AFRICAN SOFT FUR HUSBANDRY
Scientific Name: Mastomys natalensis
Common Names: ASF, African Soft Fur, Multimammate, Multi, Natal Rat.
Geographical Range: Sierra Leone – Somalia.
Activity Period: Nocturnal
Captive Temperatures: 70-85*F, 21-29*C
Newborn Weight: 1-3 grams.
Weaning Age: 2-4 weeks.
Adult Weight: 80-120 grams.
Sexual Maturity: 45-60 days.
Ovulation Cycle: Every 4 days.
Gestation Period: 20-22 days.
Litter Size Range: 4-22 babies.
Menopause Age: 12-18 months.
Captive Lifespan: 24-36 months.
ASF Rats can be housed in laboratory or commercial rodent cages, as well as homemade or professional rodent rack systems and aquariums or terrariums. I have read over the years they are avid chewers and require "chew proof" enclosures, however this is 100% contradictory to what I have found in their behavior. They are much less prone to chewing through plastic tubs than domesticated Rats and Mice and a simple wooden chew block is generally all they require to never have an issue with chew outs.
ASF Rats are very communal and polygamous and do best in colonies. The colony ratio i have found very successful is a minimum of 1 male to 4 females. This not only makes them more comfortable and secure but also will reduce stress on lone females from males trying to overbreed them. If enough space is available you may double or triple your colony ratio's. They are very susceptable to cold so care must be taken to make sure the temperatures stay within the nominal range. Cold weather can severly compromise immune systems in adults and stray pups can die from exposure at temperatures below 60*F.
ASF Rats do not have the same type of scent glands or have the same ammonia percentage found in their urine, as domesticated Rats and Mice so they smell 90% less in comparison. I have found a small base layer of compressed hardwood pelleted bedding with a generous layer of sifted, kiln dried, pine flakes on top to be ideal for their bedding layout. PDZ is not necessary with ASF Rats with routine maintenance, however you can add a dusting of baking soda between the two bedding layers if the animals are housed indoors. a weekly cleaning regiment is all that is required to keep your colonies from developing any smell other than that of the bedding.
ASF Rats are very inquisitive so providing enrichment items like wooden chew blocks, paper roll tubes, nesting material, and safe nontoxic toys are encouraged. I have found that they do like to burrow into the bedding so tube structures below the surface provide them with entertainment and security. They are also avid climbers so rack systems provide a natural layout to encourage that behavior. If you are using a different housing system providing opportunities to climb will add enrichment, which is crucial for health and immune support.
ASF Rats are generally nervous, flighty, and timid animals, that have an undeserved reputation for being overly aggressive. In fact, until sexual maturity is reached they are not prone to biting or nipping whatsoever. This aggression is usually found the most prolific in females that have pups. Females will defend their babies against perceived threats, however this behavior can be curved with social interaction, building trust, and gentle handling when cleaning or moving animals. They do not respond well to being held and will generally attempt to escape, but trust can be built on many other levels.
ASF Rats generally do not fight within their established colonies and it is not recommended that you introduce new members to an already established sexually mature colony. if any member of the colony does not accept the new introductee, they will most likely be injured or killed. It is best not to risk this behavior and if a member needs to be replaced for any reason it is much safer to leave a pup to grow up in that tub with its own colony. The only time this practice should be utilized is when incorporating new bloodlines to diversify the colonies.
When handling ASF Rats you should always pick them up by the base of the tail gently and never by the body as this will usually scare them into a bite or nip. Petting them softly is more comfortable for them than direct handling. With time even females with pups will tolerate you, and honestly that is the best that one can hope for with these animals.
ASF Rats require not only a high quality pelleted rodent diet but also fresh fruits and vegetables. Generally speaking the same fruits and vegetables that are approved for domesticated rats and mice are also ok for ASF Rats. If you are unsure, please research before feeding anything new to your animals. You will want to find a high quality pelleted rodent diet that has between 15-20% crude protein and less than 10% crude fat. ASF Rats can develop renal kidney disease if fed a consistent diet of over 20% crude protein. This is especially true in Males. Any diet with a consistent crude fat content over 10% can cause obesity in the animals and will be accompanied by numerous health problems. I personally use Mazuri Rodent Breeder 6F food and have found that 3/4 pelleted food and 1/4 fresh fruits and vegetables keep my rodents very healthy and happy with excellent lifespans, and quality of life.
Weanlings can be offered the pelleted food soaked in a little bit of water and formed into balls. This will help their transition into hard food, however be sure to squeeze as much water as possible out before giving them the food. If there is too much water content, the food will go rancid and it will not only smell terribly sour but also be inedible for your weanlings.
Treats can be offered as enrichment or to help build trust however make sure you do not incorporate treats as a staple part of the animals diet. I use black oil sunflower seeds as treats very sparingly because they contain 23% crude fat and would be unhealthy, as many seed mixes are, when used as a staple part of the animals diet. Be sure to check your percentages on whatever food you decide to feed your animals.
ASF Rats are simple to breed, you just house males and females together in the correct temperatures with the correct food and nature will take its course very quickly. There is no need, and it can be dangerous to cycle ASF Rats or remove colony members for breeding purposes. Once established the colony members are a family unit and should remain together. The males will help wrangle stray pups just the same as the females and all females will share in wet nursing all pups, even ones that are not their own.
Care must be taken to wean pups no later than 4 weeks as they will inadvertently prevent younger pups from being able to nurse. This will increase the natal mortality rate and create unsanitary conditions for the rest of the colony.
