Equine Nutrition - Water, Carbohydrates, & Energy

Midterm 2 (Part 1)

Free

Water available in a drinker, trough, or pond, not a component of consumed forages.

Preformed

Water available in food sources, primarily in the form of moisture content within plant or animal tissues.

Metabolic

water produced in the body during metabolic processes and respiration, contributing to hydration.

Oxidative

process involving the production of energy through the oxidation of nutrients, primarily glucose and fatty acids, in the presence of oxygen.

Fecal

Largest route of water loss in horses through the digestive tract, leading to dehydration if not managed.

Urine

Second largest route of water loss but also the most dynamic and based on animal (very dramatic, sudden changes)

Example of Urine Loss being Dynamic

Donkeys will change from wheat straw to alfalfa, 8x increase in N, 4x increase in urine output

Perspiration

evaporation loss through lungs and skin, third most significant route of water loss in horses, especially during exercise or hot weather.

Lactation

Increased Water Requirement: 37–74% above normal intake. Milk production demands significant water input—milk is ~85–90% water. Lactating animals need much more water to sustain milk output and avoid dehydration.

Sodium, Potassium, Crude protein

Increasing intake of this nutrient will result in increased urinary output

Ponies expected to drink more than donkeys

When housed and fed in a similar manner, _________ are expected to drink more than _________

Balance

Everything is balanced: example, if dried forage intake increases, free water intake increases

Water

the most abundant nutrient, significant component of body tissues, and essential for all physiological processes.

blood

90-95%

muscle

75%

bone

22%

adipose tissue

10%

Function of water

structural (tissue) maintenance, lubrication, cushion, aids in digestion/absorption, transportation, eliminating waste, metabolic reactions, and regulation

Foals

Experience empty body water composition. At birth total body of water is 70%, at 8 weeks, they’re just over 65%.

Variables influencing water

quality, odor, temperature, dissolved solids, N, dietary factors, environmental, production

Polysaccharides (Structural)

Cellulose & Hemicellulose + harder to digest without the help of microbials

Poly Nonstructural Carbohydrates (NSC)

starch (amylose), glycogen + energy storage and easily digested

Oligosaccharides

pectin, fos, inulin, fructans, mannan

Monosaccharides

glucose, fructose, galactosedis - absorbed in small intestine across the gut mucosa

Disaccharide

lactose, sucrose, maltose

Lactose

made of galactose and glucose

Sucrose

made of glucose and fructose

Maltose

made of 2 glucoses

Amylose

non structural polysaccharide, α-1,4 , slow digestibility

Amylopectin

nonstructural polysaccharide, α-1,4 + α-1,6 , fast digestibility

Cellulose

structural, B-1,4 , most abundant carb on earth

Hemicellulose

structural, partially resists auto and alloenzymatic digestion, only measured as part of NDF

alpha

nonstructural, horses can break down on own

beta

structural, need alloenzymatic (fermentation)

Oligo

resistant to auto enzymatic, survive in SI, and fermented in hindgut

Cecum

30% of energy comes from fermentation here

Colon

80% of energy comes from fermentation here

CHO-H

hydrolyzable fermentable carbs, degrade by both auto and alloenzymatic digestion. ex, starch, sugars (mono and di)

CHO-Fr

rapid fermentable carbs, ex. fructan, oligo, finely ground grain

CHO-Fs

slow fermentable carbs, ex. hemicellulose, cellulose, ligno-cell. Measured as NDF - lignin

Lignin

Resists auto and alloenzymatic digestion

By-pass

nutrient that escapes digestion in primary region of the GI tract and digested in the small intestines. ex. protein, fat

How to find how much hemicellulose?

NDF - ADF

ADF

Acid detergent fiber, least digestible portion of plant fiber (ex. cellulose, lignin). Collective measurement of the two.

VFAs

main energy source produced in microbial fermentation; acetate, propionate, butyrate

Acetate

primary energy producing end-product of fermentation

Propionate

production of glucose in liver (gluconeogenesis)

Methane (CH4)

gas byproduct of fermentation, energy loss, more methane = less efficient energy use, poorly absorbed in hindgut; excreted via flatulence

Lactate

Poorly absorbed in hindgut; reduces pH leading to ruminal acidosis

Insulin Resistance

When the body doesn’t properly respond to insulin, so glucose stays in the bloodstream. High IR may lead to laminitis

Laminitis

inflamation and damage of the laminae which are tissues supporting the hoof wall

What does not create energy for horses?

water, vitamins, and minerals

Minimum maintenance

30.3kcalDE/ BWkg/d

Average maintenance

33.3kcalDE/ BWkg/d

Elevated

36.3kcalDE/ BWkg/d

Thermoneutral zone

environmental temperature where horses don’t need to keep expending energy to keep cool or warm; 5-25 degree C

Hyperthemia

Keeps cool mainly through perspiration

Hypothermia

Keeps warm through rapid muscle contraction (shivering). Produces metabolic heat to help maintain

Normothermia

normal body temperature