# Cross breeding



## o&itw (Dec 19, 2008)

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I wish to increase the average size of a medium size breed.
I have never bred two rabbits together of considerably different size. 
There may not be a truly "genetic" answer to my question.

In cross breeding certain other animals that I am familiar with, it seemed that if one's main purpose was to increase the size when cross breeding, that it was considered that the male (or in some cases the female) had a greater influence. Using the larger female might have a dietetic influnce, due to a greater milk production, but I am looking to increase genetically the size of the breed.

Should I use a large buck on the doe of the (smaller) breed, or should I use the buck of the breed on a larger (other breed) doe?

Or...... does it make any difference?

.


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## SquashNut (Sep 25, 2005)

I am not sure about genetically, but physically I would go with the larger doe. It would be easier for her to kindle and have less chance of her having to pull the kits.
If you choose the larger faster growing kits from each litter you'll increase your genectic size, how ever you probably will get some hybryd vigor the first generation that may or may not be seen in following generations.


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## SFM in KY (May 11, 2002)

The majority of my crossbreeding experience has been with cattle and horses, but I'm starting with rabbits a bit now as well.

I have been told, with rabbits, that it is better to use the smaller buck on a larger doe because there is some concern that there could be problems kindling with the small doe/ large buck if the kits grow larger in utero.

With cattle this is the case ... you do not want to breed the smaller cows to a significant larger/ bigger boned bull because it can lead to calving difficulties. Oddly enough with horses, this is not the case because the mare's uterus limits the in utero growth of the foal. I don't know if any actual research has been done with rabbits and size in crossbreeding, but personally I don't plan to run the risk with a smaller doe.

With horses, particularly, what you generally see with crossbreeding involving significantly different size, the offspring will mature somewhere about the middle of the two parents.

The only mature offspring I have from a crossbred rabbit litter, larger doe to smaller buck, seems that the three I kept from the litter, all does, are about mid-way between the two parents as well ... bigger than the buck, not as big as the doe.


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## Honorine (Feb 27, 2006)

Can you tell us what breeds your working with and what size your shooting for? It'll help me figure out how to better answer your question. I assume your going to cross out and then cross back in to add the larger size to the first breed but still retaining the correct breed charateristics. Its done a lot, many don't talk about it, but knowing the breeds would really help.


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## ladysown (May 3, 2008)

i recently bred a new zealand doe to a holland lop buck (he's a bigger than average HL). The kits are all the same size as new zealand kits are at this age (2 weeks) How they will grow out I have no clue. I did the breeding only because I wanted a back up doe to a couple of first time moms.


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## o&itw (Dec 19, 2008)

Honorine said:


> Can you tell us what breeds your working with and what size your shooting for? It'll help me figure out how to better answer your question. I assume your going to cross out and then cross back in to add the larger size to the first breed but still retaining the correct breed charateristics. Its done a lot, many don't talk about it, but knowing the breeds would really help.



I am not trying to improve an existing breed, rather I am trying to create a mutt breed of my own to meet certain specifications. One of the characteristics of the base breeds, is that they are smaller than I would prefer. So I am looking for multiple one time crosses for size. The base breeds and out-cross breeds are not that different except for their size, ans since I am not doing this to "improve" a show feature, or (necessarily) to intoduce a new color, conformation is not an issue. It will be taken care of in the normal culling process.


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## ladysown (May 3, 2008)

I would then breed your biggest does to your next biggest size buck. OR if your buck isn't too much bigger than your does....breed a slightly bigger buck to a slightly smaller doe. Always keep the biggest of the litters and eventually you'll get the size that you want. I'd be hesitant to breed a much bigger buck to a small doe.


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## jil101ca (Jul 2, 2007)

If there is a considerable size between the buck and doe then I would use the large doe with the smaller buck. If the size difference is only a few lbs then the smaller doe should be ok with multible breedings from the large buck to help ensure a large litter. I'm curious as to what breeds you are working with.


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## Beaners (Feb 23, 2005)

ladysown said:


> I would then breed your biggest does to your next biggest size buck. OR if your buck isn't too much bigger than your does....breed a slightly bigger buck to a slightly smaller doe. Always keep the biggest of the litters and eventually you'll get the size that you want. I'd be hesitant to breed a much bigger buck to a small doe.


I would agree with this. Another thing to consider is litter size. I know that some of it is what has been bred for, but smaller does tend to have litters with fewer babies, in my own experience. The larger litters will give you a little bit more to select from. Rather than trying three or four breedings to get just what you are looking for, it might only take one or two breedings.

Keep us updated about how this project works out for you! It sounds like fun.

