Lumens measure light as perceived by the human eye, which means different color temperature bulbs will give different lumen readings. In a nutshell, this means that the lumen reading can vary dramatically (depending on kelvin or "color temperature") versus the actual useful intensity of the bulbs. Thus, comparing VHO
in this manner may very well be apples to oranges (not sure if similar temperature bulbs were used in this particular case).
Because of how much lumens can vary...it may be better to evaluate what your livestock needs' are and try to match your choice up as best you can with a Google search of PAR data (the measure of intensity or useful radiation).