You can't use strings in enums. Use one or multiple dictionaries istead:
Dictionary<Animal, String> Deers = new Dictionary<Animal, String>
{
{ Animal.Tiger, "TIG" },
{ ... }
};
Now you can get the string by using:
Console.WriteLine(Deers[Animal.Tiger]);
If your deer numbers are in line ( No gaps and starting at zero: 0, 1, 2, 3, ....) you could also use a array:
String[] Deers = new String[] { "TIG", "LIO" };
And use it this way:
Console.WriteLine(Deers[(int)Animal.Tiger]);
Extension method
If you prefer not writing every time the code above every single time you could also use extension methods:
public static String AsString(this Animal value) => Deers.TryGetValue(value, out Animal result) ? result : null;
or if you use a simple array
public static String AsString(this Animal value)
{
Int32 index = (Int32)value;
return (index > -1 && index < Deers.Length) ? Deers[index] : null;
}
and use it this way:
Animal myAnimal = Animal.Tiger;
Console.WriteLine(myAnimal.AsString());
Other possibilities
Its also possible to do the hole stuff by using reflection, but this depends how your performance should be ( see aiapatag's answer ).