Are the keys to "hybrid vigor" (this thread began here http://www.leerburg.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=104&t=000002&p=4

Line Breeding and outcrossing are like work and conformation, corrections and praise, and night and day. Ones not much good without the other. It seems people only understand this when it suits their current philosophy. Lean too much in any direction and you are bound to be unhappy with the results.

Too much line breeding and you will end up with crap. THE SAME CAN BE SAID WITH OUTCROSSING. It's just longer path that leads to the same place, RUIN.

Food growers have known this for a long time. You take two different apples that you are fond of and are "fixed" in type. Cross these two and you are pleasantly suprised with the results. You have a new apple that is more vigorous and tastes better than either of the parents did, and also they are very uniform in looks and flavor. (hybrid vigor)

Take one of those "hybrids" and outcross again and now what do you have? A farm full of crappy apples that are "watered down" and all very different-- very few of them measuring up to the originals that you started with. This is why you don't see any Fiesta/Fuji/Gala crosses out there.

The most sound theory for the small time dog breeder would be this, IMO.

Get yourself a bitch who has been line bred and is relatively "fixed in type" then take her to a stud that is from a completely different line breeding and is also "fixed in type" If you like the two animals that you started with and the above prerequisites have been met, then you should be very happy with the results of that F1 litter. You can breed these two P1 animals over and over and you should have similar results each time. Predictability and consistancy within the litter. This is the power of hybrid vigor, and the finest reason for an outcross.

Take an F1 pup from that litter and breed IT and this is where your smorgasbord of watered down crap to sift through and try to make sense of begins. You have to start rebuilding your line again and you won't be as happy with the consistency of your litters for a while, until line breeding brings you back to where you started, or to a better place hopefully. This should be left for people who REALLY know their stuff, and not the "small time dog breeder"

LINE BREEDING IS NECESSARY to fix and SEPERATE the different lines that we are working with or you would never be able to capitalize on the powerful phenomenon of hybrid vigor. If you fail to capitalize on hybrid vigor then you, as a breeder, are overlooking the most powerful tool in your box!

Could you build something whorthwhile by outcrossing alone? Sure, but it would be like buiding the pyramids-- you would need to have generations of people slaving away on that same goal before you realized any progress. In the mean time, be prepared to place plenty of "pets" per litter no matter how awsome the phenotypes of the parents. And good luck being able to outcross over and over with breeders that have the same taste as you. You will quickly run out of places to go and still be able to call it an outcross.

Most importantly, if some people had their way and the whole world (pick your breed) was only outcrossing, because of the evils of line breeding, there would be NO seperation of lines after a short while. Hybrid vigor would no longer be accomplished by an outcross and that would be a sad day indeed. We need our line breeders.

As in all things.... Balance is where its at <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

I am not a breeder so this cleared up some of the confussion I have had for a long time.
Thanks for making it easy to understand a very complex subject.

The way I understand it from George Padgett's book on heritability of canine diseases, if you want to suppress the expression of some unwanted gene, you outcross. If you want to eliminate a trait, inbreed to bring it to the surface and then remove the affected dogs from the gene pool. The outcrossing works short-term but allows the recessives to spread thru the genepool w/out anyone knowing WHO carries it. This makes it more likely that it will become a widespread problem in the breed. With the inbreeding, you see these undesirable traits w/in a few generations and can quickly weed them out. However, when you go back to an outside line, you run the risk of bringing these recessives back into your line.

So, if everyone would inbreed their lines for, say, 5 generations and spay/neuter or put down the affected dogs (if the trait is detrimental to quality of life) and THEN start outcrossing again, we could have healthy dogs!! But can you see EVERYONE agreeing to do ANYTHING at the same time, even if it would solve so many problems in the breed??

Oh well, it's a thought anyway! And things in real life hardly ever work out as perfect as the theory! <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

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Originally posted by jason:
Line Breeding and outcrossing are like work and conformation, corrections and praise, and night and day. Ones not much good without the other.

