2/6/2019

1

FEEDING GROWING HORSES

February Educational Webinar 2019

Dr Tania CubittPerformance Horse Nutrition

2

OUTLINE

• Nutrient Requirements– In utero

– Post natal

• Disorders

– Role of nutrition 

– Ideal Diets

3

WHY FEEDING IMPORTANT

• FUTURE EQUINE ATHLETES

• RAPID SKELETAL GROWTH

• MINERALS ARE BEING DEPOSITED

IN BONE

• IF POOR NUTRIENT INTAKE ‐ POORSKELETON

2/6/2019

2

4

BEFORE BREEDING

Ashworth & Antipatis, 2001; Hostetler et al., 2003

Phase Element Vitamin

Before Implantation Ca, Fe, Cu, Zn, Co, I, Mn, Se

Vit. A, E, B12, Choline, Folic acid, pantothenic acid, riboflavin, inositol

After Implantation Ca, Cu, Zn, Se, I, Co, Fe, Cd

Vit. A, E, B12, Folic acid, pantothenic acid, riboflavin, inositol

Factors influencing the development of fertilized egg cell in several mammalian species

5

FOAL FEEDING – IN UTERO

EARLY GESTATION• <6 MONTHS

• EARLY EMBRYONIC LOSS

• FEED

• ENVIRONMENT

• 1ST 40 DAYS CRITICAL

• HEART DEVELOPED

• ~DAY 18‐20

• ZN, CU, VITAMIN A & D

Day 9

Day 24

Day 40

6

FOAL FEEDING – IN UTERO

Mid Gestation• Months 7 & 8

• Energy and protein increasing

• ~90 g/day fetal growth

• Vitamins & minerals crucial for fetal development

2/6/2019

3

7

FOAL FEEDING – IN UTERO

Late Gestation

• Months 9,10 & 11

• Gain ~ 80% BW

• 0.5 kg/d growth 

• Fortifying fetal liver stores

• Increased energy & protein 

requirements

• Increased mass = fat and muscle

8

IN UTERO DEFICIENCY

• LOW CALCIUM INTAKE OF PREGNANT MARES IS FOUND TO REDUCE INTRAUTERINE

WEIGHT GAIN OF THE FOALS (AUSTBØ AND DOLVIK, 1996).• PROBABLY BY DEPRESSED BONE MINERALIZATION

• LOW VITAMIN A STATUS DURING PREGNANCY AFFECTS FETAL GROWTH AND THE HEALTH STATUS

OF THE NEWBORN (BASU ET AL., 2003, GAZALA ET AL., 2003, ANTIPATIS ET AL., 2000).

• REDUCED ORGAN WEIGHT

• LOWERED ELASTIC FIBERS

• DELAYED LUNG MATURATION

• REDUCED GENE EXPRESSION

• MARES AT PASTURE VITAMIN A DEFICIENCY IS RARE, STABLED HORSES, LOWSUPPLEMENT, POOR QUALITY HAY (SCHUBERT ET AL., 1991)

9

IN UTERO DEFICIENCY

• COPPER STORED IN FETAL

LIVER

• MARES MILK LOW IN

COPPER

• COPPER DEFICIENCY CAN

PRODUCE BONE PROBLEMS IN

THE HORSE(COENEN ET AL., 2003; VAN WEEREN, 2003).

Copper in the equine fetal liver and in foals after birth (Hebeler et al., 1996; Van Weeren et al., 2003).

2/6/2019

4

10

IN UTERO EXCESS

PLACENTA CANNOT PREVENT DETRIMENTAL UPTAKE OF IODINE BY

THE FETUS – BE CAREFUL WITH SUPPLEMENTS CONTAINING

SEAWEED

CONSEQUENCES OF IODINE INTAKE BY THE MARE DURING LATE GESTATION AND THE

INCIDENCE OF GOITER IN NEW‐BORN FOALS (MEYER, 1998).Iodine intake of the mare 

(mg/day)Goiter incidence (%) other

6‐7 0 ‐‐

48‐55 3 Weakness, depressed muscle development

56‐69 10 Contracted tendons

100‐300 25 Retarded growth of skeleton

83 33 Disturbed leg conformation

288‐432 50 Long hair

375 100 Absorption, osteopetrosis, disturbed leg conformation

11

NUTRIENTS

• ENERGY

• PROTEIN• ESSENTIAL AMINO ACID LYSINE

• SINGLE MOST IMPORTANT AMINO ACID FOR GROWING HORSES

12

NUTRIENT REQUIREMENTS – NRC 2007

Growing animals

Wt. (lb)

