Bootstrap.php

    protected function _initActionHelpers()
    {
        $this->_initDoctrine();

        Zend_Controller_Action_HelperBroker::addPath(
            APPLICATION_PATH . '/controllers/helpers'
        );

        $registry = Zend_Registry::getInstance();
        $entityManager = $registry['entitymanager'];

        Zend_Controller_Action_HelperBroker::addHelper(
            new Zend_Controller_Action_Helper_ServiceLocator($entityManager)
        );
    }