It is not uncommon for females to consume still born pups or pups that pass away, however if you witness a female killing and consuming a healthy pup chances are she is in need of a protein boost, from giving birth. You can offer supplemental 20% crude protein food to your normal food to help prevent future incidents. If a colony member shows neurotic behavior and kills an entire litter or someone else’s litter it is best to cull that animal immediately so it does not happen again.
ASF Rat pups should be checked on daily, with any breeding in as high volume as ASF Rats do, it is not uncommon for there to be a natural mortality rate. These deceased animals should be removed immediately for sanitary reasons. From the ages Pinky to Hopper ASF Rats are very fragile so care must be taken to prevent falls from any height. I have seen hoppers jump out of hand from a mere 2ft and seem alright only to succumb to internal injuries within a day.
Female ASF Rats will continue to provide wet nurse rolls even after menopause so they do still provide a viable roll after their breeding days are over. if at any time you see a genetic abnormality occur that is unwanted in your colony it is best to selectively breed those animals out. If you can isolate the parents of the unwanted trait that is ideal to prevent animals born with inferior genetics, however this can be difficult in large collections.
Selective breeding for healthy animals, and outcrossing into new bloodlines is necessary as these are mammals. If new bloodlines arent available I have found that animals from 3 generations, or more, removed to the present colony you wish to introduce them to, is suitable to diversify the colonies bloodline. Observation and care with introductions must be taken seriously whenever introducing any new animals into an established colony for diversifying bloodlines, as stated it can be dangerous for the introductee.
ASF Rats are heartier animals than domesticated rats and mice. They do not share the weak respiratory systems of domesticated rats, and are not prone to common colds like domesticated mice. They do however have large nocturnal eyes that can become a problem if kept on dusty bedding. Eye infections are the most common ailment that ASF Rats suffer from however here are a few less common ailments to look out for; Skin Allergies, Food Allergies, Diarrhea, Hair Loss, Rodent Lice, Stomach Cancer, Papillomavirus (MnPV), and Squamous Carcinomas. (Dermal Tumors/Warts). Animals that exhibit cancerous or spreadable diseases should be culled.
Genetic Defects such as Small Eyes, Unformed Ears, and Kinked Tails can also occur if the animals are line bred for too many generations without the introduction of new bloodlines.
In their native range, wild ASF Rats were found to be the natural host of the Lassa Fever Virus, which is transferable to humans and causes a potentially fatal Hemorrhagic Fever. There has only been one case of the Lassa Fever Virus documented in the USA and it was from a passenger flying into JFK International from Liberia in 2015. No known cases exist originating from the USA.
Often considered "Candy" for Ball Pythons, the ASF Rat has a well-deserved reputation for getting picky eaters back on food. This is not surprising as the ASF Rat is one of the natural prey items that the Ball Python consumes in its natural range. I personally attribute this not to the scent of the ASF Rat but instead the lack there-of. Domesticated Rats and Mice have a much more potent scent than that of the ASF Rat and this can be a deterrent for some Ball Pythons.
There are some common misconceptions and practices I would like to clarify for anyone who uses ASF Rats as a prey food item for any reptile. First I do not feed animals I intend to sell (such as hatchlings) ASF Rats or Mice. That said let me explain, there is this stigma that any Ball Python that eats ASF Rats will only want ASF Rats. This is completely untrue. I have fed every snake in my collection ASF Rats on many occasions and the "ASF Only" feeder has occurred exactly 1 time. I have fed Mice to my personal collection on a much less frequent occasion to fewer animals and I have created 2 "Strict Mousers" in doing so. This is a relatively small sample size in the grand scheme of things, however the results do not lie. The fact is you are much more likely to create a "Strict Mouser" than an "ASF Only" feeder. The reason I do not feed ASF Rats or Mice to my hatchlings that are intended for later sale is simply this; I want to provide an animal to a person that has absolutely no chance of preferring a prey item that will be difficult to acquire for its new owner, or cause the animal to be an extremely slow grower.
When trying to convert "ASF Only" feeders back to take domestic rats, I have personally found the conversion much easier and faster than with "Strict Mousers". Mice have such a strong scent that when an animal turns into a “Strict Mouser", it can be very a difficult and tedious process to wean the animal off Mice as prey and back onto Domestic Rats or EVEN ASF Rats!
I personally have not experienced a faster growth rate in animals that feed ASF vs. Rats, however I have seen a significant growth reduction in animals that feed Mice vs. ASF or Rats. From my research I have found the these to be the average adult crude protein percentages per body weight;ASF Rats 64.8%, Domesticated Rats 61.8%, Domesticated Mice 55.8%. Although the difference is less than 10% between Rats vs. Mice and less than 5% between ASF Rats vs. Rats, the size of the prey, muscle mass, and the protein percentages do make a difference in growth rate even when feeding multiple Mice as prey food. There is less nutrition rich mass in Mice vs. Rats so the usuable nutritional value is less no matter how small the protein percentage difference is. ASF Rats being smaller than Domesticated Rats do have the same issue with nutritional mass, however it is much less and the naturally higher percentage in protein does seem to balance the difference. I believe this is why you see them very similar in overall usuable nutritional value per body weight and hence producing similar growth rates in Ball Pythons when fed as prey food items.
I have found that it is just as important of what goes into the animals you use as food as what animals you use as food. Feeding your prey properly and making sure they are healthy will directly transfer to the reptiles you keep. I truly hope this write-up clarifies some misconceptions and will become a valuable resource for Breeders and Keepers alike.
Thank you, Mike McGrath~