Feeding The Draft Horse

By Martin W. Adams, PhD, PAS – Equine Nutritionist for Southern States Cooperative, Inc.

Tying up disease, which has been referred to as EPSM in draft horse breeds, is now called Polysaccharide Storage Myopathy (PSSM). It is an inherited metabolic muscle problem that occurs in many horse breeds. Horses with PSSM have symptoms including exertional rhabdomyolysis or tying up symptoms when they are exercised, muscle tremors and gait abnormalities. Recent research has shown that a genetic mutation causes unregulated glycogen formation in the muscle of a horse with PSSM. This mutation is in a gene called GYS1 and it is responsible for the accumulation of excess glycogen in muscle cells and symptoms of PSSM in affected horses. About 75% of Quarter Horses and 85% of draft breed horses affected with PSSM have the GSY1 mutation.

PSSM is now classified into two main types: Type-1 PSSM is due to the GSY1 mutation and occurs mainly in Quarter Horse, Paint, Appaloosa, Morgan, Tennessee Walker and draft purebreds and crosses. Type-2 PSSM is the form that affects most Warm bloods as well as all Arabians, Thoroughbreds and Standardbreds. The cause for this Type 2 form of PSSM has not yet been discovered.

Horses affected with Type-1 PSSM respond well to a low-starch diet. Southern States has feeds that can be used for PSSM horses and all fixed-ingredient formula horse feeds are analyzed for starch and sugar content by an independent laboratory. Recommendations are to feed horses a diet with less than 15 to 20% soluble carbohydrates in the total diet. Table 1 on the following page contains feeding recommendations that will provide a total diet of less than 15% starch and sugar content when fed with an appropriate source of hay.

For many years feeding recommendations for draft horses affected with PSSM have included vegetable oil as a means to reduce starch and sugar levels in the diet and possibly providing other benefits in reducing symptoms. These recommendations have been to provide 20 to 25% of the total daily dietary calories from fat sources. The most convenient source of fat for this purpose has been vegetable oil (i.e. corn oil, safflower oil, soy oil, flaxseed oil, rice bran oil). All sources of vegetable oil contain approximately 240 kilocalories (Kcal) of digestible energy (DE) per ounce, so a cup or 8 ounces of oil contains 1,920 Kcal or 1.92 Megacalories (Mcal) of DE.

Table 2 of this article contains feeding recommendations for draft horses with vegetable oil supplementation. These feeding recommendations achieve the recommended fat percentage in the diet along with a horse feed or supplement to provide proper nutrient fortification. Please note that hay should be weighed and fed according to recommended levels to prevent obesity and provide the proper fat level in the diet. If your horse won’t consume the vegetable oil readily, consider substituting some chopped hay or beet pulp that you have “presoaked” with oil for regular baled hay. You may also “presoak” your horse feed with additional oil if consumption of the oil becomes a problem.

Table 1. Feeding Recommendations for Draft and Draft Cross Horses with PSSM.

Draft/Draft Cross Weight and Activity Level	Daily Digestible Energy Requirements1	Hay (lb/day)2	Triple Crown Lite (lb/day)	Legends Performance Pelleted or Triple Crown Complete (lb/day)
1200-lb No Work	16.49 Mcal	17	2	-
1200-lb Light Work	21.79 Mcal	18	-	4
1200-lb Moderate Work	25.38 Mcal	18	-	6
1300-lb No Work	17.87 Mcal	18	2	-
1300-lb Light Work	23.56 Mcal	18	-	5
1300-lb Moderate Work	27.49 Mcal	18	-	8
1400-lb No Work	19.24 Mcal	20	2	-
1400-lb Light Work	25.38 Mcal	18	-	6
1400-lb Moderate Work	29.61 Mcal	18	-	9
1500-lb No Work	20.62 Mcal	20	3	-
1500-lb Light Work	27.19 Mcal	20	-	6
1500-lb Moderate Work	31.72 Mcal	20	-	9
1600-lb No Work	21.99 Mcal	22	3	-
1600-lb Light Work	29.0 Mcal	22	-	6
1600-lb Moderate Work	33.83 Mcal	22	-	9
1700-lb No Work	23.36 Mcal	23	3	-
1700-lb Light Work	30.81 Mcal	24	-	7
1700-lb Moderate Work	35.95 Mcal	24	-	10
1800-lb No Work	24.74 Mcal	25	3	-
1800-lb Light Work	32.63 Mcal	26	-	7
1800-lb Moderate Work	38.06 Mcal	26	-	10
1900-lb No Work	26.10 Mcal	26	3	-
1900-lb Light Work	34.44 Mcal	28	-	7
1900-lb Moderate Work	40.18 Mcal	28	-	10
2000-lb No Work	27.49 Mcal	28	3	-
2000-lb Light Work	36.25 Mcal	30	-	7
2000-lb Moderate Work	42.29 Mcal	30	-	10
2100-lb No Work	28.86 Mcal	30	3	-
2100-lb Light Work	38.06 Mcal	30	-	8
2100-Moderate Work	44.41 Mcal	30	-	12
2200-lb No Work	30.24 Mcal	31	3	-
2200-lb Light Work	39.88 Mcal	32	-	8
2200-lb Moderate Work	46.52 Mcal	32	-	12

