Have a horse that is prone to founder?
Check out this fantastic post from the folks at ECIR. https://www.ecirhorse.org/
ECIR Group - Equine Cushings and Insulin Resistance
November 23, 2015
TAKE HOME MESSAGE: If you’re choosing low or poor quality hay thinking that you are significantly reducing carbohydrates, then stop. Good quality forage can also be safe (less than 10% ESC + starch) without sacrificing nutrients and minerals.
For those who want more details, continue reading.
Last week we talked about some common recommendations when it comes to choosing hay for horses with PPID and/or IR. Once again, we would like to stress that the ECIR Group does not support recommendations to drastically restrict feeding or to feed only poor or overly mature hay. A common mistake by those told to seek “low quality hay” is lack of knowledge about how hay is graded. Therefore, they choose the lowest of the low, the standing grass skeletons in which there is very little nutrient availability.
Before we dive into the specifics, we need to be clear on some terms that you will find on your forage analysis. We’ll limit these terms to the few that we’re going to use in the next few days so it doesn’t get overwhelming.
Measures of Forage Quality: Acid and Neutral Detergent Fiber (ADF) and (NDF). ADF is the least digestible fiber in forage that includes lignin, cellulose and silica. As ADF increases, the nutrient (carbohydrate, protein, fat) digestibility decreases. NDF measures the structural components of the plant; cellulose, hemicellulose, lignin, etc. As NDF increases, consumption decreases. The higher the NDF, the lower the quality and the less palatable the forage.
Carbohydrates: Water Soluble Carbohydrates (WSC) = Fructans + simple sugars. Ethanol Soluble Carbohydrates (ESC) = Simple Sugars. Starch = starch. Because WSC includes simple sugars, we can estimate fructan by subtracting ESC from WSC, i.e., WSC – ESC = estimated fructan. Remember that fructan fermentation by bacteria in the hind-gut of the horse does not generate an appreciable glycemic response.
The data the ECIR Group Inc. reports here are from over 100 hay samples collected from the same region, by the same individual, over the course of 5 years. All of these hays range from Grade 2 to 5, and are considered average to low quality according to the American Forage and Grassland Council Quality Standards for Hay.
Question 1: How does quality affect carbohydrates? This question is important because many owners make hay choices based ONLY on them being “low sugar,” therefore, we need to understand whether opting for low quality hay is worth it. Does low quality insure low sugar? To answer this question, we’ll use 3 carbohydrate measures. 1) Estimated fructan and 2) ESC and 3) starch. We will use % NDF as a measure of hay quality. We used linear regression to predict carbohydrate levels based on forage NDF. The assumptions for linearity and constant variance were met. Extreme outliers were excluded from the analysis.
Result 1: Hay quality had no effect on estimated fructan (F(1,138) = .267, p = .61), with an R2 of .002. Mean estimated fructan was 6.7% (+/- 2.7%), Mean NDF was 54.9% (+/- 3.79), minimum 46.7%, maximum 66%. Result 2: Hay quality predicted lower simple sugars (ESC). There was a significant effect in that the higher the NDF (lower quality) the lower the simple sugars (F(1,138) = 14.8, p = .0002), with an R2 of .097. It is worth noting, however, that mean ESC was 6.9% (+/- 1.5%). Only 2 of the 140 samples were greater than 10% ESC. Result 3: Hay quality had no effect on starch (F(1,138) = 1.17, p = .28), with an R2 of .008. Mean starch was .595% (+/- .42%). Mean ESC + starch was 7.4% (+/- 1.6%). Because starch has a moderate positive association with NDF and ESC a negative association, the regression analysis for ESC + starch, was not informative or significant (p=.95).
CONCLUSION: Hay quality (%NDF) did not have a significant effect on fructan or starch; both were equal whether the hay was of good, average or poor quality. Simple sugars did decrease with hay quality. For each 1 % increase in NDF, simple sugars decreased by 0.13% (0.77 grams/lb of forage) however, simple sugars were less than 10% in 138 out of 140 samples (99%).