My 50 hour service was just to change the engine oil, check bolt torques and fluid levels. I did that myself...
My tractor is a gear machine, so the manual doesn't specify changing the hydraulic fluid.
However, I'm rapidly approaching 100 hours and, although the manual calls out for a 200 hour interval, I'm going to replace the hydraulic fluid. The only reason I'd even consider the dealer doing this job is the fluid capacity. I'm not sure where I can dispose of 5-6 gallons of hydraulic fluid...also, I do not have a pan large enough for that much fluid.