There's a list of experiments. They mostly sound pretty standard, looking at the effects of various (hormone, etc.) medications on things like breast cancer, reproduction, etc. Tons and tons of medical experiments covering all sorts of different things are carried out each year. And they're a big part of why the USA has long been a leader in drug and medical research.

Edit: The full press release:

https://www.whitehouse.gov/articles/2025/03/yes-biden-spent-millions-on-transgender-animal-experiments/