Since the start of the coronavirus outbreak in Ukraine, animals in Mykhailo Pinchuk's cash-strapped zoo have had to make do with leaner diets and less food.
High-quality beef has been partially replaced by other meats and broccoli swapped for cheaper cabbage.
Monkeys, lions, and tigers have been affected by the changes, and one of the leopards has visibly lost weight, zookeepers say. "We are ashamed, and they are sad," Pinchuk, head of Ukraine's largest private zoo, told AFP.
A steep revenue decline due to the national shutdown to control the virus has hit them hard.
Set up in 2015, the zoo is located on the outskirts of the village of Demydiv, some 40 kilometres north of Kyiv and is home to around 450 animals including leopards, bears, and giraffes.
Closed for nearly two months, the zoo is no longer earning revenue from visitors and has recently issued an urgent appeal to the public for donations.
They have already raised roughly 6,920 euros but the zoo needs more to survive.
Pinchuk, who also has a real estate business, said he had sought to cut costs as much as possible, laying off non-essential personnel and simplifying the animals' specialised diets.
Now their new diets have affected their mood, he and his zookeepers said.
"They are like people, they like variety," said Maksym Kovalev, who has worked in the zoo for nearly two years. "It's like switching to porridge after eating restaurant food."
Carnivorous animals like lions and a jaguar have had to get used to reduced rations of high-quality meat, said another zookeeper, Igor Dzharayan.
But he and others insisted that the animals are not starving and their total calorie intake remains the same.
Pinchuk said the animals sometimes skip several meals before they get used to new foods.
"At first they just don't understand what has been brought to them and don't eat it. They look at it in surprise," said 47-year-old Pinchuk.
Monkeys, whose diets are expensive, have also been significantly affected, he said.
Joseph the orangutan loves persimmons and tangerines and his mood can turn sour if he does not get his preferred fruit, Pinchuk said.
"We have to give him that, it's his favourite stuff."
Besides animal feed, there are other upkeep costs, said Pinchuk, adding it was also important to keep cages warm.
At first, the staff tried to avoid contact with monkeys, fearing they may get infected with coronavirus, but that proved too difficult.
"The way they looked at us when we did not visit them. It was simply impossible to bear," Pinchuk said, recalling how his two orangutans cried and clung to the door.
Monkeys have missed visitors too, their keepers said.
Every year several hundred thousand people visit the zoo, which spans 18 hectares and features a restaurant built in the form of a castle.
It is particularly busy in spring, with the parking lot full of cars and playgrounds packed with children.
From Monday, Ukraine is set to begin lifting lockdown measures, and Pinchuk hopes to be allowed to re-open as an open-air park.
Severe restrictions will be introduced to keep animals safe.
Pinchuk said he planned to put up posters asking guests not to give monkeys any food.
But keeping them indoors was also not an option, he said.
"There is no choice. We cannot close the zoo and watch them waste away from other diseases, a lack of sunlight, or a bad mood."