Selecting Horses for Breeding Flashcards
1
Q
Live cover/natural service
A
-all breeds/disciplines
-mare and stallion in same location
2
Q
Assisted reproduction
A
-most breeds/disciplines (not the TB)
-artificial insemination
-embryo transfer
-other technologies
3
Q
What to look for in mating decisions:
A
-reproductive health/capacity
-genetic value
-economics
4
Q
Genetic value
A
ability to pass on desirable traits
5
Q
Reproductive health/capacity
A
ability to produce an acceptable # of progeny
6
Q
Stallions reproductive health:
A
-ability and willingness to mount and breed
-libido
-physical soundness
7
Q
Busy “live cover” systems for stallions:
A
3x/day
8
Q
Busy AI systems for stallions:
A
3x/week
9
Q
Stallion reproductive capacity:
A
-adequate number of fertile sperm
-live covers: each ejaculate must contain sufficient sperm for one mare
-AI: collections are usually subdivided (multiple mares); sperm must remain fertile after cooling or freezing
10
Q
Objective measures of stallion services/pregnancy:
A
-Live cover: how many times does a stallion need to breed to get a mare pregnant?
-AI: how many times must the mare be inseminated to get pregnant?
11
Q
Under high management, how many breedings or inseminations per pregnancy?
A
~1.5
12
Q
1 ejaculate = how many doses?
A
1 (one mare bred per ejaculate)
13
Q
Under very busy live cover how many mares per day?
A
3-4 mares/day
14
Q
Under very busy live cover how many mares per week?
A
21-28 mares/week
15
Q
How many doses for AI does a normal stallion produce?
A
5-15 insemination doses
16
Q
What is the typical AI schedule?
A
4 days/week
17
Q
About how many mares would ejaculate from one stallion be “breeding” per week?
A
20-60 mares/week
18
Q
What is the pregnancy rate of stallions under high management?
A
80-90%
19
Q
Calculation of pregnancy rate:
A
(# mare pregnant/# mares bred) x 100
20
Q
Calculation of live foal rate:
A
(# live foals/# mares bred) x 100
21
Q
Live foal rate
A
65-75%
22
Q
Evaluations of reproductive capacity are…
A
dynamic (can change over time)
23
Q
When do stallions become successful?
A
when their progeny do well
-they must have enough progeny to be visible to mare owners
24
Q
Live foal guarantee
A
stallion owner gets paid if there is a live foal. If a mare is bred several times and does not produce a foal, the stallion manager has invested time and effort for no payment
25
Selection criteria for popular/busy stallions:
-may turn down mares with poor repro records
-may turn down mares foaling late in the year
-may favor young mares
26
Selection criteria for unpopular stallions:
-may want to accept as many mares as possible
-older mares
-less fertile mares
27
Selection criteria for less fertile stallions:
-may exert same criteria as for busy stallions
-may limit number of mares bred
28
Two ways to increase stud farm income:
-more live foals
-higher stud fees
29
Why might the number of mares bred to a stallion decrease?
-the stallion manager decides the stallion has reduced breeding capacity and can not or will not breed a larger number of mares successfully
-the mare owner decides the stallions progeny aren't doing well, the stud fee is more than current market value, or there is elevated risk that their mare will not get in foal
30
Why might the number of mares bred to a stallion increase?
-the stallion manager decides the stallion is capable of breeding more mares than originally expected
-the mare owners decide the stallions progeny are doing well, or the stud fee has been reduced to a better value
31
Mare reproductive health/capacity is based on:
their ability to conceive
-functional ovaries, oviducts, uterus, etc.
-applies to live cover, AI, and ET systems
32
Mare reproductive physical health/capacity depends on:
physically sound/healthy enough to carry a foal to full term and deliver normally
-applies to live cover and AI
-may not apply if embryo transfer is used
33
How else do mares need to qualify for breeding?
they must be physically and mentally sound/healthy enough to raise a foal to weaning
-may not apply if ET is used or a nurse mare
34
Live foal rate can be calculated as:
-# live foals/# years bred
-# live foals/years in service
-# live foals/years pregnant
35
Measures of reproductive ability in mares:
-live foal rate
-services or cycles bred/pregnancy
-time between foaling dates (or between foaling date and last breeding date)
36
Things to think about when considering mares:
-how old is she?
-how many foals has she had?
-at what age could she have her first foal?
-how many years could she have been bred
-how many years was she bred
-possible reasons a year was skipped
-when will she foal next year
-when can you expect to breed her next
37
Mare gestation length
320-362 days
38
Natural breeding season start:
about the beginning of April
39
Commercial breeding season start:
about the beginning of February
40
Reproductive capacity
able to produce acceptable # of progeny
41
Genetic value
able to pass on traits of interest
42
Traits of interest in breeding horses:
-physical
-athletic
-reproductive
-behavioral
43
Genotype
the genetic component of a trait
44
Phenotype
the composite characteristics of a trait that result from both genetic and environmental components
45
P = ? + ?
genotype + environmental factors
46
Heretability
the portion of variation in a trait under genetic control
47
Heritability of 0.0
no genetic influence
48
Heritability of 1.0
trait is completely under genetic control
49
For highly heritable traits is it easy or hard to assess genetic value?