That is true when you are starting a new breed out of a bunch of generic shepherd dogs as the GSD was over a century ago and when you need to establish genetic set points for the new breed. However, the GSD is already a century-old breed with well-established genetic set points.

Get yourself a bitch who has been line bred and is relatively "fixed in type" then take her to a stud that is from a completely different line breeding and is also "fixed in type". If you like the two animals that you started with and the above prerequisites have been met, then you should be very happy with the results of that F1 litter.

What "prerequisites" are you talking about? That breeding partners be linebred from different lines and that you like them? That's ALL? Any breeding objectives? Any direction you want to go as a breeder? How do you know if you will be happy with the results of the breeding? How do you know what each parent will pass on to the puppies since each parent is hypothetically pre-potent as a linebred dog? Etc.

Take an F1 pup from that litter and breed IT and this is where your smorgasbord of watered down crap to sift through and try to make sense of begins. You have to start rebuilding your line again.

You lost me. You never had a "your line" to begin with in the first place. In your example you only have two separate lines belonging to someone else. But, even so, why should you have a "smorgasbord of watered down crap to sift through"? I thought you chose "pre-filtered" lines that you liked. Where does the crap come from? BTW -- do you take ANY pup from that litter & breed it?

It seems to me that your example of outcrossing IS pretty non-productive especially if it only results in watered-down crap. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

LINE BREEDING IS NECESSARY to fix and SEPERATE the different lines that we are working with or you would never be able to capitalize on the powerful phenomenon of hybrid vigor.

So ...... let me be sure I understand .... you outcross using two linebred dogs to create hybrid vigor, then breed back your "watered-down (but very vigorous) outcross crap" to one of the lines it comes from to fix "what"? Crap? Or, do you simply breed the outcross back just so you can have more linebred dogs to outcross again despite the creation of crap just so you can "capitalize on the powerful phenomenon of hybrid vigor" yet again? Sounds rather circular.

Could you build something worthwhile by outcrossing alone? . . . . That's never going to happen in dog breeding because a common goal will never be agreed upon.

You lost me there. Is there a common goal in all the GSD lines or do they each result from somewhat different breeding goals themselves?

Most importantly, if some people had their way and the whole world was only outcrossing, there would be NO seperation of lines after a short while. Hybrid vigor would no longer be found in an outcross and that would be a sad day indeed....

First of all, we are not talking about the whole world -- we are only talking about one breed. Of course there would & could be separate lines all outcrossed within the breed and, holy crap, they would/could also all have hybrid vigor <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> . Not such a bad thing. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> . But, I wouldn't lose sleep over the thought since chances are slim to none that it'll ever happen. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

If you want to eliminate a trait, inbreed to bring it to the surface and then remove the affected dogs from the gene pool.

That's a solution but, then, it has to be weighed against the cost of what you lose in the way of genetic diversity by doing it.

The outcrossing works short-term but allows the recessives to spread thru the genepool w/out anyone knowing WHO carries it. This makes it more likely that it will become a widespread problem in the breed.

Outcrossing helps keep the unwanted recessives buried by maintaining greater genetic diversity in the breed. It does not make it more likely that they will become a widespread problem because of the diversity advantage.

With the inbreeding, you see these undesirable traits w/in a few generations and can quickly weed them out. However, when you go back to an outside line, you run the risk of bringing these recessives back into your line.

With inbreeding OR with outcrossing you can weed out the PARENTS of puppies that carry the double recessive and express the bad recessives. But unless BOTH parents carry the recessive, it will not show up in the pups and some of the pups produced by carriers bred to non-carriers will also be carriers.

The only way to test an animal for a recessive is to breed it to a known carrier and see if any of the puppies produced have the problem. The test breeding can be either outcross or inbreeding, it's irrelevant. But to eliminate the recessive, you would have to cull the parent carriers AND ALL the offspring produced since you can't tell which pups are carriers and which are not without breeding them to a known carrier also.

