In addition, the impact of parental experiences is transmitted not only through shared environment but also through epigenetic mechanisms .Although temperament would seem to be a brain construction, it also reflects adrenal, thyroid, liver, muscle and peripheral nervous system metabolism [2–4].
Temperament is also an important component of bovine social behavior which affects animal welfare, animal-animal interactions and the animal-herdsman relationship.
As expected, the broad and subjective definition of temperament leads to difficulties in the robust assessment of this trait [3,10].
Many different methods to evaluate different temperament phenotypes have been proposed .
More excitable animals react with increased aggression and/or fear to human contact or handling.
Aggressive animals present less weight gain, reduced reproductive efficiency, lower milk production, inferior meat quality and higher disease susceptibility .
QTLs for reactivity were identified on chromosomes BTA1, BTA5, BTA14, and BTA25.