Don't shoot me Carolyn, but this is what I found. :new_shocked:
Soaking Hay to Remove Excess Soluble Carbohydrate and Potassium
Copyright 2003 by Kathryn Watts, Research Director,
Rocky Mountain Research & Consulting, Center, CO
http://www.safergrass.org/
Paul Sirois, Manager, Dairy One Forage Testing Lab, Ithaca, NY
http://www.dairyone.com/
Funded with a grant from the Animal Health Foundation
http://www.animalhealthfoundation.com/
Purpose
To determine if soaking a variety of different hays in cold or hot water for specified periods of
times results in a reduction of the Water Soluble Carbohydrate (WSC) and/or potassium (K)
content as a tool in the management of horses with laminitis, insulin resistance or HYPP.
Introduction
Laminitis has long been associated with feeds that are ‘too rich’. Unfortunately, this term is far
too general to provide a strategy for a practical approach to diet management of laminitic
horses. With the new research being conducted on Equine Metabolic Syndrome, hormonal
mechanisms implicating intolerance to sugars and insulin resistance are being linked to chronic
laminitis. Other current research is focusing on fructan, another type of polysaccharide found in
cool season grasses, which can cause drastic changes in gut micro-flora that can set the stage
for laminitis. It has been widely accepted that too much grain in the diet can cause these
problems, and it has been generally thought that hay cannot have enough sugar content to be
an issue for these horses. However, for the last 20 years, plant breeders have been focused on
increasing carbohydrate levels in new grass varieties. High sugar levels in forage increase
palatability, and therefore intake. This increases weight gain and milk production in cattle. High
carbohydrate levels are also one of the mechanisms by which plants become more productive
and achieve a competitive advantage over other plants, allowing them to grow earlier in the
spring, survive drought, and long, harsh winters. Consequently, selection by plant breeders for
these survival traits will also inadvertently select for high carbohydrate levels. New varieties of
forage, while a valuable tool for the cattle industry, may be inappropriate for equines prone to
laminitis, obesity, or insulin resistance due to high sugar content.
In addition to changing genetics, it has long been known to plant physiologists that certain
environmental conditions will cause accumulation of sugars and fructans. Sugar is soluble in
water, and at least the shorter chain fructan are soluble, therefore both will be fractions included
in the term Water Soluble Carbohydrates (WCS). Sunny days combined with cold nights
causes the sugars produced by photosynthesis during the day to accumulate when growth that
occurs at night is restricted. Other factors that may increase WSC in hay are drought stress,
nutrient deficiencies, and high salt content of the soil. Because there are so many factors that
affect the WSC content of hay, appropriate analysis of each batch of hay is the only way we can
know. Testing for sugars and starch in feed is a new, emerging technology for commercial
forage testing labs, but fortunately the dairy industry is leading the way, as they are having their
own problems with high carbohydrate rations creating metabolic acidosis and laminitis.
HYPP (Hyperkalemic Periodic Paralysis ) is a hereditary genetic disease found in Quarter
Horses of the Impressive line. It is a defect in sodium channeling in the muscle tissue, which
can be triggered by high levels of potassium (K) in the blood. Horses with HYPP can
experience unpredictable attacks of paralysis, which in severe cases, can lead to collapse and
sudden death. The cause of death usually is cardiac arrest and /or respiratory failure. Some
testing facilities are showing 1% of the Quarter Horse breed to be homozygous for the trait.
Specialists in the treatment of the disease recommend limiting alfalfa in the diet, under the
assumption that grass hay is usually lower in potassium. Others recommend a specially
formulated complete pellet ration to avoid the often high levels of potassium that can be found in
all types of forage.
Sugar, fructan and potassium are all water soluble in both alfalfa and grass hay. Simple
sugars, disaccharides, and short chain fructan are soluble in cold water, while the longer chain
fructans are soluble in hot water (P. Harrison, USDA-ARS, Forage and Rangeland Research
Lab, personal communication) Potassium in forage is in the ionic form, not bound to any other
fractions, and also soluble in water. (V. Allen, Forage and Livestock Systems, Texas Tech. U.,
personal communication) Soaking hay to reduce dust and allergens for horses that have
heaves is already a common practice in horse care. We propose that soaking hay can be a
practical method for reducing WSC and potassium in the treatment of horses with laminitis,
insulin resistance, or HYPP.
