High Fructans – Why a problem?

A.  In the Fall (September –  December), many weather changes create an increase in the Fructan level of the grass.  This same surge is also seen in rapid growing Spring grass, and is a reason why Spring grass triggers many Laminitis cases.  On hay tests, Fructans are part of the WSC component.  Fructan % is approximated by taking WSC level and subtracting the ESC.  Dr. Getty 2010, Chpt. 2.

B.  Fructans increase several ways in the Fall:

• Drought – Often can go weeks with no rain.  This stresses the grass so it does not grow upward and so fructans build up higher and higher.
• Cooler weather – again, fructans level increase.
• Frost – can create a three times increase in fructans in just a few hours.  Keep horses off early season frost grass until later in the morning (6:00-8:00 AM).
• Sun – direct sun increases fructans, so pastures in the shade or at night (after 8:00 PM) have lower fructans.  Dr. Byrd, 2006, JAS – Fructans lowest at 4:00-5:00 AM (15% WSC).  Fructans peak at 4:00-5:00 PM (22-24% WSC).  As you can see, fructans can jump up quickly within the day.  So night (after 8:00 PM) or early morning (up to 8:00 AM) will be a better time to graze.  If can only graze small amounts, do 6:00 AM – 8:00 AM or 8:00 -10:00 PM.

• Mowing – Fructans in grass are at higher levels at the base than at the tip of the grass and higher in the stems than the leaves.  Smith, 1967, Crop Sci, Pavis, 2000, New Phyto.
Click here to see Article from Pavis on Fructans and Fructan-metabolizing enzymes in leaves of Lolium Perenne.  So in August-September, you need to really make sure not to over mow the grass.  It is slowing on growth and you want to keep it at 4-5 inches.  This allows less fructans into the horse.  The base of the grass is super high in fructans so mowing like a lawn makes things bad for your horse.  4”-8” mowing, height lowers sugars in grass.  A. Cairns, Grassland Institute.
• Soaking hay can bring NSC down 19% in thirty minutes and 31% in sixty minutes.  Equus, 2004.
• Cutting for Hay – cut late at night – Why?

a.  If cut in bright sun, hay has higher sugar. Individual leaves remain alive for 50 hours after they are cut.  So if cut in the sun, still has photosynthesis and accumulate sugars.

b.  “Course stemmy hay can have high sugar, soft leafy hay can be low sugar.  It depends on if it was cut when stressed, or drought, or sudden cold spell prior to cut.” Dr. Pollitt, 2010, Aust. Gov.

C.  High levels of fructans can lead to Laminitis – this is why often after the first frost, grazing time is cut back to 4-6 hours with a muzzle until grass is dead, and grazing is kept to early morning or later at night.

Dead Grass?  Fructan levels in Winter will drop faster if it is a wet Autumn.  A drought/little rain Autumn means higher levels of fructans going into Winter.  Grass must be totally brown prior to increasing pasture time or removing the muzzle.  Brown and green grass mixes can be very high in fructans such as seen sometimes in December grass with mild weather.

Once totally brown, rain and snow will leach out fructans from grass allowing muzzles to be removed.  “Sunny days, frigid nights with grasses in no way lush that dark green, half dead grass had very high sugars and fructans.” K. Watts, Rocky Mountain Research.

Steps in Fructan Laminitis:

A.  The large intestine has a normal population of bacteria to breakdown food.  These bacteria can handle normal amounts of fructans seen in hay/grass.  The bacteria mix with the Fructan sugar and ferment, much like sugars and yeast coming together to ferment in making beer/wine.

B.  Food eaten by the horse will have simple sugars to be absorbed at the small intestine.  After that, the body’s pancreas notes this increase in blood sugar and Insulin pours out.  Insulin to escort it to the cells.

C.  On the other hand, Fructans pass unaltered to the large intestine where it undergoes fermentation.  Longland, 2012, J. of Sci food/ag.re  Fructans are not degraded by mammalian enzymes but by bacteria.  Nilsson, 1988, J. of Nutrit.

D.  But too large a Fructan load creates too much rapid fermentation leading to problems.

1. Pasture-Induced Laminitis

a. “Pasture-induced Laminitis can be from over consumption of carbohydrate in the form of simple sugars, fructans, or starch.”
b. When fed frutans, in excrement, fecal pH dropped.
c. When fed fructans, in excrement, amine levels increased.
d. Produced increased in bacterial fermentation products.

Click here to see Dr. Crawford’s article in Journal of Animal Science, 2014,
Dietary fructan carbohydrate increases amine production in the equine large intestine: Implications for pasture-associated laminitis.

2. Spring Pasture, Weather, Overgrazing

a. Drought or frost increases fructans by up to 30%.
b. Fructans are stored in the bottom 2 inches of grass – avoid overgrazing.

Click here to see the article from the University of Minnesota Extension Service on Spring Pasture, Fructans and Founder.

3. Fructan Metabolization

a. Fructans metabolized in the liver can lead to Insulin Resistance.
b. Fructans metabolized in the hind gut can increase permeability resulting in toxin release.

Click here to see Dr. Johnson’s article in the Journal of Equine Science, 2013, Fructans, Fructokinase, Intestinal Permeability and Metabolic Syndrome.

4. Microbial Ecology of the Equine Hind Gut

a. Introduction of high levels of fructan resulted in large scale changes in high gut microbiota. Rapid proliferation of Strep bacteria occurred, followed by a rapid decline and a huge pH decline.
b. Previous study, all horses had diarrhea and huge pH drops in the cecum following high fructan dosing. They also have high fevers for 24 hours post dose and high heart beat rates.

Click here to see Dr. Milinovich’s article in the ISME Journal, 2008, Microbial ecology of the equine hindgut during oligofructose-induced laminitis.

5. Changes in the Equine Hindgut

a. Bacterial counts in the gut markedly changed in population increases.
b. pH also dropped.

Click here to see Dr. Milinovich’s article in the Enviorn Microbiol., 2006, Changes in Equine Hindgut bacterial populations during oligofructose-induced laminitis.

E.  Now What?  Within 8-12 hours of Fructan overloads, strep exotoxins seen in blood.  Within 24-48 hours Laminitis.  Pollitt/Visser, 2010 Vet Clin.  Next can come Diarrhea, fever, shock, and death.

Fructans Possible Treatment

In a 2014 study using sodium bicarbonate (baking soda), they demonstrated by tubing approximately 1 pound down of it with water could alkalinize (increase pH) of the large intestine. This study has huge possible therapy options for Veterinarians/owners trying to avoid or treat this type of Laminitis.  We highly recommend now if your horse is suspected of frost grass or spring grass Laminitis to have this baking soda treatment to help treat your horse.  We also recommend to try to help your horse in October/November and April/May/June by feeding a 1000 pound horse 2 tablespoons AM and 2 tablespoons PM of baking soda in the feed (add sugar-free pancake syrup to flavor).  This daily prophylactic attempt to alkalinize pH needs further testing to see effects, but it is an easy, simple step to try to avoid issues and over the last 2 years has helped many horses we have worked with to avoid relapses.  Click here to see Dr. Taylor’s study in Equine Vet J., 2014,  Effect of orally administered Sodium Bicarbonate on caecal pH.