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Post by Katt on Oct 3, 2011 12:49:03 GMT -9
PLEASE NOTE: This is simply a summary of mouse breeding procedures and should NOT replace careful research prior to beginning a breeding program. We do NOT condone careless breeding.
Think you are ready to breed? Have you done your research? Do you have access to vet care if it is needed? Do you have enough cages to separate the babies if you cannot rehome them before they begin to grow? Do you have new homes lined up already? Are you prepared to take care of orphaned young? These are just a FEW of the things you should consider before breeding. Breeding is not to be taken lightly, the lives and wellfare of the animals is entirely in your hands, and many things can go wrong when breeding animals.
FIRST: WHY are you breeding? Are you breeding feeders? Are you going to start a breeding facility such as a hamstery or a rattery? Are you breeding more pets for yourself (and of so are you prepared to go from 2 to 20)? If you cannot answer this question, then you should NOT breed. Breeding without reason is careless and can cause harm to the animals involved. Please think carefuly before beginning.
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Post by Katt on Oct 3, 2011 13:50:03 GMT -9
BREEDING MICE
Mice are, like many species of rodent, colony breeders; they typically do best in small groups. This has multiple purposes. First, having a group of 2 or more females to one male prevents the male from over breeding one female by dividing his attention among multiples, thus slightly reducing the stress on the females. Also, when the babies are born the other female will help to raise the young. This reduces the stress on the mother mouse significantly. It is not uncommon for other females to act as nannys. If both females have their litter at the same time, both females will help to nurse the babies, giving each other breaks and ensuring all young have sufficient access to milk.
Breeding Age: Females mice should NOT be bred until they are at least 12 weeks (3 months) old or approximately 25g. Breeding a female who is not yet mature can have serious consequences including a potentially painful death of the mother and litter and chances of the litter surviving are very small as the female's body is not yet able to support growing young.
Picking a Group: Females: Females should be at least 12 weeks old and free of any health issues. She should be alert, active, have bright eyes, shiny fur, and good muscle tone. If she is overweight, or especially if she is underweight she should not be bred. Larger females are preferred over smaller females as small females may have more difficulties giving birth, esp when bred to a large male.
Males: Males should be alert, active, healthy etc as well. They should be at least 8 weeks but preferrably 12-16 weeks of age to ensure virility. The male should not be significantly larger than the female as this can result in birthing complications due to babies that are too large for the female's birth canal.
Introductions: Before putting a new group together clean the cage with a mild bleach or vinegar solution (rinse very well) and put in new bedding. If one more more of the mice were living in the cage prior to coupling, it may be helpful to rearrange the cage (and clean all houses, food dishes, etc as well) so that it is a new territory to all of the mice. It is best to introduce females to each other when they are young as they can become territorial. In addition, when females are housed together long-term their estrus cycles will typically begin to line up and they will go into heat at approximately the same time. If both females give birth at the same time they can help each other nurse both litters (see above) as both will be producing milk. Also, this reduces the chances of a mother eating her young. Some mice will eat younger pups because compared to the earleir litter from the other female they seem too small and weak. (*Please note: I personally have been breeding mice for a few years and have never seen this happen, but I have heard of it happen so it is something to be aware of). The best time to introduce a new group is when the female(s) are in heat as they wil be more receptive to the male and less lkely to reject him. (it is far more common for female mice to beat up an unwelcome male than the other way around)
Estrus: Female mice go into heat approximately every 3-4 days. You can visibly check to see if she is in heat. The vulva will be pink and open. After mating you may notice a seminal plug of off-white to yellow coloration. It takes practice to see this. I recommend checking mice daily for a while until you can confidently tell the difference. This will also help them get used to being handled and make them more open to allowing you to check up on new litters. The best way to check is to place the mouse on a flat surface and gently lift her tail (do NOT pick her up by the tail as this is very uncomfortable for them). OR you can hold them with your hand in an "O" shape. Have the female's head poke out at one end and her butt poke out at the other (like a mosue burrito). Hold her gently but firmly and use your other hand to lif the tail from underneath with one finger so that you can see the vulva. Do not keep her restrained for too long as you will cause undue stres. Be sure to talk to her gently and let her explore on your hands for a while afterwards so that the handling is a positive experience.
