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
