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.
This stage is the big time! Now your pregnant cat will start to have major contractions. She will be breathing deeply and you will see visible movement and shuddering of her belly. In the beginning, the contractions for cats giving birth to kittens may be once every 30 minutes and possibly longer. They gradually become more frequent and occur every 30 seconds until right before the birth of the first kitten.