ADG/Milk (lb/day)

DE (Mcal)

CP (g)

Lys(g)

Ca (g)

P (g)

4 mo. 370 1.85 13.3 669 28.8 39.1 21.7

6 mo. 476 1.59 15.5 676 29.1 38.6 21.5

12 mo. 708 0.99 18.8 846 36.4 37.7 20.9

18 mo. 853 0.64 19.2 799 34.4 37 20.6

Forage Concentrate Total

Nursing Foal 0 1.0 – 2.0 2.5 – 3.5

Weanling, 6mo. 0.5 – 1.0 1.5 – 3.0 2.0 – 3.5

Yearling, 12 mo. 1.0 – 1.5 1.0 – 2.0 2.0 – 3.0

18 mo. 1.0 – 1.5 1.0 – 1.5 2.0 – 2.5

2 yr. 1.0 – 1.5 1.0 – 1.5  1.75 – 2.5

Expected Feed Consumption by growing horses (% Body Weight), NRC 2007.

2/6/2019

5

13

COMMON QUESTIONS

• WHEN TO BEGIN FEEDING?

• MARES MILK PRIMARY

NUTRIENT SOURCE

• PEAK MILK PRODUCTION PRIOR

TO 3 MONTHS

• FOALS NEED SUPPLEMENTAL

FEED BY 90 DAYS OF AGE

14

CREEP FEEDERS

15

GROWTH DISORDERS

DEVELOPMENTALORTHOPEDIC DISEASE(DOD)

• DOD IS AN UMBRELLATERM THAT INCLUDES:• OSTEOCHONDROSIS• PHYSITIS• ANGULAR LIMBDEFORMITIES

• FLEXURAL DEFORMITIES• CERVICAL VERTEBRALMALFORMATIONS

2/6/2019

6

16

GROWTH DISORDERS

APPROXIMATE TIME OF ONSET OF CLINICAL SIGNS & SITESINVOLVED FOR DEVELOPMENTAL SKELETAL PROBLEMS

17

BONE GROWTH IN YOUNG HORSES

• AT BIRTH HORSES HAVE ONLY 17% OF THEIR MATURE BONE

MINERAL CONTENT

• BY 60 DAYS OF AGE, A HORSE SHOULD GROW TO AT LEAST 75% OF MATURE WITHER HEIGHT.

• MOST LOWER LIMB GROWTH IS COMPLETE BEFORE THE

YEARLING PHASE

• BY 18 MONTHS OF AGE, THE AVERAGE LIGHT HORSE WILL REACH

90% OF HIS MATURE HEIGHT. 

18

STAGES OF BONE GROWTH

• Fetus• CARTILAGE PRE‐FORM

• Bone depositing cells ‐Osteoblasts living in cartilage deposit spongy bone (Gray)

• Osteoblasts on shell of bone deposit compact bone (Black)

2/6/2019

7

19

STAGES OF BONE GROWTH

• Late Fetus & Neonate• Osteoblasts colonize the ends of bone and create separate centers of ossification 

(epiphyses)

• Neonate & Foal• Marrow cavity develops

• Hyaline cartilage develops to protect ends of long bones

• Growth Plate remains 

20

STAGES OF BONE GROWTH

• Horse• Marrow Cavity expands to full size

• Hyaline cartilage remains on the ends of bone

• Growth plate is converted to bone

21

GROWTH‐PLATE CONVERSION TO

BONE

• SHORT PASTERN – BOTTOM BEFORE BIRTH; TOP BETWEEN 9‐12 MONTHS.

• LONG PASTERN – BOTTOM UNITES WITH SHAFT AT OR SHORTLY BEFORE BIRTH; TOP 13 TO15 MOS.

