14: Nutrient requirements of exercising horses Flashcards

1
Q

What is required for bone remodeling? Why?

A

Moderate exercise with rest causes remodeling of long skeleton bones

bone structure changes with rest (most porous)

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2
Q

What are the risks of exercise?

A

Risk of microfractures and injury if intensity increases too rapidly
Full bone turnover takes approximately 6 months

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3
Q

Slide 6

A

Look

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4
Q

3 types of fiber in equine muscles? What are they for/do they do

A

Type 1: Slow-twitch for endurance
- aerobic
- oxidize triglycerides

Type 2A: intermediate fast twitch
- anaerobic + aerobic
- can use both intramuscular glycogen and triglycerides

Type 2X: fast-twitch for sprints
- anaerobic
- fully reliant on glucose, glycogen for E
- low oxidative potential

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5
Q

Kinetics of gas exchange in equine physiology

A
  • maximum rate of O2 uptake/min is double that of human athletes
  • splenic reserve of RBC (carry oxygen; releasing them from the splene increases oxygen carrying capacity of horse)
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6
Q

Factors affecting nutrient/energy requirements of hoses during exercise

A
  • Duration
  • Intensity (speed, ground resistance, incline)
  • other (number and height of jumping efforts, performance of extended and collected gaits, amount of weight carried/pulled)
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7
Q

Energy is required in an exercising horse for…

A

maintenance + energy for daily exercise effort

May need additional E for transportation, stress, etc

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8
Q

Energy requirement of a horse varies depending on

A
  • the horse
  • level of exercise
  • type of exercise
  • rider weight and experience
  • climate
  • ground conditions
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9
Q

Categories of exercise in horses

A

Light, moderate, heavy, very heavy

slide 11

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10
Q

Oxygen utilization is used to measure… What is it related to?

A

Used to measure energy expenditure

Closely related to heart rate
Linearly related to speed

Slide 12, 13

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11
Q

How does the energy requirement for exercise calculation change in light, moderate, heavy and very heavy work

A

Light work
DE = (0.0333 x BW) x 1.20

Moderate = 1.40
Heavy = 1.60

correction factor to support exercise

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12
Q

What nutrient is most used in high intensity exercise?

A

Carbohydrates

Increased intensity = increased CHO use bc of recruitment of fast-twitch muscle fibers

Anaerobic metabolism

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13
Q

Where does the body get glucose (CHO) for exercise

A

Muscle glycogen, blood glucose, hepatic glycogenolysis, or hepatic gluconeogenesis

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14
Q

What happens when glycogen levels re depleted? Does CHO loading work in horses?

A

Fatigue resistance reduced (get tired easier)

A little bit, but they are mostly hindgut fermenters and too much starch for too long = metabolic issues

Look at slide 16

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15
Q

Supplementation of _________________ may spare glucose during _______________

A

Fats and fatty acids for at least 2-3 months

Low and moderate exercise (beta-oxidation)

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16
Q

Important n-3 and n-6 f.a.

A

Linoleic acid forms arachidonic acid (n-6’s)

a-linolenic acid forms EPA and DHA (n-3’s)

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17
Q

Why might EPA and DHA supplementation be beneficial?

A

They alter cell membranes of platelets, erythrocytes, neutrophils and monocytes

  • Increase fluidity of RBC
  • Decrease inflammatory response
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18
Q

Protein use during exercise? Prolonged exercise reduces…

A

Protein metabolism estimated to be only 5-15% of E expenditure during exercise

Serum concentrations of branched chain AA are reduced (oxidized for E)

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19
Q

Effects of high protein intake on performance

A

No detrimental effects proven, but no evidence of better performance either

20
Q

Supplemental protein/aa is required for what during exercise?

A

For developing and repairing muscle

21
Q

Lysine requirement formula

A

= 4.3% x CP requirement

22
Q

What minerals are important in exercising horses? Why?

A

Calcium, Phosphorus, and Magnesium
- all required for bone development
- increased requirement met through additional feed for energy (increase intake must be accompanied by exercise for metabolism)

23
Q

Vitamin requirements in exercising horses

A

No clear requirements established for working horses (most likely met through increased feed intake)

Thiamin (B1) supplementation may help improve glucose metabolism and prevent lactate accumulation

24
Q

Water loss during exercise? Requirement depends on? Intake increases how much?

A

Can account for 3.6-7.7% BW loss during performance

Dependent on conditions (more sweat in hot, humid environments) and duration of exercise

Intake can increase 2- to 3- fold over maintenance requirements

25
Q

Three disorders associated with exercise

A
  1. Gastric ulcers
  2. Post-exhaustion syndrome
  3. Polysaccharide storage myopathy (PSSM)
26
Q

What are gastric ulcers? Symptoms? Prevalence?

