Balance Index
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 20 20 20 20 20
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 101
Ram B 1.8 4.2 0.0 0.9 -0.2 101
Ram C 0.4 1.1 0.5 0.7 11.1 101
Ram D 0.5 1.5 1.0 1.2 2.1 101
Ram E 0.3 1.0 1.0 1.1 5.2 101
Balanced Composite Indexes give us a means of comparing rams relative worth. However, such indexes can be misleading if
it is the only criteria we use for ram selection. The above 5 rams have the same composite index. Would each of them be
equally good in your flock? Probably not.
Ram A is a balanced average ram.
Ram B is exceptional in the weight traits but below average in maternal traits.
Ram C is below average in the weight traits, average in milk and exceptional in number born.
Ram D is exceptional in milk and milk & growth but below average in the other traits.
Ram E is very good in maternal traits especially milk but below average in the weight traits.
If your flock has no particular trait weaknesses, Ram A would work OK.
Ram B would work well as a terminal sire or in a flock that is well above average in maternal traits but needs some help in the
weight area.
Ram C can only help a flock that is exceptional in all traits other than number born. His ewe lambs will be prolific but not
much else.
Ram D and E will help most flocks in milk but not much else.
All of the rams are average when compared to the Polypay population and they could help you if their exceptional traits will
increase these traits in your flock without detracting too much from the ram’s weak traits.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 20 20 20 20 20
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram F 3.5 8.7 2.5 2.8 25.0 429
Ram G 3.0 8.0 2.0 3.5 8.6 338
Ram H 3.4 8.5 2.2 3.9 1.0 338
Ram I 2.0 6.5 2.0 3.0 20.3 338
Here we have exception rams with indexes well into the 90 percentile. If you find a ram with the index of Ram F, you’ve found
a ram that equals the EPDs in all 5 traits in the Spring 2007 NSIP run.
Rams G, H and I will improve most flocks. However, Ram I would help most in number born. Ram H would improve all traits
except for number born where he is below average. Ram G is just pretty good across the board. Which one would be best
for your flock? You have to look at the weakest traits in your flock and select one of these good rams that will improve that
trait or traits.
Weighed Index
We can use weighted indexes to place selection emphasis on the traits that we need to improve in our flock. Here are a
couple of examples.
On the following index, maternal traits of Maternal Milk and Percent Lamb Crop (Number Born) have been increased by 10
percent while the weights have been decreased by 10 percent. Milk & Growth was left the same, as it is a combination of
weight and maternal traits.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 10 10 30 20 30
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 100
Ram B 1.8 4.2 0.0 0.9 -0.2 60
Ram C 0.4 1.1 0.5 0.7 11.1 123
Ram D 0.5 1.5 1.0 1.2 2.1 112
Now we can see that the index changes. So by placing emphasis on two of the maternal traits we see that Ram C and D
have a higher index. Now we have to decide whether milk or number born is the biggest weakness in our flock to determine
which of these two rams will work best for our flock.
Now let’s look at another example where we emphasize weights because that is the weakest point in our flock.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 30 30 10 20 10
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 102
Ram B 1.8 4.2 0.0 0.9 -0.2 143
Ram C 0.4 1.1 0.5 0.7 11.1 78
Ram D 0.5 1.5 1.0 1.2 2.1 90
Now Ram B is the highest indexing ram. So if the weight traits are the weakest link in our flock, Ram B is the ram we want.
You need to take a critical look at your flock and decide upon the trait or traits you want too improve. Working on a single
trait or area will bring about the fasted improvement.
A Balanced Index gives an indication of which is the best ram overall. However, most flocks as well as individual animals
have their weak points. Therefore we need to assess our flock as well as the ram we are looking at and determine the best
fit for genetic improvement. The Composite Index Calculator shown here or the Iowa State “Ram Selection Emphasis Index”
will help you decide upon a ram but first you need to determine where your flock is. Then place your emphasis on the trait
needing improvement and assess the rams using this emphasis.
These examples do not show Percent Rank because of the small population. See the section on Sample NSIP with Percent
Rank and Composite Index for a discussion of Percent Rank.
