Therefor I have changed that in this LotsOMobs update. All mobs are now registered as: lom_Deer. Since LotsOMobs has a modid that is lom, this wont cause any trouble with other mods as they will have a different modid.
I also want to reccomend a mod that is cool to use together with LotsOMobs, OceanCraft. This mod also adds new mobs to the game. OceanCraft is focused around Minecraft's ocean biome, which is extremly boring in vanilla, and brought it to life! Get it here: http://www.minecraftforum.net/topic/2014577-mc-172-oceancraft-v14-crabs-whales-turtles-more-forge-new-anglerfish-fish-net-block-server-fix/
Use forge 1060