A

Erosion (lesions) of the squamous mucosa due to exposure to gastric acid

Reduced appetite; causes pain after eating

Effects 40-90% of performance horses (increases with increase in activity); up to 100% in racing TBs

27
Q

Causes of gastric ulcers

A
  • contracted stomach (small)
  • continuous HCl secretors
  • contraction of abdominal muscles
  • high rapidly digestible CHO meals (starch and sugar)
  • fasting and amylolytic bacteria
28
Q

Prevention/treatment of gastric ulcers

A

Let the horse graze (remove GI stress and exercise)
Get CHOs out of the diet

29
Q

What is Post-Exhaustion Syndrome? Cause?

A

Muscle stiffness and reluctance to move that occurs 2-4 days post-exercise
Preface trying up or rhabdomyolysis

Cause is muscular accumulation of lactate, depletion of glycogen (exposure to anaerobic metabolism)

30
Q

Prevention of post-exhaustion syndrome

A
  • addition of electrolytes to diet
  • feeding calcium carbonate
  • alter training to increase conditioning (increasing aerobic metabolism)
  • allow for adequate slow cool-down after heavy exercise
  • if severe administer IV calcium gluconate, magnesium, phosphate ions, vitamin D
31
Q

What is Polysaccharide storage myopathy? Cause?

A

Genetic disorder (PSSM1 or PSSM2): difficulty storing glucose as glycogen in muscle tissue

Cause is high concentrations of glycogen and glucose-6-phosphate in muscle

32
Q

Clinical signs of PSSM

A
  • exercise intolerance
  • muscle stiffness/pain
  • shifting lameness
  • camped-out stance
  • colic symptoms
  • muscle atrophy
33
Q

What is PSSM1? PSSM2?

A

PSSM1
- single base substitution on GYS1
- increase glycogen synthase with inadequate glycogen branching enzyme
- prevalent in draft horses

PSSM2
- no GYS1 mutation
- unknown cause
- Prevalent in quarterhorses, warmbloods

34
Q

Prevention of PSSM1

A
  • feed minimum of 1.5% BW as forage
  • remove concentrates containing grain and molasses
  • use alternative energy sources (fat, protein, fiber)
  • implement a daily exercise regimen (use glucose in blood so it does not need to be stored as glycogen)

Do what you can to ensure horse does not need to create glycogen

35
Q

Grazing behaviour in horses

A

Graze continuously, prefer herds
Graze 10-17 hours/day if on pasture
- usually during day, 20-50% at night
- nocturnal intake depends on season

36
Q

Horses adjusting to diet energy density

A

Horses do not adjust food intake to diet energy density
- seasonal pattern of feed intake
- increase weight in spring; reach max weight in summer; progressively lose weight in fall and winter

37
Q

Voluntary intake affected by…

A

Palatability
- defined by orosensory sensations
- alfalfa > grass

Highly selective eaters
- select forage on basis of growth rather than species of grass
- meal size and frequency affected by diet
- preference for what is known

38
Q

Group vs individual feeding in horses

A

Group feeding affected by social status, variation in appetites, intake rate

Limited feed creates aggressive behaviour

39
Q

How does environment affect grazing time

A
  • seasonal eating
  • rain, wind and high temps decrease grazing
  • high humidity increased grazing
  • snow cover can influence grazing time
40
Q

Anorexia in horses

A
  • typically indicative of an illness
  • may be caused by dental problems
  • can be a learned behaviour (attention)
41
Q

Coprophagy in horses

A
  • not a normal behaviour in horses
  • adult horses will not graze in areas contaminated with equine feces
  • exception: foals will consume dam’s feces up to 2 months of age (to establish microflora with moms microbes before start consuming fiber)
42
Q

Geophagia in horses

A

Dirt-eating
- not an uncommon behaviour
- may be used to to acquire salt and trace minerals
- sand may create colic or diarrhea

43
Q

Wood chewing in horses

A
  • undecided if this is a normal behaviour of predecessor to cribbing
  • not uncommon in feral horses and TBs
  • may cause SI obstruction
  • typically caused by inclement weather or lack of fiber in diet (timber is insoluble fiber)
44
Q

Stereotypic behaviours in horses

A

Cribbing: incisor teeth grip an object, horse pulls back and gulps air. Associated with drop of stomach pH and incidence of gastric ulcers

Stall-walking: constant movement in circles around an enclosed stall

Weaving: shifting weight from foreleg to foreleg while stationary, usually in confined space

45
Q

How can stereotypic behaviours be alleviated by feed management

A

A bit
- providing more forage (more hindgut fermentation = more GOP1 (incretin w calming effect))
- providing fewer concentrate meals per day