McDonald's score of 70 leaves him two shots behind a quartet of players who lead on 68.
Ayrshire's other representative in the competition, Michael Smyth (Royal Troon) was one of five Scots who opened with a 75.
The leaders, on 68, are :-
Marcus Kinhult (Germany), Oliver Roberts (Hong Kong), John Axelsen (Denmark) & Cormack Sharvin (Ireland)
The scores returned in round one by the Scots in the field were :-
70 - Jack McDonald (Kilmarnock Barassie)
75 - Ewen Ferguson (Bearsden), Graeme Robertson (Glenbervie), Michael Smyth (Royal Troon), Scott Gibson (Southerness), Jamie Savage (Cawder)
77 - Fraser Moore (Glenbervie)
78 - Connor Syme (Drumoig)
79 - Nick MacAndrew (Royal Aberdeen)
81 - Matt Clark (Kilmacolm)