Today, we see a very clear future for Darling Ingredients as our dedicated global team of 10,000 plus employees continue to execute our business strategy in a safe and efficient manner.
Our earnings for the first quarter of 2021 we're certainly energized by a rising commodity price environment, which undoubtedly had a positive impact and enabled Darling to report a record $284.8 million of combined EBITDA for the quarter.
The Feed segment's EBITDA was $124.4 million, which was $34 million better than the fourth quarter of 2020 and $54 million higher than the first quarter of 2020.
Protein and fat prices averaged in the range of 40% to 60% higher than the year ago period and have continued to move higher into the current period.
Our Food segment turned in a solid performance to start 2021 with an EBITDA of $46.4 million, which was approximately 18% higher than a year ago.
In the Fuel segment, we continue to see solid results from our European bioenergy business, which reported another solid quarter, producing $20.5 million of EBITDA in Q1.
Diamond Green Diesel generated another outstanding quarter with a $2.77 EBITDA per gallon on 78 million gallons sold.
Darling's half was $108.2 million of EBITDA plus our bioenergy results produced a strong $128.7 million of combined EBITDA in Q1 for our Fuel segment.
As travel increases, we are seeing energy prices go higher as ultra low-sulfur diesel is trading above $2 a gallon in the NYMEX spot for the first time in a couple of years.
Net income for the first quarter of 2021 totaled $151.8 million or $0.90 per diluted share compared to net income of $85.5 million or $0.51 per diluted share for the 2020 first quarter.
Net sales increased 22.7% to $1.05 billion for the first quarter of 2021 as compared to $852.8 million the first quarter of 2020.
Operating income increased 62% to $199.5 million for the first quarter of 2021 compared to $122.8 million for the first quarter of 2020.
The 62% increase in operating income was primarily due to the first quarter 2021 gross margin improving approximately $68 million over the prior year and increasing from 24.1% to 26.2%.
Depreciation and amortization declined $6.1 million in the first quarter of 2021 when compared to the first quarter of 2020.
SG&A increased slightly by $1.2 million in the quarter as compared to the prior year and there were $778,000 of additional restructuring and impairment charges related to the biodiesel facilities shutdown in the prior quarter.
Lastly, regarding the improved operating income, our 50% share of Diamond Green diesels net income was $102.2 million as compared to $97.8 million for the first quarter of 2020.
Interest expense declined $2.7 million for the first quarter of 2021 as compared to the 2020 first quarter.
The company recorded income tax expense of $28.7 million for the three months ended April 3, 2021.
The effective tax rate for the first quarter is 15.8%, which differs from the federal statutory rate of 21% due primarily to the biofuel tax incentives, the relative mix of earnings among jurisdictions with different tax rates and excess tax benefits from stock-based compensation.
The company also paid $15.6 million of income taxes in the first quarter.
For 2021, we are projecting an effective tax rate of 20% and cash taxes of approximately $30 million for the remainder of the year.
Looking at the Q1 balance sheet, our total debt declined $63.5 million to $1.44 billion and the bank covenant leverage ratio ended the first quarter at 1.6 times adjusted EBITDA.
Capital expenditures were $60.8 million for Q1 2021 and is in line with Darling's planned capex spend of approximately $312 million on capital expenditures for fiscal 2021.
As you saw at the end of March, Diamond Green Diesel successfully entered into a new $400 million senior unsecured revolving credit facility.
We feel comfortable with the increased range of $1.075 billion to $1.15 billion of combined EBITDA as the increase is coming from two segments, our Feed segment and our Fuel segment.
Yes, commodity prices have steepened versus on the futures curve, but that futures price is still 30% to 50% higher than the historical price when you get to that future period.
And with that, the Q2 margin is averaging in the current environment, we are putting a potential range of $2.25 to $2.40 EBITDA per gallon for DGD for 2021.
As our joint venture partner announced several weeks ago, we believe the start-up at Norco expansion will be in the middle of Q4, that DGD will ultimately sell 365 million gallons of renewable diesel in 2021.
Those higher gallons and the range of EBITDA per gallon provided puts Darling's half of the EBITDA from DGD between $410 million and $435 million for 2021.
Since the beginning of 2020, Darling has had 100% ownership of EnviroFlight.
I'd like to note that we are proud to be selected by Bloomberg and TV Media Group as one of the 50 sustainable climate leaders in the world.

Summary:
Net income for the first quarter of 2021 totaled $151.8 million or $0.90 per diluted share compared to net income of $85.5 million or $0.51 per diluted share for the 2020 first quarter.
Net sales increased 22.7% to $1.05 billion for the first quarter of 2021 as compared to $852.8 million the first quarter of 2020.
We feel comfortable with the increased range of $1.075 billion to $1.15 billion of combined EBITDA as the increase is coming from two segments, our Feed segment and our Fuel segment.