Mar 31, 2014

Rollercoasters of Nests

Nestbox stuffed full of straw.
This weekend marked 28 days after breeding for another four does.  Each of them were given a nest box stuffed full of straw (and I do mean stuffed).

Some of the girls' bellies were getting obviously swollen.  Keep in mind, though, that not all rabbits will show signs of being pregnant.  Some rabbits carry their litters really high up and their bellies don't seem to expand.  Some does maintain the same personality and behavior throughout the entirety of their pregnancy.  Just because a doe doesn't look or act different doesn't mean that she didn't conceive.  On the other hand, a false pregnancy can cause a doe to change her personality, behavior, and even appearance.  My personal rule is that if a doe has been exposed to a buck, she should get a nestbox, no matter what.

Aster's late-term pregnancy belly.

Sweetie's prego belly.

Buck lifts feet as he "falls off"
Of course, not all breedings are successful.  This weekend also marked the 40th day after Mena was bred to Tron.  I was actually surprised to see that her breeding was unsuccessful, given how eager she was to breed.  Then again, her nest only got flatter each day.  In general, a doe that is pregnant (or thinks that she's pregnant) will fluff the nesting material rather than flatten it.  However, that's not a steadfast rule.  Since neither Mena nor Tron is proven, I can't say why the litter didn't take.

Godiva's nest with fur after 24 hours.
Excitingly, Godiva, who was also bred to Tron, made a nice hollow in her nest and even added a bit of fur.  Hopefully, that means that Godiva is really pregnant, and Tron will become proven.  (Meaning that Mena's lack of litter was because of something relating to her, only).

Sweetie's nest after 24 hours.

Rabbits seem to like keeping us on our toes, though.  The very next day, both of the nests with nice hollows had been evened out.  In exchange for that, Aster decided to fill her nest box (and cage) with fur, but no kits just yet.

Godiva's flattened nest

Sweetie's flattened nest.

Aster's cage filled with fur.

Aster's nest box of fur.

Mar 30, 2014

How Genes Work

Many people have requested that I do a blog post on genetics.  Genetics--even if we limit it to the basic color genes of rabbits--is a rather large topic, which really won't fit into a single blog entry.  So, I'm going to break it down into sections.  If you think that the blogging method is too slow for you, go check out my website on rabbit genetics.

This post is going to just go over the basics of how genes work.  Nothing specifically applies to rabbits.  In fact, the following applies to genetics in just about everything!

There are genes which control just about every possible trait.  Many traits are controlled by several genes, which, in combination make the end result.  For each trait, a gene is contributed by each of the parents (except for sex-linked traits, but they're a non-issue with rabbits, so far).  Whichever gene of the resulting pair is most dominant determines what version of the trait the offspring will have.

Let's say that we have a pair of rabbits, one of which shows the dominant version of the trait, D, and the other which shows the recessive version of the trait, d. (In genetic notation, genes which are in the same series are represented by the same letter, with the capital letter designating dominance, and the lower case letter representing recessive).  Every rabbit has two genes for every trait.  For the sake of simplicity, let's say that both of these rabbits have two identical genes (called homozygous ["homo" means same, "zygo" means pair]), meaning that no matter what, they will give the gene for the trait that they show.
The resulting offspring will have one gene for the dominant version and one gene for the recessive version (called heterozygous ["hetero" means different]). In most cases, this results in a rabbit which shows only the dominant version of the trait.  However, because the rabbit has the gene for the recessive version--in other words, "carries" for it--it may be able to produce kits which show the recessive version of the trait.

When a rabbit is heterozygous, it could pass on either gene.  Essentially, it's a coin flip which gene a kit will get from each parent.  There's a way to predict the outcome on paper, using a tool called a Punnet Square, which looks like this:
To set up a Punnet Square, you put each of the parents' genes on the outside of the box.  One parents' genes get to be the labels for the top, and the other's make up the side. In this case, both parents are Dd (heterozygous), but they could just as easily be any combination of that, or DD, or dd. Inside the squares, you combine the two labels associated with that square.  So, the first box is under the blue D, and next to the red D, so it gets to be DD.  In the second box, it is under the blue d, and next to the red D, so it would be dD.  However, when writing genetics, you always write the most dominant gene first, so the letters would get switched around to be Dd.  Keep filling out the squares until it's complete.