Procedure
Fifteen hay samples of multiple varieties were split into four representative subsamples of up to
50g each. When original sample size was insufficient the samples were split into four samples
of equal weight. The four subsamples were designated as A) Dry, no soaking, B) soaked for 30
minutes in room temp. tap water, C) soaked for 60 minutes in room temp. tap water, or D)
soaked for 30 minutes in hot tap water. The room temp tap water averaged 27.8 C and the hot
tap water, 50.3 C. Samples were soaked in 4 L of water. Upon cessation of the soaking period,
the water was poured off and the samples were removed from the beakers and allowed to
briefly drain. Samples were placed in aluminum pans and dried at 60 C overnight. Once dry,
they were ground through a UDY Cyclone Mill fitted with a 1 mm screen and analyzed for sugar
and potassium (K). The Dry (A) samples were simply dried, ground and analyzed.
Sugar was determined using the procedure of Hoover and Webster as outlined in their
publication “Determination of Nonstructural Carbohydratesâ€. Samples were extracted in hot
water followed by an acid hydrolysis and reaction with potassium ferricyanide to measure sugar
colorimetrically.
Potassium was measured by inductively coupled plasma (ICP) spectroscopy. Samples were
“dry†ashed at 500 C for 4 hours followed by a “wet†ash with 6N HCl. The resultant residue was
extracted with a mild acid solution (1.5N HNO3 + 0.5N HCl) and analyzed for potassium using a
Thermo Jarrell Ash IRIS Advantage inductively coupled plasma radial spectrometer.
Table 1: Results from various soaking treatments
Percent dry matter
___________Sugar,%___________ ___________Potassium,%_______
Sample Dry 30m 60m 30m-hot Dry 30m 60m 30m-hot
1 10.0 8.0 6.2 8.2 2.68 1.43 1.01 1.39
2 13.0 10.8 10.8 9.9 2.02 1.26 0.92 1.08
3 10.0 9.3 6.6 6.4 2.45 1.63 1.13 1.24
4 16.1 12.2 10.8 10.8 1.89 0.86 0.75 0.61
5 10.6 8.9 9.2 8.9 1.95 1.06 1.06 0.79
6 19.3 20.0 13.9 16.8 1.47 0.94 0.82 0.83
7 12.2 10.4 7.6 11.2 2.49 1.01 0.72 0.92
8 4.4 4.4 3.0 3.6 2.61 1.06 0.71 0.90
9 7.5 4.3 4.1 2.9 1.09 1.22 1.06 1.15
10 7.3 5.1 4.0 3.8 3.45 1.27 1.03 1.12
11 14.2 11.6 10.7 12.2 2.01 1.14 1.06 1.11
12 7.0 5.4 6.2 5.3 1.95 1.11 1.19 1.09
13 8.9 8.7 8.9 8.6 0.96 0.66 0.76 0.68
14 34.4 26.5 22.8 17.6 2.51 1.52 1.23 1.04
15 16.1 8.5 7.1 8.3 1.75 0.85 0.72 0.99
avg 12.7 10.3 8.8 9.0 2.09 1.13 0.94 1.00
Average Reduction -19% -31% -29% -46% -55% -52%
Description of hays used in the test:
1. Alfalfa, 100% San Luis Valley, CO, very bright green, some blooms, leafy, some coarse
stems
2. Alfalfa 100% cut in Sept. SLV, very bright green, leafy, some coarse stems, more stems
than #1
3. Alfalfa 50%, brome 50%- SLV. duller green. Alfalfa is fairly stemmy with blooms, brome
is headed out, and fairly coarse in texture.
4. Alfalfa 75%, brome 25%, SLV, cut in Sept., very bright green, alfalfa is fine stemmed, no
blooms, brome is leafy, fine texture, no heads
5. Alfalfa 75%, brome 25%, SLV. Very bright green, alfalfa has some coarse stems, but
leafy, brome is fine texture, no heads with a few brown leaves. Same hay as #2, but
from a grassy bale.
6. Mixed grass 95%, 5% alfalfa mix, eastern WA, alfalfa is coarse and mature with few
leaves, grass is fine textured, and mature, grown under drought stress
7. Brome grass 90%,10% alfalfa, SLV 2001 only one cutting in Aug. Alfalfa over mature
and stemmy, brome is headed, coarse, stemmy, duller green, some brown leaves.
8. Fescue/orchard? Mix grass, NC,. dull green with tan, coarse, headed out.
9. Garrison meadow foxtail/brome/Canadian thistle, SLV, 2nd cut, duller green, medium
texture, headed out
10. Orchard grass, CA all leaf, no heads, dull green, some brown leaves, fine texture
11. Garrison meadow foxtail 40%/native meadow 60%(Carex, Juncus) SLV, bright green,
very fine texture, headed, cut under drought stress,
12. Coastal Bermuda, East TX, pale green/mostly tan, fine textured but stiff, headed out
13. Blue grama grass straw, SLV, mostly tan, very fine stemmed, but stiff, after threshing 2X
for seed production.