• CANNON BONE – TOP UNITES WITH SHAFT AT OR SHORTLY BEFORE BIRTH; BOTTOM UNITES

WITH SHAFT AT ABOUT 18 MOS.

• SMALL BONES OF THE KNEE – TOP AND BOTTOM OF EACH, BETWEEN 18 MOS. AND 2  YEARS

• RADIUS‐ULNA – UPPER WEIGHT BEARING SURFACE, BETWEEN 15‐18 MOS.; DISTALSURFACES, BETWEEN 3 AND 3.5 YEARS

• HUMERUS – BOTTOM, BETWEEN 1.5 AND 2 YEARS; TOP, BETWEEN 3 AND 3.5 YEARS

• SCAPULA – GLENOID OR BOTTOM (WEIGHT‐BEARING) PORTION – BETWEEN 3 AND 3.5 YEARS

2/6/2019

8

22

EQUINE SKELETON

• MOST FRACTURES & INJURY OCCUR IN THE FORELIMBS

• CARRIES MOST WEIGHT , SIDEWAYS TORQUE

• FUTURITY QH RACING

• FUTURITY BARREL RACING

• FUTURITY CUTTING HORSES

• FUTURITY REINING HORSES

• YOUNG HORSE DRESSAGE

• YOUNG HORSE JUMPING

23

FACTORS THAT CONTRIBUTE TODOD

• NUTRITION

• GENETICS

• INJURY

• STRESS ‐MECHANICAL

• DISEASE

24

FEEDING THE FOAL

Why feeding is important•Nutrition mistakes are amplified

•Mistakes may result in reduced performance potential

2/6/2019

9

25

NUTRITION AND DOD

• ENERGY

• FOCUS ON MINERAL NUTRITION

• MACRO‐MINERALS

• CA + P

• TRACE MINERALS

• COPPER

• ZINC

• MANGANESE

26

NUTRITION’S ROLE IN DOD

DIGESTIBLE ENERGY

• EXCESS DE

• GROWTH RATE

• FOAL’S ACTIVITY, PUTS MORE STRESS/TRAUMA ON BONE

• FEEDING 129% NRC ENERGY REQUIREMENTS TO FOALS FROM 130 DAYS OF AGE RESULTED IN AN

INCREASED INCIDENCE OF LESIONS COMPARED WITH THE CONTROL GROUP (FED 100%) (SAVAGE ETAL., 1993).

• CYMBALUK ET AL., 1990 REPORTED AD LIBITUM CUBE FEEDING RESULTED IN A HIGHER INCIDENCE

OF CONFORMATIONAL AND LOCOMOTOR ABNORMALITIES AT 25MONTHS OF AGE THAN THE MORE

RESTRICTED DIET.

• GLADE AND BELLING IN 1984 COMPARED THE GROWTH OF FOALS FED EITHER 70 (R) OR 130% (H) OF THE NRC (1978) RECOMMENDED LEVELS FOR ENERGY. THE H GROUP SHOWED DEVELOPMENTAL

DISTURBANCES OF GROWTH PLATES WHEREAS THE R GROUP HAD NORMAL DEVELOPMENT OF THE

BONES BUT AT REDUCED SPEED.

27

OSTEOCHONDROSIS

Plasma glucose and insulin after glucose load in healthy foals and foals withosteochondroticlesions (Ralston, 1996).

Mare Nutrition?

2/6/2019

10

28

ENERGY TYPE

• CYCLICAL CHANGES IN GLUCOSE AND OR INSULIN MAY

INFLUENCE BONE MATURATION VIA EFFECTS ON THE

SOMATOTROPIC AXIS INCLUDING:• GROWTH HORMONE (FREUD ET AL., 1939).

• THYROXINE AND TRIIODOTHYRONINE (GLADE AND REIMERS, 1985).

• INSULIN‐LIKE GROWTH FACTOR I AND EQUINE CHONDROCYTES(CYMBALUK AND SMART, 1993; HENSON ET AL., 1997; STANIAR ET AL., 2001A; STANIAR ET

AL., 2001B; STANIAR ET AL., 2002; BURK ET AL., 2003).