Once a Punnet Square is filled out, it shows you all possible combinations of those genes.  On top of that, it tells you how likely each combination is.  The above Punnet has four squares.  In one of the squares, the combination is DD, meaning that about 1 in 4 kits from that crossing should be DD (homozygous dominant).  Two of the squares show Dd (the color at this point doesn't matter), which means that 2 in 4--or half--of the kits would be expected to be Dd (heterozygous).  The remaining 1 square is dd, so you'd expect 1 in 4 kits to be dd (homozygous recessive).

DD, Dd, and dd are examples of genotypes--that is, genetic codes.  However, DD and Dd rabbits will look the same, because both will express the dominant version of the trait.  That makes them the same phenotype (physical expression).  If you look at the Punnet Square, you'll see that 3 in 4 squares have a D in them, meaning that they will show the dominant phenotype.  (You can further break that down to say you'd expect 2 out of 3 dominant-versions to be heterozygous). Only 1 in 4 of all the offspring will show the recessive phenotype, because recessive only shows when there is no dominant gene to override it.  That also means that any rabbit which shows a recessive phenotype must be homozygous for that gene, which in turn means that they must contribute that gene to every one of their offspring.

However, the 1 in 4, 2 in 3, etc. are only averages over an extended period of time.  It's a coin flip every time, and the coin doesn't care what the last flip came up as.  To illustrate this point, I'll cite the fact that you should expect about half of every litter to be male, and the other half to be female.  But, it's really not all that uncommon to end up with a whole litter (even a whole litter of 8 or 9 kits) be entirely one sex.

That's why you can't say, definitively, that a rabbit with a dominant trait doesn't carry for the recessive trait. Most breeders will feel fairly confident if that rabbit has produced at least 16 kits, from breeding to a rabbit that is the recessive trait, without a single kit showing the recessive trait. However, if it ever produces even a single kit with the recessive trait, it absolutely must carry for it.  Also, if either of its parents show the recessive trait, it must carry for it.

In sum:

  • The trait a rabbit shows is its most dominant trait; the other gene must either be the same (homozygous) or recessive to it (heterozygous)
  • A rabbit which shows the recessive trait must be homozygous recessive
  • A homozygous rabbit always throws that gene
  • A rabbit with a recessive-trait parent must carry for the recessive gene
  • A rabbit which has thrown a kit with the recessive trait must carry for the recessive gene (applies to both parents)
  • If a rabbit that shows a dominant trait comes from unknown or same-trait parentage, and has not been bred, there is no way to know if it carries a recessive or not until it's been test-bred
  • Punnett Squares show all possible outcomes
  • Punnett Squares can estimate the likelihood of a particular genotype or phenotype, but only show long-term averages 
Test your knowledge! (Fillable PDF form that you can save, requires a PDF reader, such as Adobe Acrobat).  Answer sheet here.

Follow up topics: Punnet Squares for multiple traits at once, exceptions to some of the above rules, and how to apply this knowledge to specific genes in rabbits.

Mar 27, 2014

Moon Cycle?

So, you've heard about the moon affecting rabbits' breeding habits and results, right?  You haven't?  Well, neither had I until a couple months ago.  Like you, I was definitely skeptical.  What sane, scientifically-minded person wouldn't be?  (And, if you know me, you know that I'm quite scientifically-minded--although I won't say one way or the other on the sanity part.  Give me anything to do with the scientific method, and I'm there, especially if it has to do with rabbits.)

The general points to the moon-phase theory are:
  • You get more does than bucks when you breed during the full moon[1]
  • You get more bucks than does when you breed during the new moon[1]
  • You get larger litters when you breed during the full moon than when you breed during the new moon[2]
  • You get larger litters when you breed when the moon is waxing (getting bigger) than when the moon is waning (getting smaller)[3]
I will be honest, here, and say that I consider myself a Witch, and practice along the lines of Wicca (not completely, but mostly).  In that theology (as well as a number of other ancient culture theologies), the moon plays an important role.  The moon can be a powerful force (it controls the tides, after all!).  However, I've never applied it to my everyday life.  I don't even use it for gardening, which so many people do.  Despite my belief in the power of the moon, spiritually, and knowledge of its effects, geographically, I've never held to the thought that it had any power over biology.

Anyway, the topic has come up frequently in recent days, so I figured I'd take a look at my old records and see if there's any foundation to these [highly improbable] claims.

Scope of Data
23 does were used, all either purebred Californian, New Zealand, or Rex.  They were all bred to purebred bucks of the same breed.  Does were between the ages of 5 and 49 months. 74 breedings were recorded (where the buck definitely fell off while lined up properly), which resulted in 49 litters.  Kits were sexed at weaning between 6 and 8 weeks old.  Kits which died before weaning were not counted for gender, although they were counted for average litter size.

