In most biotechnology research laboratories, you would likely find mice the most often.

Here's why:

* Size and Lifespan: Mice are small, relatively inexpensive to house and care for, and have a short lifespan, making them ideal for research studies.

* Genetic Similarity: Mice share a significant amount of genetic similarity with humans, making them useful models for studying human diseases and conditions.

* Ease of Manipulation: Mice can be easily bred and genetically manipulated, allowing researchers to create models for specific diseases or conditions.

* Established Research Models: There is a vast amount of existing research using mice, making it easier to build upon previous findings and compare results.

While other animals are also used in biotechnology research (like rats, zebrafish, and even larger mammals like pigs), mice are the most commonly used due to the reasons mentioned above.