Equine Nutrition & Feeding

1. Equine Nutrition & Feeding Peggy M. Auwerda

2. Time-Budgets Feral Horses • Select highest fiber, lowest protein content • 70% of its day foraging Stabled Horses • 10% of their day feeding • Meal fed

3. Digestive Tract • The Mouth- first part of digestive system. • Mouth has 2 main functions- masticate food and wet food with saliva.

5. Mastication • Jaw sweeps 60,000 times/day when grazing • Saliva contains little, if any amylase

6. Digestive Tract • Stomach – • 9-15 liters • Trickle feeders • Transit time <2 hr • Cardiac sphincter does not relax to allow regurgitation

7. Digestive Tract • Small Intestine • 30% of digestive tract • 40-50 liters • Transit time – 45 min to 8 hrs • α-Amylase – low & varies widely between horses • Starch digestion occurs in the stomach and small intestines • Amino acids and fat digested and absorbed in small intestine • Vitamins/minerals absorbed in small intestine

8. Digestive Tract Hindgut – 60% of digestive tract capacity • Cecum – • 25-35 liters • Transit time < 5 hr • Large Colon • 50-60 liters • Small Colon • 18-19 liters • Large & small colon transit time 48-72 hours • Fiber digesters most active pH of 6.2-6.8 • Starch digesters prefer pH 5.2 – 6.0

9. Aspects of The Foal GI Tract • Small digestive tract • The small intestine does not increase in length from 4 wks of age • Cecum not fully functional until 15-24 mo of age • The large intestine increases with age even up to 20 yrs

10. Metabolized For Energy Volatile Fatty Acids Gas Wasted Energy B-vitamins & Vit. K Protein and Amino Acids? Microbial Fermentation Microbe Fibrous & Non-Fibrous Carbohydrate

11. Starch is an important and valuable component of the equine diet. Equine athletes need carbohydrates for efficient energy use. Mares need carbohydrates to help produce healthy foals. Mares need carbohydrates for milk production. Starch

12. %

13. Postprandial Cecal pH Change

14. Starch Overload • Starch not digested in SI is delivered to hindgut for bacterial fermentation. Too much starch may… • Cause radical changes to hindgut flora • Increase VFA & lactic acid concentrations – hindgut acidosis • Cause laminitis, colic, endotoxemia, metabolic acidosis, behavioral problems (wood chewing) • Critical capacity for hydrolysable carbohydrate overload ~0.4% of BW Cuddeford, D. 1999; Harris et al. 1999

15. How hindgut acidosis can occur in hindgut and how it can be attenuated Pagan, J. 2007. Feedstuffs

16. Carbohydrates

17. Starch Comparisons (what’s low, what’s high)

18. Methods Of Maximizing Starch Digestion In Small Intestine • Properties of the starch granule • Grain processing • Plant cell walls • Transit time through the small intestine • Availability & concentration of enzymes

19. REMEMBER! “The number one cause of deaths from colic is from starch overload due to feeding mismanagement.” Dr. John Reagor, PhD Chief of Toxicology Texas Veterinary Medical Diagnostic Laboratory

20. Hyperglycemia occurs after digestion of grain meals Affects substrates utilized during exercise Glucose & insulin peak 60-90 min after a meal Insulin promotes fat storage Sugary meals before exercise will  CHO to muscle & ↓ fat oxidation Glycemic Response

22. Feeding Horses • Feed intake usually expressed as • % of Body Weight • Lbs feed/100 lbs body weight • Free Choice • Forages – Maximize in the ration • Provide fiber & energy • Min. at least 1% of body weight (dm basis) • Concentrates • Provide energy • Supplements • Provide protein, minerals and vitamins

23. Estimating Weight (lbs) Heartgirth (in) x Heartgirth (in) x Body Length (in) 330

24. Body Condition Score Measures amount of body fat (1-9 scale) Determines balance between energy intake & expenditure Simple, repeatable, consistent method Comparison between animals EnergyDetermines Weight & Condition Of Horse

25. Body Condition Score Fat laid down in predictable patterns Organs Behind the shoulder Ribs Rump Back Withers Head and Neck

26. Body Condition Score Evaluation Visual assessment and actual touch Palpate fat areas Avoid mistaking longer hair covering for fat areas Avoid being fooled by conformation differences

27. Body Condition Scoring • 1-3 Poor-Thin • 4 Can see ribs, vertebra ridge evident • 5 Back flat, can’t see ribs, but can feel them • 6 Crease down back, fat deposits • 7-9 Fleshy - Extremely fat

28. Time & Additional Grain Required To Improve BCS by 1 level

29. Optimum Body Condition Score Each horse has its own ideal condition for the breed & use Average horse 5-6 Broodmare 5-7 Breeding stallion 5-6 Performance horse 4-6

30. Building a Horse Ration • Start with horse needs • Maximize forage • Add energy if needed • Add protein & minerals if needed • Consider adding vitamins & supplements • Consistency is key to good feeding practices Feed concentrate that makes-up the difference between nutrients needed & nutrients in roughage