Need help. Contact us or ask any NSIP Polypay producer.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 20 20 20 20 20
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 101
Ram B 1.8 4.2 0.0 0.9 -0.2 101
Ram C 0.4 1.1 0.5 0.7 11.1 101
Ram D 0.5 1.5 1.0 1.2 2.1 101
Ram E 0.3 1.0 1.0 1.1 5.2 101
Balanced Composite Indexes give us a means of comparing rams relative worth. However, such indexes can be misleading if
it is the only criteria we use for ram selection. The above 5 rams have the same composite index. Would each of them be
equally good in your flock? Probably not.
Ram A is a balanced average ram.
Ram B is exceptional in the weight traits but below average in maternal traits.
Ram C is below average in the weight traits, average in milk and exceptional in number born.
Ram D is exceptional in milk and milk & growth but below average in the other traits.
Ram E is very good in maternal traits especially milk but below average in the weight traits.
If your flock has no particular trait weaknesses, Ram A would work OK.
Ram B would work well as a terminal sire or in a flock that is well above average in maternal traits but needs some help in the
weight area.
Ram C can only help a flock that is exceptional in all traits other than number born. His ewe lambs will be prolific but not
much else.
Ram D and E will help most flocks in milk but not much else.
All of the rams are average when compared to the Polypay population and they could help you if their exceptional traits will
increase these traits in your flock without detracting too much from the ram’s weak traits.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 20 20 20 20 20
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram F 3.5 8.7 2.5 2.8 25.0 429
Ram G 3.0 8.0 2.0 3.5 8.6 338
Ram H 3.4 8.5 2.2 3.9 1.0 338
Ram I 2.0 6.5 2.0 3.0 20.3 338
Here we have exception rams with indexes well into the 90 percentile. If you find a ram with the index of Ram F, you’ve found
a ram that equals the EPDs in all 5 traits in the Spring 2007 NSIP run.
Rams G, H and I will improve most flocks. However, Ram I would help most in number born. Ram H would improve all traits
except for number born where he is below average. Ram G is just pretty good across the board. Which one would be best
for your flock? You have to look at the weakest traits in your flock and select one of these good rams that will improve that
trait or traits.
Weighed Index
We can use weighted indexes to place selection emphasis on the traits that we need to improve in our flock. Here are a
couple of examples.
On the following index, maternal traits of Maternal Milk and Percent Lamb Crop (Number Born) have been increased by 10
percent while the weights have been decreased by 10 percent. Milk & Growth was left the same, as it is a combination of
weight and maternal traits.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 10 10 30 20 30
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 100
Ram B 1.8 4.2 0.0 0.9 -0.2 60
Ram C 0.4 1.1 0.5 0.7 11.1 123
Ram D 0.5 1.5 1.0 1.2 2.1 112
Now we can see that the index changes. So by placing emphasis on two of the maternal traits we see that Ram C and D
have a higher index. Now we have to decide whether milk or number born is the biggest weakness in our flock to determine
which of these two rams will work best for our flock.
Now let’s look at another example where we emphasize weights because that is the weakest point in our flock.
Trait Ave. 0.9 2.1 0.5 0.9 4.9
Trait Wt. 30 30 10 20 10
Eartag WW PWW MM MGR NB Composite
EPD EPD EPD EPD EPD Index
Ram A 0.9 2.1 0.5 0.9 4.9 102
Ram B 1.8 4.2 0.0 0.9 -0.2 143
Ram C 0.4 1.1 0.5 0.7 11.1 78
Ram D 0.5 1.5 1.0 1.2 2.1 90
Now Ram B is the highest indexing ram. So if the weight traits are the weakest link in our flock, Ram B is the ram we want.
You need to take a critical look at your flock and decide upon the trait or traits you want too improve. Working on a single
trait or area will bring about the fasted improvement.
A Balanced Index gives an indication of which is the best ram overall. However, most flocks as well as individual animals
have their weak points. Therefore we need to assess our flock as well as the ram we are looking at and determine the best
fit for genetic improvement. The Composite Index Calculator shown here or the Iowa State “Ram Selection Emphasis Index”
will help you decide upon a ram but first you need to determine where your flock is. Then place your emphasis on the trait
needing improvement and assess the rams using this emphasis.
These examples do not show Percent Rank because of the small population. See the section on Sample NSIP with Percent
Rank and Composite Index for a discussion of Percent Rank.
Need help. Contact us or ask any NSIP Polypay producer.
| Using Indexes Uncompahgre Polypay Farm The home of production Polypays |
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