parsing date time in 24 hour format

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ASP.NET

C#5.0

Dear all,
i do have a requirement that to pass datetime in 24 hour format to a storedprocedure in sql server.
for that i have written as follows:-
DateTime fromdate=DateTime.Now;
DateTime todate=DateTime.Now.AddDays(-5);
these are giving o/p as
8-06-2015 12:00:00 and 3-06-2015 12:00:00
But i need to pass to an stored procedure as
2015-06-08 00:00:01 and 2015-06-03 23:59:59
i have searched many sites but unable to find exact matching to my requirement plz help me solve this....
Thanks in Advance.