A union leader for employees in the state parks, Marlene Sifontes, told Reuters news agency some had spent two weeks without food before they died.
She said lions and tigers in the zoo in Caracas were fed mango and pumpkin to make up their meat rations.
Government officials have denied the deaths were due to a lack of food.
In other cities zoos are reported to be in a worse situation, forced to ask for donations of fruit, vegetables and meat from local businesses.
The problem is because Venezuela is in the midst of a severe economic crisis which has led to a lot of food shortages.
President Nicolas Maduro blames the country's problems on what he says is a competitive war waged by businessmen and government opponents.