Performance Products
Net sales of $50.3 million for the nine months ended March 31, 2021, increased $4.9 million, or 11%, driven by increased volumes of copper-based products.
Gross profit
Gross profit of $201.5 million for the nine months ended March 31, 2021, increased $5.2 million, or 3%, as compared to the nine months ended March 31, 2020. Gross margin increased 100 basis points to 32.9% of net sales for the nine months ended March 31, 2021, as compared to 31.9% for the nine months ended March 31, 2020. The nine months ended March 31, 2020, included $0.3 million of acquisition-related cost of goods sold.
Animal Health gross profit increased $0.5 million, due to increased volumes of nutritional specialty products and favorable production costs, primarily related to foreign currency movements. These increases were partially offset by lower volumes of MFAs and other and vaccine products and unfavorable product mix. Mineral Nutrition gross profit increased $1.1 million, driven by favorable raw material costs and product mix, partially offset by declines in average selling prices. Performance Products gross profit increased $3.3 million, driven by higher volume coupled with decreases in raw material and production costs.
Selling, general and administrative expenses
Selling, general and administrative expenses (“SG&A”) of $145.8 million for the nine months ended March 31, 2021, increased $0.6 million, or less than 1%, as compared to the nine months ended March 31, 2020. SG&A for the nine months ended March 31, 2021 included $1.1 million of stock-based compensation. SG&A for the nine months ended March 31, 2020, included $1.7 million of stock-based compensation, $0.4 million of restructuring costs, $0.5 million of acquisition-related transaction costs and $0.2 million of other acquisition-related costs. Excluding these costs, SG&A increased $2.3 million, or 2%.
Animal Health SG&A decreased $0.6 million primarily due to the favorable effects of foreign currency exchange and decreased marketing and sales team travel costs driven by COVID-19 limitations. These expense declines were partially offset by increased professional fees to support the continued use of carbadox and investments in market expansion initiatives in certain international regions. Mineral Nutrition and Performance Products SG&A were comparable to the prior year. Corporate expenses increased $2.9 million, driven by investments in strategic initiatives, as well as incremental costs for performance-related compensation, professional fees and information technology. These cost increases were partially offset by lower travel expenses driven by COVID-19 limitations. The stock-based compensation, restructuring costs, acquisition-related transaction costs and other acquisition-related costs resulted in a net $1.7 million decrease to SG&A.
Interest expense, net
Interest expense, net of $9.0 million for the nine months ended March 31, 2021, decreased $1.1 million, or 11%, as compared to the nine months ended March 31, 2020. Interest expense, net decreased primarily due to favorable variable interest rates, partially offset by higher levels of debt outstanding and lower interest income from short-term investments.
Foreign currency (gains) losses, net
Foreign currency gains, net for the nine months ended March 31, 2021, were $3.6 million, as compared to net losses of $1.9 million for the nine months ended March 31, 2020. Foreign currency gains primarily arose from intercompany balances, driven by the movement of the Mexican, South African, Turkish and Brazilian currencies relative to the U.S. dollar.
Provision for income taxes
The provision for income taxes was $13.1 million and $11.2 million for the nine months ended March 31, 2021 and 2020, respectively. The effective income tax rate was 26.0% and 28.7% for the nine months ended March 31, 2021 and 2020, respectively. The provision for income taxes during the nine months ended March 31, 2021, included (i) a $1.5 million benefit for the years ended June 30, 2020 and 2019 related to final regulations issued in July 2020 for the Global Intangible Low-Taxed Income (“GILTI”) tax, (ii) an $0.8 million benefit related to exchange rate differences on intercompany dividends, (iii) a $0.6 million benefit for the reversal