How many investment loans can I get per year?

[Jessica Maalouf]

I recently invested in a multifamily unit in Detroit using an investment loan. I have the unit fully tenant occupied and I am looking to move on to the next property. 

Do lenders do more than one investment loan per year (for the same person) given you still meet all the criteria? Is it true you have to have the rental rented for one year before they will not consider it as part of your debt to income ratio? My lender wasn't real clear about the requirements and never got back to me.