Tuesday, November 27, 2007
Breeding and Genetic Problems
Here's a quick little exercise to do before you read this post. Think of three genetic problems in rabbits.
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. . .
. . .
Okay, time's up. What did you think of? Butting teeth, white nails, split penis, eye spots, pigeon breast? Did you list narrow shoulders? undercut and/or pinched hindquarter? thin ears? temperment? thin fur? You didn't? Why not? These, too, are problems that are genetically passed down to the next generation.
My point is that we tend to treat certain genetic problems differently than others. But the results are the same: you want to cull out those characteristics. So why do you still breed rabbits with genetic faults? Probably because you don't have two perfect rabbits to breed together. I know that I don't. My reasoning is that I'll breed in the good qualities and breed out the bad ones, ending up with a better product down the road.
So now let's think about the list of genetic problems that we tend to think of as genetic. First of all, I don't think there's total consensus on some of these that they are indeed genetic. I'm not sure that a split penis is always genetic. Sometimes it does run in lines. That would give more support to that line having a genetic predisposition to it. But other times, there's no real pattern. In fact, I have a friend who bred a split penis to a doe that produced a split penis. She was unable to replicate the problem in the young. That's not enough trials to base any conclusion on, but one would have expected half of the males to have a split if we are talking about a simple dominant-recessive situation.
I would love to see some more research on that.
As for eye spots, I'm convinced that many are caused by e cuniculi. That could appear to run in lines if dams continue to pass e cuniculi down to their young. Before you process an entire herd for eye spots, treat for e cuniculi. See if that stops further eye spots in new generations. I use fenbendazole (found in Safeguard) to treat my rabbits for e cuniculi.
As for other problems, some may indeed be genetic. But how much of a problem is that in breeding?
Well, it depends. First of all, the nearer you are to the beginning of developing your herd, the greater affect genetic problems will have on the future generations. However, you are also less likely to have great specimens to breed together, which makes a great rabbit with a problem more desirable. So here is my litmus test. If I wanted to try to breed a rabbit with butting teeth (butting since it was a kit), for example, I would have to ask myself whether the good qualities of that rabbit were so good that it would be worth breeding out the tooth problem for possibly generations to come.
I wouldn't even think of breeding an average rabbit with any type of genetic problem.
Or, if the line were already developed and I start to see a problem in the offspring, I have to ask myself how many keepers that line produced versus how many rabbits with that problem. Now, you already know that I breed tightly, so if there is a problem, I'll see it in many places.
So let's say that I decided to breed a rabbit with long shoulders. I did this because the head, hindquarter, bone, and fur are outstanding. After two or three generations, I find that that line has produced 100 rabbits, 10 of which are grand champions, another 30 of which were worthy of pedigreeing, and 60 of which were pet quality. Now I can ask myself whether it is worth it to continue working with this line, seeing that the ratio of different kinds of rabbits are reproduced.
Some people feel that they are making a great decision by getting rid of a "genetic problem" with a rabbit that could produce 30% keepers while they continue to breed rabbits with no genetic red light items that have yet to produce anything worthwhile.
I once decided to work with a line that I thought had a tooth problem. I had calculated that a certain buck's offspring had produced teeth problems 1/3 of the time (though it was a small sample). That sounded genetic to me. But he had also produced grand champions and a buck that was second at Convention. Because of the possibility of really nice rabbits from the line, I worked it for a while.
However, I worked it in seclusion from the rest of my herd, meaning that I just bred the two rabbits together or with their offspring. If I had seen a tooth problem, then I could have eliminated that branch of my rabbitry without halting the progress across the board.
So I bred half brother and sister together. Neither had teeth issues themselves. They eventually had 10 kits, 8 of which were pedigreeable (just 2 were pets). One was a grand champion. What a great keeper rate! Two had teeth problems. One self-corrected by six months and the other went from bad to just barely, barely butting by six months old. It was so close that judges would probably only catch it part of the time (I processed her anyway, though).
