The Science Station:

An introduction to Breeding and Genetics

Deciding to breed:

Raising chinchillas is a lot of fun, but it is also a big decision. Once you have become comfortable with chinchillas as pets you may decide you want to try raising them. Before deciding to breed you need to consider the following:

• Will you be able to find homes for the babies?
• Do you have the extra time, money, and space for any new chinchillas you get and any babies that are born?
• Do you have a cage that is "baby-proof"?
• Why are you going to raise them?

Chinchillas aren't very prolific, but without an outlet for your little ones you can get over run with chins! Breeding usually means more chinchillas, including any breeding stock you purchase and any babies that are born. More chinchillas means more time, energy, and money you'll need to put into them. A baby-proof cage is about the only special equipment you'll need to raise chins. Babies can wiggle out of wire mesh that is 1" square or greater, so you may need to invest in a "maternity" cage. Another thing to consider before breeding is that raising chinchilas probably won't make you rich. If you are lucky you'll make enough by raising chinchillas to cover feed, etc. Unless you plan on raising a couple of thousand chinchillas don't plan to make money raising them. If, however, you are addicted to chinchillas and want to raise them for the love of the animal, then raising chinchillas is a very rewarding hobby!

The Basics:

Chinchillas are a unique rodent to raise. Unlike hamsters, mice, and most other rodents, chinchillas have a long gestation period, small litters, a long lactation period, and precocial young. Female chinchillas can usually be placed with a male for the first time when they are about 8 months old. Female chins come into heat every 30-40 days, but the female won't allow the male to mate with her unless they have "bonded," which could take from days to months to never. Chinchillas have a gestation period that lasts 111 days or about 3.5 months. The babies are born with fur, eyes open, and they hit the ground running. Litters range in size from 1-8, but anything over 3 or 4 is very uncommon. The average litter size is 2. The babies can be weaned at 6-10 weeks of age, depending on their size and what condition their mother is in. Chinchillas are able to breed for most of their lives; there are 17+ year old females that are still having a litter a year!

Starting out:

When selecting a mate for your chin look for a healthy chinchilla with a good personality. If you have an older female she may accept a younger male easier than an older one, but young males tend to be inexperienced and have no idea of when and how to mate properly and often end up irritating the female! They will even try when a female isn't in heat and they can be very persistent about it! If you have a male, he'll accept just about any female, but an older female will have a harder time accepting him. When you have selected a mate for your chinchilla place her in a cage next to your chinchilla's cage. This will allow them to get to know each other. Leave them in the adjoining cages for a few weeks and then try introducing them. Place the female in the male's cage or whichever cage is the largest. Step back and watch them for awhile. If they start to fight remove the "visiting" chin and leave them in adjoining cages for a few more weeks and try again. Most chinchillas will eventually get along together, but sometimes they just won't settle down. If they won't accept each other all you can do is try another chinchilla. If they seem to get along, leave them together.

Is she pregnant?

After the pair has been together for awhile the female may become pregnant. It may take months before a new pair settles down and the female becomes pregnant so patience is a must. Pregnancy detection in chinchillas can be tricky, some will show and others will not, but there are a few signs to watch for:

• the mating plug
• weight gain
• the female sleeps on her side
• the female stops eating for a few days and then resumes
• the female drinks more or spends more time licking the mineral block

The mating plug is a long, skinny "stick" that is formed after a sucessful mating. They are usually eaten by one of the chins or lost in the bedding, so they aren't often seen. But if you do find one start counting down! The rest are signs of pregnancy, but some chinchillas won't show any signs at all and the only way you know she is pregnant is when you find a litter! If you suspect your female is pregnant remove the male and place her in the "maternity" cage. The male can be put back in with her 72 hours after the babies are born. Male chinchillas make good fathers; the only reason for removing the male is to prevent a breed back. The female will come into heat again soon after giving birth and the male is removed to prevent another pregnancy. A constant cycle of pregnancies and nursing wears down a female, so she should be allowed to recover between litters.

Caring for a pregnant chinchilla:

Care for your mom-to-be as usual, but make sure she has as little stress as possible. She needs plenty of peace and quiet, a good diet, and plenty of fresh water. Avoid any unnecessary handling and make sure she has a large nest box that is big enough for her and her babies. Otherwise leave the rest to nature. Female chinchillas usually don't have any trouble giving birth, but if she does have problems call the vet immediatly.

Caring for the babies:

After the babies are dry and have nursed you should handle them a little to get them used to people. Watch to make sure that each baby is nursing and that the kits aren't fighting. When you handle the kits for the first time it is also a good idea to weigh them. The kits should weigh between 1-3 ounces, if any weigh under an ounce they may not survive. The kit's bellies should be round and full, this lets you know that they are getting enough to eat. Usually mom has enough milk, but if she doesn't, if there are more than 3 babies, or if she can't produce milk you may have to hand feed or supplement the kits. The babies can be weaned at 6 weeks of age, but they can be left with their mother until they are about 10 weeks old. If the female looks like she could use a break and the kits are doing well then wean them early, but if the kits are small or the female is in good shape keep them together longer. Handling the kits frequently is important because it helps them adjust to their future homes better and they are more comfortable around people.

