cows in field

Supplementation of Organic Dairy Cows; Getting Started

By Jerry Brunetti, Managing Director of Agri-Dynamics
Added December 5, 2011

Grass based dairies often struggle with the question of what to supplement their cattle with. How does one know what dairy cattle on grass really need? Am I buying too much? Not enough? Is it "balanced?" What about the "missing factors", etc?

This article will attempt to provide some foundational information for dairy grazers. First, nutrition begins in your soils. It's a lot more costly to supplement your cattle with the elements that are missing from your soil. Second, the amount of plant diversity you have immensely effects the variety and amounts of minerals, vitamins and plant secondary metabolites (PSM's) that are in the diet. PSM's are those medicinal phytochemicals that regulate inflammation, the immune system, the hormonal system, digestion, lactation and reproduction. Keep in mind there are tens of thousands of these molecular medicines in nature and they are profoundly important in livestock health, production and longevity.

Grazing a mineral-rich, biodiverse paddock in my opinion means you have (mostly) "arrived." No need for expensive TMR's, depreciating equipment and sophisticated computerized nutritionists that incessantly have to "balance" the ration for the "average" cow in the herd. (Who is the "average" cow?)

Mineral Premixes

To cut to the chase: If you're feeding some grain, I would supplement a small amount (2 oz/hd/day) of a 1.5:1 complete premix in the feed. In other words, a mineral premix that contains a ratio of 1.5 parts of Calcium to 1 part Phosphorus. (For example, the Grazier's Essentials premix we make contains 13% calcium and 8% phosphorus, along with the remaining spectrum of macro and micro elements, vitamins, enzymes and probiotics).
Then I would supply free-choice, a 2:1 and a 1:2 Calcium: Phosphorous premix that can allow those animals needing more calcium or more phosphorus to select one of those two as needed. (That's because again, there are no "average" cows.) You may find that these animals may either a) "engorge" in one or the other temporarily; or b) completely ignore one, or both premixes for weeks, even months, until something changes, like weather, gestation or lactation status, an illness or injury, the seasonal changes in pasture quality and so on. It's important to remember that livestock on diversified, mineral-rich pastures don't consume a lot of minerals, thus it's not a costly expenditure. And if suddenly they do consume a bunch of these supplements, they no doubt have a metabolic requirement for it.

There are other supplements that are also very cost effective to put out in the paddock free choice, which provide their own contributions to the overall health and performance for these animals and I'll discuss a few of them.

Edible Clay

If you have livestock, you probably witnessed a phenomenon known as "geophagia" or the eating of the earth. It's not only common with farm animals, but also in wild animals, from groundhogs to elephants, and it's a customary practice worldwide with humans as well. There's been a lot of research as to why animals and people travel to these "mineral licks" often at times of great peril, to consume a suite of minerals, especially at particular times of the year.

We've been excavating and selling edible clay called "Dyna-Min" since 1984 and it was prior to then, being fed to livestock as far back as 1947. What we have observed in beef cattle, dairy cows, sheep, goats and pigs is that these animals have a particular craving for this "earth" when certain metabolic challenges arise. With dairy cows, it appears to be craved when the new spring pastures are growing, probably to slow down the production of rumen ammonia that comes from the very soluble protein (NPN) in the young forages. Also, the cation balance of Ca:K is often overly tilted in favor of the potassium (K), causing animals to crave an available calcium source. Rations rich with carbohydrates (from cereals) can create lactic acid acidosis and the clay will be devoured as a buffer to neutralize these acids. Grain or silages contaminated with mold or mold poisons (mycotoxins) will invite livestock to consume clay, often in large quantities, as the clay absorbs these toxins (as well as other toxins). Clay is also a source of available minerals. It is this property along with its ability to scavenge and bind rumen ammonia and toxins that contributes to cattle having healthy feet and legs. Livestock that are ill, mineral deficient or digestively comprised may also consume clay. It's not unusual to determine who isn't feeling the best, when at milking time the dairyman notices certain animals have a tan dusted muzzle covered in clay. The typical feeding rate is 4 oz per head/day (force fed), but provide free choice too.

