Q. Last week in your article about helping horses stay warm in winter you mentioned feeding sugar beet pulp to horses in need of extra calories from a forage source. It doesn’t seem like that would be a good choice for a lot of horses. Isn’t sugar beet pulp high in sugar?
A. The name certainly implies that this common equine feed ingredient is high in sugar. However, you might be surprised to learn that by the time it makes it to your horse’s feed bucket sugar beet pulp, in most cases, is actually very low in sugar.
Sugar beets are a root crop with a high concentration of sucrose sugar (think table sugar) grown commercially for sugar production. According to the American Sugarbeet Growers Association, sugar beets are grown in many Western and Northern states. The sugar beet is about a foot long and weighs between 2 to 5 pounds. With a sucrose content of about 18%, sugar beets make up a little over 50% of the domestically produced sugar.
However, we’re not feeding horses whole beets. Rather we feed what‘s left after manufacturers have extracted sugar for human use. What’s left is referred to sugar beet pulp and is a source of fermentable fibrous material that requires microbial fermentation in the horse’s hindgut. Sugar beet pulp is used extensively in livestock feed and, for horses, is sold as an ingredient in commercial feeds or separately as shreds or pellets.
Like starch, sugars such as sucrose are absorbed from the small intestine and result in an increase in blood glucose levels, which in turn increases circulating insulin. For horses with metabolic issues such as insulin resistance, equine metabolic syndrome, and polysachharide storage myopathy significant increases in blood glucose can have negative health consequences, hence the interest in keeping dietary starch and sugar levels low for affected horses.
The glycemic index is a system used to rank sources of carbohydrate and the potential impact they have on blood glucose; it’s a way to compare carbohydrates from different sources and how they might impact blood glucose. The method compares available carbohydrate gram for gram in different feed ingredients by measuring blood glucose levels after a meal. Measurements are taken over time at regular intervals for several hours, and blood glucose levels are compared.
In human research white bread is used as the standard response against which other foods are compared. In horses we use whole oats, because oat starch is more readily digestible than the starch in other grains such as barley and corn. Oats have a glycemic index value of 100. This means that if a feed ingredient is fed and results in a higher blood glucose value then oats, it receives a higher glycemic index value, and vice versa.
Studies in horses have shown that plasma glucose levels peak about 90 to 120 minutes after a meal, depending on the ingredients. While products such as traditional sweet feed and oats have high glycemic index values, sugar beet pulp has a glycemic index as low as 34.
It needs to be noted that some sugar beet pulp sold for horses has added molasses to improve palatability and reduce dust. As expected, this will result in a higher glycemic index. Unrinsed sugar beet pulp with molasses might have a glycemic index higher than 70. Therefore, if you want to avoid adding sugar to your horse’s diet, be sure to buy unmolassed beet pulp or rinse it after soaking and before feeding.