Horse Nutrition October 29, 2012

1. Horse NutritionOctober 29, 2012 M.E. Persia Iowa State University 4/16/2012

2. Digestive Anatomy Adapted: Atlas of Topographical Anatomy of the Domestic Animals, Popesko, P., W.B. Saunders

3. Purpose of Feeding • Physiological Stage • Growth, pregnancy, lactation • Geriatrics • Environment • Health & Well Being (body condition) • Clinical Conditions • Exercise

4. Feeding Behavior and General Considerations • Feeding behavior affects feed intake • Forages of considerable variety are primary diets consumed by wild horses • 65% Grasses and Sedges • 25% Shrubs • 5% forbs (such as wildflowers) • Preference between wild and domestic horses for grasses is similar but difficult to measure and data are inconsistent. • Highly selective grazers and will graze down to ground level. • Prefer young, rather than mature plants • Grasses are preferred to legumes and herbs.

5. Appropriate & Palatable Forage Species • Cool Season Grasses • Perennial ryegrass, meadow fescue, timothy, orchardgrass, creeping red fescue, Kentucky bluegrass, brome grass, tall fescue • Warm Season Grasses • Bermuda grass, crabgrass, prairie grass, India grass, canary grass, wheat grass, switch grass • Legumes • Alfalfa, white clover, vetch • Herbs • Dandelion, ribgrass, chicory • Cereals • Oats, barley Soft brome

6. Forage quality

7. Anti – Nutrients in Forage • Many warm season grasses contain higher concentrations of oxalates and phytates – can lead to Calcium/Phosphorus concerns. • Cyanogenic glycosides are high in Sorghum, Sudan grass, hybrid Johnson grass, and Sorghum – Sudan hybrids; therefore, not recommended for horses.

8. Anti-Nutrients in Forage • Clostridium, Listeria can be issues with ensiled forages • Endophyte contamination • Mycotoxins • Yellow and White Sweet Clover – Penicillium spp. – product dicoumarol poisoning • Toxic plants

9. Insect Contamination - Blister beetles • 2 species of concern • Epicauta vittat • Epicauta pennsylvanica • Toxin = cantharidin • Fatal

10. Grazing Time • Constant Grazers • http://www.youtube.com/watch?v=s5FJgsHx6gY • Accounts for up to 1.5 – 3 miles per day • Move more than cattle (damage to pasture) • Horses will graze for 10 – 17 hours per day • Compared to cattle? • http://www.youtube.com/watch?v=L5xRBoyNIzc • Affected by light and season • 20 – 50% nocturnal (higher in summer) • Affected by group • Herd animals > single • Affected by gender, age, breed • Mares > stallions • Mature > weanlings • Yearlings > 2 year olds • Arabians > Thoroughbreds Crowell-Davis, et al., 1985; Kaseda, 1993; Mesochina et al., 2000, Rogalski, 1977

11. How much will a horse eat? Maximal DMI = 3 – 3.2% Body weight

12. General Feeding Considerations • Meet nutrient needs while maintaining normal feeding behaviors. • Forage based rations • Benefits? • Grain by-products, pasture, harvested forages • Forages should be a minimum of 1% of the body weight. • Example: 1,000 Lb horse • 1% = 10 Lb

13. Feeding Considerations • What is the management system?

14. Feeding Considerations • Does diet affect behavior? • http://www.youtube.com/watch?v=NyYLfUlwfMs • Goal is to prevent boredom that could lead to stable “vices” and “sterotypies” • Orosensory sensations of feeds are extremely important for horses and contribute to palatability. • Smell, texture, and taste • Prefer variety

15. Feeding considerations – oral behaviors • Lack of fiber, too much grain in the diet • Reduce gastric pH (3.3 compared to 5.5) • Lower saliva production • Associated with increase oral behaviors such as “cribbing” • Hay should be at least 14 Lb per day if pasture can’t be offered. • Feed at least 2 types of forage, provide pasture if possible. • Feeding frequency of grain (more often is not better) • Limit concentrate feeding • http://www.youtube.com/watch?v=b4lmVaIqZIo&feature=related

16. Considerations for Senior Horses • Age related changes in nutrient digestion, absorption and metabolism may occur • Reduction in digestion and absorption in the large intestine (5% lower digestion of CF) • 5-10% reduction in protein digestibility • Supplemental lysine (20 g/d) and threonine (15 g/d) – may help reduce the lean tissue loss • Dental issues • Energy requirements – decrease 15 – 20% • In the absence of disease • With disease can increase as much as 40%

17. Considerations for heat and cold stress • Water – during hot periods, voluntary water intake increases 30 – 75% • Salt should be available during hot weather • Additional vitamins and minerals do not seem to be useful • During cold weather – DE should be increased 2 – 3% • Hay should be offered ad lib to allow horses to feed to energy requirement

18. Considerations for exercise • How exercise is defined • Light • 1-3 hours weekly • Mean heart rate is 80 beats/min • Recreational trail riding • Moderate • 3-5 hours weekly • Mean heart rate is 90 beats/min • Show horses, light ranch work • Heavy • 4-5 hours weekly • Mean heart rate is 110 beats/min • Eventing, race training • Very Heavy • 6-12 hours weekly (or 1 hour speed work) • Mean heart rate is 110-150 beats/min • Elite eventing, racing

19. Exercise Considerations - Energy • Digestible Energy • Light work = (0.0333 x BW) x 1.20 • Moderate work = (0.0333 x BW) x 1.40 • Heavy work = (0.0333 x BW) x 1.60 • Very heavy = (0.0363 x BW) x 1.90 Ex. 500 Kg race horse = (0.0363 x 500) x 1.9 = 34.5 Mcal per day (> 70% more energy than light working)

20. Exercise Considerations - Protein • Protein requirement for maintenance • BW x 1.26g CP/Kg BW • 500 Kg horse x 1.26 = 630 grams Crude Protein • Range of 1.08 – 1.44 as the multiplier • Exercise losses in protein are due to: • Muscle gain • Nitrogen lost as sweat • Add protein to basal requirement • Light = BW x 0.089 g CP (630 + 44.5 g = 675 g CP) • Moderate = BW x 0.177 g • Heavy = BW x 0.266 g • Very heavy = BW x 0.354 g (630 + 177 = 807 g CP) • 20% more protein needed than lightly worked horses

21. Clinical Nutrition • Hyperkalemic periodic paralysis (HYPP) • Polysaccharide storage myopathy (PSSM) • Developmental orthopedic disease (DOD) • Laminitis • Nutritional Secondary Hyperparathyroidism • Gastric ulcer syndrome • Colic • Enterolithiasis • Recurrent airway obstruction • Obesity

22. Body Condition Scoring • Necessary means of managing weight when weighing isn’t possible. • Farm/Stable Dependent. • What is function? • It is dependent on structure

24. BCS = 1

25. BCS = 2

26. BCS = 3

27. BCS = 4

28. BCS =5