The table above is a representation of how you might see bulls in a sale book or breeding catalog. Remember, there are many more traits, but for sake of learning we will just focus on these for now.
So what does it all mean?
First, it is important to undertand the numbers above are deviations from the breed average. Each cattle breed reports average measurements for each trait then EPDs are reported as deviations from that average value. For instance, a breed may report an average BW of 72 lbs so a BW EPD of -2 would mean that, on average, that animal produces calves that are 70lbs. Second, you must be able to accurately interpret each trait EPD. If you think back to Applications you'll remember there was a short introduction to each EPD. Using that information we can determine the best bull for each trait. For CE, Bull 1 has a higher score so he is more likely to produce calves that will be born without incident. Typically, animals with a higher CE score will have a lower BW EPD becasue that indicates smaller calves--this situation is no exception. Bull 1 has calves that are -2.8 lbs lighter than the breed average. A smaller calf at birth will likely also be smaller later in life as well however which is not ideal if you are producing animals for market. For both WW and YW, Bull 2 performs better because his calves weigh more than calves of Bull 1. This can seem very confusing so we'll do a few more examples.
Look at the two bulls below. Which would you choose for a heifer breeding program? Remember, heifers are young females who have never had a calf.
Bull
CE
BW
WW
YW
Golden Boy
3
-1.0
39
62
Fantastic Sam
5
-3.5
30
56
Both of these bulls would be desirable as they both have positive CE values and negative BW values, but Fantastic Sam would be the best. With a higher CE score--related to his lower BW score--he would be best to breed with first time heifers.
Example 2: Selecting a Sire for a Terminal Breeding Program
Look at the two bulls below. Which would you choose for a terminal program? Remember, a terminal program is one that produces animals for meat production.
Bull
CE
BW
WW
YW
IDK My BFF Jill
-1
4
55
87
L8R G8R
1
2
43
64
You would choose IDK My BFF Jill because he produces calves with a heavier WW and YW. You may notice that neither of these bulls are particularly strong performers for CE, but that is okay in a terminal herd that typically consists of older cows who have previously produced calves.