ELi5: How do some animals get enough nutrients out of eating hay or grass or a single variety of leaf for their entire lives?

Question

ELi5: How do some animals get enough nutrients out of eating hay or grass or a single variety of leaf for their entire lives?

In: 293

Answer 1

Here’s your reminder that its very common for wild animals to not get enough nutrition, and as a result “their entire lives” are much shorter, not to mention the parasites.
Farm animals eat the plants as well as getting grains, additives, pills, vaccines, and extensive attention that they do not get in the wild.