Researchers in both the U.S. and England conducted the earliest vitamin research on rats in the early 1900's. Rats are popular today in other types of research, such as psychological and biological tests, because they're easy to use. Their light food consumption makes them economical in the lab. It is possible to evaluate the effects of minute amounts of experimental material on rats -- a test that is impractical with larger animals.
Physiologically, rats are similar to other single-stomached animals, except for their lack of a gall bladder and their diffuse pancreas, an organ that is well-formed in other monogastric animals. Three bile ducts lead directly from the liver to the duodenum. The best research results are obtained from uniformly sized rats that are produced in closed colonies. By using rats from the same source you can ensure uniformity of size, good reproduction, and fewer genetic variations.
Frequent handling of the animals will make them gentle and easier to control. Handling will permit you to check them for physical defects and the presence of external parasites. A gentle, firm grip around the thoracic cavity is comfortable for the rat, while still restricting movement. Young rats usually have to become accustomed to handling gradually because they are so playful and active.
Psychological tests have proved that rats are highly intelligent and sensitive. They need attention and will usually come to the front of their cages when a human being approaches. Rats will stay cooperative and easily manageable if they are treated kindly and if their cage area is kept clean and quiet.
Take a look and see what diet is best for the rodents in your facility.
http://www.animalspecialties.biz/RodentDiet.html