When you take two dogs from different lines and you cross them this produces hybrid vigor. The further removed these two lines are, the more predictable the results will be. That the two lines be as far removed as possible is the main prerequisite, they should also be line bred so they are "prepotent" and this is also very important. All dogs that you breed should be awsome. What constitutes "awsome" will change from breeder to breeder so I said two dogs "that you like".

When you cross these two lines, the prepotent genes of both parents go into a full out brawl over "inheritability rights". The result is that both parents equally influence the cross. All pups in that litter will be very uniform for this reason. This is the most predictable of all crosses in breeding, and for that reason, it should be the bread and butter of any breeding program. More predictable than linebreeding. With linebreeding you will have pups that are like Mom, Dad, Uncle Charley, aunt Marge etc. With the "two seperate line" breeding, all pups tend to fall between the two parents and you won't see too many aunt marges show up in the litter. This is why it is phenomenal and the most powerful tool in your box.

No, This does NOT happen with just any old outcross.

When I say "watered down crap" I am refering to the extremely less predictable/uniform results that occur IF you choose to continue beyond that original outcross to improve your line. A necessary step to improve your line, part of the full circle of breeding, but line breeding should be left for people who really know their stuff AND are putting out several litters per year. Outcross after outcross will also produce extremely less predictable/uniform results, only you won't be able to bring the same consistency back as you would with line breeding. Not in a thousand years, no matter how perfect your selections are.

All I'm saying is the small time dog breeder should stick to hybrid vigor breedings only. By doing this I feel that you/me have the best chance of putting predictable and uniform litters on the ground. I have a hard time believing that this is "news" to dog breeders. It's not news to breeders of anything else.

Here are two articles that may be of interest with regard to the pros & cons of inbreeding, line breeding & cross breeding.
http://www.ckcusa.com/genetic1.htm http://www.ckcusa.com/openregistry.htm

I have been caught up with some problems here and so don't have time right now to respond myself. These articles seem to express my own thoughts pretty well. As soon as I can, if there is any interest, I will describe how a man I respect a great deal bred an unbroken line of performance champions by breeding less than one litter every year or two over a 40 year period paying NO attention to inbreeding or line breeding -- that leaves basically outcrossing albeit WITHIN the GSD breed.

Taken from the Dr Denny Article on the ""Principles of Genetics"". part 1

""Hybrid vigor has occurred when the performance of the offspring is different from that of the average of their parents. The actual mechanism of hybrid vigor is not well understood, however, matings can be made to increase the beneficial effects of hybrid vigor. Mating of animals which are not alike in their pedigree or that are not related are those which will generally exhibit higher levels of hybrid vigor. Closely related animals do not exhibit high levels of heterosis.
Crossbreeding in plants and animals is done to take advantage of both hybrid vigor and complimentarity. Complimentarity is the term used to describe the "combining" of desirable traits from two breeds or lines that are not related. Hybrid vigor is also maximized when animals are mated that have little or no genetic history in common.""

All the books and articles on dog breeding I've read, including these two, just don't go into hybrid vigor deep enough considering its value. When they do, it's easy to get caught up in the complexity of it all and miss the most important points because they don't stress their value and how to apply them. They don't bother to make it easily understood. The fact is Dr Denny has not disagreed with me at all.

He didn't really go into the predictable/uniform outcome of such a cross but you folks can see that in the Melrose apple, the tangelo, or a mule, and all over the agricultural and animal husbandry world for that matter. (smack dab between the two parents every time)

I almost missed it. He does go into it when he says in part 2

""Crossbred progeny arising from the mating of purebred parents from two separate breeds are referred to as F, progeny, and for traits which are under the control of many genes, might be expected to perform at a level intermediate to the two parent breeds""

I would of had fireworks shooting out of that sentence (at least bold print!) because this is of EXTRAORDINARY value to the breeder, predictability is the breeders best friend, and this is the most predictable cross of all (bread and butter). You can take the word "breeds" to read "lines". Its only a matter of degree after all.
He also mentioned the "prerequisite" that I keep bringing up. When he says in part 1

""Hybrid vigor is maximized when animals are mated that have little or no genetic history in common.""

