Horse Production and Management Exam 1

horse habitat evolution

marshy land with tree cover to wide open grassland

horse physical evolution

grew taller

multiple toes to a single toe

legs, head, neck got longer; legs longer to gain momentum when running

jaw got deeper

feral horses

horses that were once domesticated but now live in the wild

wild horses

horses that were born in the wild, no human interference with genetics

Przewalski’s horses

last truly wild horse in the world

native to Mongolia, rage throughout Europe and Asia

mitochondrial DNA indicated their divergence from the horse about 500,000 years ago

feral horse challenges

invasive, no natural predators, so population is increasing while natural food supply is diminishing

gov’t uses tax money to feed, current political controversy

main component of equine diet

60lbs of plant matter/20lbs dry plant matter per day

equine teeth

incisors and molars

root is deep within the gumline, which is why jaw evolved to be deeper

as horses chew, they get worn down, which is why so much tooth is deep in gumline

equine gastrointestinal tract

bigger, heavier because they consume a lot more food compared to carnivores

rigid spine to support the weight

domestication of horses

earliest - around 5500 years ago - culture died and horses were wild again

4000-3000 BC (recent evidence around 2000 BC) - modern horse domestication in Eurasia

early domestication - meat and milk production, maybe riding or harness

later domestication - pack animals, plows, warfare

horse breeds

over 300 of them

hot bloods

thoroughbreds, riding horses

built for speed, leaner horses w less muscle

excitable, faster metabolism

cold bloods

draft horses

bred for power, heavy horse breeds with lots of muscle

slower metabolism, docile/quiet

Belgian, Clydesdales, Percheron

warm bloods

usually a cross between draft + thoroughbred

mix of speed and power, good for jumping and dressage

Holsteiner, Dutch Warmblood, Hanoverian, Trakehner

pony breeds

metabolically different from horses

easy keepers, do not need to feed a lot

<14.2 hands (not always a pony but generally)

miniature horses

no more than 38” tall (or 34” depending on breed)

genetically more similar to ponies

hardy, prone to dental and mouth issues

gaited horse breeds

Tennessee Walking Horse

Missouri Fox Trotter

Paso Fino

Saddlebreds

Standardbreds

measuring horses

at the withers, which is the highest fixed point on the horse

1 hand = 4 inches

donkey/burro

member of Equus family

different species than horse!!

62 instead of 64 chromosomes

mules

offspring of male donkey crossed with female horse

sterile

hinny

offspring of female donkey crossed with male horse

sterile

donkeys, mules, hinnys

generally hardy and tough, less prone to some illnesses

metabolically efficient, obesity is an issue

less likely to run from danger compared to horses, preferred in warfare for this reason

Arabian

oldest modern horse breed, dates back over 5000 years to the Middle East

light horse breed, hot blooded

refined, triangular head with long, arched neck

dished forehead

known for endurance; lighter muscle mass dissipates heat faster

Appaloosa

thought of as being from Native American origins, ancient cave drawings depict spotted horses

were introduced to America by the Spanish

hearty performance horse

Nez Perce tribe in Palouse River region selectively bred for color and other traits

LP (leopard complex) gene must be present for spotting to occur - incomplete dominant gene and it must interact with other genes to produce spotting

American Quarter Horse

one of the oldest breeds in the US, also one of the largest breed registries

breeding heavy in southwestern US rangeland (ranch work)

known for versatility and temperament

sprinters - fasted over ¼ mile - very muscular

Thoroughbred

ancestry traces back to 3 sires

sustained speeds - brought about the modern sport of horse racing

lighter athletic build, long legs, lighter muscles compared to QH

distance runners instead of sprinters

Shire

can be over 2000lbs

tallest horse in history was this breed named Sampson, he was 21.2 (avg is 15.2), also heaviest in history weighing 3360

the walk

flat foot, 4-beat gait

each foot hits the ground and is supported by another foot both diagonally and laterally

~4 mph

the trot/jog

natural 2 beat diagonal gait with moment of suspension between beats

~9 mph (record ~30 mph by Standardbred)

the pace

2 beat gait that is lateral instead of diagonal

the canter/lope

natural 3 beat gait with moment of suspension between each series of 3 beats

~12-15 mph

the gallop/run

natural 4 beat gait, the extension of a canter/lope with 1 beat of suspension between each series of 4 beats

