did SOURCE® micronutrients come about?

SOURCE® president and founder Susan Domizi developed the product more than three decades ago after her eventing horse, Hull, had hoof problems and couldn't maintain his body weight despite the finest feeding program and veterinary care. Drawing on Norwegian and Japanese seaweed research and her Columbia University background, she developed a finely ground, dry mixture that became SOURCE.

What exactly is SOURCE — is it a feed, a vitamin, or a mineral supplement?

SOURCE is a micronutrient supplement, not a feed, protein supplement, vitamin supplement, or major mineral supplement. The product is intended to fill a different gap: many horsemen provide adequate feed, protein, vitamins, and minerals yet still see horses with subclinical or clinical disorders that suggest a missing micronutrient piece.

What does SOURCE add to a horse's diet that other supplements may not?

SOURCE is built on a finely ground, dry seaweed-based mixture, drawing from research developed in Norway and Japan and adapted by the founder using both that research and her own data analysis. The formulation targets micronutrients — trace elements that horses may lack even when their main feeding program looks complete.

Is SOURCE available in more than one form?

Yes. SOURCE is offered in two formulations: SOURCE Original (the finely ground, dry mixture) and SOURCE Pelleted Original, both of which are described as Original Micronutrients for Horses.

Who is behind SOURCE® today?

The company traces back to founder Susan Domizi, an eventing competitor whose own horse's nutritional puzzle led to the original product. Her research grounding — Columbia University degree work plus international seaweed-research literature — remains the technical foundation of the SOURCE product line.

What is SOURCE Original and what makes it different from a vitamin-mineral supplement?

SOURCE Original is a broad-spectrum micronutrient supplement made entirely from pure dehydrated North Atlantic seaweed meals — and nothing else. Rather than supplying a few isolated synthetic vitamins or minerals, a single half-ounce serving delivers roughly 60 naturally occurring elements and compounds in a biologically active form. The company stresses it is a micronutrient supplement, not merely a 'hoof product' or 'coat product,' because micronutrients are involved in virtually every physiological process.

Who founded SOURCE and when?

SOURCE was introduced in 1975 by Susan Domizi, who is still the company's president and founder. She developed it after a seaweed-based blend dramatically improved the condition of her own eventing horse, Hull, when she was competing with hopes of reaching the US equestrian team. SOURCE micronutrients LLC is based in North Branford, Connecticut, with a processing plant in Brunswick, Maine.

What are the ingredients in SOURCE Original?

The ingredient statement is simply 'our proprietary blend of Pure Dehydrated Seaweed Meals...and nothing else.' It contains no artificial colors, flavors, preservatives, synthetics, or drugs. The exact seaweed species and the formula are closely guarded proprietary information developed over more than 35 years specifically for horses.

How many nutrients does SOURCE actually contain?

A daily half-ounce serving carries approximately 60 elements and their associated micronutrient compounds. That includes 14 naturally occurring vitamins, 14 essential trace elements, and 21 additional trace elements that are still under study for essentiality. Because marine plants concentrate a far wider spectrum of micronutrients than land plants, seaweed delivers many nutritive factors a typical grain-and-hay ration misses.

How much SOURCE Original do I feed?

Feed one heaping measure — about 1/2 oz daily — per 1,000 lbs of body weight, using the included measuring scoop. Mix it into one daily feeding rather than offering it free-choice. A 5 lb container provides roughly a five-month supply, which works out to only pennies a day per animal.

What is SOURCE Nuggets and how does it differ from the powder?

SOURCE Nuggets is the pelleted version of the same micronutrient blend. The original powder couldn't be pelletized without degrading its bioactive ingredients, so SOURCE developed a process using all-natural ingredients added to protect the micronutrients during pelletizing. Nuggets are especially convenient for horses on pasture, on restricted diets, or fed only pelleted concentrates, since they can be mixed in or hand-fed.