14. Oat hay, SLV, very bright green, coarse texture, cut in flowering stage, early Oct after
many nights with hard freeze, and extremely low humidity (nurse crop for alfalfa)
15. Oat hay, SLV, cut milk-soft dough, pale green to mostly golden
Typical composition of hays appear in Table #2. This data is from hay samples analyzed by
the Dairy One Forage during the period spanning from 5/01/02 – 4/30/03. Samples are from
across the US and are broken down into four broad categories:
Legume; >85% legume
Mixed Mostly Legume; 50 - 85% legume
Mixed Mostly Grass; 50 – 85% grass
Grass; >85% grass
Table #2. Average values for hays analyzed by the
Dairy One Forage Lab from 5/01/02 to 4/30/03. (All values DM basis)
Legume MML MMG Grass
n avg sd n avg sd n avg sd n avg sd
CP% 8811 21.3 2.7 2279 16.9 3.1 2868 12.1 3.5 3957 10.8 3.8
ADF% 8731 30.0 3.7 2277 34.7 4.6 2866 38.7 4.3 3918 39.0 4.5
NDF% 8741 38.6 5.3 2277 49.2 7.5 2867 60.4 6.9 3936 63.1 6.4
Sugar% 3806 9.1 1.7 1072 9.0 2.0 1268 9.7 2.6 1711 10.5 3.6
Ca% 7842 1.54 0.27 2219 1.19 0.30 2800 0.74 0.28 3832 0.54 0.22
P% 7842 0.28 0.05 2219 0.28 0.05 2800 0.26 0.07 3832 0.24 0.09
Mg% 7789 0.31 0.06 2210 0.28 0.06 2798 0.23 0.06 3814 0.21 0.08
K% 7794 2.35 0.52 2212 2.08 0.47 2800 1.91 0.49 3822 1.89 0.56
n= number of samples analyzed
Discussion: Factors affecting Sugar levels in Forage:
The San Luis Valley, in south central Colorado, is 7,600 ft. altitude at the valley floor. The
high altitude, thin, dry air, extreme diurnal temperature fluctuation, overall cool temperatures
and abundant sunshine make it a perfect climate to study the affects of high WSC
accumulation in forage. Although it is very feasible to duplicate these conditions in other
areas of the country, as shown the data summarized from nationwide tests in table 2, the
majority of the samples used in this test are not representative, but might better be
considered ‘worst case scenario’. Sugar levels this high may be found anywhere that the
various environmental conditions conducive to accumulation may manifest. During the 2002
growing year, when these SLV samples were grown, the San Luis Valley experienced an
extreme drought. Although everything grown here is under irrigation, most were under suboptimum
irrigation, and there were hotter, drier winds than normal, creating stress conditions
even if the soil was wet. Based on known history, the hays that were subjected to notable
drought stress were Sample # 6,11 and 15, all of which tested on the higher end for sugar
content.
Hay that dries quickly will have more sugar than the same hay dried slowly. This is
because cut forage will continue to respire and metabolize sugars until the moisture levels
are below about 40%. The drought in 2002 created conditions that both caused more
accumulation of sugars in the hay during growth, and the extreme low humidity created
optimum conditions for maintaining the high sugar levels during hay drying in the field.
Another known trigger for the accumulation of sugars in forage is cold stress, which is
exacerbated by high levels of sunshine. If photosynthesis is at maximum, while respiration
and growth during a cold night are slowed, the sugars, which are the products of
photosynthesis, accumulate rather than proceeding with assimilation into other plant
constituents. This instigates the development of fructan, which is the preferred storage
carbohydrate in cool season grasses. Nightly freezes are normal by the end of September
in the San Luis Valley, and the data shows that hay cut during this period is higher in sugar
as shown by samples 2,4,5 and 14. Sample #14 is a very special case. This was a late
planting of oats used as a nurse crop for alfalfa. The week before cutting it was subjected to
repeated hard freezes in the low 20 0 F range. The days were very sunny and with low
humidity, allowing the hay to dry very quickly, which minimized respiratory losses. The
resulting sugar level of 34.4% of dry matter is probably unusual, although it’s inclusion in this
data set is hopefully educational for just how high sugar levels can get in forage under worst
case conditions. This hay is extremely attractive, very palatable, and if purchased without
knowledge of its sugar content would undoubtedly make the buyer feel that they had made a
very good choice.
