Looking at the results for the quarter, we maintained our top line momentum with strong sales across categories and markets around the world, resulting in organic sales growth of 12.7% with battery up 11% and auto care up 27%, globally.
We delivered adjusted gross margin of 40.7% as we were able to meet the demand while incurring lower incremental costs than we did last quarter.
This combination of strong top line growth and improving margins resulted in adjusted earnings-per-share growth of 38% and adjusted EBITDA growth of 17%.
With lower interest expenses due to the refinancing, we are increasing our outlook for the full year adjusted earnings per share to a new range of $3.10 to $3.40.
Globally, battery category value was up 6.9% and we continue to see consumers purchasing batteries for immediate use.
With a gain of 2.5 share points, Energizer is growing faster than the category, driven by distribution gains in the U.S. and in international markets, including Canada, France, Korea and the UK.
With auto care, the U.S. category grew more than 10% as a result of changes in consumer behavior, including an increased focus on cleaning and disinfecting as well as an increase in do-it-yourself activities.
In the first quarter, we realized $20 million in synergies and we remain on track to achieve $40 million to $45 million in 2021 and to deliver more than $100 million in total synergies.
As Mark indicated, our organic revenue growth of 12.7% coupled with cost controls and favorable currency tailwinds resulted in strong adjusted earnings per share of $1.17, adjusted EBITDA of $192 million and adjusted free cash flow of $90 million.
Taking a deeper look at the top line, both our Americas and International segments grew organically more than 12% with batteries up 11% and auto care up more than 27%.
Finally, the growth we are seeing this year is off of prior-year first quarter organic sales decline of 3.4%.
Adjusted gross margin decreased 110 basis points versus the prior year to 40.7%, although this represented a sequential improvement versus the last quarter.
Gross margin was impacted primarily by incremental COVID costs of approximately $12 million, largely related to air freight, fines and penalties and personal protection equipment necessary to meet the sustained elevated demand, end channel customer and product mix as well as increased operating costs resulted from increased tariffs associated with higher volumes, commodity cost and transportation cost, consistent with inflationary trends in the global market.
Partially offsetting these impacts to gross margin, the first quarter benefited from synergies of $13 million and favorable currency exchange rates.
A&P as a percent of net sales was 5.8% versus 6.4% in the prior year, due primarily to the strong top line growth experienced in the current quarter.
Consistent with our priorities, we continue and invest, on an absolute dollar basis, in A&P to support our brands with total A&P up $3 million or 6%.
Excluding acquisition and integration cost, SG&A as a percent of net sales was 13.4% versus 15.1% in the prior year.
On an absolute dollar basis, adjusted SG&A increased $2.7 million, driven in part by higher overheads associated with the top line sales growth and the timing of costs partially offset by synergies of $7 million and lower travel expense due to COVID.
As Mark mentioned, we realized $20 million of synergies in the quarter with $13 million in cost of goods sold and $7 million in SG&A.
For the full year, we continue to expect to realize $40 million to $45 million of incremental synergies.
In total, we have recognized nearly $90 million since we completed the battery and auto care acquisitions and remain on track to realize in excess of $100 million by the end of fiscal 2021.
We also took advantage of accommodating debt markets to refinance our existing short-term secured debt and our 2027 unsecured bonds with a new $1.2 billion term loan.
Based on the new all-in interest rates, we anticipate annualized interest savings of roughly $25 million with about $19 million to be realized over the remainder of fiscal 2021.
Our net debt to credit defined EBITDA at the end of the quarter was 4.6 times, reflecting improved EBITDA performance and debt pay down during the quarter of $80 million, excluding refinancing activities.
At the end of the quarter, our total debt was approximately $3.4 billion, with nearly 85% now at fixed rates and an all-in cost of debt of approximately 4.3%.
And finally, we continue to drive shareholder returns through our balanced approach to capital allocation, by investing in our business through innovation, brand-building activities and the projects we mentioned earlier to modernize our core and drive cost out of the business, delivering a quarterly cash dividend of $27 million; repurchasing 500,000 shares for $21 million, representing an average price of $42.61; paying down $80 million of debt excluding refinancing activity; and finally, completing two bolt-on acquisitions.
Net sales growth is expected to be at the upper end of the range of 2% to 4%, driven in large part by continued elevated battery demand in North America and favorable currency impacts.
Adjusted EBITDA is expected to be at the upper end of our previously provided range of $600 million to $630 million and free cash flow of $325 million to $350 million remains unchanged due to working capital requirements, in particular, inventory, as we look to rebuild safety stock.
Adjusted earnings per share is now expected to be in the range of $3.10 to $3.40.

Summary:
With lower interest expenses due to the refinancing, we are increasing our outlook for the full year adjusted earnings per share to a new range of $3.10 to $3.40.
As Mark indicated, our organic revenue growth of 12.7% coupled with cost controls and favorable currency tailwinds resulted in strong adjusted earnings per share of $1.17, adjusted EBITDA of $192 million and adjusted free cash flow of $90 million.
Based on the new all-in interest rates, we anticipate annualized interest savings of roughly $25 million with about $19 million to be realized over the remainder of fiscal 2021.
Adjusted earnings per share is now expected to be in the range of $3.10 to $3.40.