Kayleigh


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## Honorine (Feb 27, 2006)

Okay then, I see what your trying to do. I have bred a Flemish Giant buck to a Harlequin doe, one that had been bred before with no problems. She was about 8 lbs, the buck was one of my smaller ones at 13-14lbs. She kindled and carried fine, although its not something I would repeat. The one thing that did come to mind was the importance of increasing body size while keeping the bone light, for instance the Flemish/Harly cross babies were like smaller Flems, big ears big paws, heavy bone. They were lanky and had the growth pattern of the Flemish. I also bred the Harley to my Florida White buck. Babies were smaller, compact, light boned, and carried more body mass than the Flem/Harley babies. Thats why I asked you what breeds, if your trying to add body mass and size use a buck that will give you more muscle but still less bone. It may take more than one generation to add reliable size, and you may still get an occasional smaller rabbit. I'd probably use a really good buck and breed his daughters back to him to increase size. Good Luck!!


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## o&itw (Dec 19, 2008)

I was originaly concerned that breeding a smaller doe to a (much) larger buck would be a big problem for the doe upon kindling. I have since been told that the size of the individual kits upon birth would not be any different than a normal mating, only that they would develope to be a larger amimal. So I guess their are really two questions here. 1) Will a smaller doe breed to a larger buck really have larger kits at birth? (it would seem so to me, but I am looking for substantiated experience) and 2) Since the are likely a number of different "size" genes, are any of them (phenotypically) sex-linked?


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## SFM in KY (May 11, 2002)

To answer your question, I can only refer back, again, to my experiences with cattle and horses ... I just don't have the range of experience with rabbits at this point.

The biggest problem in breeding small females to large males in both cattle and horses seemed to be primarily a result of bone structure. If the sire was the larger and some of that size was due to bigger bone structure, there could be problems with the birth ... if the offspring inherited the heavier bone, the pelvic opening could be too small for normal calving/foaling.

At least in horses, the size of the mare's uterus does limit the actual size of the foal ... the additional growth comes later. However, if the foal inherited a much heavier bone structure from the sire, you could see the foal "hang up" at the shoulders or hips.

As far as crossbreeding in rabbits, the only cross I've gotten any specific information on is that the extreme head type in Holland Lops may pose a problem if a HL buck is used on (for example) a Mini Rex doe. The size is not necessarily of substantial difference, but the bigger, broader head on the HL may pose a problem if the HL buck is crossed to a doe of a breed with a much narrower head.

So ... based on my experience in other species ... actual size probably isn't going to be an issue. A big difference in type could cause difficulties.


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## Honorine (Feb 27, 2006)

Well I knew of someone who bred a Netherland Dwarf doe to a NZW. She conceived one large kit, and tore it apart trying to get it out of her body. I call those people 'The Stoopidheads' now. How much a of a difference in size are we talking about? Structure, bone, width of body? For instance I would not breed a Silver, which is a narrow hipped rabbit to a meat breed buck that was 3 pounds heavier than her, but I might breed a Florida White doe to him. One reason why is numbers, Silvers normally throw 4-6 kits, FW's are often 8-12, so smaller kits, less stress. Structure is important, only you can decide if she has the broad enough body to handle a possibly larger kit. Basic rule of thumb with rabbits is no, you do not breed a much smaller doe to a substantially larger buck. If we're talking a 5-6 lb difference I'd have to say no just because I haven't seen the rabbits in question.


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## mcramer (Mar 15, 2009)

I have been reading this post and responses with interest. I recently found a British website when I was looking at Mini Lop information and there is interesting info related to this very topic of but of breeding a French lop buck to a Netherland Dwarf Doe in the history of the development of the Mini Lop. Please refer to the link below:

http://images.google.com/imgres?img...&sa=N&start=18&um=1&ei=NLLBSar2B8XR-Qb73fD_Bg

Hope this is helpful.

MCramer


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## mcramer (Mar 15, 2009)

Sorry that link didn't come through entirely. When you go to the link above first click on Mini Lop and then Mini lop history. I am also going to try and post it again below:
http://images.google.com/imgres?img...&sa=N&start=18&um=1&ei=NLLBSar2B8XR-Qb73fD_Bg


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## SFM in KY (May 11, 2002)

mcramer said:


> When you go to the link above first click on Mini Lop and then Mini lop history. I am also going to try and post it again below:


Very interesting reading! I've always been interested in crossbreeding and find projects like this very fascinating.

Thanks for finding/posting!


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## o&itw (Dec 19, 2008)

mcramer said:


> Sorry that link didn't come through entirely. When you go to the link above first click on Mini Lop and then Mini lop history. I am also going to try and post it again below:
> http://images.google.com/imgres?img...&sa=N&start=18&um=1&ei=NLLBSar2B8XR-Qb73fD_Bg


Thanks for the link!, it is what one would have thought, but I have recieved varing opinions. The size difference I am speaking of is not near as large, but then knowledge is always good to have.


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