How do I get people to read my announcements?

Hi all. I work at a mid-sized public university and employ roughly 40 student employees that troubleshoot tier 1 style technology issues. I regularly need to notify them of new initiatives, and ask for their feedback, among other things. In the past I have emailed them, but find that very few actually read the emails. Immediately at my disposal I have email, a group discussion board, and walkie talkies they all have access to.

So my question is, how do I best ensure that people read/get my announcements? I'm open to any suggestions. Thanks!