Earthly Mobs

Cow Shearing:

Wooly and Umbra cows can be sheared like sheep by hitting them with a pair of shears. When sheared, they drop 1-3 wool (brown for Wooly, black for Umbra) and enter a cooldown period for 30-120 seconds. While in this cooldown, they will have a new texture and will no longer drop wool when killed.
Mooblooms and Moolips can be sheared like mooshrooms by hitting them with a pair of shears. When sheared, they will drop a flower (dandelion for Mooblooms, pink tulip for Moolips) and become a temperate cow.
When you 'shear' a cow, it should be healed instantly
Warm cows no longer drop brown wool when killed

Moon Cows:

Moon cows from the A or B April Fool's snapshot now spawn in The End, specifically in the End Highlands, End Midlands, and a little more frequently in Small End Islands
Due to the lack of natural light in The End, they don't spawn under normal conditions. If you light up an area enough and wait, chances are you'll see one eventually.
Just like in their snapshot of origin, Moon cows have a custom loot table. They drop cheese, glass bottles and bones when killed
Added cheese. Functionally it's the same as steak, but it has an animation when you eat it.

Magma Cows:

Magma Cows should now spawn in basalt deltas
They're fireproof
Magma cows drop basalt and steak in place of leather and beef
I haven't actually seen these guys spawn naturally in the nether. I'm PRETTY sure they can, but there's a non-zero chance they're still functionally unused.

False Jolly Llama:

The grey llama texture has been replaced by the Jolly Llama
By putting a green carpet and some sweet berries in a crafting grid, you can get the Jolly Carpet, which resembles the Jolly Llama's unique carpet design. Placing it will revert it to a normal green carpet.

Egg Laying Changes:

Reverted making all data-driven chickens lay temperate eggs
Cluckshrooms now lay red mushrooms instead of eggs
Fancy Chickens now have an equal chance to lay any of the three types of eggs instead of just the standard temperate egg
Amber and Bronzed chickens now lay brown eggs
Stormy and Midnight chickens now lay blue eggs
Skewbald and Gold Crested chickens still lay temperate eggs
These changes don't affect the type of chicken that come out of the eggs, sadly

Responsive Muddy Pigs:

Added the Bucket of Mud. It can be crafted with a bucket and either 8 dirt blocks or one mud. It can be used like a block of mud, or you can use it on a temperate pig to turn them into a muddy pig.
Muddy pigs will change to their Dried Muddy texture if standing in a warm biome
Dried Muddy pigs that stand on Mud or Muddy Mangrove Roots will be reverted to Muddy pigs
Muddy and Dried Muddy Pigs will become temperate pigs when floating in water

Config Menu:

Journal:

Whenever you interact with (or smack) a mob variant for the first time, you get a new entry in the journal, found in the advancements tab
Each entry has an icon of the mob's face, the biome you can find them in, and sometimes a little entry about them.
Works for cows, chickens, pigs, and wolves

Misc:

Compatibility