Pasture Adequacy: Are Your Fields Doing Their Job?By Kentucky Equine Research Staff · November 8, 2011
As herbivores, horses require large volumes of forages for optimal well-being. Just how much forage do horses require, though?
To calculate accurately how forage contributes to the overall feeding program of horses, forage intake as well as composition must be known. Hay intake can be determined simply by recording the total weight of hay offered minus any hay wasted or refused. This record does not take into account the differences in composition between hay that is eaten and not eaten, but it is accurate enough to do an adequate field evaluation.
Pasture intake is significantly more difficult to estimate. This measure varies depending on the season, species, and quality of pasture grazed, and the total amount of time horses are allowed to graze. Horses will generally eat about 1-1.4 lb (0.45-0.64 kg) of pasture grasses and legumes per hour on a dry matter basis if they have enough pasture available. With all-day access to good-quality pasture, a horse grazing 17 hours each day can consume up to 25 lb (11 kg) of forage, which is more than enough to satisfy forage requirement.
Distinction should be made between absolute minimum, recommended minimum, typical, and maximal forage intake.
Absolute minimum forage requirement is 1% of body weight (10 lb or 4.5 kg dry forage for a 1000-lb or 450-kg horse).
Recommended minimum forage intake requirement is 1.5% of body weight.
Typical forage intake is 1.8 to 2.2% of body weight.
Maximal forage intake for most horses is 3 to 3.5% of body weight, though lactating mares and other horses with extreme energy needs might consume as much as 5% of body weight daily.
Does My Pasture Offer My Horse Enough to Eat?
Pastures offer horses the most natural of feedstuffs, a variety of plants to derive nutrients. Well-maintained pasture provides the most economical of all feedstuffs, but it must be of sufficient quality to nourish a given horse appropriately. Take a peek into the lives of these five horses and determine if the pasture suits its occupant. When you’re through, think about your own situation, and decide if you’re using your pastures to their utmost.
Description of horse: A 14-hand, 750-lb (340-kg) overweight Welsh pony gelding.
Scenario: The only exercise he indulges in is whatever it takes to grab the next bite of grass or saunter to the water trough. He is on a five-acre lot with one small pony, and the pasture is maintained meticulously year-round. How much forage is this pony likely consuming each day? Using the aforementioned estimates, he is likely eating at least 17 lb, which is approximately 2.2% of his body weight. Considering his current body condition, he is probably taking in too many calories.
Risk: Many ponies are predisposed to laminitis, a debilitating condition that could render the pony useless as a riding or driving partner. Laminitis is life-threatening in many instances. If the pony manages to sidestep laminitis, the constant state of obesity is likely setting him up for metabolic conditions later in life.
Action: Reduce the forage intake by confining the pony to a stall or drylot for part of the day or by using a grazing muzzle. He should be fed no concentrates at all, but a low-calorie vitamin and mineral supplement is a wise addition to his diet. Placing the water source as far away as possible from the most desired grazing areas is one strategy for getting him to move more. Forced exercise such as riding, driving, longeing, or hand-walking will help him lose weight and will stave off the development of metabolic issues.
Description of horse: A 16.2-hand Thoroughbred gelding that was recently retired from the racetrack. His ribs are clearly visible, his withers are peaked and camel-like, and his hip bones jut out prominently.
Scenario: He has been introduced into a herd of five other horses, all of which run on about four acres of pasture. The late-summer pasture has suffered from a lack of rainfall. The pasture grass is not completely dormant, thanks to the occasional rain shower, but growth is slow, and there are obvious lawns and roughs (areas in which horses graze consistently and areas in which horse refuse to graze; this pasture profile is a sign of infrequent mowing or spotty pasture management).
Risk: The primary risk for this horse is insufficient forage, as the stocking rate for this pasture is high, with less than one acre per horse. A more realistic stocking rate is one to two acres per horse, but this recommendation varies depending on numerous factors such as pasture care and weather. There might be much for this horse to nibble on throughout the day, but the quality of the grass at his disposal is mediocre. Therefore, he is probably not satisfying his forage requirements on pasture alone.
Action: Because of this horse’s poor body condition, he should probably be separated from the herd when fed. This ensures that he receives all of the feed intended for him, and it allows the horse to eat peacefully without anxiety caused by horses that might be more dominant than him. A diet of concentrate and good-quality hay is in order. The concentrate should provide energy from a variety of sources such as starch, fat, and fermentable fiber. When he is separated from the other horses, feed him as much hay as he will eat. A large horse such as this will take months to gain sufficient weight to cover his bony protuberances, so patience is paramount.
Description of horse: A 15-hand, 1000-lb (450-kg) Paint mare in moderate body condition with a two-month-old colt at her side.
Scenario: This pair shares a 10-acre field with two other mares and their month-old foals. The pasture is adequate, though it has not been seeded or fertilized in several years. Adequate rainfall has ensured that there is plenty of forage, and the manager keeps the pasture mowed so that it is never more than a foot and a half tall. Mares are fed the lowest recommended daily amount of a concentrate specifically formulated for broodmares once each day in shallow rubber pans spread about 50 feet apart. Mares show mild antagonism toward each other during feeding time, and this Paint mare is the meekest and most submissive in the group.
Risk: There seems to be very little risk of this mare not consuming adequate forage under these conditions, despite consuming at least 30-35 lb (14 to 16 kg) of forage daily and perhaps more. The stocking rate is adequate for this field and its inhabitants at just over three acres for each mare/foal pair. If the pasture was in some way stressed, such as during a drought, there might be a concern, but as it stands, these broodmares and foals are likely receiving adequate nutrition from their current diets, including sufficient forage.
Action: Keep a close eye on the condition of the mare. Peak milk production occurs two to three months following birth, so this mare is probably nearing her maximal milk output. Lactation is extremely hard on a mare from an energy-output perspective. If her weight begins to drop off, consider increasing her concentrate intake. This will likely mean that she will have to be fed two meals a day, as no single meal should be more than 5 lb (2.2 kg).
Aged, sedentary gelding
Description of horse: A 26-year-old Morgan gelding with several missing teeth (a couple incisors and a few molars). His body condition seems to be slipping over the past several months despite carte blanche access to pasture.
Scenario: He whiles away the hours with another pensioner on mediocre pasture. Though the three-acre field is weedy, there seems to be sufficient grass for the pair of geldings. In addition to all-day grazing, he is fed a few pounds of oats once each day.
Risks: Though the pasture quality is probably adequate for these two horses, especially if it is mowed regularly and otherwise cared for, this gelding might have issues nipping sufficient grass because of the lost incisors. The severity of this situation will depend on which incisors are missing. Similarly, he might not be able to properly grind the oats if certain molars have fallen out or if there are other dental anomalies.
Action: The gelding’s teeth should be examined by a veterinarian with expertise in dentistry or another qualified dental professional. The state of his teeth will dictate the course of action, but a change in dietary management will likely be warranted. If the incisors are found to be incompatible with efficient grazing, he should be offered early-maturity, soft hay that is easy for him to grasp with his lips and chew with his remaining cheek teeth. An example would be leafy alfalfa (lucerne). He may leave some of the stems in favor of the tender leaves, but the leaves contain the most nutrients. The concentrate portion of the diet should be revisited as well. Without a reliably strong dental surface on which to chew textured concentrates, it might be wise to switch to a pelleted senior feed or concoct a wet mash. If alfalfa is also too difficult for the horse to chew, hay cubes or hay pellets may be fed as a mash with a concentrate designed for senior horses.
Description of horse: A 12-year-old Andalusian gelding that is ridden four or five times weekly as a lower-level dressage horse. He is overweight but not grossly so.
Grazing scenario: He spends about two-thirds of his time in a two-acre lot that he shares with a similar-sized gelding. The pasture offers little in the way of lush grass, but there is plenty to snack on when he is out. When stalled, he is given just enough textured feed to mix in a pelleted vitamin and mineral supplement, and a few flakes of mid-quality grass hay.
Risks: Few risks are readily apparent. The horse is overweight but appropriate measures are being taken to keep excessive weight off of him (very little concentrate, and middle-of-the-road hay and pasture), while still supplying him with macro- and microminerals. The near-daily exercise will help ward off potential metabolic problems if he is genetically prone to them, and as a member of a notoriously easy-keeping breed, he might be.
Action: In his present management situation, no alterations are necessary. If a drastic change is made in his day-to-day life, such as cessation of exercise or assignment to a flourishing pasture with lush grass, re-evaluation of his nutritional management would most definitely be in order.