The Horse

JAN 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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Page 38 of 51 | The Horse January 2019 39 development manager for Equi-Analytical Labs, a subsidiary of Dairy One, in Ithaca, New York. Taking a representa- tive hay sample is fairly easy. "To pull a sample, we recommend using a hay probe (a long, hollow metal cylinder with a sharp tip that you can either drive or twist by hand or with an electric drill into a bale of hay)," she says. "We have them available to order or you can contact your local extension office or feed mill." Use the hay probe to core sample at least 12 to 20 square bales from various sections of your supply to get the best representative sample. With round bales, take three to five core samples from each. Combine all samples into one, mix them thoroughly in a resealable plastic bag, and submit them to a lab for nutrient analysis. Don't have access to a hay probe? Buy- ing hay in small batches? In some instanc- es, pulling a core sample doesn't make much sense. Resources such as the Dairy One Forage Lab keep a large database of hay analyses you can use to estimate nutrient content in these situations. "If you know precisely the type of hay, you can look at the average values in our interactive feed library," says Fessenden. Use the same feed library to look at nutri- ents in pasture grasses and grains, too. As for grains and concentrates, you can secure a list of the nutrients in single grains (corn, oats, barley, etc.) from several sources, including the NRC or Dairy One's interactive feed library ( analytical-services/feed-and- forage/feed- composition-library). But what about that commercially mixed ration balancer for an easy keeper? Or the high-fat fortified pellet fed to a barrel racer? For bagged commercial concentrates you can find nutrient values in the guar- anteed analysis printed on the bag or tag. In the U.S. most analyses list protein, fat, fiber, calcium, phosphorus, copper, sele- nium, zinc, and vitamin A values for their products as either minimum or maximum amounts. Individual states regulate how nutrients are listed on the guaranteed analysis. Depending on where you live, the labels probably won't supply all the information needed to balance a diet. "I always call the manufacturer for more detailed information, because what is on the tag is in some cases the bare minimum," says Clair Thunes, PhD, inde- pendent equine nutritionist with Summit Equine Nutrition LLC, in Gilbert, Arizona. She says some companies share the inde- pendent analysis they've had completed on the feed in question, while others just give expected levels based on formulation. Another option is to have the feed analyzed yourself, but this can be timely, expensive, and less accurate. "The data you get back from such a sample is not going to be as representative as a sample that includes feed taken from multiple bags in a batch," says Thunes. But if you want to go this route, labora- tories like Equi-Analytical can test grains, mineral mixes, and finished feeds. The supplements you mix into your horse's grain every day might not seem like much. But you'd be surprised how a small amount of a few supplements could tip the balance of micronutrients such as selenium. Therefore, it's important to properly capture the nutrients being delivered in all supplements. As with con- centrates, the label's guaranteed analysis provides some information, but for the most accurate nutrient values, contact the supplement manufacturer. STEP 3 Weights and Measures It's been drilled into our heads to feed horses by weight, not by volume—scoops or coffee cans. And there's a practical reason: Nutrient levels included in a hay analysis report or feed tag are listed as a concentration, such as percentage or grams per pound. So, without knowing the exact amount being fed in pounds (or kilograms) per day, it's impossible to calculate these nutrients. Feeding a large round bale or free- choice hay? Grazing pasture? We can't eas- ily measure our horses' free-choice forage intake, but science can help us guess in- take levels (see Table 1). Many factors play a role in these estimates; number of horses on pasture, season, drought, or overgraz- ing can negatively affect pasture intake. Certain grass species, such as Kentucky bluegrass and orchardgrass, can posi- tively impact intake (Hayes et al., 2011). Equid type and class affect intake, too. For example, lactating broodmares grazing pasture consume well above average— around 2.8% of their body weight per day vs. 2% (Marlow et al., 1983). Ponies graz- ing pasture can consume almost 50% of their total daily dry matter in about three hours (Ince et al., 2011). Have a horse that naps in his hay? Feeding outside in a muddy pasture? Not all feed, especially hay, gets eaten on a daily basis. For complete ration evalua- tion accuracy, weigh and subtract from the total amount fed any feed refusals (what's left in the feed bucket) or wasted feed (like soiled hay in a stall). STEP 4 Doing the Math With your nutrient information and quantities in hand, it's time to do the math. Simply calculate the amount of each nutrient being provided in each feed. Some calculations will be simple, such as for digestible energy. Here's an example: Calories (per lb) Amount (per day) Total Calories (per day) 1,000 Calories MULTIPLY BY 15 Pounds 15,000 Calories Nutrients such as selenium require more steps. The selenium amount on the feed tag reads 0.3 ppm (parts per million) or milligrams per kilogram of feed. If your horse eats 5 pounds of that feed a day, how much selenium is the feed providing? First, convert pounds to kilograms (there's about 2.2 pounds in 1 kilogram): Amount (per day) Pounds (per kg) Amount (per day) 5 Pounds DIVIDED BY 2.2 2.27 Kilograms Next, multiply this amount by the sele- nium concentration: Selenium Amount Total Selenium (per day) 0.3 mg/kg MULTIPLY BY 2.27 Kilograms 0.68 Milligrams Each feedstuff contributes different nu- trient amounts based on the amount fed, so it's important to capture those values correctly. Here's an example with calories: Feedstuff Amount (per day) Calories (per lb) Total Calories (per day) Hay (in stall half of the day) 10 lb 1,000 Calories 10,000 Calories Pasture (out half of the day) 12 lb 900 Calories 10,800 Calories Concentrate (ration balancer) 2 lb 1,200 Calories 2,400 Calories TOTAL 23,200 Calories STEP 5 Waving the White Flag Is all this math making your head spin? An online search can lead you to ration-

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