IACUC Learning Module - Xenopus laevis | Previous Next |
Appropriate well balanced diets include Nasco Frog Brittle or a commercial salmon pelleted diet ("soft-moist" salmon diet).
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The pellets called "Soft-Moist Salmon Diet" by Rangen, Inc., can be ordered in 50lb boxes at approximately .60¢/lb + shipping: Rangen, Inc. POB 706, 115 13 Ave So Guhl, Idaho, 83316. Telephone (208) 543-6421. |
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Analysis of Soft-Moist Salmon Diet |
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| Crude protein, not less than | 45.0% |
| Crude fat, not less than | 19.0% |
| Crude fiber, not more than | 3.0% |
| Ash, not more than | 12.0% |
| Added mineral ingredients, not more than | 2.0% |
| Ingredients: fish meal, wheat feed flour, blood meal, fish oil, ascorbic acid, biotin, choline chloride, folic acid, niacin, panthothenic acid (d-calcium panthothenate), pyroxidine(hydrochloride), riboflavin, thiamine (mononitrate), vitamin B12 supplement, vitamin A (acetate), vitamin D (d-activated animal sterol), vitamin E (dl-alphatocopheryl acetate), vitamin K3 (menadione sodium bisulfate complex), copper sulfate, manganese sulfate, potassium iodate, salt, zinc, sulfate, ethoxyquin (preservative), proprionic acid, sorbic acid, propylene glycol. | |
| (ILAR news, Vol XXX, No 3, Summer 1988) | |
For years, labs have fed solely minced beef liver or beef heart. Beef liver is no longer recommended as a balanced diet since it has been implicated as a cause of Vitamin A toxicity and other amphibian diseases.
Nutrition - Tadpoles
Tadpoles have a high calcium requirement and in addition to their diet, absorb calcium through their gills and skin. Good nutrition and adequately hard water are essential for normal development. Iodine deficiencies can develop when amphibians are fed deficient or goitrogenic diets. This causes tadpoles to fail to metamorphose. Tadpoles fed spinach may develop oxalate calculi in the kidneys and die at the time of metamorphosis.
Xenopus laevis tadpoles are filter feeders and will begin to feed on suspended food particles at about 10 days old.
Their typical posture is to hang, head down at a 45 angle in mid water with their long, whip-like tails rapidly vibrating. This produces a current in the water which brings their microscopic food to them. By regular gulping of water and expelling it through their gill slits, microorganisms and edible detritus are filtered out and eaten. The first food is usually algae, but strained baby food (green beans or peas) at a rate of 1 drop per 100 ml of water that houses 25 or less tadpoles is commonly used. Food in captivity may range from liquified fish food, to commercial powdered tadpole food (Nasco), to "organic soup" taken from natural ponds.
Food should only be added when the "cloudiness" from the previous batch of food has been consumed by the tadpoles.Sanitation
Ideally cages should be changed daily! Practically speaking, adult Xenopus cages should be cleaned at least 3 times per week. References note that regurgitation of food is common in Xenopus that are disturbed too soon after eating. A 3-5 hour period after the animals have been fed has been adequate to avoid this problem. In addition, changing the cage a few hours after eating removes uneaten food that would putrefy and foul the animal's environment.
Disinfectants
Most amphibians are susceptible to intoxication by phenol and cresol type disinfectants such as Lysol. Intoxication symptoms may include convulsions, flaccid paralysis and death.
Ten percent bleach or betadine scrub are the disinfectants of choice. Both still require thorough rinsing
to avoid harmful residues on all amphibian cages or equipment. Tadpoles and aquatic forms are particularly susceptible to chemicals! If automatic cage washing facilities are used, caging and equipment should be run through two complete rinse cycles and should be rinsed again by hand with deionized water. If deionized water is used, be sure to verify a correct pH range (6.5-8.5) by means of a pH test tape or a pH meter.Health Risk to Caretakers
Most amphibians pose no risk for caretakers provided normal handwashing procedures are followed after working with animals, caging or feces. The habit of wearing plastic or latex gloves affords additional protection. It is important to remember not to touch your own mucous membranes (eg. rub your eyes) after handling frogs. Secretions from the parotid glands rubbed into the conjunctival sac of the human eye can range from irritating to very painful.
Identification and Records
Amphibians normally shed skin thus making any type of tattooing or branding ineffective since it will be illegible in a few months to a year. Species such as urodeles and Xenopus can regenerate toes, thus toe clipping is not an acceptable method to identify these animals.
The most common method to identify Xenopus is cagecards and documented skin patterns (via drawings or photographs). A system of colored plastic or glass beads of appropriate size can be sutured into the toe webs with plastic suture or monofilament line. This system can work well to identify animals kept for long periods of time. Plastic colored leg banding has been tried on Xenopus, but the skin is so slippery that if the bands are tight enough to stay on, they are too tight.
Circulation to the foot is restricted, causing the feet to swell and become necrotic within hours of the banding. This method must not be used!Humane Handling
If Xenopus are being moved during cage changing or for other manipulations, a net may be the best method to catch and handle the frog. Use the net to scoop the frog out of the water. Place your free hand over the top of the net opening while moving the frog. This should prevent the frog from jumping out of the net during transport. The net avoids damage to the protective mucous layer on the frog's skin and is less traumatic than physical hand contact with the frog.
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When picked up properly, the
frog's head will face the handler's wrist. The handler should grasp the frog
with the palm down while placing fingers on each side and between the legs.
Lift the animal up and use your other hand to gently but firmly secure the
animal if it squirms and struggles to escape.
Gentle handling is essential to minimize stress! Frogs should be kept moist if restrained for any length of time. |
| Restraining an African clawed frog. |
Xenopus laevis have a very thick, slippery mucous covering over their skin which makes it very much like trying to pick up an oyster or a wet bar of soap!
Take precautions to avoid damaging the mucous layer, or dropping frogs on the floor and chasing them around the room. This is obviously stressful to the frog and handler. When holding Xenopus, use your hands as a cage rather than applying pressure to grasp the animal.Shipment and Arrival of New Xenopus
During shipment, adult Xenopus are usually shipped in sealed buckets with moist foam cubes or damp moss to prevent desiccation and to cushion any bumps or shocks. Shipment containers should provide appropriate temperature, space, oxygen, separation and clean water. If animals arrive in water, the animals and container should be allowed to adjust to room temperature or to the new enclosure's temperature.
The shipment water should be kept with the new arrivals and gradually be replaced by slow dilution over several days with facility water to avoid "shock" to the new animals.
All new amphibians should be "quarantined" on arrival. This may be as simple as separate cages for new animals or it may mean separate animal rooms. New animals should be quarantined at least 7-10 days and examined daily for activity level, skin discoloration, ulceration, petechial (pinpoint) hemorrhages on the legs, abdominal swelling or any other unusual changes.
The purpose of the quarantine is to allow animals to stabilize following shipment, to seek replacement animals for sick or damaged animals from the vendor, to avoid exposure to incoming disease from new stock, and condition new animals to current environmental conditions prior to commencement of an experiment.
New arrivals should be handled last, the person providing care should always tend first to established healthy collections and breeding colonies. Maintain separate holding tanks and separate handling equipment (nets, scoops, etc) for quarantine animals. Caretakers should adhere to frequent handwashing procedures and glove changes between cages of different shipments and between individual animals.
Preventative treatments for newly shipped animals may include placing frogs in a 0.6% calcium hypochlorite solution (or a 0.06% sodium chloride solution) to reduce the growth of Aeromonas hydrophilia and occurrence of "Red Leg".
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Updated
01/02/2008
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