relatively easy...what you see is what you get
50
The lower the heritability value is it easier or harder to assess genetic value?
more difficult
51
Heritability of size
0.5-0.9 - highly heritable
52
Heritability of leg conformation
0.1-0.7 - wide range
53
Heritability of jumping
0.1-0.3 - low genetic influence
54
Heritability of cutting
<0.1-0.2 - low genetic influence
55
Heritability of fertility
<0.1-0.2 - low genetic influence
56
Heritability of TB racing ability
0.2-0.5 - low to mid range
57
Heritability of QH racing ability
0.2-0.4 - low range
58
Heritability of StB racing ability
0.2-0.4 low range
59
What heritability do most performance traits have?
below 5.0
60
Predicting genetic value accurately you need:
must have objective records of the horse of interest
61
What are types of objective records?
-wither height/body weight
-color
-competition earnings
-race times
62
What are types of subjective records?
-jumping ability
-temperament
-breed type
63
Subjective
based on opinion
64
What might make subjective records more objective?
scoring systems
-if competitions use specific scoring standards
65
No record is not the same as...
a poor record
66
Bias
a situation that could influence records in a systematic way
67
Who's records are available?
-individual's own
-individual's progeny
-individual's parents
-individual's grandparents'
68
When is the heritability and assessment of genetic value in stallions the highest?
when they have 200 or more progeny
69
How can a mares genetic value be assessed?
-higher number of progeny the better (but most have <10 so it is hard to assess)
-mare's performance record
-records of relatives
70
What relationship to a stallion or mare gives their best prediction of genetic value?
progeny
71
What must the records be for genetic value accuracy?
they must have records of a comparable population
72
Average TB
winning a race
73
Above average TB
placing 2nd or 3rd in a black type stake
74
Far above average TB
winning a black type stake
75
Elite TB
winning a G1 race
76
Average progeny starters %
65-70%
77
Average progeny winners %
45-50%
78
What % of progeny is black type stakes winners?
3-4%
79
Average Earnings Index (AEI)
a ratio comparing the average earnings of a stallions progeny with the average earnings of all other horses running in a given country during a specific year or time period
80
An average AEI
1
81
An above average AEI
AEI>1
82
A below average AEI
AEI < 1
83
What is above average for TB progeny?
-more than 50% winners
-more than 3.5% black type winners
-AEI > 1
84
Primary source of bias
mare quality is not the same across all stallions
85
Secondary source of bias
environment (management is not the same for the progeny of all stallions)
86
Comparable Index (CI)
-provides insight into quality of mares bred to a specific stallion
87
How is the CI calculated?
calculated from the average earnings of starters from mares that he bred, when they were bred to other stallions, divided by the average earnings of all contemporary starters
88
CI = 1
means when bred to other stallions the mares produced progeny that had earnings equal to the average horse in the population
89
CI = 2
means when bred to other stallions the mares produced progeny that had earnings two times the average horse in the population
90
The higher the CI,
the better the mare quality
91
A lower CI, above 1, would means what?
the stallion "improved" the progeny of the mares he bred the most
92
About what % of the progeny of the best stallions never win a black type race?
90%
93
What is the AEI of the best stallions?
around 2 or higher
94
What does the CI tell us about mare quality?
the CI helps us understand whether the stallion is breeding mares that are above, at, or below average
95
Owner goals
-breed to sell
-breeding to keep for performance
-breed to compete and keep for breeding (fillies usually)
96
Budget and cash flow considerations
-not all mares warrant the same investment in stud fees
-some breeders will breed to sell and breed to compete
97
Physical attributes of mare and stallion that are considered:
-usually avoid duplicating defects
-sometimes select to correct a defect/weakness
-like to like or opposites attract?
98
Mating schemes within breed:
-outcrossing
-inbreeding
-nicking
99
Outcrossing
mating of two "unrelated" horses of the SAME breed
-unrelated through usually 4th or 5th generations
100
Crossbreeding
mating of horses from different breeds
-introduce new traits
-not used in TB's
-important to creating new breeds
101
Inbreeding
increase the influence of desirable ancestors
-a horse is considered inbred if an ancestor appears on both sides (maternal and paternal) of the pedigree
102
2 x 3 inbreeding
not common, but sometimes seen
103
3 x 3 inbreeding
occasionally, usually with excellent individuals
104
3 x 4 inbreeding
common
105
4 x 4, 4 x 5 inbreeding
very commone
106
A horse that is not "inbred" itself may still...
have inbreeding in their pedigree
-the sire could be inbred to one or more horses
-the dam could be inbred to other horses
107
When is crossing of two inbred lines sometimes practiced?
to duplicate a successful cross of a certain sire and dam in the past
108
Nick
a successful cross
109
Nicking patterns
-some stallions do well with any type of mare, others have more success with mares from certain sire-lines
-some mares come from families with more success when bred to certain sire lines
110
Nicking programs
input a mare for a particular stallion
-program usually grades the success of the cross of the stallions sire line over the mares sire line
111
What do nicking programs disregard?
the maternal families of both stallion and mare
112
What do nicking programs do for young stallions?
go back to their sire or grandsire's records