Comparison of Full Moon vs. New Moon breeding.
Unfortunately, only 5 of the 74 breedings were done on the actual day of the full or new moon (not considered a significant research pool).  Of those, only one resulted in a litter.  That breeding was on a full moon and resulted in 6 kits, all of which died before weaning.  Again, this is not significant data, but I'm providing it anyway.

However, in Wicca, the full- and new-moon phases are considered to be on three-day spans, so I can expand my data to look at the 3-day spans.  When you consider the data that way, there were 22 total breedings (11 each for full and new moon).

Full MoonNew Moon
Number of breedings1111
Number of successes95
Success %81.8%45.5%
Average litter size when successful6.17.4
Average Number of Kits Dead Before Weaning3.44.4
Mortality rate56.4%59.5%
Average Net Litter Size2.73
Average Number of Bucks Weaned per Litter1.71.6
Average Number of Does Weaned per Litter1.01.4
Weaned Buck:Doe ratio1.7:11.1:1

What this data suggests is that:

  • Full-moon breedings are more likely to be successful (almost twice as likely)
  • New-moon breedings tend to result in larger litters than full-moon breedings (21.3% larger)
  • Mortality rate is marginally increased for new-moon breedings, but not significantly
  • Even after mortality, new-moon breedings still result in more kits being weaned, but the difference may not be significant
  • Full-moon breedings tend to produce a higher percentage of bucks at weaning
What I want you to note is that my data shows that New Moon breedings resulted in larger litters, which is contrary to the proposed theory.  However, if you look at litter size after mortality, the new moon litter size is not much larger.

I also want you to note that while this data leans toward confirming that you get a higher percentage of bucks with full-moon breedings, but not much more.  Also, if you were to consider the number of kits of unknown gender, there are more than enough to completely reverse the ratio (potentially even quadruple it in favor of the other direction).  Then again, should the gender of the unweaned kits really be considered?

Keep in mind that the above assessment does not take into consideration p-values, which are what researchers use to determine if data is significant.  (I may come back to this, when I'm feeling up to some higher math, and calculate p-values).

Comparison of Waxing vs. Waning
Waxing days include the day immediately following the singular day of the new moon to the day immediately before the singular day of the full moon.  Waning days include the day immediately following the singular day of the full moon to the day immediately before the singular day of the new moon.

Number of breedings3435
Number of successes2523
Success %73.5%65.7%
Average litter size when successful6.46.5
Average Number of Kits Dead Before Weaning3.22.5
Mortality rate50.0%38.8%
Average Net Litter Size3.23.0
Average Number of Bucks Weaned per Litter1.82.4
Average Number of Does Weaned per Litter1.41.6
Weaned Buck:Doe ratio1.3:11.5:1

This data suggests that:

  • There is a slightly greater chance of success when breeding while the moon waxes
  • There is no significant litter size difference
  • There is a slightly greater mortality rate from breedings done while the moon waxes
  • There is a slightly higher percentage of bucks when breeding while the moon wanes
I do not consider this data to be significant enough to say that there is indeed a difference between breeding during the waxing or waning moons.  When I'm feeling math-y, I'll come back here and calculate the p-values, which will show more definitively.  (I will probably also add some more litters to the stats, and promise to start trying to document number of bucks/does alive AND dead).

Mar 25, 2014

Bucks or Does?

Young buck. Note the gap.

Young doe. Note the slit that leads directly to the anus.
Up until about a year ago, I thought that it was impossible to determine the sex of kits that were any younger than 10 days old.  In many cases, it could be impossible until 5 or 6 weeks.  A year ago, I came across an image and some information that changed that idea.  It is actually possible to sex kits in the first 2--sometimes 3--days of life.  The reason this works is that the hormones which trigger the doe's labor actually affects the kits as well, which causes their genitals to swell (it can also make their teats swell, too, even on males).  I knew about this phenomenon in humans, but hadn't ever considered it for rabbits.

The image I originally saw had actually been passed around the internet quite a bit, but I finally managed to track down the original photographer, Moorcroft Stud Rabbits.  With the original post, she said, "[Y]ou can see a distinct difference between the bucks 'gap' and the does running str[ai]ght into the anus."

