The stomach has three types of contractions: There are rhythmic, 3 per minute, synchronized contractions in the lower part of the stomach, which create waves of food particles and juice which splash against a closed sphincter muscle (the pyloric sphincter) to grind the food into small particles.
7 What is the gestation period, how many babies do they have, and when are they weaned? 1  The gestation period for rats is 19â22 days, for mice it is 17â21 days.  Rats and mice average 8â12 babies in a litter, but can have as few as 1 or as many as 20.
Report Abuse. Rats are able to be seaperated from their mothers at bout 4 to 5 weeks of age, that would be the best time to get them. If your a first time rat owner, please read up as much as you can about them.If you have any questions I can try to help feel free to email me at stacy4ever2000@yahoo.com. breeder will be able to help you with any questions you have, and will also give you the rat at the perfect age for adoption (if you go the pet store route, I think the best age is about 5 or 6 weeks).