The less-than-truckload carrier Old Dominion Freight Line Inc. on Monday reported a year-over-year increase in tons per day for May of 9.6%, following growth of 9.7% for April.

Based on these results, Old Dominion updated its 2015 second-quarter expectations for growth in LTL tons per day to a range of 9.5% to 10% over the second quarter of 2014. This is up from an earlier expectation of a 9% to 10% increase.

The North Carolina-based fleet also updated its expectations for year-over-year growth in LTL revenue per hundredweight, excluding fuel surcharges, for the second quarter to a range of 5% to 5.5%, down from the previously announced range of 5.5% to 6.5%.

“We are pleased with the continued growth in our LTL tons per day, especially with the slowdown of the domestic economy this year,” said David S. Congdon, vice chairman and CEO. “We have, however, decreased our second-quarter guidance for revenue per hundredweight because the year-over-year increase in May was not as strong as we had anticipated.”

He said the quarterly year-over-year comparison will also be affected by the company’s general rate increase implemented in May.

“Our yield metrics for May 2015 were consistent with those in April 2015, and our updated second-quarter guidance continues to assume sequential improvement for the quarter. We remain disciplined with our pricing and believe the industry pricing environment continues to be stable,” Congdon said.