Mating: Mice typically mate at night, so you may never actually see them "in action." (Also, this is one of many reasons wny providing a natural day-night cycle is important). However, if you are up early enough in the morning you may notice a seminal plug in the female right after mating as described above. These help to keep semen in the female and ensure fertilization. They only stay in for a few hours so if you don't see a plug this does not mean that the female has not been mated. To ensure mating it is best to leave the male in with a group of 2+ females for approximately 2-2.5 weeks. This ensures the females wil have multiple esturs cycles in which to accept the male while they are housed together.
Rotating Males: It is best to rotate one male between 2-4 small groups of females. Groups of 2-3 females typically work best, but larger breeding groups are possible with sufficient cage size. Rotating males allows the females to have a break between litters, keeping them healthy and able to breed longer. Gestaion is approximately 21 days (3 weeks) and pups can be weaned at 3 weeks of age. For this reason having a minimum of 3-4 breeding groups to one male is ideal. This allows rotations of 2-3 weeks, giving the females a short after weaning before beginning to breed again. Even if the male is reintroduced right after weaning the last litter, this is still easier on the female than back-to-back breeding (see below for more). However, if you are able to either have 4 female groups, or a separate "vacation cage" for the male (which you should alwaysh ave on hand anyways in case of fighting or illness) you can give the females a logner break between litters. This is healthier for the females but by rotating between groups you will still have a constant in-flow of litters.
Breeding Back to Back: Mice have a gestation period of approximately 21 days and a weaning period of approximately 21 days (see below for more). This means that they are able to breed back to back very quickly. Females go into heat within a few hours of giving birth. If the male is left in the cage the female will usually become pregnant again right away. This means that by the time she finishes weaning her first litter, she will be jsut about ready to have her second litter. When this happens the female will somteimes (but not always) wean the older litter on her own, pushing them away from nursing after the second litter is born. She will have a new litter every 3 weeks. However, while this is possible it is not very healthy on the mom. Females do not always fully wean their first litter upon the birth of the scond litter, and thus is required to produce milk for 2 litters. This puts a lot of strain on the female, as well as reducing the amount of milk available for the new litter. It will also wear out the female much earlier.
Gestation: The gestaion period for a moust is approximately 19-23 days (3 weeks). You may notice the female gaining significant weight around week 2 of gestation and during week 3 she will become very noticeably plump. The belly will look round and taut and the nipples may begin to look slightly swollen. While every female carries slightly differently (just like humans do), you will typically see 2 rounded bulges on either side. The nipples will swell and may become slightly red (watch for bright red coloration on and around the nipples and excessive swelling as infections are possible).
Litters: Mice have litter ranging from 8-12 pups on average, but smaller or larger litters are not uncommon.
Weaning: Pups should be weaned at about 3-3.5 weeks of age. Males and females should be separated at this time as well to prevent unwanted and unhealthy breeding.
Litter Cannabilism: It is fairly well known that most rodents eat their young. However, if bred responsibly the chances of this happening are significantly reduced. A healthy female, bred properly and kept in a quiet, secure place will only eat the young that would not have survived otherwise. Mice are able to determine the health of their young often better than us and will eat pups that are sick, weak, too small, etc. If a female has a litter too large for her to suppoert she wil also eat the smallest and weakest of the litter to reduce the litter size and ensure that the survivors get addequate care and a better chance at survival. If you notice a female eating too many pups and are concerned it is possible that she is over stressed or has mental health issues (no uncommon in pet-store mice). Make sure that she gets a break, and move her cage to a more secure location where she will feel quiet and safe before attempting to breed her again. If she continues to cannabalize her young she should be removed from the breeding program immediately. Another common reason for cannabalizing young is that it is a female's first litter. Many females become over stressed and are unsure of what to do when they have their first litter. It is not uncommon for them to eat many to all of their pups the first time, especially if the cage is disturbed frequently. Again, if this behavior continues then remove that femal from breeding.