I kept in touch with the new owner of the patriarche of this line. I was told that he had produced over 100 offspring with no teeth problems.
Because I lost the doe that was the flagship of my project, I eventually sold off everything in that project. But I did so knowing that there was no huge tooth problem after all. And the keeper rate was very, very good.
As a side, I gave away the 2nd place at Convention boy to a friend with advanced coursework in genetics. He has beaten the pants off of me with two different sons. And he reports no teeth problems whatsoever. Did I throw out the baby with the bathwater?
If you have produced a rabbit yourself that has a problem, let's say light nails, what do you do? If you have siblings that do not have the problem, that's certainly the way to go, assuming the rabbits are good enough to deal with an occasional problem cropping up. That way, you may luck out and get clean genes from the beginning (at least on that issue). Still, you have to know that you've chosen to work out any potential genetic problem down the sibling line.
But what if the rabbit is your only chance to work with a certain gene pool? Suppose you need the qualities that the rabbit has? If you can't get that gene pool any other way and you really want it, go for it. Just know that you have taken on a multi-generation project, that you need to keep this rabbit's line separate from your main line until you are convinced it is clean. And don't forget to evaluate the value of the keepers against the risk of dealing with a known genetic problem. Many rabbits that seem so promising just don't produce up to your expectations.
Yes, I've bred a doe with a fantastic front and a weak lower hindquarter. Now I get to work with her grand champion daughter who has a lovely hindquarter. Normally, I skip anything without a great hindquarter, but her front end was so good it was worth the risk.
You certainly should give genetic problems that affect a rabbit's quality of life differently than you do other types of genetic problems.
One last item: if you are working on a line with a genetic problem in hopes of eradicating it, please do not sell any of these rabbits to others without full disclosure until/unless you have determined that the line is clean. You may have chosen to work hard to clean up that line, but don't force that process on someone else without their consent.
I believe that you will find as your herd develops that you have less and less need and desire to work with anything even remotely suspicious. Once you have a base to work from, you don't need to take as many chances.
Laurie ¶ 10:42 AM
. . .
. . .
. . .
Okay, time's up. What did you think of? Butting teeth, white nails, split penis, eye spots, pigeon breast? Did you list narrow shoulders? undercut and/or pinched hindquarter? thin ears? temperment? thin fur? You didn't? Why not? These, too, are problems that are genetically passed down to the next generation.
My point is that we tend to treat certain genetic problems differently than others. But the results are the same: you want to cull out those characteristics. So why do you still breed rabbits with genetic faults? Probably because you don't have two perfect rabbits to breed together. I know that I don't. My reasoning is that I'll breed in the good qualities and breed out the bad ones, ending up with a better product down the road.
So now let's think about the list of genetic problems that we tend to think of as genetic. First of all, I don't think there's total consensus on some of these that they are indeed genetic. I'm not sure that a split penis is always genetic. Sometimes it does run in lines. That would give more support to that line having a genetic predisposition to it. But other times, there's no real pattern. In fact, I have a friend who bred a split penis to a doe that produced a split penis. She was unable to replicate the problem in the young. That's not enough trials to base any conclusion on, but one would have expected half of the males to have a split if we are talking about a simple dominant-recessive situation.
I would love to see some more research on that.
As for eye spots, I'm convinced that many are caused by e cuniculi. That could appear to run in lines if dams continue to pass e cuniculi down to their young. Before you process an entire herd for eye spots, treat for e cuniculi. See if that stops further eye spots in new generations. I use fenbendazole (found in Safeguard) to treat my rabbits for e cuniculi.
As for other problems, some may indeed be genetic. But how much of a problem is that in breeding?
Well, it depends. First of all, the nearer you are to the beginning of developing your herd, the greater affect genetic problems will have on the future generations. However, you are also less likely to have great specimens to breed together, which makes a great rabbit with a problem more desirable. So here is my litmus test. If I wanted to try to breed a rabbit with butting teeth (butting since it was a kit), for example, I would have to ask myself whether the good qualities of that rabbit were so good that it would be worth breeding out the tooth problem for possibly generations to come.