Results: Sugar reduction:
The amount of reduction in sugar content was linear in respect to the period of time that
the samples were soaked. The average amount of sugar reduction after 30 and 60 minutes
in cold water was18.9 and 30.7%, respectively. Generally, soaking for 60 min in cold water
extracted the same amount of sugar as 30 minutes in hot water. Two exceptions were
sample #9, which had a considerable amount of Canadian thistle mixed in the hay. The fact
that the type of fructan in broadleaf plants is of the inulin type, whereas grass has fructan of
the phlein type may be a factor in that longer chain fructan requires hotter water for
extraction. One other exception was sample #12, which was Coastal Bermuda grass. This
may be explained by the fact that as a C4 plant, Bermuda accumulates starch rather than
fructan, which would also be more soluble in hot water. In this study, the amount of WSC
remaining after a 60 minutes soak in cold water was strongly correlated (r2=.892, p=0.0001)
to the initial amount of sugar in the sample.
There was a fairly wide range of % reduction in sugars, from a high of 55.9% and a low of
zero reduction. There is some correlation with the maturity of the samples. Those that did
not release as much sugar tended to be very mature, stemmy and ‘stiff’. An explanation for
this might be that high levels of lignin may prevent penetration of water through the tissue.
Further studies that quantify other constituents are needed to better define those hays that
may not be salvageable by soaking. .
Sugar levels
Factors affecting Potassium levels in forage:
Note that the samples highest in potassium in this study included grass and oat hay. Those
over 2.5% initial K were an orchard grass hay, a mixed grass, an oat hay, and one alfalfa
sample. Potassium levels in soils vary widely by geographic region. Generally speaking, in
areas of low rainfall, such as the desert southwest, soils often have high levels of potassium
due to high levels in parent material and absence of rainfall to leach out the excess. Areas
with high rainfall have soil that is generally lower levels of potassium, and subsequently
farmers are often required to add fertilizers containing potassium. Long-term flood irrigation
may leach out excess potassium, as it is also fairly soluble in soil. This dissolved potassium
may also accumulate in irrigation tail water, and if subsequently returned to the main
irrigation canal may increase potassium levels downstream. Application of manure may
result in high levels of soil potassium, with poultry manure being especially high. Both grass
and alfalfa hays may accumulate high levels of potassium, as clearly shown by the samples
used in this study. Attempts to avoid high potassium forages must include analysis, rather
than relying on the general trend that grass is lower than alfalfa.
Result: Potassium Reduction:
Potassium was leached out rather easily in this study, with the gradient being steeper over
time, showing it to be more soluble than the carbohydrates. Average reduction after 30
minutes in cold water was 45.9%, with 55.0% coming out after 60 minutes in cold water.
The range of amount extracted was from 70.1 to 2.8%, with the lowest reduction in the 2
samples that were low initially, having K levels that would not create a problem to HYPP
horses to begin with. 30 minutes in hot water extracted generally the same amounts as 60
minutes with cold. There was a trend toward a correlation with amount extracted out vs. the
initial amount of K, but this was not significant statistically. The maturity, texture, or
stiffness did not seem to affect the amount of K that was extractable.
Potassium levels
Conclusion:
Both sugar and potassium can be leached out of all types of hay in significant amounts by
soaking for at least 60 minutes in clean, cold water, or 30 minutes in hot water, and draining. .
The average reduction in sugar over 15 samples of a variety of hays was 31%. As the amount
of sugars dissolved increased over time, this suggests that a longer soaking period may allow
more even more sugar to be leached.
The average reduction of potassium after soaking for 60 minutes in cold water was 55%.
Although a couple of the samples did not decrease significantly, these were also low enough in
K that they would not create a problem for an HYPP horse before soaking. All the samples,
including those very high in potassium, were decreased sufficiently to be considered acceptable
forage for a horse with HYPP.
Preliminary data from another lab showed that soluble carbohydrates and potassium were the
only nutrients that were reduced by rinsing hay in distilled water. This corresponds with research
on the affects of rain damage on alfalfa. Further research that includes complete analysis of all
nutrients after soaking for 60 minutes is needed to assure that no other valuable nutrients are
being lost by this treatment. More work, with replicated samples to eliminate the effect of testing
error is needed.
Horses readily accept wet hay. Caution should be exercised to feed wet hay before it has a
chance to mold or heat, which could feasibly degrade protein or other valuable nutrients.
