Menu
Forums
New posts
Search forums
What's new
New posts
New media
New media comments
New profile posts
Latest activity
Media
New media
New comments
Search media
Members
Current visitors
New profile posts
Search profile posts
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Forums
Cattle Boards
Breeds Board
EPD's What Do They Mean?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support CattleToday:
Message
<blockquote data-quote="Saltydawg" data-source="post: 169986" data-attributes="member: 2944"><p>Missed this thread till now hehe.</p><p></p><p> I'm afraid my schooling in mathematics isn't much use here because I don't have all the input information they use to calculate epd's.</p><p> These calculations and ammount of variables are far to large to attempt to work out without the aid of computers or a whole lot of paper and time lol.</p><p> The database and computers they are using to crunch these numbers has got to be HUGE.</p><p></p><p> From what I know of EPD's they are only guides....tools as has been pointed out.</p><p></p><p> BW epd is not going to tell you how much the calf will weigh when its born.</p><p> What it does is allow you to compare bull a with bull b and see which one is more likely to produce a heavier calf if bred to comparable cows/heifers.</p><p></p><p> If you were to take every calf ever born that was registered to a particular breed and average their weights you would come up with a mean value. This is known as value 0 for BW epd.</p><p> Ok so now we have a bull we want to figure BW epd for.</p><p></p><p> We need to look at all the calves sired by him, all the calves sired by his parents, grandparents, great grandparents....as far back as we can trace within his bloodline. Then we look at all the calves sired by his siblings...and so on and so forth....I'm not sure where they draw the line but I do know it is quite extensive.</p><p> Some of these figures will have more direct relevance on his performance than others so they assign weighted values to some of these....a curve.</p><p> Then we average these out and come up with a mean value for all his calves.</p><p> If it is higher than the mean for the breed then he recieves a positive score, and a negative if its lower than mean for the breed.</p><p></p><p> So now we know how this bull is expected to perform with regards to the breed average....its not a guarantee.</p><p> Most associations are going to assume that the animals are going to get all the feed they need to reach their potential.</p><p> If you don't feed your animals well or feed them too much then you can expect to see variation.</p><p> Due to the size of the sample used to compute most epd's, environment and phenotype is not really an issue. These differences get lost in the averages...they are not significant variables.</p><p></p><p> A bw 2.0 Bull can be expected to perform the same in Canada as it does in Texas when bred to a comparable cow.</p><p></p><p> The reason they won't give an outright breed expected weight is because it constantly changes everytime they run the figures through the computer and get new data.</p><p> When this mean value changes so do all the other values for every animal in the program.</p><p> Standard deviation will also change as these mean values are adjusted.</p><p> They can give you exact values for the last time they ran the numbers but its likely to change the next time around.</p><p></p><p> Thats the "problem" with averages.....change any value at all and every other value is effected as well.</p><p></p><p> I know there's a lot of oldtimers on here a lot more experienced than me but IMO the epd's are good guidelines.</p><p> They have sufficient information to make pretty accurate statistical analysis.</p><p></p><p> I think of EPD's like the weatherman on TV.</p><p></p><p> The weatherman is usually pretty good at telling you whats going to happen...... but sometimes he just plain aint right lol.</p><p></p><p> I guess thats Mother Nature getting her kicks.</p></blockquote><p></p>
[QUOTE="Saltydawg, post: 169986, member: 2944"] Missed this thread till now hehe. I'm afraid my schooling in mathematics isn't much use here because I don't have all the input information they use to calculate epd's. These calculations and ammount of variables are far to large to attempt to work out without the aid of computers or a whole lot of paper and time lol. The database and computers they are using to crunch these numbers has got to be HUGE. From what I know of EPD's they are only guides....tools as has been pointed out. BW epd is not going to tell you how much the calf will weigh when its born. What it does is allow you to compare bull a with bull b and see which one is more likely to produce a heavier calf if bred to comparable cows/heifers. If you were to take every calf ever born that was registered to a particular breed and average their weights you would come up with a mean value. This is known as value 0 for BW epd. Ok so now we have a bull we want to figure BW epd for. We need to look at all the calves sired by him, all the calves sired by his parents, grandparents, great grandparents....as far back as we can trace within his bloodline. Then we look at all the calves sired by his siblings...and so on and so forth....I'm not sure where they draw the line but I do know it is quite extensive. Some of these figures will have more direct relevance on his performance than others so they assign weighted values to some of these....a curve. Then we average these out and come up with a mean value for all his calves. If it is higher than the mean for the breed then he recieves a positive score, and a negative if its lower than mean for the breed. So now we know how this bull is expected to perform with regards to the breed average....its not a guarantee. Most associations are going to assume that the animals are going to get all the feed they need to reach their potential. If you don't feed your animals well or feed them too much then you can expect to see variation. Due to the size of the sample used to compute most epd's, environment and phenotype is not really an issue. These differences get lost in the averages...they are not significant variables. A bw 2.0 Bull can be expected to perform the same in Canada as it does in Texas when bred to a comparable cow. The reason they won't give an outright breed expected weight is because it constantly changes everytime they run the figures through the computer and get new data. When this mean value changes so do all the other values for every animal in the program. Standard deviation will also change as these mean values are adjusted. They can give you exact values for the last time they ran the numbers but its likely to change the next time around. Thats the "problem" with averages.....change any value at all and every other value is effected as well. I know there's a lot of oldtimers on here a lot more experienced than me but IMO the epd's are good guidelines. They have sufficient information to make pretty accurate statistical analysis. I think of EPD's like the weatherman on TV. The weatherman is usually pretty good at telling you whats going to happen...... but sometimes he just plain aint right lol. I guess thats Mother Nature getting her kicks. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Cattle Boards
Breeds Board
EPD's What Do They Mean?
Top