Pruebas con Ad Manager sin Partner

<script>
            window.googletag = window.googletag || {cmd: []};
            googletag.cmd.push(function() {

                   googletag.pubads().addEventListener('slotRenderEnded', function (event) {
                                        if(event.isEmpty){
                                            //acá ejecutas tu código adicional, como cargar el js de otra red
                                        }
                                    });
                var mappingads = googletag.sizeMapping()
                         .addSize([1024, 0], [[750, 300], [728, 90], 'fluid'])
                         .addSize([640, 0], [[336, 280], [300, 250]])
                         .addSize([0, 0], [300, 250])
                         .build();
                responsiveAdSlothome = googletag.defineSlot('/numeros/masnumeros', [[300, 250], [336, 280], [728, 90], [750, 300], 'fluid'], 'nombredetudiv').defineSizeMapping(mappingads).addService(googletag.pubads());
                googletag.pubads().enableSingleRequest();
                googletag.enableServices();
                googletag.display(responsiveAdSlothome);
            });
          </script>