Last spring, I decided to give it a try.  These are my results from last year:
Tri# 6 (1 day old) - Doe (confirmed)
Tri#5 (3 days old) - Doe (confirmed)
Ott - Buck (confirmed)
Poppy - Buck? (confirmed)
Pee on buck makes it look like a doe.
I had several others, but I unfortunately forgot to write down whether they were confirmed.   In some cases, I forgot to maintain the Sharpie marks I was using to distinguish them.  One thing I did note was that if the kit pees, it makes it really hard to tell.  So, if you're photographing these to have others help you, make sure that the parts are as dry as possible.

So, now we come to our latest litters.  I'm not the best at this, so don't take the following determinations as gospel.  I'll confirm or refute these when the kits are old enough to sex by the traditional method.

C#1 - Doe?

C#2 - Buck

C#3 - Buck?

C#4 - Buck

C#5  - Buck

C#6 - Buck?

C#7 - Buck?

C#8 - Buck?

Z#1 - Doe?

Z#2 - Buck?

Z#3 - Buck?

See how they've changed at Day 12 >

Mar 24, 2014

Chubby Bunnies

Big milk belly on a 1-day-old Californian kit.
Eight 1-day-old Californian kits.
Even though Chesna's abilities as a mother are questionable, Lisi is amazing!  Checking on Lisi's kits, the day after they were born, I find that they are all big ping pong balls.  In the picture above, you can actually see that the stomach is full of milk (the pale area taking up most of the very-distended abdomen).

Of course, healthy kits won't necessarily have such distended abdomens.  In fact, an overly-full stomach can actually result in deformities such as splay leg from the kit being unable to move its legs properly.  Usually, though, overfeeding is only a concern with smaller litters.

The reason these kits were so full is probably because their mom had just finished feeding them.  Their tummies usually only stay this round for about an hour or so, and slowly shrink back down to a more normal profile.  Rabbits also usually only feed once--sometimes twice--per day, so most hours, the kits look more streamline, but still hydrated and healthy.

Mar 23, 2014

Daily Nest Check

Dead kit on edge of nest.
Sadly, Chesna has lost another kit, leaving her with only three live kits.  It was the one from the second delivery that didn't get completely cleaned off.

This is another reason that it is important to check nests daily. Dead kits usually isolate themselves from their littermates (this one, and the ones that died the day before, had all crawled off to another corner of the box, away from their siblings).  However, sometimes they don't.  Those cold bodies pose a risk to their living littermates.  The cold bodies can draw out the heat of the others, which can cause the others to die.

Even when the dead kits crawl off to another corner, they can get squished, and may attract the attention of flies or other nasties, which can also spell disaster for the littermates.

Undeveloped nest.
Upsettingly, Mena still has yet to kindle.  I had hoped that since she had been so eager to breed that she would conceive, no problem.  Of course, it's only been 33 days since she was bred, so there's still a possibility that she may kindle.  (The record for latest litter at my rabbitry is 35 days, but others have seen as late as 40 days).  Still, the state of her nest (very flat and undeveloped) instills little confidence in the idea that she is actually pregnant.

Both she and the buck were unproven, so I can't really point fingers, if she didn't take.  Both were an estimated 8-1/2 to 9 months old, which is usually a prime breeding age.  But, Tron had taken the winter kind of hard, and Mena has been a pig, so it may have just been their condition.  Tron was also bred to Godiva, who is due in another week or so, so we'll just have to wait and see.

Mar 22, 2014

Is It Dead?

Kits born on the wire.  One was chewed after it died.
Unfortunately, part of raising rabbits is having to deal with dead kits, no matter what you might have done differently.  The morning after Chesna kindled, I walked into the rabbitry to a rather gruesome sight.  There were two kits on the floor of her cage, one of which had been very chewed up.  Contrary to popular belief, most rabbits will not eat their kits unless they are already dead.  Most likely, Chesna was just trying to clean up a stillborn or a kit that had died because it had been born on the wire.

Of course, the thought did occur to me that these two might be one of the four born the previous night.  I hoped, though, that this meant that she had decided to kindle more kits.  It's not uncommon for a doe--even one that was only brought to the buck once--to kindle part of a litter one day, and then deliver the rest of the litter the following day (up to a couple days apart).

Cold kits settled away from their littermates.
There were more kits in the nest!  Three more, in fact, bringing the total (including dead) to eight (nine, if you count the undeveloped kit that was born). Unfortunately, two of them were cold and apparently lifeless.  One of them appeared to be the kit that had been cold last time (it was darker than the other kits).  Also, one of the kits in the main pile still had blood on it from its birth.  None of the kits had blood on them the day before.

Ah, but that's not the end of it!  Many rabbit raisers have a saying: "It's not dead until it's warm and dead."  While this is a good starting point, you can still save yourself a little bit of headache by looking at other things, too.

