<select id="selectPrimaryObject" class="form-control" ng-change="getPrimaryRelations()" ng-model="relation.from">
                <option id="md-option" ng-repeat="item in primaryObjectsList" value="{{item.id}}">{{item.name}}</option>
            </select>

element.all(by.id('selectPrimaryObject')).each(function (values, index) {
        values.click();                    // select the <select>
        browser.driver.sleep(5000);              // wait for the renderings to take effect
        element.all(by.id('md-option')).click();   // select the first md-option
        browser.driver.sleep(5000);              // wait for the renderings to take effect
    });