~15-18 mph (record ~38 mph by Thoroughbred, ~40 mph short distance record by Quarterhorse)

the back/reinback

2 beat diagonal gait in which the legs are moved backward

similar to a trot, done very slowly

DMRT3 Gene

transcription factor (protein) expressed in certain spinal cord neurons and is important in controlling limb coordination and movement

research suggests gaited horses have this type of mutation

how to identify horse

sex, color, markings, age

colt

young male <5 years old

filly

young female <5 years old

stallion

male (5+ years old)

mare

female (5+ years old)

gelding

castrated male

when and why castration

6mo-2yrs

reduces aggression

spaying mares

not common at all

much more invasive than castration, vets aren’t really trained on it, very expensive

foal

birth to 6mo

weanling

5-6mo old (age at weaning) to 1 year

yearlings

most show animals are considered 1 year old on Jan 1 of the year after they are born

riding age

2 years old

horse lifespan

20+ years

older age leads to arthritis and PPID

snip

star

stripe/strip

blaze

bald face

coronet

pastern

sock

stocking

3 base colors

bay, black, chestnut

bay

chestnut

black

white

they have pink skin but are not true albinos, only have pigment loss in hair and skin

produced by dominant white genetics rather than albinism

grey

may appear white but have dark skin

are born dark, have a loss of pigmentation as they age

palomino

buckskin

pinto

basic coat color genes

melancortin-1 receptor (MC1R)

agouti signaling protein (ASIP)

MC1R

controls production of red and black pigment

3 known alleles: E, e, and e^a

e and e^a are recessive, considered “loss of function”; double e and double e^a produce red pigment

if there is E allele horse will show black pigment

ASIP

distribution of black pigment, A/a

A restricts black to points, recessive a distributes black evenly over body

EA

bay (chestnut with black points)

Eaa

fully black

eeA and ea

chestnut

dilution genes

one of several genes that reduce the amount of pigment produced and/or reduce pigment transferred from pigment cell to hair follicle

some affect one type of pigment, others affect both

some dilute both coat and points, others dilute just points or coat

the cream gene

N/Cr - dilutes body color and points (only 1 dilution)

Cr/Cr - dilutes any color to pale cream (2 dilutions)

chestnut N/Cr

palomino

bay N/Cr

buckskin

black N/Cr

smoky black

chestnut Cr/Cr

cremello

bay Cr/Cr

perlino

black Cr/Cr

smoky cream

dun gene

dominant trait

dilutes black and red but does not dilute points

homozygosity doesn’t produce extreme dilution

dd = no color dilution

red DD/Dd

red dun

bay DD/Dd

bay/yellow dun

black DD/Dd

grulla

white patterns

distributed white - white hairs dispersed in coat

• roan and grey

patch white - white patches

• appaloosa

• dominant white

• sabino 1

• splashed white

• tobiano

• overo

gene G

causes progressive depigmentation of hair

N - not grey, G - grey

NN - not grey

NG - grey (50% transmission)

GG - grey (100% transmission)

completely obscures action of other coat color genes

gene R

roan pattern, causing interspersed white hairs that are present at birth

NN - not roan

NR - roan (50% transmission)

RR - roan (100% transmission)

chestnut RR

red roan

bay RR

bay roan

black RR

blue roan

gene W

dominant white gene - causes white or white spotting

obscures action of other coat color genes

having 2 copies of this gene leads to embryonic death

gene TO

tobiano spotting

white crosses back between ears and tail

legs are white, dark covers flank and head

N - normal, TO - tobiano

NN - normal

NTO - tobiano (50% transmission)

TOTO - tobiano (100% transmission)

gene O

overo spotting

white does not cross back, legs are dark, splashy white patches

caused by O allele

NN - not overo

NO - overo

OO - white foal, lethal white syndrome

lethal white syndrome

foals have underdeveloped intestinal system

colic within first few hours of life, dies within first few days of life

no treatment, prevention comes from careful breeding

tovero spotting

both tobiano and overo gene

dark pigmentation around ears, mouth, and parts of face

one or both eyes blue

chest spots of varying sizes that may extend up neck

flank spots ranging in size

coat color by genetics

1 - G or W? then animal is grey or white.

2 - E or A? if ee, A is irrelevant. if E, look at A and do 3 first

3 - if A is present, base color is bay. if aa, base color is black

4 - D or C? if so, dilution occurs

5 - R, TO, O? then white spotting