To enter experimental information, there are several optional groupings which will assist in analysis.
Measurements which occur together are grouped into experiments, which are then grouped together as a Study
When animals are treated with something, they are grouped into Treatment groups (see here. A particular treatment (such as High Fat Diet) may be performed on several different groups of animals. Several treatments together, done at the same time are called Cohorts (see here). Therefore a study may consist of several cohorts, which themselves may consist of several treatment groups.