You can once again set animals/monsters via /mvm set.

pom.xml

@@ -198,7 +198,7 @@
         <dependency>
             <groupId>me.main__.util</groupId>
             <artifactId>SerializationConfig</artifactId>
-            <version>1.6a</version>
+            <version>1.6b</version>
             <type>jar</type>
             <scope>compile</scope>
         </dependency>

src/main/java/com/onarandombox/MultiverseCore/MVWorld.java

@@ -74,6 +74,8 @@ public class MVWorld extends SerializationConfig implements MultiverseWorld {
         propertyAliases.put("mode", "gameMode");
         propertyAliases.put("diff", "difficulty");
         propertyAliases.put("spawnlocation", "spawn");
+        propertyAliases.put("animals", "spawning.animals.spawn");
+        propertyAliases.put("monsters", "spawning.monsters.spawn");
     }
     /*
      * We have to use setCBWorld(), setPlugin() and initPerms() to prepare this object for use.