Nutritional Management of Overweight, Pasture-Fed Horses

Jennifer C. GillB. A. Equine Science PhD Graduate Research Asst.Dept. of Animal SciencePolk Hall 209, NCSUjcgill2@ncsu.edu610-703-7861

• Dr. Shannon Pratt-Phillips– Associate Professor

– Specialization: Equine Nutrition, Exercise Physiology• Dr. Paul Siciliano

– Professor

– Equine Nutrition, Grazing Management• Dr. Scott Whisnant,

– Professor

– Neuroendocrinology• Dr. Richard Mansmann, DVM

– Equine Podiatry and Rehab.

Weight loss in twenty-four overweight client-owned

horses

Funded by NC Horse Council

AAVN Research ConferenceNashville, TN 2014

Abstract and Presentation

• Digestible energy intakes of thirty-five horses over a 42-d period

• Funded by Kemin® Industries Inc. (KemTRACE)• 2015 Equine Science Society Research Symposium• St. Petersburg Beach, FL

• Equine Research Unit NCSU (Spring 2015)– Pasture digestible energy intakes

• GPS and heart-rate monitors to measure energy expenditure

Overview

• Identifying the Overweight Horse• Feeding for Weight Loss • Controlling Pasture Intake in

Overweight Horses• Special Topic: Equine Metabolic

Syndrome

Research

• Prevalence of obesity• Reasons:

– Overfeeding• Choices • Pasture?

– Recognition• Incremental weight gain

– Weight reduction is difficult

Evaluation of Body Condition Score• An ideal body weight

is different for every horse

• 1-9 point scale• 1 = emaciated• 9 = obese

• Evaluation of fat deposition

Henneke, 1983

What is a Healthy Body Condition?BCS = 5

BCS = 3

BCS = 8

BCS = 4

BCS = 6

BCS = 9

www.the horse.com

Excess Fat – Why is it so bad?

• Similar risks seen in humans and small animals

• Adipose (fat) tissue is an endocrine organ that produces and regulates hormones

• Pro-inflammatory cytokines – “the bad cell signals that cause disease”

http://www.mdpi.com/ijms/ijms-15-06184/article_deploy/html/images/ijms-15-06184f2-1024.png; ;

• Heightened levels, especially in horses with a history of laminitis • The degree to which an individual, overweight horse is affected varies

– Obesity-associated inflammation is likely age dependent• Obesity may not cause immediate complications, but may cause a

decline in health as the horse ages

Vick et al. 2007; Suagee et al. 2011; Holbrook et al. 2012; Goer 2015

InsulinCortisolGlucose

Why Diet?

• Maintaining health– A better quality of life as they age

• Disease prevention – Laminitis– Insulin Resistance– Obesity-related colic (lipomas)– Arthritis and musculoskeletal injuries

• Better performance and stamina• Thermoregulation

Determining Body Weight• Large animal scale

• Weight tape

• Body measurements– Girth circumference– Belly circumference– Neck crest

Determining Body Weight• By calculation (Hall)

– BW (kg) = girth circumference (cm)2 × body length (cm)/11,880

– R2 = 0.42; underestimated BW• http://www.thehorse.com/articles/31852/adult-horse-weight-calculator

– Martinson et al. (2014)• BW (kg) was [girth (cm)1.486 × length

(cm)0.554 × height (cm)0.599 × neck (cm)0.173]/3,596, 3,606, and 3,441 for Arabians, ponies, and stock horses

– R2 = 0.92; more accurate

Energy (Calorie) Requirements• Nutrient Requirements for Horses - NRC 2007

– based on weight, basal metabolism, and activity level

• Idle horse– Maintenance ± 10% based on basal metabolism

and voluntary exercise• Performance horse

– Light Work, Moderate Work, Heavy Work• Growing horse (< 36 months)

Feeding for Weight Loss

1) Reduce Feed Intake

2) Increase Energy Expenditure

Energetics for Weight Loss

• A 500 kg (1,100 lb) horse requires 16.65 Mcal/d to maintain its current body weight (NRC 2007)– 1 unit change in BCS = 16-20 kg (35.2-44 lb) BW– 1 kg gain/loss = ~20 Mcal above/below maintenance

• A decrease in BCS from 7 to 6 involves a difference of ~ 400 Mcal total– Reducing intake by 4 Mcal/d will take 100 d

• 12.65 Mcal/d or less (500 kg horse)• 76% DE/calorie restriction level

Mcal: Mega calories; kg = kilograms; DE = digestible energy; NRC 2007

Reducing Feed Intake

• 70 - 90% of maintenance DE requirements (calories)

• 1.25 - 1.5% BW in total DMI

1) Body weight, requirements, and nutritional analysis2) Weigh all feeds consumed per day3) Maintain a balanced nutritional ration for

vitamins/minerals

Van Weyenberg et al. 2008; Dugdale et al. 2010; Argo et al. 2012; McGowan et al. 2013; Gill et al. 2015 (unpublished)

http://nrc88.nas.edu/nrh/

DMI: dry matter intake; DE: digestible energy

Calorie Restriction• Reduce Concentrates

– Feed small meals• Grass hay• Extruded feeds• High fiber/fat, low starch feeds

» Hoffman et al. 2003

• Ration balancer• Vitamin/mineral supplement• Hay pellets or cubes

• Reduce pasture intake• Grazing muzzle• Time at pasture• Dry lot (12 m x 12 m or 24 m x 24 m)

Going “Grain-Free”

