End of Breeding Season

Well it is that time again.  Summer marks the end of my breeding season – I feel that the heat is too stressful for the does and I am not willing to risk a doe to get an extra litter.  This spring has been remarkably cool – last year the temperatures were well in the 90s at this time.  It has been a whirlwind of a season and we have had a lot of lovely kits. Now that everyone is been born and has a home it is time to let this years babies grow and evaluate the juniors for breeding and the breeders for retirement.  I hope everyone is happy with their bunnies.  For those who missed out or want to grow their herd – I might have a few litters this fall if the bucks are willing and able, send me an email to get your name on the waiting list.  Please stay cool this summer.

Calculating the odds

Breeding rabbits can be very expensive, in time, facilities and of course dollars.  While we hope that each litter can pay for itself, that is not always the case, so it is important to carefully choose each breeding to have the most likelihood of producing the bunnies that we are hoping to get.  Most breeders just pick two rabbits that have characteristics that they want and hope for the best.  However, if you keep good records and are willing to pull out a calculator, you might be able to get better odds.  Since color genetics are fairly well understood, let me give you an example using them.  If you have read up on color inheritance (and if not, you should check out www.threelittleladiesrabbitry.com which has an excellent introduction),  you know that blue is a recessive trait, where the bunny needs two copies of the recessive gene “d” (dd), in order to become blue.  One or more copies of the full strength gene, “D” (DD or Dd), will give you a black bunny.  So, let’s say that I want blue babies.  I have a doe and a buck that I know from looking at their pedigree each recessively carry “d.” I want to know whether breeding these two would be worthwhile.  Since each of these rabbits have two genes (a D and a d), I know I have a 50% (or .5) chance of the baby getting the “d” from each parent.

If you go back to your math lessons, you will remember P(A and B)=P(A)*P(B) or the Probability of two independent events occurring together = Probability of one event multiplied by the probability of the second event.  Therefore, to determine the chance that I have of a blue baby I multiply the Probability that the baby will get a dilute gene from the father, .5,  times the probability that it will get a dilute gene from the mother, .5, which gives me a .25 or 25% chance of a blue baby.  The following chart is an easy way to visualize this:

Inheritance Diagram 1

If my litter size is a typical 8, I should end up with two blue babies out of the match (.25*8=2).  I can use this information to decide whether or not two blue babies would be worth the trouble of raising a litter.

Now let’s change the situation slightly.  Say instead of a blue baby, what I really wanted was a lilac bunny.  From our color genetics we know that lilac is created when the bunny has the full dilute recessive or dd as well as the brown recessive, or bb.  Well, I’m in luck – my doe is chocolate so both her genes are bb and I know that the probability of her contributing a “b” is 100%.  The buck only carries b so the probability of him contributing a b instead of black(B) is 50%.  The probability that the baby will be brown, or P(brown for doe and brown from buck) is P(brown from doe)*P(brown from buck) = 1.0*.5=.5=50% of the babies will be brown.  But I want lilac instead of brown so I pull out the calculator again and calculate that the probability that the baby will have both dd and bb = probability of dd times the probability of bb = .25*.5=.125 or 12.5% chance.  That means that if I have a typical litter size of 8, on average I could expect one baby to be lilac (.125*8).  That is not a good chance – I might be better off checking with other breeders and buying my lilac baby rather that wasting breeding time and money on a full litter.  But let’s say that I am less picky – I would be happy with a blue or brown or lilac.  Back to statistics class, I know that P(A or B)=P(A)+P(B)-P(A and B).  That complicated equation simply states that I take the chance that I will get a blue baby add the chance I will get a brown baby and take out the chance I will get both at the same time so I do not count it twice.  You can see how that works with the circles below – in order to calculate the total “Red overlapped with Blue” you must add the Red circle with the Blue circle and remove the amount that the Blue circle overlaps with the Red circle because we already accounted for it.

