In the game Breeding Farm monsters can have certain additional traits. Most of them change the monster in a positive way. But there are also some traits that have a negative effect on the monster. Each of these additional traits of a monster has a level. The higher this level, the stronger its effect on the monster.
Traits and their levels cannot be removed or added from a monster. They must be passed on to the offspring by skillful breeding of mother and father. With a little patience and luck, it is possible that the offspring will have better characteristics than their parents.
Here are all the traits (known to me) that are available in Breeding Farm 0.5.1.
Smart Trait

This monster gives partners more XP than normal.
- Level 1: Gives 2x more XP
- Level 2: Gives 3x more XP
- Level 3: Gives 4x more XP
- Level 4: Gives 5x more XP
Loving Trait

This monster gains more affection points when breeding.
- Level 1: Gains 2x more affection points
- Level 2: Gains 3x more affection points
- Level 3: Gains 4x more affection points
- Level 4: Gains 5x more affection points
Fertile Trait

Increases pregnancy chance of this monster.
- Level 1: Increases pregnancy chance 2x more than normal
- Level 2: Increases pregnancy chance 3x more than normal
- Level 3: Increases pregnancy chance 4x more than normal
- Level 4: Increases pregnancy chance 5x more than normal
Valuable Trait

You get more money when selling this monster.
- Level 1: You get 10% more money
- Level 2: You get 2 0% more money
- Level 3: You get 3 0% more money
- Level 4: You get 4 0% more money
Lightning Trait

Reduces energy costs by this monster's actions.
- Level 1: Reduces energy costs 5% more than normal
- Level 2: Reduces energy costs 10% more than normal
- Level 3: Reduces energy costs 15% more than normal
- Level 4: Reduces energy costs 20% more than normal
Cute Trait

This monster gains more XP from breeding.
- Level 1: Gains 2x more XP
- Level 2: Gains 3x more XP
- Level 3: Gains 4x more XP
- Level 4: Gains 5x more XP
+XP Trait

This monster gains more of the total XP gained by breeding.
- Level 1: Gains 20% more XP
- Level 2: Gains 40% more XP
- Level 3: Gains 60% more XP
- Level 4: Gains 80% more XP
Unfertile Trait

This monster can't produce newborns.
Selfish Trait

This monster takes all the XP it would have normally given its partner.