Despite popular belief, most males will not cannabalize their own young. If you put males into a cage with a new litter, you are taking the chance that the male or female may eat the pups. However, if you leave the male in the cage for the duration of the pregnancy and raising of hte pups (i.e. when back-to-back breeding) the male will usually help to raise the litter. This works best when starting with virgin females, and in some cases you may have to wait out one litter. However, if a male is eating pups then he should be removed from breeding for multiple reasons. For one, the male most likely has a mental instaiblity and you do not want to pass those genetics on to future litters. Secondly, you don't want all of the litters eaten. Again - a healthy male will help raise the young.
Setting up a Cage: A breeding cage should allow sufficient space for a breeding group and their young litter. A 10 gallon tank is sufficient for a breeding group of 2 females and 1 male, but absolutely no smaller, and preferably bigger. The cage should have soft, clean bedding and nesting material like toilet paper, paper towels, cardboard, and newspaper should be provided to allow the does to nest. Water and food should be easily accessible, and low enough for young weanling mice to reach easily. There should be a nice dark hide for the does to build a nest and raise pups, and preferably an additional hide so that mom can take a break from the babies on occasion. NEVER leave an exercise wheel in the cage with a nursing mother. Remove any wheels in the last week of pregnancy, and do not put it back until the pups are weaned, or close to weaning. Many females will become addicted to the wheel and neglect their young in favor of the wheel. Also, babies can get hit and caught in the wheel as they try to reach their mother to nurse. I have witnessed this with my own eyes and it is NOT pleasant. So please, NO WHEELS WITH NURSING MOTHERS.
Holdbacks for future breeding: You may want to keep some of your young mice for future breeders. This has multiple benefits: you know the genetics of the mouse, you know the health of the mouse and it's parents, you know the breeding productivity of the mouse's parents, and you don't have to spend money buying a new pet store mouse. With holdbacks though, you must be careful that you do not end up inbreeding as this can cause major health problems through recessive genes. It is a good idea to keep track of each mouse's linage, and to occasionally bring in "new blood." With any new addition, be sure to quarantine before allowing contact with your healthy mice.
Genetics: It is very important to know and understand basic genetics before you begin breeding. You should know the genetic background of your breeders so you are not breeding mice that have recessive or lethal mutations, or other genetic disorders in their backgrounds. Having a good understanding of mouse genetics will help you ensure that you are producing healthy mice.
Other things to know: Female mice who are pregnant or nursing need a higher amounts of protein in their diet. This can be accomplished by feeding the occasional cooked egg (hard boiled or scrambled, plain). Another, less healthy option, is to supplement with dog biscuits or kibble. Do not use ferret or cat kibble as they are too high in protein.
Myths: Males eat babies. FALSE! Mice are colony breeders and males kept in the cage with the doe and pups will actually help to raise the young, acting as a babysitter so that mom can take a break. The female is actually more likely to eat the young if she feels stressed or threatened. If you notice a male or female mouse eating young, immediately remove the mouse from your breeding program as the mouse is mentally unstable. An exception is if it is the female's first litter, the female has an unusually large litter, or the female has been disturbed in some way that has caused her to feel stressed and threatened. That being said, even these situations should cause for closer monitoring of the doe. If she continues to cannibalize her young, is too easily disturbed, etc she is not a good candidate for breeding and should be removed. Keep in mind that her pups are more likely to have inherited this as well. Mentally healthy males will not cannibalize their own young. The only exception is if the male does not thing the pups belong to him. If the male was left with the doe for the duration of the pregnancy there is usually no problem. I have even been able to introduce males to females carrying a litter already with no problems. This all goes back to choosing physically and mentally healthy breeders. If any male or female is caught cannibalizing litters, they are immediately removed from my breeding program. As a result, I have very few problems with either males or females eating the pups. The healthy groups will work together to raise the young as a family unit. (*Note: The downside to this is that leaving a male in with a pregnant/nursing female will result in back-to-back breeding which causes more strain on the doe, physically and mentally).
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