31. Grass Bromegrass Orchardgrass Tall Fescue Timothy Grain Hay Oat Hay Wheat hay Straw Legume Alfalfa Birds Foot trefoil Clovers Lespedeza Forages are the FoundationPasture, Hay

32. Good Quality Sources: Beet Pulp Soybean Hulls Dried Citrus Pulp Dried Apple Pectin Pulp Alfalfa Meal Poor Quality Sources: Peanut Hulls Oat Hulls Ground Straw Cottonseed Hulls Rice Hulls Rice Mill Feed Ingredients Used In Place of Hay for Roughage

33. Forage Isn’t Everything • Most do not have all the minerals &/or vitamins a horse requires. Four ways to add these. • Add 1 to 4 oz mineral or mineral/vitamin supplement per day or • Add 1 to 2 lbs ration balancer (mineral plus protein) per day or • Feed 5 to 7 lbs fortified grain per day or • Feed 12 – 14 lbs complete feed (forage & grain)

34. Oats variable crimped vs. whole Corn cracked, steam rolled Barley Sorghum & wheat less than 30% rolled, cracked, flaked, Energy Sources - Grains

35. Fat/Fatty Acids • No gall bladder • Horses can be safely fed up to 20% fat in the total diet • Energy from fat is 90% utilizable • Often used to supplement calories for hard-working horses and hard keepers • Reduction in DM intake & bowel weight • Calmer temperament

36. Protein • Muscle & bone growth, milk production, fetal growth, normal metabolism • Most horses requirements can be met with good quality hay or pasture forage

37. Protein • Quantity = amount • Quality = amino acid balance • Very important for young horses • Lysine, methionine, tryptophan most limiting for growth & milk production

38. Soybean Oil Meal Flax - Linseed Meal Sunflower Meal Cottonseed Meal Peanut Meal Corn Gluten Meal Whey Dried Skim Milk Sources of Protein for Horses

39. Minerals • Content in the diet • Determined by soil & water • Quality of feed & proportion of grain to hay • Macro-minerals • Ca & P - quality forages usually provide adequate amount • This ratio is very important: 1.5:1 to 2:1 • Grains are rich in P and low in Ca • NaCl (Salt) • Salt block will meet many horse’s needs • If horses sweat a lot - need salt in the ration • Trace Minerals • Look for iron, zinc, copper, selenium

40. Minerals • Macro-minerals • Ca & P - quality forages usually provide adequate amount • This ratio is very important: 1.5:1 to 2:1 • Grains are rich in P and low in Ca • NaCl (Salt) • Salt block will meet many horse’s needs • If horses sweat a lot - need salt in the ration • Trace Minerals • Look for iron, zinc, copper, selenium

41. A guide to the recommended concentrations of trace elements in the diet, mg/kg dry matter. (Modified fromthe NRC 2007). These will need to be adjusted to suit individual circumstances, growth rate and appetite etc.

42. Vitamins Fat soluble: • stored in body - A, D, E, K • Toxicity’s can occur if fed in excess Water soluble: • must be continuously supplied • B-complex; niacin, thiamin, riboflavin

43. Vitamins • High quality fresh forages = maintenance for mature horses • Hay is poor in Vitamin A • Supplement Vitamin A in the ration • Exposure to sunlight provides Vitamin D

44. Guide to recommended levels of Fat-soluble vitamins (need to be adjusted according to individualcircumstances).

45. Adult (no work) Working Light exercise Moderate exercise Heavy exercise Very heavy exercise Stallions Pregnant Mares < 5 mo 5th, 6th, 7th, 8th, 9th, 10th, 11th mo Lactation 1st, 2nd, 3rd, 4th, 5th, 6th mo Growing 4, 6, 12 mo 18 mo Light exercise Moderate exercise 24 mo Light exercise Moderate exercise Heavy exercise Very heavy exercise Nutrient Requirement Varies With Class of Horse – NRC 2007

46. Water • Essential for all body functions • Temperature regulation • Feed digestion • Amount of water intake • Level of exercise • Ambient temperature • Quality of feeds in ration • Proportion of diet that is forage • Minimum 1 gallon/100 lbs BW/day

47. Size: body weight Environment Individual differences Dry matter intake: 1.5% of the BW Most - energy requirements are met with forage alone Maintenance

48. Recommended Daily Feed Intakes as % of Body Weights

49. Nutrient Considerations Reduced salivation CF digestibility ↓ Total fiber < 30% CP digestibility ↓ 10-14% CP Energy: Increase soluble carbohydrates, fats, & oils Caloric Restrictions Supplement minerals & vitamins including vitamin C Geriatric Horses

50. 28 yr old horse Selection of Feed For the Geriatric Horse • Highly palatable • Easy to chew & swallow • Forage - chopped, cubed, pelletized, or in a wafer • Grains - rolled, crimped, or flaked 32 yr old horse