Inheritance Diagram 2

So our Probability(brown or blue) = P(brown) + P(blue) – P(both, or lilac) = .5 +.25 – .125 = .625 or about 62%. So if I have a litter of 8, I know that 2 of them should show blue, 4 of them show brown but since one is lilac or “both blue and brown”, I remove one from the blue group and one from the brown group and just count it as lilac. Therefore one will be lilac, one will be blue and three will be brown, (5 out of 8 = 5/8=.625=62.5% chance of blue, brown or both/lilac). I think that I would be willing to try for a litter with a 63% chance of getting a baby that I want.

You can take it further: assuming that I kept good records, I know that my buck has been throwing good hips in the last 7 out of 16 babies, so the babies should have a 7/16=.44 or 44% chance of nice hips.  Therefore my chances of getting a blue or brown showing baby with good hips is P(brown or blue)*P(good hips) = .625*.44= 28%.  And let’s say the doe has a white toenail that she passed on to 6 of the kits in her first litter of 8 so the chance of a baby NOT inheriting a white toenail is 1.0-6/8 or 25%.  So the chance of getting a blue or brown showing baby, with good hips and matched toenails is .28*.25=.07 or only 7%.  Since I am not feeling lucky, maybe I will pass on that litter after all!

Statistics is only gives you the most likely outcome; just like you can flip a coin five times and get five heads, you can get lucky, but it does give you the knowledge to plan your breedings better.  Maybe you would have a better chance of getting what you want if you pick a different doe or buck.  There is not an unlimited market for rabbits and any tool that gets you where you want to be without creating extra mouths to feed is valuable.  The better records you keep, the more you can make statistics work for you.

 

Sneak Peak at some New Litters

I have two new litters that are upcoming:

One is a French Angora litter: a broken copper agouti doe, a broken copper agouti buck, two broken chinchilla does, and a white doe.

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I also have a 94% German Angora litter: 3 chestnut bucks, 3 white does, a white buck and a black doe with a white leg.

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Thoughts on Breeding

I always get a lot of questions on breeding, specifically line-breeding and inbreeding and the difference between the two. It is a hard concept to grasp when you start out because it is not something we humans practice – in fact there is a huge cultural taboo against mating with any relative. The difference between us and the rabbits is that we control which rabbits reproduce and line-breeding is the only way to improve the quality of our lines. All modern breeds where created by line-breeding; the Chihuahua and the Great Dane all had the same ancestors. Even breeds we think of as “native” were line-bred, just breeding was limited by geographical area instead of human guidance. When you start to consider breeding and read the books, a lot recommend getting a trio, or two does and a male. So most people, doing what seems logical to humans, go out and pick three very nice, completely unrelated animals, start breeding and end up with…mush. Their litters will be all across the board in quality. So they will pick out the best of the babies and since they do not want to mate the baby to a parent, will go out and find another completely unrelated animal, breed the two and end up with…more mush. So what is problem here? The problem is that even the simplest genetic structure is incredibly complicated. Most people have a hard time understanding color genetics and that is relatively simple. A lot of genes contribute to even one attribute. Say your buck has lovely hips and you pick out a doe with good hips as well. There is no guarantee that the babies will have good hips because the buck might have gene XY contributing to his hips and the doe, WZ and the babies might get XZ or WY which causes cowhocks. And this is why we line-breed. If instead the doe was a cousin of the buck and so she had WX instead and was bred to the same buck, the babies would have a far greater chance of ending up with XY or WX than the dreaded WY.

To put it another way, I like to use the analogy of working with clay. When you first start out you want the clay to be soft and malleable so you can try to mold it the way you want. As soon as you get something close to what you want, you let it set, or dry out a little so it stays in its shape. Then you can start adding a little water to the areas you want to change so you can start refining the sculpture. If you add too much, you turn it all back to mush; if you add too little, you are stuck with what you have. Line-breeding is like setting the clay – it “fixes” attributes so they are hard to change without adding a lot of “water” or new bloodlines. You do not want to set your rabbit line too quickly or it will be stuck and you will have to start over by outcrossing, but if you continually outcross you will never get consistent quality in the animals you produce.

