Snakes feed almost exclusively on vertebrate or invertebrate prey. A few species are specialized egg feeders. Most boids, pythons, vipers, colubrids, crotalids, and elapids are fed mouse pups, mice, chicks, hamsters, rats, guinea pigs, chickens, ducks, or rabbits. Frozen, thawed prey are usually used in zoos; thawing under refrigeration is recommended. After thawing, prey should not be fed cold but at room temperature, or preferably warmer. Some species (eg, king cobra, hognose snake, garter snake) feed primarily on other poikilotherms in the wild. Some of these species can be switched, at least in part, to homeothermic prey, which is often more available and less expensive.
Minced prey is sometimes fed in agar, gel, or sausage form. Advantages include the ability to formulate and feed a nutritionally complete diet, to add a balanced vitamin and mineral mixture, and, if needed, to add antibiotics or coccidiostats. Mostly a complete diet is fed in a sausage; however, tests are also being done with gel feeding to reptiles.
The scent of preferred foods can be rubbed on the new item. Alternatively, the preferred foods can be inserted into, or attached to, the new food. Anoles, yellow rat snakes, frogs, and smelt, depending on natural feeding habits, can be fed when homeotherms are not accepted. Prey size is usually proportional to snake size and should not be much larger in diameter than the snake’s head. Snakes that are routinely handled can be fed in a separate tank to reduce biting. To reduce the chance of regurgitation, snakes should not be handled for 3 days after feeding.
Most species should be fed every 1–2 weeks. Some large, less active snakes may typically go 6 weeks between feedings. Force-feeding should be used only if necessary. Animals can be force-fed whole prey lubricated with egg white by gently inserting the food a few inches down the throat using forceps. Tube feeding is also possible using ground (homogenized) prey.