Dark red blood in the nails, indicating pooled blood.
One of the things to look for is pooled blood.  Many breeders pay particular attention to the toenails on the kits.  Sometimes, the blood doesn't pool in the nails, though.  It pools at whichever point of the body is lowest.  On other parts of the body, it often looks like a large bruise. If any blood is pooled, the kit is almost certainly dead.

Blood pooled in legs.

Nails of a potentially-revivable kit.
One of the cold, lifeless kits showed no signs of pooled blood--it wasn't even stiff--so I knew there was chance that we might be able to revive the kit.  Like many hypothermia victims, it was quite pale (even for an albino).  So, like many of my fellow female rabbit-raisers, I stuffed the kit into my bra (positioned so that it was secure, but wouldn't get squished).  Any little bit of heat can help, and the sooner the kit gets it, the better.  Putting it in a bra allows me to keep my hands free while I finish tending the other rabbits.

I've heard it asked why cold and stiff doesn't necessarily indicate that it's dead. The answer is that kits get hypothermia, relatively easily, since they have no fur to keep them warm.  They may be cold to the touch (maybe even comatose or rigid), and likely their heartbeats have slowed down drastically (it's hard enough to hear a young rabbit's heart, as is). When you warm them up, the blood and muscles thaw, and gradually, the heart rate picks up, and metabolism kicks back in so that the body is able to start keeping itself warm again.

Kit warming on a rice bag.
So, when you have a dead kit, get it to some warmth as soon as possible. My preferred method (after the initial bra warming) is to put the kit on a rice bag inside a box, and drape a towel over them.  The rice bag only needs to be heated about one minute (you should be able to grasp the bag without feeling like you're going to burn your fingers).  I put it inside a box because when the kits come to, they sometimes try to wander away from the rice bag (they start getting too warm).  The towel draped over them helps trap more heat in, just like a blanket.

Unfortunately, after being on the warm bag for an hour, the kit was warm to the touch, but still lifeless.  I suspect that it may have had internal injuries, as you can see abdominal bruising in the picture above.

Californian Kits!

Fur-lined nest in back of nestbox.
On the 31st day after breeding, Lisi, our Californian doe has delivered a litter, which we discovered at 9 a.m.

It looks like there are 8 total kits, and all very healthy.

Pile of 8 Californian kits.

Mar 21, 2014

The Waiting Game

Nest 30 days after breeding.
Every rabbit breeder has experienced "the waiting game".  Since rabbit gestation can be so varied--I've seen litters as early as 25 days after breeding, and some people have documented as many as 40 days after breeding--you really can't be sure just when you'll get to see those little wigglers.  Even at the narrowest expectations, the kits could be born on day 30, 31, or 32.

Chesna pulled fur 30 days after breeding.
On the 30th day after breeding, I made my rounds at 8 a.m.  Everything was the same as it had been the night before.  At noon, I decided to go check on the rabbits again (no idea what made me do it).  Chesna, the New Zealand doe, had pulled quite a bit of fur.  Some of it was even flying out of her cage, she had pulled so much.  However, there were no babies in the nest.  Of course, this set me into checking on her nest every few hours to see if she had finally kindled.  Time after time, nothing was changing.  Neither of the other does were doing anything to their nests, either.  Needless to say, I didn't get a whole lot of sleep that night.

Birthing blood in nest.
Finally, the next evening (32 hours after discovering the pulled fur), something changed again.  Some of the hay in Chesna's box had blood on it!  This can alarm many people, but it wasn't a serious amount, and just told me that she had probably at least started giving birth.  (Birth in any mammal species is actually a fairly bloody ordeal.)

Undeveloped kit delivered with litter.
Of course, the first thing that I see in the nest is actually an undeveloped kit, about the diameter of a quarter.  It's not terribly unusual, but disheartening to see.  Something had to have happened to that kit to make it stop developing.  It could have been stress, bad diet, too many other kits in the womb, or any number of things.

Four newborn New Zealand kits.
Nestled in, a little further back, there were four little kits, snuggled in together, under the fur.  They weren't as lively as I'd have liked to see, and one of them was awfully cold (and darker than the others, most likely indicating hypothermia).  The cold one seemed to still be open to curling up with its siblings (which were plenty warm), so I left it with them.

