Ryder System lowered its second-quarter and full-year earnings estimates, primarily due to weaker demand for truck rentals.

UPS Inc. posted a 6% increase in first-quarter net income, boosted by the performance of its U.S. package operations.

Canadian transportation firm TransForce Inc. said its first-quarter profit improved, boosted by acquisitions.

Landstar System Thursday reported its first-quarter net income rose to $26.8 million, or 57 cents per share, from $20.6 million, or 43 cents, a year ago.

Canada National Railway Co. reported lower first-quarter earnings and Canadian Pacific Railway Co. reported a rise.

Canada’s two biggest freight railroads reported higher earnings for the first quarter.

Business in the first quarter was better for most trucking companies than the first three months of 2011, according to returns from publicly traded fleets and comments from privately held firms.

Union Pacific Corp. said Thursday its first-quarter profit rose 35%, boosted by higher intermodal revenue.

TransForce Inc.’s fourth-quarter net income rose to C$41.7 million, or 41 cents a share, from C$34.8 million, or 36 cents, a year earlier, the Montreal-based trucking and logistics company said Wednesday.