29

OSTEOCHONDROSIS

• FOALS WITH EXTREME GLYCEMIC RESPONSES HAD ATYPICAL

INCIDENCE OF OCD• HIGH RESPONSE HIGH OCD

• LOW RESPONSE LOW OCD

• BODY WEIGHT AND CONDITION OF WEANLING POSSIBLE FACTORS

• CAN INCIDENCE OF OCD BE REDUCED BY FEEDING A LOW

GLYCEMIC FEED?

• HIGH SUGAR & STARCH VS. HIGH FAT & FIBER DIETS

30

NUTRITION’S ROLE IN DOD

DIGESTIBLE ENERGY• EXCESS DE

• JUST BECAUSE DIET IS HIGH IN DE DOESN’T GUARANTEE DOD

• IF PROTEIN, MINERALS AND VITAMINS ARE INADEQUATE TO SUPPORT THE

RATE OF GROWTH PERMITTED BY HIGH DE, DOD MORE LIKELY TO RESULT

• IF ALL NUTRIENTS ARE SUPPLIED IN PROPORTION TO DE, MAY NOT CAUSE

BONE GROWTH PROBLEMS

2/6/2019

11

31

NUTRITION’S ROLE IN DOD

PROTEIN• EXCESS PROTEIN

• OFTEN IMPLICATED, BUT NOT SUPPORTED BY RESEARCH

• A HIGH PROTEIN DIET DOES NOT MAKE FOAL GROW FASTER THAN A DIET

THAT JUST MEETS NRC MINIMUM PROTEIN REQUIREMENTS

• NO EFFECT OF INCREASING PROTEIN ON THE INCIDENCE OF DOD (SCHRYVERET AL., 1987; SAVAGE ET AL., 1993A)

• LOW PROTEIN (QUALITY)• IMPAIRS GROWTH; COULD LEAD TO DOD

• PROTEIN COMPONENT OF BONE & CARTILAGE

32

NUTRITION’S ROLE IN DOD

CALCIUM & PHOSPHORUS

• EXCESS CA• GENERALLY NOT A PROBLEM

• HIGH CA ZN, MN & FE ABSORPTION INOTHER SPECIES, BUT NOT IN HORSES

• EXCESS P• ONLY A PROBLEM IF CA CONTENT IS LOWER

THAN P• OPTIMUM RATIO CA:P 2:1• MAXIMUM RATIO CA:P 5:1• A TIGHTER RATIO MORE IMPORTANT IN

FOALS THAN MATURE HORSES

33

NUTRITION’S ROLE IN DOD

CALCIUM & PHOSPHORUS

• DEFICIENT CA & OR P• CAN CAUSE DOD

• SO FAR THERE ARE NO REPORTS OF DETRIMENTAL EFFECTS OF HIGHCALCIUM INTAKE (UP TO 5 TIMES REQUIREMENTS) IN GROWINGHORSES, PROVIDED THE INTAKE OF PHOSPHOROUS IS ADEQUATE(NRC, 1989; MEYER AND COENEN, 2002).

• JORDAN ET AL. (1975) REPORTED SOME EFFECTS OF ACALCIUM/PHOSPHORUS RATIO OF 6 :1 ON THE RELATIVE SIZE OFMEDULLARY REGION (LARGER) AND CORTICAL BONE AREA (SMALLER) IN PONIES

2/6/2019

12

34

NUTRITION’S ROLE IN DOD

• COPPER

• DEFICIENT COPPER• CAN CAUSE DEVELOPMENTAL PROBLEMS

• CU PART OF LYSYL OXIDASE; CARTILAGE CROSS‐LINK FORMATION

• COMMON TO SUPPLEMENT 2 – 3X REQ’MT

• REQUIREMENT: 10 MG/KG

• INDUSTRY: 20 – 30 MG/KG

35

SCIENTIFIC EVALUATION OF CU & OC

Harris, P. et al., Effect of exercise and diet on the incidence of DOD. In: The rowing horse: nutrition and prevention of growth disorders. P 273.

36

COPPER

• PARAGON ET AL. (2002) DID NOT FIND DIFFERENCES IN THE

INCIDENCE OF DOD IN RELATION TO COPPER INTAKE. IN THIS

STUDY COPPER REQUIREMENTS OF 10 MG/KG DRY MATTER

WERE MET OR EXCEEDED. 

