Animal enclosures with sloped, self-cleaning floors, emptying into a manure gutter or pit.
How does the potable water take up only 20% of the physical space of the animals when most creatures will take in over 100% of their body weight in just a few weeks?
When the God who created the universe enacts His miraculous powers, dontcha figure He could tap that energy to make the animals sleep for a bit?
They were green and caught rain water...:)
SOURCE: http://www.answersingenesis.org/articles/am/v2/n2/caring-for-the-animals
How Were the Animals Cared For?
We must distinguish between the long-term care required for animals kept in zoos and the temporary, emergency care required on the Ark. The animals’ comfort and healthy appearance were not essential for emergency survival during one stressful year, where survival was the primary goal.
Studies of nonmechanized animal care indicate that eight people could have fed and watered 16,000 creatures. The key is to avoid unnecessary walking around. As the old adage says, “Don’t work harder, work smarter.”
Therefore, Noah probably stored the food and water near each animal. Even better, drinking water could have been piped into troughs, just as the Chinese have used bamboo pipes for this purpose for thousands of years. The use of some sort of self-feeders, as is commonly done for birds, would have been relatively easy and probably essential.
Animals that required special care or diets were uncommon and should not have needed an inordinate amount of time from the handlers. Even animals with the most specialized diets in nature could have been switched to readily sustainable substitute diets. Of course, this assumes that animals with specialized diets today were likewise specialized at the time of the Flood.
It is reasonable to believe that one relatively small window would have adequately ventilated the Ark. Of course if there were a window along the top center section, which the Bible allows, all occupants would be even more comfortable. It is also interesting to note that the convective movement of air, driven by temperature differences between the warm-blooded animals and the cold interior surfaces, would have been significant enough to drive the flow of air. Plus, wind blowing into the window would have enhanced the ventilation further. However, if supplementary ventilation was necessary, it could have been provided by wave motion, fire thermal, or even a small number of animals harnessed to slow-moving rotary fans.
recycling?