B71 Heritability, EPDs & performance data
Name ____________________________________
Date ____________
Define Heritability:
Those traits that are more highly heritable can be used by the producer in selecting
breeding stock.
Heritability Estimates
Heritability
Low:
Medium:
High:
Calculating genetic improvement using heritability estimates:
A producer currently has ewes that wean 70 lb lambs
They want to raise weaning wt to 110 lbs
They select a ram with a wean wt of 110 lbs
The heritability of weaning wt is 30%
What can you expect new lamb crop to weigh at weaning?
Use the information from the Heritability Estimates Table to calculate the degree of
genetic improvement for the following traits:
Formula:
Difference in Production (Current level of production minus goal)
Times the Heritability Estimate = Degree of genetic improvement.
1. You are currently experiencing a lot of calving problems in your herd. Your calves are
averaging 90 pounds at birth. You would like to reduce calving weight to 80 pounds. You
have selected a bull that produces calves that are around 80 pounds. How much lighter
would you expect next year’s calves to be?
2. Your ewes always have two and often three lambs. Even when you pull the third lamb
off the mother, the two remaining lambs don’t seem to be growing like they should. You
think it is because your ewes are not producing enough milk. You select the best ewes in
your flock that weaned lambs that were 20 pounds heaver, and produced 25% more milk
than the flock average.
When their offspring are bred, how many pounds heavier will there lambs be?
How much more milk should they produce?
3. Your sows produce good litters that grow fast but are not producing the long, well
muscled, lean hogs that the current market demands. You select a boar that is 10%
longer, 15 percent leaner and is carrying 25 % more muscle than your herd average.
Herd Average
Length
33 inches
Back Fat
1inch
% Muscle
70%
Degree of Genetic Improvement
EPDs
What does EPD stand for?
They predict the expected difference in performance of a sire’s or dam’s
____________________ when compared to the average for that ________________.
Breed Specific (can’t compare epds of different breeds)
Performance data is researched, collected, computer analyzed to provide the predicted
outcome or genetic merit.
EPDs & Units of Measurement
Expressed as _______ or _______
Birth weight in __________________
Weaning weight in pounds at _________ days
Yearling weight in pounds at ________ days
Gestation length in ____________________
Yearling height in _________________
Scrotal circumference in ________________________
Carcass weight in ________________________
Marbling in USDA marbling ____________________
Ribeye area in ___________________________
Fat thickness in _____________________
Performance Data
Data is collected in three important areas:
1.
2.
3.
Ancestry
If you were breeding race horses, what information would you want to see to help you
select the right stallion?
The performance records of ancestors are a valuable tool and should be considered in
the selection process.
The performance records on ancestors are analyzed in the equation and they offer a
good indication what the EPD of the animal might be.
Individual Performance
If the animals in a herd are raised under similar ______________________________
the top producing animals must have had a genetic advantage over the average or
poor producing animals.
Records on the individual’s performance provide a way to ensure that the genetics of
the ancestors were passed on to the individual and are used to calculate EPD’s.
Progeny Records
________________________ are the best indication of the three genetic merit, of the
sire.
This is especially true if the progeny are distributed in different herds and under
different environmental conditions, but still constantly out produce the animals in the
contemporary group.
Accuracy
Accuracy value reflects the _________________________ of and
______________________ of information included in the evaluation.
What an EPD looks like
Important EPDs for Beef Cattle
Lbs
Fewer lbs = Fewer Calving Problems
Lbs
More lbs = faster calf growth
More lbs = Heavier Feeder Calves
Lbs
More lbs = More Cow Milk Production
Lbs
More lbs = faster steer growth
More lbs = Reach market faster
More lbs = greater mature size
More in2 = heavier muscled calves
Square
Inches
%
Higher % = more intramuscular fat
Higher % = higher quality grade
Bull
A
B
C
D
BW
0.0
-1.6
+2.1
-0.2
WW
+20
+16
+42
+35
Milk
+15
+22
+21
+30
YW
+40
+32
+55
+44
REA
-0.3
+0.8
+0.4
-0.7
MARB
+0.05
-0.02
+0.08
+0.12
1. Which bull would be the best choice to breed to heifers? _________________
Why?