As an example, say the best rabbits I could find are a doe with a white toenail and a buck with pinched hips. I breed these two and they produce two kits out of a couple of litters, buck(A) and a doe(B), without either fault. With the rabbits I have, I have two options breed the babies back to their parents or breed them together. I do not want to breed them back to their parents because I risk “setting” either the white toenail or the pinched hips into the line. I do not want to breed them together because the pinched hips or white toenail might be a recessive trait (or a hidden trait that only shows up when two copies are present) and the resulting litter would be full of unacceptable rabbits with the trait “set”. The best option in this case is to “throw another handful of water on the clay” and find another rabbit. So I go out and the best rabbit I can find is a buck with a screw tail. I breed the new buck to the doe produced from the original set of rabbits and produce half nice rabbits, half screw tail rabbits. I pick a nice buck(BX) and doe(BY) out of the litter. I do not want to breed the doe(BY) back to her sire and risk setting the screw tail trait, and I do not want to outcross again and risk adding new problems, so I breed the buck(BX) to his mother(B) and the doe(BY) to her uncle (A), to try to “set” the attributes of the buck (A) and the doe (B). You continue on in this manner, always aiming for your perfect rabbit.

Diagram

Here is a simple decision tree:

Do I already have a rabbit that complements this one, or does not have or carry the faults that this one has or carries? If yes, then breed the two and keep the best resulting kit. If not, then look for another rabbit that complements yours and start over.

The other important thing to keep in mind is that the closer the relationship between rabbits mated (half-sibling, mother-son, father-daughter), the quicker the traits will be set so you might inadvertently set an undesirable recessive trait like poor mothering ability or cryptorchidism. The longer you have been line breeding, the less likely this will be since you would have already identified the bad recessive trait and removed the carriers from your line. The only breeding that is generally frowned upon is full brother-sister pair. This is because it is not only a close breeding which we know strongly sets traits, it is also impossible to guess which traits will be set because we do not know recessives they inherited from their parents. It can be done, but it is very risky – you could end up having to cull the entire litter or the entire resulting line due to the recessives, and you will not likely have a market for the kits – most buyers are hesitant to buy from full-sibling matches.

Spring Romp

I let some of the 3 month old juniors out for the first time to play.  It was peaceable kingdom until a certain rascal decided it was fun to chase the cats.

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International Association of German Angora Breeders (IAGARB)

If you have German Angoras, or would like to have German Angoras, please consider joining the IAGARB.  This organization is focused on promoting the breed – they try to bring owners together and provide a lot of great information.  I am the first Alabama member – if we get enough members in our district which includes LA, MS, TN, AL, GA, and FL, we can set up get togethers with shearing parties and registration events.  Even if you do not join the website and yahoo group has a lot of information you should check out.  http://iagarb.com/ and http://pets.groups.yahoo.com/group/IAGARB/

For Sale: 94% German Angoras – SOLD

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AngieChester94 Litter 011

These cuties are now available.  I have 1 REW doe, a REW buck, a chestnut buck and a black doe with a white toe left.  These guys have a lot of sheen, a lot of crimp and they are already showing signs of great density.  I tried to take a picture of their wool – it was hard to get a good picture since it kept trying to spring back.  You can see how much it reflected the light of the camera flash.

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I am very happy with this litter.  I wish I could keep them all but unfortunately I do not have the room.  I am selling them for $100

Upcoming – 94% German Litter

German94 Does

I am real excited by this litter.  All of them have a lot of sheen and a lot of crimp.  Angie outdid herself producing and raising 10 healthy kits, 6 does (4 REW, 1 Chestnut, 1 Black) and 4 bucks (1 REW, 3 Chestnut and 1 Black).  While it is too early to tell, I have high hopes on density since their sire, Chester, is quite productive.