Nutritional analysis of pastures


If you’re moving your horse to a different facility, or purchasing a place of your own, you need to make sure his new pasture is going to measure up by completing a nutritional analysis.

Whether you’re switching to a different horse-boarding barn, or buying your own farm, it’s sometimes necessary to move your horse to a new location. One of the many things you need to consider is the quality of your horse’s new pasture. What condition is it in? Is it going to be a good source of nutrition for him? How many months out of the year will you be able to rely on it?

Initial nutritional assessments

If there are already horses on the pasture, you can get some information about the area through observation. Do you see spots that are eaten down to the ground, and others where the grass is tall? This condition is called “greens and roughs”. When management does not involve rotating horses through different parts of the pasture, it is normal for “greens and roughs” to develop; horses will not graze where they pass their manure, and may choose less desirable grazing spots for manure depots. However, if the greens are heavily grazed down, the density of horses per acre is too high to allow for good plant growth, either simply because there are too many horses or because the grasses are not the best choice.

As a rule of thumb, when the stand of plants is healthy it can support one horse per acre during the grazing season. The grazing season depends partially on your location and weather, and partially on the grasses in the field. Clover and cool season grasses like Timothy or ryegrass will thrive in the early spring and fall, while warm seasonal grasses like Bermuda are well suited to summer heat, which can slow the growth of other species.

The possible presence of poisonous plants

Plant poisonings rarely occur when there is a healthy stand of good grasses in a pasture. But there is always the odd horse that develops a taste for something he shouldn’t eat, and severe weather can inhibit good grass growth in any pasture. Spring and fall are particularly dangerous times if you don’t feed enough supplemental hay. Hungry horses will eat things they would normally ignore. Walk your pastures regularly and note any odd plant growth.

Determining deficiencies and imbalances

Once you’re decided that the pasture has the potential to meet your specific needs, it’s a good idea to have a nutritional analysis completed to confirm good energy and protein levels, as well as determine the mineral profile. Mineral deficiencies and imbalances, especially of important trace minerals like iron, copper, zinc, manganese and selenium, are extremely common.

A common profile in grasses is high iron and/or manganese with low zinc and copper (low selenium is also common in many areas). Since certain minerals can compete with each other for absorption, providing more iron and manganese will cancel out copper and zinc.

When you know the issues specific to your pasture, you can choose a product or design a custom supplement program that eliminates what you don’t need and provides the correct levels of what you do need. Locate an independent nutritional consultant to help you with this.

Soil analysis

A soil analysis is valuable if you own the land, or the owner is open to input. By optimizing growing conditions, you can guarantee good protein levels, reduce the risk of harmful nitrates or excessively high sugar content, and even alter the mineral profile. When submitting the sample, be sure to note the grass species in the pasture, and any special goals such as limiting iron and manganese levels.

Analysis results are only as good as the samples

When collecting pasture samples, use stainless steel scissors to cut the grass off at the same height as the horses do, and put the samples in a paper bag. In a case of obvious greens and roughs, sample only the greens. If you have a mixture of growing conditions, such as slopes and low-lying wet or boggy areas, these should be sampled separately. As a general guide, you want to collect about 20 samples per acre. Your agricultural extension office probably has a publication that gives detailed instructions for pasture sampling.

There will be some variation in protein levels, and to a lesser extent mineral levels, depending on the season and the growth stage of the plants. For most situations, however, you will get good results by sampling the pasture around midseason to get a representative average. There may be exceptions depending on the precise species in your pasture — for example, a field with a heavy growth of clover early in the season that switches to a predominantly warm-season grass as temperatures heat up. Discuss this with your extension agent.

There is more to assessing the nutritional analysis of a new pasture than noting how pretty it looks, but information and experienced help is readily available. If you invest the time and take advantage of resources, you can generate a detailed profile of your pasture, then make a plan to supplement your horse and amend the soil for the best possible outcome.

Take advantage of local data

It’s a good idea to get in touch with your local state agricultural extension agent to discuss your new pastures. Their services are free and they will have a wealth of information on topics such as soil types, soil treatments that may be needed, the best grasses to grow for the longest grazing season and how to establish them, as well as poisonous plants local to the area and how to identify them.

Your extension agent will also have general data on the energy/calorie and protein levels in the various grass options, as well as any special considerations. For example, fescue is a hardy and nutritious pasture grass, but should be avoided for broodmares. It commonly has an endophytic fungus that strengthens the grass but can cause problems with foaling and udder development in mares. Bermuda has great heat and drought tolerance but is often very low protein unless the fields are fertilized.

Dr. Eleanor Kellon, staff veterinary specialist for Uckele Health & Nutrition, has been an established authority in the field of equine nutrition for over 30 years, and is a founding member and leader of the Equine Cushing’s and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via the integration of research and real-life clinical experience.  Preventing laminitis is the ultimate goal.