<pre>{{ a | json }}</pre>
<select ng-model="a" ng-options="value.field as getDesc1(key,value) for (key,value) in t"></select>

$scope.getDesc1 = function(key, value) {
  return (parseInt(key, 10) + 1) + "->" + value.field;
};

<select ng-model="a" ng-options="l.field as getDesc1(key,value) for (key,value) in t " class="ng-valid ng-dirty">
 <option value="0" >1->jw_companyTalent</option>
 <option value="1" >2->jw_reportgroup</option>
 <option value="10" >11->jw_ads</option>
 <option value="11" >12->jw_jobcomment</option>
 <option value="12" >13->jw_companyInfo</option>
 ....
</select>

<pre>{{ b | json }}</pre>
<select ng-model="b" ng-options="l.field as getDesc(l) for l in t | index "></select>

var app = angular.module('plunker', []);
app.controller('MainCtrl', function($scope) {
   $scope.t = [{
    "field": "jw_companyTalent"
   }, {
    "field": "jw_reportgroup"
   }];
   $scope.getDesc = function(l) {
    return l.order + "->" + l.field;
   };
}).filter("index", [
   function() {
    return function(array) {
     return (array || []).map(function(item, index) {
      item.order = index + 1;
      return item;
     });
    };
   }
]);