Equine Selection Flashcards
Why are horses the least studied of livestock?
- recreational use
- long GI (generation interval)
- long gestation
- age to puberty
- offspring/year
- lack of accurate records
What does a higher GI result in?
reduced rate of genetic change
What is the gestation length of horses?
336 days
Why are there problems determining heritability in horses?
- variation
- tremendous environmental variation
- data bias
- limited information available is probably higher than reality
What problems arise determining heritability in racing horses?
- surface
- condition
- age
- level of training
- nutrition
Why is horse age a problem?
horses have a universal birth date
Why is level of training a problem?
are you measuring the genes of the horse of the trainer
What problems result from data bias?
- not all contemporaries are allowed the same opportunity (performance)
- selection of animals is based on likelihood to excel
What horse traits are of economic importance?
- fertility
- performance
- cow sense
- jumping ability
What is the heritability of fertility?
0.05
How do horses perform fertility compared to other species?
lower performance
Why do horses have lower fertility performance compared to livestock species?
- duration of estrus/time of ovulation
- artificial birth date
- hand mating/pasture mating/AI
How does heritability reported measure to actual heritability of fertility?
it is probably higher than reported due to man’s influence
Have horses had improvement in fertility from selection?
very little
How have horses had more successful fertility?
changes in environment
What changes are made to environment to improve fertility?
- nutrition
- health care
- breeding seasons
What is horse performance important for?
- racing
- cattle work
- barrel racing
What is the basis for racing?
anatomy and physiology
What is important for racing?
- stride length
- frequency of strife
- muscle fiber type
What are the two types of muscle fiber types?
- slow twitch or type 1
- fast twitch or type 2
For performance, obvious some degree of heritability based on _____.
skeletal structure
Has there been any improvements on the speed index?
not in the last 60 years
What are sales of horses based on?
pedigree
What methods are there to measure heritability?
- speed index
- lifetime earnings
- average earnings
What is the speed index for horses?
AQHA
What may limit heritability accuracy in performance?
limited contemporary measuring
what is heritability of racing ability in TB?
0.35
Is trotters dominant or recessive?
dominant
Is pacers dominant or recessive?
recessive
Can you teach trotters to pace?
it’s difficult
What is the heritability of trotters/pacers?
0.10-0.25
What are the functions of cattle work?
- ranch work
- roping
- cutting
What is ranch work?
work livestock over rough terrain
What is roping include?
- close contact to animals
- high agility
What does cutting include?
- highly athletic
- respond to calf movement after separation from herd
What is cow sense?
horse appearing to have a great interest in cattle
Can cow sense be researched?
it’s difficult to
What is barrel racing based on?
speed and agility
What is the history of horse selection?
- development of distinct breeds and types of horses in last few thousand years
- manufactured “registered” breeds
Are color breeds purebred?
no
Do Palominos breed true?
no
What mating systems are used for horses?
- linebreeding
- Positive assortative mating
- inbreeding
- crossbreeding
How common is linebreeding?
very common
What is linebreeding?
concentrating the genes from one individual
What is positive assortative mating?
breeding the best to the best
What is a major selection criteria for positive assortative mating?
sire performance
Is Inbreeding commonly used?
used little
Is crossbreeding commonly used?
somewhat
When is crossbreeding used in horse industry?
- breed development
- warmbloods
- trotters
What detrimentals are selected against?
- CID
- Bleeders
- OCD or DOD
- Wobblers Syndrome
- HYPP
- Lethal White Foal Syndrome
- HC/HERDA
- GBED
