Ykhjuy

How do they know how many calories to feed? How do they ensure that all the animals are fed, and not fed multiple times from multiple people by accident? Do they have sign in sheets or computer logs? And what happens to all the feces?

I volunteered for 3 years at a large mammal laboratory where we diligently tracked the weight and caloric intake of each of our animals. Diets were weighed out each morning and total calories could be calculated based on the known caloric value of the particular food item.

We fed our animals during training sessions and would adjust the individual's food intake based on their appetite/motivation (i.e. if an animal was full, they'd drop the piece of food they earned or leave the session). This would indicate that we could decrease the individual's diet in small increments.

The animals were also weighed each week. Weight and caloric intake were recorded in daily logs using FileMaker Pro. This allowed us to view fluctuations of each throughout the year and compare to previous years. If an animal's weight was a bit lower at a certain time of year than it typically was in past years, we could increase their diet.

Diet items were selected based off of the animals' natural diet.

I assumed there was a formula such as the Harris-Benedict equation, for other species. When @MeganMcE said they were fed "based on their appetite/motivation"; I have concluded that most animals are pretty much fed freely, so long as they are not apparently obese or anorexic.