Foreign currency (gains) losses, net
Foreign currency (gains) losses, net for the six months ended December 31, 2016, amounted to net gains of $0.2 million, as compared to $2.9 million in net gains for the six months ended December 31, 2015. Foreign currency gains in the six months ended December 31, 2016, were primarily due to the movement of the Turkish and Mexican currencies relative to the U.S. dollar. Foreign currency gains and losses primarily arise from intercompany balances.
Provision (benefit) for income taxes
The provision for income taxes was $11.3 million for the six months ended December 31, 2016, as compared to an income tax benefit of $9.3 million for the six months ending December 31, 2015. The effective income tax rates for these periods were 30.6% and (23.6)%, respectively. The negative effective income tax rate for the six months ended December 31, 2015, was primarily due to a $20.4 million income tax benefit from the reversal of the domestic valuation allowance we previously had recorded against domestic deferred tax assets and a benefit related to a discrete item. Excluding the effect of the reversal of the valuation allowance and the discrete item, the effective income tax rate for the six months ended December 31, 2015, was approximately 28.0%.
Our future effective tax rate may be affected by discrete items, the fluctuation in tax rates in foreign jurisdictions and the amount of income earned in our foreign subsidiaries, some of which may have significant net operating loss carryforwards. As of December 31, 2016, we maintained a full valuation allowance against the deferred tax assets related to our foreign net operating loss carryforwards. We review the realizability of our deferred tax assets and evaluate our valuation allowances on a quarterly basis, or whenever events or changes in circumstances indicate that a review is required. We will continue to evaluate the necessity of these foreign valuation allowances in future periods, and to the extent that a positive earnings trend continues, a significant portion of these allowances may be released in future periods.
Net income
Net income of $25.6 million for the six months ended December 31, 2016, decreased $23.3 million, as compared to net income of $48.9 million for the six months ended December 31, 2015. The decrease was a result of the factors described above, including a $20.4 million income tax benefit in the prior year period, plus an unfavorable change of $2.7 million in foreign currency (gains) losses, net.
Adjusted EBITDA
Adjusted EBITDA of $61.0 million for the six months ended December 31, 2016, increased $4.9 million, or 9%, as compared to the six months ended December 31, 2015. Animal Health Adjusted EBITDA increased $3.4 million, or 5%, due to sales growth and increased gross profit, partially offset by increased SG&A. Mineral Nutrition Adjusted EBITDA increased $1.4 million, or 19%, due to improved operating margins from lower raw material costs, partially offset by lower average selling prices. Performance Products Adjusted EBITDA increased $0.9 million, due to higher volumes and lower product costs, partially offset by lower average selling prices. Corporate expenses increased $0.8 million due to increased compensation and benefit costs and business development costs.
Pension Plan and Retirement Savings Plan Changes
In July 2016, we amended our domestic noncontributory defined benefit pension plan to eliminate credit for future service and compensation increases, effective as of September 30, 2016. The amendment resulted in a curtailment of the pension plan. During the three months ended September 30, 2016, we recorded a pension curtailment gain of $6.8 million in other comprehensive income and an offsetting reduction in the liability for pension benefits included in other liabilities. We also modified the 401(k) retirement savings plan effective October 1, 2016, to include, for all domestic employees, a non-elective Company contribution of 3% of compensation and an additional discretionary contribution of up to 4% of compensation, depending on the employee’s age and years of service.
Separately, we offered a lump sum settlement option to certain pension plan participants. During the three months ended December 31, 2016, we recognized a partial settlement of the pension plan with respect to the lump sum settlement, which resulted in a charge to the consolidated statement of operations of $1.7 million, which we recorded as a component of SG&A.