
His absence fueled speculation that the leader is close to death and may not return to power, but Alexandre Trudeau told CTV Newsnet no one is making any firm statements on his health.
"My feeling is no one really knows," said Alexandre, who was in Havana for the Saturday morning parade.
"He didn't show up for his birthday celebrations, he didn't show up for the big parade this morning. That could mean he's still recovering and getting better, but listening to his doctors it seems that he's very ill."
Trudeau's father, former prime minister Pierre Trudeau, was a friend of Castro. Castro attended Trudeau's funeral in Montreal six years ago.
Alexandre said the ailing leader, who hasn't been seen for months in public, is still wildly popular among Cubans.
"They love Castro and at least through his ideas he will live on, whether he comes back to power or not."
He added: "The official line is he's still fine and could come back to power."
Other leaders, such as Nicaragua's President-elect Daniel Ortega and Bolivia's Evo Morales, were also in attendance at the anniversary celebrations.
Castro, who turned 80 on Aug. 13, has been recovering from intestinal surgery, but U.S. officials have said they believe Castro is suffering from some form of inoperable cancer and will not live through the end of 2007.
In recent photographs and videos released by the government Castro has appeared thin and pale.
Speculation had abounded all week on whether Castro would make an appearance at the anniversary.
The reigns of power in Cuba are currently being held by Castro's brother, Defence Minister Raul Castro, who was the key speaker at the anniversary celebrations.
He made no mention of his ailing brother during his 30-minute speech on Saturday, instead taking aim at the U.S. for it's policy on Iraq and making reference to U.S. attempts to "annex Latin America," through trade policies.
But then Raul made overtures to Washington, opening the door to resolving old trade disputes.
"We take this opportunity to once again state that we are willing to resolve at the negotiating table the long-standing dispute between the United States and Cuba," he said.
"In the meantime, after almost half a century, we are willing to wait patiently until the moment when common sense prevails in Washington power circles."
A message purportedly from Fidel Castro was read to 5,000 supporters celebrating his birthday earlier this week at a Havana theatre that he was too sick to meet with them.
"I direct myself to you, intellectuals and prestigious personalities of the world, with a dilemma," said the note that was read aloud. "I could not meet with you in a small locale, only in the Karl Marx Theater where all the visitors would fit, and I was not yet in condition, according to the doctors, to face such a colossal encounter.
"My very close friends, who have done me the honor of visiting our country, I sign off with the great pain of not having been able to personally give thanks and hugs to each and every one of you."
With files from The Associated Press