Apple Cider Vinegar

80% of the energy needs of a ruminant should come from the production of volatile fatty acids (VFA's) and acetic, proprionic and butyric are the three primary VFA's. For dairy animals, 50-60% of these VFA's need to be acetic acid (aka vinegar).

VFA's depend upon the digestion of soluble fibers such as cellulose, hemi-cellulose, pectins and glucans as well as mono and polysaccharides. Acetic acid is the precursor that drives growth hormone, which in turn drives butter fat and milk production. (That's the reason why rBGH, or somatotropin, is injected into cows to increase milk production.) Apple cider vinegar is a wonderful rumen tonic and can actually buffer an acidic rumen affected by lactic acidosis because it contains only 10% of the molar acidity that lactate from starch contains. Raw apple cider vinegar contains "the mother"- fermentation metabolites which are stimulatory to the microflora in the G.I. Tract. It's also a wonderful source of electrolytes and since it is a VFA, it can really fortify the ration with energy. Drought stricken pastures and hay convert much of their digestible fiber into indigestible lignin, dropping the potential of that forage to produce milk and butterfat. The typical feeding rate of apple cider vinegar is 3-4 oz per head per day.


This ocean plant is actually an algae that grows in large "kelp forests" by attaching to rocks by a holdfasts using a kelp glue. There are 1000 species of kelp living in cool seas worldwide and it's the fastest growing plant in the sea, growing an amazing 60 cm (24 inches) per day. The most popular agriculture kelps are Bull Kelp (Nereocystis luetkeana/ Durvillaea antarctica), Ecklonia radiata and Ascophyllum nodosum. Kelp has a long history of use in agriculture and for good reasons: it's a treasure trove of minerals due to its growing in a mineral broth of seawater; it's got a generous suite of vitamins and amino acids; it's rich in polysaccharides or long-chain sugars; plus, it's a great source of alginates, which are potent detoxifiers, including heavy metals. Kelp is a wonderful nutrient-dense supplement that provides many of the missing biological factors that our terrestrial plants are deficient in. Thus, it's no surprise that kelp often performs as the "cure all" supplement for issues like reproduction, pink eye, high SCC, etc. Typically, 2-4 oz/head/day is a feeding target. Others free choice it with 50/50 salt or 1/3 salt, 1/3 clay, 1/3 kelp.

Black Strap Molasses

Although many dairymen, both conventional and organic, feed molasses, they may not be aware of all the reasons why it's a good supplement. Most ruminant livestock owners feed it because it's a great source of soluble energy to balance out the rumen microbes' calorie requirements that are consuming soluble proteins in the forages. Black strap molasses is also a great source of highly available minerals, like iron, chromium, copper, and zinc etc. That's because molasses is extracted from sugarcane, which is a mineral hungry grass. It's a wonderful biostimulant for both soil and rumen microbes and is especially a "turnkey" energy supplement, to prime the rumen microbial factory in animals subjected to climatic conditions that have really compromised energy production in the pasture or hay forages because of very wet or very hot/dry weather. Typically, a maximum of 5% of the DMI is the "ceiling" and most stockmen will feed 1-2 lbs per head per day. In cases of elevated MUN levels that are affecting health or performance, feeding upwards to 5-7 lbs/head/day can often reconcile the emergency.

Loose Salt

Last, but not lease is loose salt. Any time free choice supplements are provided loose salt is an absolute must. Livestock need sodium and chloride to provide the raw materials for hydrochloric acid (HCl) and sodium for buffer and the sodium-potassium pump to balance cellular metabolism. Typically, adult cattle will consume about 3 oz per head per day.
One should take advantage of the lessons your livestock can provide via free choice behavior. Writing down what animals consume monthly will teach you a great deal about your farm. Keeping written records of what is consumed alongside soil and forage reports, average production levels, health issues, the weather and so forth can be an immensely important tool to "connect all the dots." Not only will you understand the biological systems that are interwoven but you'll also generate educated guesses that can predict and therefore assist you in your planning to create a farm with more resilience.

Jerry Brunetti is managing director of AgriDynamics, which specializes in products for farm livestock and pets, and consults on a wide variety of other issues. He can be reached at Agri-Dynamics, P.O. Box 267, Martins Creek, Pennsylvania 18063, Phone 877-393-4484, email:, website: