Ask the Expert: Maple Leaf Toxicity

Question: Our horse pasture has several maples trees. I was told they are toxic to horses, but our horses seem fine. Are they toxic? If they are, do we have to remove them from our pasture?   

Answer: Wilted (not fresh) maple leaves are toxic to horses. However, horses must eat 1.5 to 3 pounds of wilted maple leaves per 1,000 pounds of bodyweight to become sick.  Wilted maple leaves can remain toxic for four weeks, but they aren’t generally believed to retain toxicity the following spring. Thus, illness normally occurs in the fall when normal leaf fall occurs. 

Illness from maple leaves has only been reported in horses. Common signs after the first day of eating leaves include depressed behavior, tiredness, not eating, and dark red/brown urine. Signs may progress to going down with labored breathing and increased heart rate before death. Don’t cut down maple trees in horse pastures. Instead, keep branches out of reach of horses (for example, trimmed above their reach) and fence horses out of areas with a lot of wilted maple leaves. However, horses will rarely choose to ingest wilted maple leave unless very hungry. For more information on wilted maple leave toxicity, click here

Written by Krishona Martinson, PhD, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Pasture Management – How to Prepare for Fall

Managing pasture can be a very important tool in controlling feeding cost for all livestock, including horses being kept on small acreages.  If pasture is going to provide a substantial amount of the required nutrition for a horse, it takes about 2-3 acres, per 1,100 pound adult horse.

Even with adequate acreage, weather conditions can limit pasture regrowth and decrease the amount of forage available.  Avoiding over-grazing is important for both the pasture and for the animals.   Keep the following in mind:

  1. Remove animals from the pasture when plants are grazed down to 3-4 inches in height. Grazing  too long and allowing animals to eat the grass off too close to the ground, will kill the grass and turn the pasture into a dirt lot where the only green plants are weeds, potentially requiring expensive renovation.   Also, if animals eat the grass too close to the ground on sandy ground, the risk of sand colic may increase.  Animals may also consume potentially toxic weeds if no other forage is available.
  2. If you have limited acreage, consider purchasing some temporary fencing so that you can rotate the pasture. The outer fencing should be a safe, permanent fencing.  You can cross fence the pastures with temporary fencing such as capped steel posts and appropriate electric wire.  By allowing the animals to graze one section, then moving them to another, total pasture yield can be increased substantially, helping to control total feed costs and improve pasture health.  Clip and drag the pastures after you pull the animals off to control weeds, parasites and flies.
  3. As pasture declines, you will need to adjust the amount of forage that is offered to maintain dry matter intake and nutrient intake. If the forage available is lower protein and lower energy than the pasture has been, you may have to adjust the concentrate portion of the diet. If you are using a ration balancer, you may need to move to the higher feeding rates.  If the higher feeding rates do not maintain Body Condition Score and Topline Score, you may need to switch to a different feed to allow higher feeding rates.  It is essential to monitor both Body Condition Score and Topline Score.
  4. Declining pasture quality can be a particularly serious issue for young growing horses, pregnant mares and senior horses.
  5. Make certain that fresh clean water is available at all times and that salt is available at all times. If you are not feeding a balanced feed or ration balancer, offer appropriate mineral free choice as well.
  6. If space is very limited, keep a dry lot area where animals can be fed and watered to prevent areas of pasture from being overgrazed.

Managing the pastures and selecting the right feeds as pastures change can help manage total yearly costs as well as improve animal health and condition.