¹Based on National Research Committee 2007 Recommendations, “no work” is maintenance requirements for a mature horse in a stall with no or little turnout, “light work” is 1-3 hours of activity per week (riding, driving, light training, showing, etc.) and “moderate work” is 3-5 hours of activity per week (riding, driving, training, showing, etc.).

²Based on hay nutrient levels of minimum 8% crude protein, 0.85 Mcal DE/pound and a starch and sugar (ethanol soluble carbohydrate or simple sugars) content of 15% or less.

 

Table 2. Feeding Recommendations with Vegetable Oil Supplementation for Draft and Draft Cross Horses with PSSM.

Draft/Draft Cross Weight and Activity Level	Daily Digestible Energy Requirements1	Hay (lb per day)2	Triple Crown 30% (lb per day)	Vegetable Oil (cups/ounces per day)	Legends Performance Pelleted or Triple Crown Complete (lb per day)
1200-lb No Work	16.49 Mcal	17	1	2/16	-
41200-lb Light Work	21.79 Mcal	18	-	2/16	4
1200-lb Moderate Work	25.38 Mcal	18	-	2/16	6
1300-lb No Work	17.87 Mcal	18	1	2/16	-
1300-lb Light Work	23.56 Mcal	18	-	2/16	4
1300-lb Moderate Work	27.49 Mcal	18	-	2/16	7
1400-lb No Work	19.24 Mcal	20	1	2/16	-
1400-lb Light Work	25.38 Mcal	18	-	2/16	5
1400-lb Moderate Work	29.61 Mcal	18	-	2/16	8
1500-lb No Work	20.62 Mcal	20	1	2/16	-
1500-lb Light Work	27.19 Mcal	20	-	2.5/20	5
1500-lb Moderate Work	31.72 Mcal	20	-	2.5/20	8
1600-lb No Work	21.99 Mcal	22	1	2.5/20	-
1600-lb Light Work	29.0 Mcal	22	-	2.5/20	6
1600-lb Moderate Work	33.83 Mcal	22	-	2.5/20	9
1700-lb No Work	23.36 Mcal	23	1	2.5/20	-
1700-lb Light Work	30.81 Mcal	24	-	2.5/20	6
1700-lb Moderate Work	35.95 Mcal	24	-	2.5/20	9
1800-lb No Work	24.74 Mcal	25	1	3/24	-
1800-lb Light Work	32.63 Mcal	26	-	3/24	6
1800-lb Moderate Work	38.06 Mcal	26	-	3/24	9
1900-lb No Work	26.10 Mcal	26	1	3/24	-
1900-lb Light Work	34.44 Mcal	28	-	3/24	6
1900-lb Moderate Work	40.18 Mcal	28	-	3/24	10
2000-lb No Work	27.49 Mcal	28	1	3/24	-
2000-lb Light Work	36.25 Mcal	30	-	3/24	6
2000-lb Moderate Work	42.29 Mcal	30	-	3/24	10
2100-lb No Work	28.86 Mcal	30	1	3/24	-
2100-lb Light Work	38.06 Mcal	30	-	3/24	6
2100-Moderate Work	44.41 Mcal	30	-	3/24	10
2200-lb No Work	30.24 Mcal	31	1	3/24	-
2200-lb Light Work	39.88 Mcal	32	-	3/24	7
2200-lb Moderate Work	46.52 Mcal	32	-	3/24	11

¹Based on National Research Committee 2007 Recommendations, “no work” is maintenance requirements for a mature horse in a stall with no or little turnout, “light work” is 1-3 hours of activity per week (riding, driving, light training, showing, etc.) and “moderate work” is 3-5 hours of activity per week (riding, driving, training, showing, etc.).

²Based on hay nutrient levels of minimum 8% crude protein, 0.85 Mcal DE/pound and a starch and sugar (ethanol soluble carbohydrate or simple sugars) content of 15% or less.