Cost of revenues, exclusive of depreciation and amortization. Total cost of revenues for the three months ended March 31, 2025 was $163.9 million, an increase of $85.0 million from $78.9 million for three months ended March 31, 2024. The change was primarily attributable to a $41.4 million increase in product cost of goods sold, a $27.3 million increase in personnel expense due to increased activity levels due to the Merger, and a $9.0 million increase in supplies and general manufacturing expenses. This change was offset by a decrease of a net $4.5 million in variance, scrap and absorption expense due to reduced costing in lower cost geographies along with increased inventory absorption costs due to the Merger. The remaining difference is attributable to increases in facilities costs, inventory reserves, property taxes, and other miscellaneous costs.
Selling, general and administrative expenses. Selling, general and administrative expense for the three months ended March 31, 2025 was $32.3 million, an increase of $11.0 million from $21.3 million for the three months ended March 31, 2024. The change is primarily attributable to a $11.2 million increase in salaries, wages and other payroll costs caused by an increased headcount due to the Merger.
(Gain)/loss on sale of assets. (Gain)/loss on sale of assets for the three months ended March 31, 2025 and 2024 was $0.1 million and $(0.1) million, respectively. The change during the two periods was due to normal variations in property and equipment sales activity.
Depreciation and amortization. Total depreciation and amortization expense for the three months ended March 31, 2025 was $14.9 million, an increase of $10.1 million from $4.8 million for the three months ended March 31, 2024. The change in depreciation and amortization was primarily due to additional depreciation for assets acquired related to the Merger.
Long-lived asset impairments. Long-lived asset impairment expense for the three months ended March 31, 2025 was $2.9 million, an increase of $2.9 million from $0.0 million for the three months ended March 31, 2024. The impairment expense in 2025 was related to a land and building in Mexico acquired as part of the Merger, that is held for sale at March 31, 2025 and being marketed at an amount that is lower than the net book value, which ultimately resulted in an impairment expense of $2.9 million.
Acquisition and integration costs. Acquisition and integration costs for the three months ended March 31, 2025 was $4.3 million, an increase of $3.5 million from $0.8 million for the three months ended March 31, 2024. The change in acquisition and integration costs was due to the costs incurred in connection with the Merger and the acquisition of DWS and SCF.
Interest expense. Total interest expense was $0.7 million for the three months ended March 31, 2025 and 2024. Interest expense is comparable during both periods due to lower long-term debt balances during the three months ended March 31, 2025, offset by increased finance lease interest due to an increase in finance leases during the comparative periods.
Other (income) expense. Total other (income) expense for the three months ended March 31, 2025 was $(0.2) million, a decrease of $0.7 million from $0.5 million for the three months ended March 31, 2024, with the change primarily being due to the net change in our foreign currency exchange gains (losses).
Equity method earnings. Equity method earnings consist of the net earnings in DWS, along with the amortization of our proportional ownership interest in the step up of the fair value of the intangible assets acquired, during the period that DWS was accounted for as an equity method investee. With the purchase of the remaining 80% equity interest in DWS on November 29, 2024, the Company will not recognize equity method earnings in 2025. Total equity method earnings, excluding the amortization of the step up in fair value, for the three months ended March 31, 2024 was $0.8 million. The amortization of the step up in the fair value of the intangible assets acquired for the three months ended March 31, 2024 was $0.4 million.
Income tax expense. Our operations are subject to U.S. federal income tax at an entity level, as well as various state income and franchise taxes. In addition, our operations located in international jurisdictions are subject to local country income taxes. Income tax expense for the three months ended March 31, 2025 was $6.6 million, an increase of $1.5 million from $5.1 million for the three months ended March 31, 2024. The change was primarily driven by changes in mix of income before income taxes by geography and tax jurisdiction, discrete items recorded in the quarter, and other non-deductible expenses. For the three months ended March 31, 2025, income before income taxes was $21.4 million, representing a decrease of $0.1 million from $21.5 million for the three months ended March 31, 2024 primarily due to the factors discussed above.
Net income. Net income for the three months ended March 31, 2025 was $14.8 million, a decrease of $1.6 million from net income of $16.4 million for the three months ended March 31, 2024, as a result of the factors discussed above.