0. Horse Nutrition – Seasonal Changes
February 2017
Karen E. Davison, Ph.D.
Director, Equine Technical Solutions
Purina Animal Nutrition

1. Do changing seasons mean nutritional changes for horses?
Forage amount and quality
Ambient temperature
Forage quality
Calorie Requirements
Horse activity level

2. Forage – The Foundation of the Diet
Does all forage provide the same nutrition?
Horses on lush, high-quality, green pasture most likely have all vitamin requirements met…they also probably have protein and energy requirements met as well. The one nutrient group that will need to be supplemented would be minerals.

3. Does your pasture provide nutrition or just space to roam?
Did you know?
Does your pasture provide nutrition or just space to roam?
Horses consume 2 - 3% of body weight per day in dry matter ( lbs/1000 lb horse)
Voluntary consumption declines when forage quality declines
Hay is roughly 87% DM, pasture around % DM
11.5 pounds of hay = 10 lbs DM
pounds pasture = 10 lbs DM
Min of 1% BW hay or pasture equivalent is necessary for proper gut health and function
Spot grazing?
Manure piles?
Pasture management

4. Good Quality Hay High leaf:stem ratio Small diameter stems
Few seed heads/blooms
Fresh smell and appearance
Free of molds, weeds and trash
Color
Does season affect hay quality?
Plant maturity at time of harvest
Ambient temperature during growing period
Amount of moisture during growing period

5. Is Forage All They Need?
Fat & Shiny = Healthy?

6. Body Condition Score (Henneke, 1983)
A- Crest of Neck B- Withers C- Topline D- Tailhead E- Ribs F- Behind Shoulder
Thin
Underweight
Overweight
Emaciated
The Henneke body condition score chart is easy to learn and is an excellent tool to help evaluate calorie nutrition. It is very objective and is based on evaluating where horses deposit body fat. A score of 1 is a very emaciated horse and a 9 is an extremely obese horse. The 5 – 6 range is the ideal range for most horses. You can find this chart in the Purina horse product brochure or on our website. Notice that it takes 40 – 50 lbs to gain or lose a body condition score in an average horse.
Ideal
Obese
40 – 50 lbs BW to change 1 body score 1 2 4 5 6 3 7 8 9

7. Ideal Body Condition? Reduced energy stores Decreased muscle mass
BCS < 4.0
Reduced energy stores
Decreased muscle mass
Reduced stamina and recovery
Reduced cold tolerance
BCS > 6.0
Increased dead weight
Impair thermoregulation
Excess weight on joints and hooves
BCS 7.0+ increased risk for insulin resistance and laminitis
It must be emphasized that these NRC values are only a guide and it can be hard to predict the needs of an individual horse - some will fall into the category of “easy keeper” in that they seem to maintain body weight on almost no food, whereas there are other horses that seem to lose weight even though they fed a huge amount - these horses are “hard keepers”
The best guide to a horse’s energy needs is the regular use of body condition scoring. This system, which is used internationally including Japan, uses a scale of 1-9 where 1 is very thin and 9 is very fat. A score of 4 to 5 is best for most sport horses. This photo shows an endurance horse that is on the thin side, with a condition score of 3 to 3.5.
You should condition score your horse every 2 months or so and adjust feeding and exercise programs depending on changes in body condition.

8. Missing Nutrients? Good Pasture Adequate calories, protein, vitamins
Lacking minerals, especially trace minerals
Good Hay
Adequate calories
Lacking protein, vitamins and minerals
In addition to controlling calories and managing hay intake, the other short-fall of an all-hay diet is that hay does not provide a nutritionally balanced or adequate diet for a horse. Good quality pasture is different nutrition than the same pasture cut and baled for hay. There is also poor quality pasture and poor quality hay, so there isn’t just one good answer for which is better nutrition. But, even on good pasture, most horse owners understand the concept of spot grazing? Do horses prefer to graze the tall grass? No, they leave the taller grass and choose to graze on the short, very immature, new growth in a pasture. That’s not the same forage as would be harvested to make hay. The hay is the taller plant so it is less nutritious than the pasture plants the horse would graze. Pasture may provide adequate calories, protein and vitamins for horses at maintenance but it will be short most minerals, especially trace minerals such as copper and zinc. Hay will often provide adequate calories but the protein, vitamins and minerals will not be in adequate amounts to support optimal health even in maintenance horses and surely not for performance horses or growing horses. Even high protein hay like alfalfa won’t provide adequate protein quality, amino acid balance, to support optimal muscle mass and performance…more on that later…
Age/Activity Level?

9. Calorie intake is easy to evaluate, other nutrients are more difficult
What about protein, vitamins, minerals?
Protein – specifically amino acid balance
hair coat, muscle tone, hoof growth and quality, antibodies
Vitamins/minerals
immune function, bone density, hoof growth and quality; often not visible signs until significant deficiency over time

10. Horse nutrition needs do change with seasonal changes
Supplement forage with a product that will meet protein, vitamin and minerals needs when fed to maintain body condition
Pay attention to body condition
Pay attention to recommended minimum feeding rates
Pay attention to hay consumption
Feed ration may change with the seasons
Amount fed
Possibly different product

11. Questions?