Holes in beam

A structural engineer is drawing up some plans for me to use a beam to replace a load bearing interior wall that is currently supporting a roof strut and a ceiling runner . I have told him I already have a second-hand Douglas Fir (Canadian Oregon) beam (300mm X 125mm) and he is happy to use that. I don't know, but I'm guessing that this size more than meets the requirements for the beam (the span is 4850mm).

At the time I bought the beam I noticed that there were several vertical bolt holes (width 24mm) drilled along the length (through the 300mm depth and approx every 1 metre) but didn't pay much attention to this.

However, now I'm concerned that this will weaken the beam. Does anyone know what holes can be safely drilled (vertically) through the beam without weakening it?
Pictures attached:

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