• Reducing grain and feeding hay – Horses are hindgut fermenters – Possible for idle horses– A nutritional analysis is essential– Weigh and feed hay at the proper amount

• > 1.0% BW in forages for healthy gut

Hay Quality

• Choosing a lower calorie dense hay means you can feed the same amount and achieve calorie restriction– 2.2 Mcal/kg hay = 0.015 X 500 kg = 7.5 kg

x 2.2 Mcal/kg = 16.50 Mcal/d – 1.7 Mcal/kg hay = 0.015 X 500 kg = 7.5 kg

x 1.7 Mcal/kg = 12.75 Mcal/d

• 16.50 vs. 12.75 Mcal/day (78% DE restriction)

Controlling Pasture Intake in Overweight Horses

• Pasture is a valuable resource

• 1.5 – 2 acres per horse• 70% of the time grazing +

voluntary activity• Some horses can

maintain BW on pasture alone– Depends on many factors– Lush pasture = Obesity?

CAUTIONS

• Modern pasture is high in sugars: glucose, fructose, and fructan – Spring and late fall

• Fructan cannot be digested in the SI – Fermentation in the LI– Decreased cecal pH– Possibility for colic or laminitis

SI: small intestine; LI: large intestine

Pasture Dry Matter Intake (DMI) Estimates • Horses may consume a large amount of

pasture if given the opportunity

Marlow et al. 1983; Moffett et al. 1987; Fleurance et al. 2001; Grace et al. 2002a,b; McMenimen et al. 2003; Edouard et al. 2009; Fleurance et al. 2009; Glunk and Siciliano 2011; Longland et al. 2011

24 hour pasture intake estimates for MATURE, IDLE HORSES

1. 20.3 g/kg LW, 97g/LW^.75 = 2.0% BW

2. 21.9±2.4 kg/d,166.2 ± 20.8g/LW^.75/d = 3.2% BW

3. 98.6g DM/kg BW^.75 = 2.0% BW

4. 15-22 gDM/kg BW = 1.8% BW

5. 2.34 kg/100 kg BW and 56.2 g/100 g DMI = 2.3% BW

(1) Dulphy et al. 1997 (mature light horses), (2) Fleurance et al. 2001 (mature, 674 kg mares), (3) Chenost and Martin-Rosset 1985 (mature light horses), (4) Marlow et al. 1983 (mature thoroughbreds), (5) Chavez et al. 2013 (mature light breed geldings)

2.4% BW

2.3% BW

24-h Pasture Intake (calories)• Example:

– Two 500 kg BW mature idle horses

– 5 acres of pasture – 1,300 kg DM/acre; 2.2 Mcal

DE/kg) – DMI ~ 2.3% BW– DE intake 25.30 Mcals/d

• > NRC (16.65) by 8.65 Mcals/dDulphy et al. 1997; Fleurance et al. 2001; Chenost and Martin-Rosset 1985; Marlow et al. 1983; Chavez et al. 2013Example by Siciliano, 2012

Controlling Pasture Intake: DMI Rates

• Horses increase intake rate when time at pasture is restricted – DMI/ h of grazing is not linear

Dowler and Siciliano 2012DMI: dry matter intake; h:hour

Siciliano 2013

NRC 2.0% BW/d in DMI

Potential factors that may influence pasture intake:

• Plant chemical composition– NDF is inversely proportional to intake

• Plant species/variety– Selective grazers/palatability

• Horse physiological class• Gorging behavior?

NDF: neutral detergent fiber

Dry Lots

Grazing Muzzles• Glunk et al. (2014)

• “Interaction of Grazing Muzzle Use and Grass Species on Forage Intake of Horses”

• Different types of grasses and pasture intake efficiency• 30% of non-muzzled intake

• Longland et al. (2012)• “The effect of wearing a grazing muzzle vs. not wearing

a grazing muzzle on intakes of spring, summer and autumn pastures by ponies”

• 0.047 % BW/h

Conclusions for feed restriction:• Don’t feed free-choice, round barrel hay

to overweight horses• Don’t feed a large amount of grain• Don’t let obese horses have 24 h access

to lush pasture• Do utilize dry lots and exercise paddocks• Do consult with an equine nutritionist

and your veterinarian about restricting intake

• Do use a grazing muzzle Horse.com

Increase Exercise

• Encourage play• Large enclosures• Riding • Walking, ponying, or lunging

https://www.facebook.com/video.php?v=820226518039218&pnref=story

http://4legsandatail.org/the-art-of-ponying

Special Topic: Equine Metabolic Syndrome

paardenlifestyle.com

Equine Metabolic Syndrome (EMS)• EMS is obesity accompanied by…• Laminitis

• Endocrine-mediated (inflammatory)• Pasture-associated (oligofructose)• Hyperinsulinaemia

• Insulin Resistance• Fasting serum insulin concentration > 20 μU/ml• Fasting blood glucose >100 mg/dl

• Regional Adiposity• Neck crest• Large fat deposits

Management of EMS• Consult with your veterinarian and equine nutritionist• Endocrine blood panel (elevated insulin/Cushing’s)• Oral or intravenous glucose tolerance test• Reduce body weight• Exercise as much as possible

– Increases metabolic efficiency (improvement in insulin sensitivity)

• Powell et al., (2002) “Effect of short-term exercise training on insulin sensitivity in obese and lean mares”

• Treiber et al., (2005) “Dietary energy sources affect insulin sensitivity and B-cell responsiveness of trained Arabian geldings during endurance exercise”

NCS: non-structural carbohydrates

Thank you!

• Questions?