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Did this teach you anything Matt?

What is inbreeding depression measured against?

not really. i didnt actually read it to the end either.

i just thought it was kinda entertaining and was happy they didnt portray inbreeding to be something sinister like many publications.

the average of the population?

Check the Case Studies. Linebreeding to the most popular sires of the most diverse pedigrees selected for the most of one or more things. The case studies focus on the fear of too much inbreeding.

When the industry has problems with consistency and uniformity, could it be because we have a fear pounded in our head from the time of comprehension, and sometimes before, that the methods to create what we need are so scary that they must be avoided at all costs?

Why are these same folks still clinging to breeds?

In the past, when you were told that it was an Anxiety 4th bull, that told you quite a bit about what he possessed and what he would produce. Today we know generally what to expect from modern OCC and Shoshone cattle. Even somewhat with Wye cattle. They are what their line represents. The rest are a son of this a daughter of that.

What has happened to the great sires of their day who were widely used yet did not have a line built around them? Their influence is diluted 50% per generation. They just disappear. It is just as well, because the selection criteria has also changed and they no longer fit.

If 036 is such a fine rascal, as I gather is believed from the case studies, then why would they be so insistent on pussy footing around with linebreeding to him. You don't learn to swim by dipping your toes in the water. If he has what they want, why not build the herd around him and make him the average? Of coarse, this would mean that the selection criteria must be set too. Few have the fortitude to quit changing with the wind, both genes and selection.

As to the article, where is the list of breeding accomplishments of the Author through linebreeding, inbreeding, outcrossing, or crossbreeding?

I suspect it is folly to think you can inbreed enough to increase consistency without experiencing inbreeding depression. They are the same thing and they will be happening at the same time.

As for inbred matings occasionally producing a superior performing animal, that may be true-- and you might treasure such calves-- but it's probably an inbreeding failure, assuming inbreeding is about consistency.

Inbreeding Depression is the opposite of heterosis. I think Matt is right-- its measured against the average-- I think. So, yeah, outcrossing and crossbreeding benefit from heterosis.

Heres how they do it, apparently:
http://digitalcommons.unl.edu/cgi/viewc ... lscifacpub

Here's how I think it works:
(1) Identify a total population. A herd, or a breed, or a random sample of the herd. Determine its average performance in the trait of interest. That'd be your average to which you compare.
(2) Then you calculate inbreeding coefficients for the animals in the population. Based on that, you separate inbreds from non-inbreds, and you calculate the average performance of the inbred group and the not-inbred group.
(3) Then you compare the performance of the inbreds to the average performance. The result should be a measurement of inbreeding depression.
(4) You can compare the performance of the not-inbreds to the average performance too. The result would be a measurement of heterosis.

Or some such.

read those two lines over and over till they make sense.

a measurement is a measurement, nothing heterosed, nothing depressed.

both lines have a word in them that are a problem and ruin the sentences.

what if the two measurements are not equal from the mean? which one is wrong/right?

one thing that bugs me about the article right off the bat is that they don't indicate a way to measure relatedness to the animal they think they are concentrating other than through pedigree which is annoying.

a second annoying part is that the appearance of bad traits in inbred populations is assumed to be increased. what they don't seem to understand is that you want to increase the risk these bad genes will appear so you can get rid of them instead of hide them by identifying the homozygous alleles that are beneficial and keeping them. some will be dominant, some will be recessive and some will have other influences. they seem to understand the cull rate is high but don't understand that is required in the beginning and the cull rate later will be lower.

the goal of inbreeding is not to produce a single superior individual.

mostly useless information and no real insight into the advantages of linebreeding. sad, pathetic. must be some other agenda that is against linebreeding. this article is a disservice to animal breeding as it really isn't about breeding.

I ruin lots of sentences, pretty much everyday. (Probably one of the sentences in this post is ruined-- I apologize in advance).

I did actually think about those sentences some when I drafted them, and decided they were sufficient to display how I thought one might reasonably measure these things, in two minutes or less. I understand the problems with the sentences. To be clear, if there is no difference between the groups' performances, nothing is heterosed or depressed. 100-100=0. Heterosis is zero, depression is zero. I'd guess that many traits that can be measured probably are not heterosed or depressed.

my comment on the sentences was not a personal comment. i only used them because they so clearly described the problem of the difficulty of measuring or talking about linebreeding. we go through this argument every day at work when comparing kit lots of reagents, control sample pools, assay lots and use several methods to measure things. one measurement that is becoming apparent that it is weak is the median of the means as it easily hides extreme variation of a small subset when those subsets equally offset each other. it's basically why i think the breeding values used by all the gene marker companies are annoying, in addition to training set questions and across breed issues. it's difficult to go from a single center training set to the general population.

i want the allele information because no one knows which two animals to use to compliment each other if they have the same score. a complete waste of time if one is trying to introgress markers. to me, this is total crap as they will know which animals are homozygous for their markers, can go out and get semen on the bulls, validate them further and get advance notice on the "value" of the bulls.

there is no reason at all not to reveal the allele information. it is not hard to put that in an spreadsheet, even for 1000 markers and prioritize them based on impact with unheard of tools such as sort.

There is a very good reason. We must avoid confusion in the general public. We are not smart enough to know what to do with the information. We are only competant to write the check. All valuable information has to be watered down to be both paletable to the public and to ensure a longer necessity for the product.

With Allele documentation from any of these DNA Tests the test is fairly obsolete in one to two generations. Motion and commotion prevail.

I was glad to read Dave K address the "Feed efficiency" standard being transformed from a ratio of pounds of feed/pound of gain to what it is today. It never made sense to me, now I know why.

you didn't say why. if and a big if, a snp is causal and not just correlated, your comment is false. the motion and commotion would then be attributable to what is passed on in the offspring.

When the animals are homozygous for the trait, the test is no longer necessary.

that was the part i most disagreed with.

If it works call it linebreeding
If it does not work then go back a call it inbreeding

An old faithful in Academic Animal breeding circles. A true sign of a circle to stay out of.