• KNIGHT ET AL. (1985) A HIGH INCIDENCE OF DOD WAS

ASSOCIATED WITH LOWER COPPER INTAKE.

• PRUDENT TO INCREASE COPPER CONTENT IN ADDITIONAL FEEDS

FOR SUCKING FOALS TO 20‐25 MG/KG DRY MATTER (MEYER, 1994), IN ORDER TO INCREASE THE COPPER CONTENT IN THEIR

DIET TO A TOTAL OF AT LEAST 10 MG/KG DRY MATTER

2/6/2019

13

37

NUTRITION’S ROLE IN DOD

ZINC• DEFICIENT ZINC

• CAN CAUSE DOD• COMPONENT OF METALLOENZYMES; CELL REPLICATION & PROTEIN SYNTHESIS

• HARRINGTON ET AL. (1973) FED FOALS A PURIFIED DIET WITH EITHER5 OR 40 MG ZN/KG DRY MATTER. THE FOALS EATING 5 MG ZN/KGDRY MATTER DEVELOPED CLINICAL SIGNS OF DEFICIENCY WHEREASTHE OTHER GROUP GREW NORMALLY.

• EXCESS ZINC (>200 MG/KG) • MAY CAUSE DOD• CA ABSORPTION

• CU ABSORPTION (IN OTHER SPECIES)

38

UNIVERSITY OF ILLINOIS2007

• STANDARDBRED FOALS• 122 FOALS

• FEEDING PROGRAM – MARES WERE NOT

EATING FORTIFIED DIET

• 50% (61 FOALS) HAD OCD LESIONS

• 28% HAD LESIONS IN MORE THAN 1 JOINT

39

Zn++

2/6/2019

14

40

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

Zn++

41

MISINFORMATION

• ZINC HYDROXYCHLORIDE• NOT A CHELATE!

• JUST ANOTHER INORGANIC COMPOUND!

• AMERICAN ASSOCIATION OF FEED CONTROL OFFICERS (AAFCO)

• NOT NEW TECHNOLOGY

• BUYER BEWARE!

• PHD NUTRITIONISTS OR HIGH SCHOOL SCIENCE CLASS

42

PROTEINATED TRACE MINERALS

A PROTEINATE IS A TRACE MINERAL (ZN, CU, MN, FE, OR CO) 

THAT IS CHELATED TO AMINO ACIDS AND/OR PEPTIDES

C

R NH2

NH2 RO

C O

O

OTrace

Mineral

2/6/2019

15

43

TIMELINE

44

FOAL FEEDING – TREATMENT

TREATMENT

• DIET• WEAN FOAL• REDUCE ENERGY• SLOW GROWTH

• ANALYZE DIET

• REDUCE EXERCISE• STALL REST• PREVENT DAMAGE

• MAINTAIN PROTEIN VITAMINS AND MINERALS• DAC COLT GROWER

45

DODMANAGEMENT

• CONTROL GROWTH RATE AMOUNT OF HAY/GRAIN

• ADEQUATE MINERAL FORTIFICATION ADJUST

MINERAL INTAKE TO GROWTH RATE

• CONTROL EXERCISE

• MEDICAL TREATMENT OF SYMPTOMS

• EXAMPLE DIET

LOW ENERGY, ADEQUATE PROTEIN, VIT/MIN

2/6/2019

16

46

Pace Diet

Used with horses experiencingDOD (Growth Problems)

Restrict Growth Rate80% of NormalControl energy intake

Maintain IntakeProteinVitaminsMinerals

Common MistakeEliminate all grain

47

• Limit Dietary EnergyHorses often switched low rich hay to grass hayGrain is often eliminated

• Yearling will still grow, must make other nutrients adequateProtein, Ca, P, Cu, Zn, etc.

• Utilize low intake protein, vitamin and mineral pellet

Grass Hay free choiceDac Colt Grower –2ozAlfalfa – 1-2 lbs/day

PACE DIET

Dac Colt

SUMMARY

• Mare nutrition is the key to foal health

• In‐utero

• Adequate nutrition

• Strong healthy foals

2/6/2019

17

49

QUESTIONS