The very best way to get animals to cross with "little or no genetic history in common" is for them to be in the hands of breeders that line breed them to keep them seperated. As a matter of fact, it's the only way, because WITHOUT LINEBREEDING THERE WOULD BE NO OUTCROSSING (night and day, bla bla bla). Line breeders still must use the outcross to bring vigor to their line as needed, and they can still use the "two seperate line" cross for their bread and butter. By all means though, also keep your line as seperate as possible from as many other lines as possible. Guard this seperation with a passion. This way you will have more lines to go to for hybrid vigor.

If you only outcross after outcross etc., and you only use excellent examples for breeding, your going to be able to find some excellent puppies in these litters aren't you. The problem is that the line loses it's seperate identity quickly and hybrid vigor decreases with each outcross. Until finally your left with zero kennels out there that will bring any vigor at all. Watered down crap indeed, also self-defeating. Those breedings will never be able to compare to the predictability and uniformity of a "two seperate lines" hybrid vigor breeding. These books and articles always fail to go into this subject deep enough and plain enough for the average dog breeder to take advantage of it. The most important points aren't stressed enough.

From Dr Denny's article taken from part 2. (his closing paragraph)

""Purebreeding and line breeding are used to maintain distinctly separate breed types, but crossbreeding uses those distinct types to improve production, survival and longevity through the use of both complementarity and heterosis. Choice of mating system depends on sound selection practices which allow for the combining of desirable traits from different breeds and the generation of heterosis.""

This is exacty what I've been describing for this entire thread. LINE BREEDING IS WHAT PROVIDES FOR THE OUTCROSSING THAT EQUALS HYBRID VIGOR. TAKE OUT ANY PART OF THAT EQUATION AND EVERYTHING GOES TO CRAP. Once again, you can take the word "breeds" to read "lines" when reading this as it is only a matter of degree.

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If you only outcross after outcross etc., and you only use excellent examples for breeding, your going to be able to find some excellent puppies in these litters aren't you. The problem is that the line loses it's seperate identity quickly and hybrid vigor decreases with each outcross. Until finally your left with zero kennels out there that will bring any vigor at all.

That's just not true if you "outcross" within a breed. It may be true if you outcross using different breeds, but, as I pointed out before, the GSD already had its genetic set points established nearly a century ago which means if you outcross within the breed you aren't going to produce a basset hound -- at least not for one helluva long time.

If you outcross after outcross with a specific purpose/objective clearly in mind, and, if you select for future outcross breeding ONLY the offspring that has PROVEN itself to have inherited ALL of what you are breeding for (no compromise), you will find that subsequent generations of your selectively bred outcrosses will produce litters with increasingly higher percentages of puppies that carry all or most of the traits you have been selecting for. AND, far from losing separate identity as a line, you will have created a line.

The hybrid vigor effect should decrease with each outcross -- the vigor will remain at a high level because you won't have any genetic degeneration due to inbreeding or line breeding from which to lose it.

Once again, you can take the word "breeds" to read "lines" when reading this as it is only a matter of degree.

No, you can't -- the "matter of degree" is just too great. Different breeds have entirely different breed-specific genetic set points -- different lines within a breed do not.

As we lament the loss of the working dogs of the past, it must be remember that they were produced by out-crossing. It was more important to be known for good dogs rather than for a "distinct line". Line breeding is of fairly recent development. It is rare for a breeder to maintain a "distinct" line without the ability to maintain control over a large number of dogs and even then they have to go out side that line on a regular basis.

It would seem to me that it is much more important to be known for sucessfuly breeding good dogs, rather than for producing a "distinct" line. As Ed is fond of saying, breeding is like cooking, it takes the proper mix of ingredients, and some luck. Being known for good dogs is more important than having your name 12 times on a pedigree.