The headline result was from 283.3m at the Lynx deposit, which lies immediately northwest of Windfall.
Other highlights included 3.3m at 48.7g/t from 542.3m at Lynx, and 9.2m at 9.01g/t from 920.1m at Underdog.
A preliminary economic assessment for the Windfall and Osborne-Bell deposits released in July envisaged initial capex of C$397.3 million (US$301 million), an after-tax IRR of 33% and average annual production of 218,000oz over an 8.1-year mine life.
At the time, the company said it expected the "great initial numbers" to improve as its 800,000m drilling programme continued.
Osisko's exploration ramp at Windfall reached Zone 27 earlier this month, signalling the start of a 5,000 tonne bulk sampling programme which is expected to be processed next month.
The company has expanded its foothold in the Abitibi belt after last week completing its acquisition of neighbour Beaufield Resources.
Osisko closed a C$76.4 million (US$58.4 million) placement in September, issuing common shares at $1.70 apiece and two tranches of flow-through shares priced at $2.85 and $2.30.
Its shares, which were trading around C$4 a year ago and dropped to $1.60 as the gold price fell in August, rose 3.91% yesterday to $3.19 to give it a market cap of $765 million.