Genetics is the study of how different traits are transmitted from one generation to the next and how genes function. In this section you'll find a brief introduction to genetics and how to determine the possible colors of the offspring when breeding chinchillas.

What are genes and how do they relate to chinchillas?:

To put it simply, genes are the blueprints of life. The body of every living organism is made up of cells, and in each of those cells are chromosomes. The chromosomes contain the genetic material that determines everything from what you look like to your blood type. Encoded in your genes are the instructions that determine every minor detail of your body and its functioning. You have 2 of each type of gene (2 genes for eye color, 2 genes for blood type, etc.) and you recieved one gene for each trait from each of your parents. Each gene in a pair may or may not be the same (one gene for green eyes and one gene for blue eyes or two genes for brown eyes). If the genes are the same, then the trait that they determine will be that trait (two genes for brown eyes results in brown eyes). But if they are different the trait they determine could vary depending on the strength of each gene. If you have a gene for blue eyes and a gene for green eyes the color eyes you end up having depends on which gene is stronger. If blue is stronger than green you will get blue eys, but if the green is stronger than blue you will get green. If neither green nor blue is stronger, then you could get blue-green eyes. The same applies to chinchilla coat color. Some colors are stronger than others and the results can be interesting.

Genetic terms and color key:

When discussing genetics there are some terms you will run across quite often and others that are needed to describe certain aspects of the science. The following is a list of basic terms and also the abbreviations for certain colors that will be used later on.

Dominant: the stronger gene of a pair.
Recessive: the weaker gene of a pair.
Codominance: when two genes are equal in strength and are both expressed (blue-green eyes).
Homozygous: two of the same gene (two genes for brown eyes).
Heterozygous: two different genes (one for blue and one for brown).
Punnet Square: a sqaure divided into 4 smaller squares (2X2) used to predict possible gene combinations from a certain crossing.

Color Abbreviations:

Standard (gray, the color of the wild chinchilla): S
Beige (ranges from light to dark, has a white belly): B
Black Velvet (black on top, white belly): Bv
White (includes mosaic (white w/ spots), and Wilson white (pure white with gray ears and dark eyes)): W
Brown Velvet (like a black velvet, but brown, also called touch of velvet): TOV
Pink White (white with pink ears and light eyes, possible pinkish tones in fur, cross between a white and a beige): PW
These are some of the commoner chinchilla colors you'll find. Ebony, tan, charcoal, and various other colors aren't covered here.

Determining color possibilities and using a punnet sqare:

This is a punnet square showing the cross between 2 chinchillas that are homozygous standards (each has 2 genes for standard). One parent's genes are list across the top (one gene over each column of boxes) and the other parent's genes are listed down the side (one gene in front of each row of boxes). The possible genetic combinations of the offspring are listed in each of the boxes. In this case all of the babies would be homozygous for standard. The gene on top of each column is listed in each box in the column and each gene in front of each row is listed in each box in the row. By using a punnet square you can see the possible colors that will result from a certain mating.

The above is a cross between a black velvet (BvS, it carries a gene for standard and a gene for black velvet, a BvBv is not possible because of the lethal factor (explained later)) and a homozygous standard. The babies will have a 50% chance (2/4) of being BvS (black velvet) and a 50% chance (2/4) of being SS (standard).

The above is a cross between a white chinchilla (WS, like BV a WW chinchilla is not possible) and a heterozygous beige chinchilla (BS, it carries a beige and a standard gene, B is dominant). The babies have 25% chance (1/4) of being standard (SS), a 25% chance (1/4) of being white (WS, white is dominant), a 25% chance of being beige (BS, beige is dominant), and a 25% chance of being Pink white (BW, condominance).

The above is a cross between a Black velvet (BvS) and a Black velvet/white cross (BvW, it would probably be mosaic with gray and/or black spots). The resulting offspring are quite a mix! As mentioned above a BvBv is not possible; this is called the lethal factor. It basically means that a BvBv or a WW will not develop. A Bv egg fertilized with a Bv sperm will not develop into a zygote and eventually into a baby chinchilla; it will just break down. A BvW, a BB, or a BvB etc. will develop normally, but a BvBv or WW will not develop. So mating a Bv to a Bv or a W to a W will result in 25% fewer babies (1 out of 4 will not develop). The other offspring will be black velvet, white, or BvW.

This may sound Greek at the moment, but eventually you will get the hang of chinchilla genetics and will be able to predict what crossing one color with another will give you.

Here's a list of dominance and color combinations:

Bv: dominant over S, condominant with B and W, lethal with Bv.
S: recessive or codominant to many colors, standard is expressed only with SS (at least with the colors Bv,B and W).
W: codominant with most colors, lethal with W.
B: dominant over S, codominant with Bv and W, BB isn't lethal.

Colors:
BvBv: lethal factor, won't develop
BvS: black velvet
BvW: probably mosaic (white w/ spots) with gray and/or black spots
BvB: tov (brown velvet), codominance
SS: standard
WS: mosaic w/ gray spots, silver (white with gray tone), or Wilson white
WW: lethal factor
WB: pink white, codominance
BB: homozygous beige
BS: heterozygous beige

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