I am creating a form in the following manner:

$form = $this->createFormBuilder($breed)
             ->add('species', 'entity', array(
                  'class' => 'BFPEduBundle:Item',
                  'property' => 'name',
                  'query_builder' => function(ItemRepository $er){
                      return $er->createQueryBuilder('i')
                                ->where("i.type = 'species'")
                                ->orderBy('i.name', 'ASC');
                  }))
             ->add('breed', 'text', array('required'=>true))
             ->add('size', 'textarea', array('required' => false))
             ->getForm()

How can I set a default value for the species listbox?

Thank you for your response, I apologise, I think I should rephrase my question. Once I have a value that I retrieve from the model, how do I set that value as SELECTED="yes" for the corresponding value in the species choice list?

So, that select option output from the TWIG view would appear like so:

<option value="174" selected="yes">Dog</option>