Mar 19, 2014

Getting Ready for Kits

Nest box after 1 day with expecting doe. 
If you've been following this blog, you may remember that about a month ago, we got a few does bred.  Rabbit gestation is normally anywhere between 28 and 33 days, with days 31 and 32 being the most common.  However, I've had litters born as early as day 25, and as late as day 35.  I've heard of others who've had litters born on day 40!

It is my policy to give nest boxes to the does 27 days after they've been bred.  Some hutches have built-in nesting areas, so they don't have to worry about when to put in a nest box.  Once upon a time, I used to put boxes in at 2 weeks.  The reason I wait until day 27 anymore is for cost-control and sanitation.  Putting the nest in early often means that the doe will consume or waste more of the nesting material.  Also, does may often choose to use the nest box as a potty box, instead, if given it too early.  Besides that, in my experience, any doe that starts nesting before day 16 is most likely experiencing a false pregnancy.  (A false pregnancy is when the pregnancy hormones are all there, so the doe thinks that she's pregnant, when in fact she is not.)  But, if you feed hay (I don't do it often, myself), and a doe starts nesting after day 16, go ahead and give her a box to put it all in.

Doe scattered nesting material over her cage.
I prefer to use metal nest boxes with removable wooden floors.  Metal boxes are easier to sanitize than wooden boxes, which makes for healthier kits.  The downside is that metal boxes can be deadly in winter, if you don't prepare them right.  When I'm doing winter litters, I line the inner walls of the nest box with corrugated cardboard, which keeps the kits away from the cold metal.  The removable wooden floor allows for drainage around the edges of the flooring, and makes it easier to scrape out leftover nesting material after removing the box.

Another nesting option is all-wire nests, which are particularly good for hot-weather litters, since it avoids trapping heat in.  The flip side to that is that they don't work very well for winter litters, because of an increased likelihood of draft, and less heat being kept by the kits.  Some people like to use wire floors in wooden nest boxes simply because the drainage is the best you can get (no trapped urine), which means less chance of nest box eye.  In a pinch, you can use an empty case of soda or beer, but keep in mind that the urine will eventually break the box down.

Doe collecting straw for her nest.
More important than the material which the nest is made out of is how big the nest is.  A nest box should be only a couple inches wider and longer than the doe.  A nest box which is too big will encourage the doe to hang out in the nest, which puts the kits at risk for being trampled.  Does that hang out in the nest box are also more likely to potty in the nest, which can make sick kits.

You also want to make sure that the nest is deep enough.  In particular, the lowest part of the wall (where the doe will be hopping in and out of the nest) should be no lower than 4 inches.  Six inches may be better.  If the lowest wall is too low, young kits will be more likely to accidentally hop out on their own, and likely catch chill and die.  Some nests are made with an extra lip on the entrance wall, the purpose of which is to scrape off any kits that don't detach from the nipple when the doe decides she's done feeding.  I've never found it necessary to have the scraper lip, and have only lost a couple kits to being dragged out, in all the years I've raised rabbits.

Does will sometimes put anything they can lift into the nest.
My nesting material of choice is plain old straw.  I've tried using hay, but my does always ate all of the hay (even though I always stuff past the brim) within a couple of days.  Some people use wood shavings, but I generally advise against it.  Cedar shavings are an absolute no-no; cedar oil causes serious respiratory issues in rabbits, especially young ones.  Pine shavings are probably the most commonly used, but still puts the kits at an increased risk for nest box eye, because of the oils. (I don't know how many times I've heard people mention that they used to have issues in every litter with nest box eye, until they switched away from using pine shavings).  If you really want to use shavings, I suggest using hardwood shavings, such as aspen.  In a pinch, you can use black-and-white newspaper shreds, but the paper gets soaked quickly, rather than wicking it away, so you should plan on changing out the paper every couple of days after the kits are born.

Doe stuffing her nest with straw.
Always stuff the box as full of nesting material as you possibly can.  The doe will rearrange it as she sees fit. Usually, during summer, a doe will pull most of the nesting material out, but there's no harm in having it scattered across her cage.  If the doe pulls all of the nesting material out, just restuff with a couple more handfuls.

Pay attention to which corner of the cage the doe uses for her potty.  When you put the nest box in, put it in a different corner.  If you put the nest box in the same corner she uses for her potty, chances are that the nest box will become a potty box, which puts the kits at risk for nest box eye and other infections, and will mean that you will have to change out the nesting material frequently.

Tufts of fur added in the first day of having the nest.
Some does will start nesting as soon as they have a nest box, and may even pull a few tufts of fur.  Many does, though, won't start nesting until they're in full labor, and may not pull fur until after the kits have all been born.  Each doe is different.