Firefighters remain at the scene of a large blaze at a storage unit in Duncrue Street, north Belfast.
The fire service was called to the fire at Devenish Nutrition's distribution centre at 23:10 GMT on Thursday.
Four fire engines were initially sent to the scene, but this was increased to 13, including appliances with cranes, as 60 firefighters tackled the blaze at its height.
Fumes from the blaze could be smelled across Belfast on Friday morning.
On Friday night the fire service said crews were turning over burnt materials to cool hotspots and that operations would be scaled down overnight.
It added that it expects the fire to be fully extinguished on Saturday.
When they arrived late on Thursday night, firefighters found a well-developed blaze in a storage unit containing agricultural feed.
Crews "worked hard throughout the night in difficult conditions to bring the fire under control and to protect neighbouring property", the fire service said.
Smell of burnt agricultural feed in the air
At the scene: Michael Sheils-McNamee, BBC News NI
By mid-morning, the black clouds of smoke from Thursday night had turned white, but still shrouded local roads.
The acrid stench of burnt agricultural feed hung in the air.
Water is being pumped from the nearby Lagan by firefighters - an effort that is expected to carry on all day.
Owners of neighbouring businesses, while shocked by the night's events, are pressing on with their day's work.
Speaking on Friday morning, NI Fire and Rescue Service group commander William Johnson said while it was a "huge operation" it was quickly established that no lives were in danger and no-one had been injured.
"Due to the structural integrity of the premises, we had to withdraw some crews and scale down activities until the light came this morning," he said.
"The crews have changed over, the attack on the fire is about to continue."
Mr Johnson said commuters on the M2 motorway would notice the smell of the animal feed burning.
"Because of all the moisture in the air, it's starting to drift across the motorway and the docks area," he said.
"What we would ask the many members of the public who are planning to drive around that area, or going to work this morning, is just to try and avoid the Duncrue Street area.
"Some of the fire hose and equipment that we're using is quite substantial and it's preventing some traffic through that area."
In a statement, animal nutrition company Devenish said they were working with police to establish the cause of the fire and that "no employees were inside the building" when it broke out.
It said the Northern Ireland Fire and Rescue Service "were called to the scene quickly" and the fire had "not impacted production at our separate mill facility, which continues to operate as normal".