2. Which bull would produce the lightest feeder calves? ________________
Why?
3. Which bull will produce calves with the highest quality grade? ____________
Why?
4. Which bull will sire steers that reach market weight the quickest? _________
Why?
5. Which bull will sire the poorest milk-producing daughters? _____________
Why?
6. Which bull will produce the heaviest muscled calves? _____________
Why?
7. Which bull’s calves will be the oldest when sold as feeder calves weighing 500
pounds?
Why?
8. Which bull will sire the heaviest calves at birth? _______________
Why?
9. Which bull will make the most improvement in milking ability? ______________
Why?
10. Which bull will sire the most growth? _______________
Why?
Additional Scenarios
The situation or environment that these cattle (bulls or heifers) are going to be placed into
once the selection process is complete should always be considered, so you can determine
what traits to emphasize when evaluating the EPD and the phenotype.
Here are some examples.
Scenario 1
1. All offspring are sold at weaning.
This indicates that the ____________________________ EPD should be emphasized
heavily.
Scenario 2
2. These bulls will be mated to first calf heifers and their offspring will be kept as
replacements.
This indicates that ___________________________ EPD should be strongly
evaluated and that ______________________ and _____________________ EPD’s
should be considered as well. Moreover, since the scenario says that all replacements
are being kept, then the _____________________ EPD is important also.
Scenario 3
3. Forage is low quality for the heifers.
This should indicate that __________________ _____________________________
should be emphasized. Thus, a high milk EPD should be discouraged in the decision
making process.
Scenario 4
4. Forage and feed are high in quality and abundant.
This signals that a ______________ _______________________ EPD should be
emphasized.
Scenario 5
5. The producer is retaining ownership through the feedlot.
This indicates that the owner does not sell the castrated bull calf (steer) or heifer until
after they are fed in the feedlot and go to harvest. _______________________
(weaning and yearling EPD ) are important. Specifically, the
________________________ EPD is by far the most important trait to evaluate in
this scenario.
Scenario 6
6. The ranch labor is limited.
This means that there is no one there to pull calves if cows or heifers are having
trouble calving. Thus, a _________________________________ EPD in potential
sires is a much more desirable economic trait.
EXPECTED PROGENY DIFFERENCES EVALUATION WORKSHEET
Name ____________________________________
Bull
Date ____________
Birth Weight
Weaning Weight
Yearling Weight
Milk
EPD
Acc.
EPD
Acc.
EPD
Acc.
EPD
Acc.
A
6.6
0.75
31.3
0.75
39.5
0.68
-5.6
0.58
B
0.1
0.82
14.6
0.83
24.6
0.80
6.0
0.73
C
0.0
0.89
0.3
0.89
11.1
0.88
18.9
0.87
D
-5.9
0.87
-3.8
0.87
-14.4
0.86
10.3
0.85
Producer 1 is looking for a sire that can be used on heifers; he wants a bull that
will produce low birth weights and he wants to keep some heifer calves as
replacements. Growth performance is not his first priority.
Which bull would producer 1 choose? _____________________________
Why?
Producer 2 has a sound-breeding program; he is looking for a sire that will
maintain performance and milking ability. He will select a bull that will increase
growth performance and milk while maintaining calving ease.
Which bull would producer 2 choose? _____________________________
Why?
Producer 3 has a herd of above-average-frame cows and is not planning on
keeping heifers as replacements. She is looking for a bull that will give her the
most profit at weaning.
Which bull would producer 3 choose? _____________________________
Why?
Producer 4 wants to maintain his calving performance and growth performance
but would like to increase the milking ability in his females.
Which bull would producer 4 choose? _____________________________
Why?