I wouldn't even think of breeding an average rabbit with any type of genetic problem.
Or, if the line were already developed and I start to see a problem in the offspring, I have to ask myself how many keepers that line produced versus how many rabbits with that problem. Now, you already know that I breed tightly, so if there is a problem, I'll see it in many places.
So let's say that I decided to breed a rabbit with long shoulders. I did this because the head, hindquarter, bone, and fur are outstanding. After two or three generations, I find that that line has produced 100 rabbits, 10 of which are grand champions, another 30 of which were worthy of pedigreeing, and 60 of which were pet quality. Now I can ask myself whether it is worth it to continue working with this line, seeing that the ratio of different kinds of rabbits are reproduced.
Some people feel that they are making a great decision by getting rid of a "genetic problem" with a rabbit that could produce 30% keepers while they continue to breed rabbits with no genetic red light items that have yet to produce anything worthwhile.
I once decided to work with a line that I thought had a tooth problem. I had calculated that a certain buck's offspring had produced teeth problems 1/3 of the time (though it was a small sample). That sounded genetic to me. But he had also produced grand champions and a buck that was second at Convention. Because of the possibility of really nice rabbits from the line, I worked it for a while.
However, I worked it in seclusion from the rest of my herd, meaning that I just bred the two rabbits together or with their offspring. If I had seen a tooth problem, then I could have eliminated that branch of my rabbitry without halting the progress across the board.
So I bred half brother and sister together. Neither had teeth issues themselves. They eventually had 10 kits, 8 of which were pedigreeable (just 2 were pets). One was a grand champion. What a great keeper rate! Two had teeth problems. One self-corrected by six months and the other went from bad to just barely, barely butting by six months old. It was so close that judges would probably only catch it part of the time (I processed her anyway, though).
I kept in touch with the new owner of the patriarche of this line. I was told that he had produced over 100 offspring with no teeth problems.
Because I lost the doe that was the flagship of my project, I eventually sold off everything in that project. But I did so knowing that there was no huge tooth problem after all. And the keeper rate was very, very good.
As a side, I gave away the 2nd place at Convention boy to a friend with advanced coursework in genetics. He has beaten the pants off of me with two different sons. And he reports no teeth problems whatsoever. Did I throw out the baby with the bathwater?
If you have produced a rabbit yourself that has a problem, let's say light nails, what do you do? If you have siblings that do not have the problem, that's certainly the way to go, assuming the rabbits are good enough to deal with an occasional problem cropping up. That way, you may luck out and get clean genes from the beginning (at least on that issue). Still, you have to know that you've chosen to work out any potential genetic problem down the sibling line.
But what if the rabbit is your only chance to work with a certain gene pool? Suppose you need the qualities that the rabbit has? If you can't get that gene pool any other way and you really want it, go for it. Just know that you have taken on a multi-generation project, that you need to keep this rabbit's line separate from your main line until you are convinced it is clean. And don't forget to evaluate the value of the keepers against the risk of dealing with a known genetic problem. Many rabbits that seem so promising just don't produce up to your expectations.
Yes, I've bred a doe with a fantastic front and a weak lower hindquarter. Now I get to work with her grand champion daughter who has a lovely hindquarter. Normally, I skip anything without a great hindquarter, but her front end was so good it was worth the risk.
You certainly should give genetic problems that affect a rabbit's quality of life differently than you do other types of genetic problems.
One last item: if you are working on a line with a genetic problem in hopes of eradicating it, please do not sell any of these rabbits to others without full disclosure until/unless you have determined that the line is clean. You may have chosen to work hard to clean up that line, but don't force that process on someone else without their consent.
I believe that you will find as your herd develops that you have less and less need and desire to work with anything even remotely suspicious. Once you have a base to work from, you don't need to take as many chances.
Laurie ¶ 10:42 AM
