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.
females come into heat every 5 - 6 days, unless they're pregnant, and even then they may come into heat a few times early into pregnancy. the gestation period is normally 22 days. birth process takes about an hour or two. the average litter is 6 - 13 pups.pups start to grow hair at 7 days old, and their eyes fully open at 14 days old. with all that, you can probably guess that they multipy REALLY fast.hen food is in short supply, the rats lower in social order are the first to die. If a large fraction of a rat population is exterminated, the remaining rats will increase their reproductive rate, and quickly restore the old population level.