How much SOURCE Nuggets do I feed?

Feed one level measure — about 1.5 oz daily — per 1,000 lbs of body weight, every day including competition days, using the included scoop. The larger serving size by weight reflects the protective natural ingredients added during pelletizing. Nuggets are sold in 3.5 lb and 25 lb sizes.

What do SOURCE products cost?

SOURCE Original (powder) is priced $41.53 – $204.58 across its 5 lb and 30 lb sizes. SOURCE Nuggets (pelleted) ranges $24.45 – $133.65 across 3.5 lb and 25 lb sizes. Because the daily serving is so small, the company describes the cost as only pennies a day per animal.

How long before I see results?

SOURCE advises patience, since problems developed over time and improvements are rarely overnight. One of the earliest signs is reduced undigested matter in the manure within days or weeks. Hoof changes typically become visible by the second or third farrier trimming, and a complete hoof replacement takes close to a year.

Where and how is the seaweed harvested?

SOURCE harvests in cold, northern North Atlantic waters, cutting each species at a specific point in its growth cycle. The seaweed is bundled into thousand-pound loads and delivered to the SOURCE plant in Maine — never dumped in bulk, which would cause heating and composting. From ocean to finished meal takes under 24 hours, with the bundles hung in overhead racks under strict dehydration controls to preserve nutrients.

Is SOURCE safe and how is quality assured?

Every component undergoes independent laboratory testing that exceeds human-food standards, including pesticide and herbicide residue analysis, heavy-metal analysis, and microbiological testing for yeasts, molds, salmonella, and staphylococcus aureus. SOURCE is a founding member of the NASC (National Animal Supplement Council) and carries the NASC Quality Seal. Founder Susan Domizi has personally consumed the product for more than 30 years.

Can insulin-resistant or metabolic horses use SOURCE?

Yes — SOURCE recommends it without hesitation for insulin-resistant horses. The products contain no molasses or rapidly metabolized carbohydrates. Research suggests certain seaweed compounds may inhibit alpha-glucosidase and alpha-amylase, which could be beneficial for horses with metabolic concerns.

Can I feed SOURCE free-choice?

No. The company specifically warns against free-choice feeding of seaweed products. Individual taste preferences can lead some horses to overconsume — taking in excess iodine — while others reject it entirely, and the product can absorb moisture and develop mold if left out. Always mix the measured amount into a daily feeding.

Does SOURCE contain too much iodine or selenium?

A daily half-ounce serving of SOURCE provides about 9 mg of iodine, a safe and controlled level, with zero reported iodine-toxicity cases over the life of the proprietary blend. Selenium is present as naturally occurring organic selenium at very low levels — about 0.025 mg per serving — which is below a therapeutic dose, so SOURCE is not meant to correct severe selenium deficiency but helps the body use dietary selenium more effectively.

Will SOURCE upset my horse's calcium-phosphorus balance?

No. SOURCE contains only minimal naturally occurring calcium (about 213 mg) and phosphorus (about 23 mg) per serving, against daily requirements measured in the tens of thousands of milligrams. Because no calcium or phosphorus is added, it contributes negligibly and will not alter the calcium-phosphorus ratio of your existing feeding program.

Can I feed SOURCE to animals other than horses?

Yes. The original SOURCE powder is used across many species, with the company suggesting roughly 1/4 teaspoon per 25 lbs for dogs, 1/8 to 1/4 teaspoon for cats, 1 to 3 tablespoons for cows, 1 to 2 teaspoons for sheep and goats, and about 1% of the ration for birds. The same broad-spectrum seaweed micronutrients support general health across species.

How do I order SOURCE or get advice on which product to use?

You can order directly and ask questions by calling SOURCE at 800-232-2365, Monday through Friday from 9 AM to 5 PM ET, or by visiting www.4source.com. The company can help you decide between SOURCE Original powder and SOURCE Nuggets pellets based on how your horse is fed and managed.