Predicting Feed Consumption and Dry Matter Intake
In general, the first step of the ration evaluation process is to determine daily dry matter intake or how much feed should your horse be eating. Feeds are composed of two basic components – 1) water and 2) dry matter. The dry matter is composed of protein, fiber, carbohydrates, fat, minerals, etc. Animals consume feed to meet their daily needs for these nutrients and therefore, it is important to establish the amount of feed potentially consumed.
Feed consumption or intake calculations are based on body weight, level of activity, reproductive status and growth stage. These physiological factors also influence energy requirements and therefore, the percentage of forage and grain required to meet energy needs.
The Feed Consumption Table is adapted from the 1989 NRC for horses. These values are averages based on typical horses and forages. Individual intakes may vary from the average, but should be within the reported range. If intake is substantially different, check the following:
- Body weight – use a livestock scale or heart girth tape to get a reliable weight.
- Scales – check the scales used to weigh the feed for accuracy. Weigh a variety of objects of known weight (such as dumbbells or plate weights) and adjust as required. Use several weights, such as 2, 5, and 10 lbs. to check accuracy across a range of weights.
- Wasted feed – horses will often toss hay around their stall when pulling it from the manger or sometimes, from boredom. Both hay and grain refusals should be weighed. Weigh the refused feed and deduct it from the total to determine actual consumption.
Feed Consumed = Feed Offered – Feed Refused
Predicting dry matter intake is simple. From the Feed Consumption Table, locate the class that best describes your horse and calculate as follows:
Lbs. dry matter intake = Body Weight x (%Dry Matter Intake/100)
Example: An 1100 lb. horse under light work consumes about 1.8% of it’s body weight per day.
Lbs. dry matter intake = 1100 x (1.8/100) = 19.8 Lbs.
Taking this a step further, based on forages of average quality, approximately 65% of the diet should be forage and 35% grain to meet daily energy needs.
Lbs. Forage dry matter = 19.8 x (65/100) = 12.87 Lbs.
Lbs. Grain dry matter = 19.8 x (35/100) = 6.93 Lbs.
If the diet consists of only hay and grain, the amounts to feed can be calculated by assuming both feeds are 90% dry matter.
Amount fed = Lbs. dry matter / (Dry Matter %/100)
Lbs. Hay fed = 12.87 / (90/100) = 14.3 ~ 14 Lbs.
Lbs. Grain fed = 6.93 / (90/100) = 7.7 ~ 8 Lbs.
The dry matter intake values presented are averages. An individual horse may consume more or less than predicted, but should be within the estimated range. The percentages of forage and grain are guidelines based on average quality forage. The percentages will vary depending upon forage quality. Typically, the better the forage quality, the lower the amount of grain required. Use your forage analysis to determine the proper level of grain to feed. Always consult with your nutrition professional to determine the best feeding program for your horse.