Livestock are responsible for [14% of global GHG emissions](http://www.fao.org/3/i3437e/i3437e.pdf). Part of what those 100 companies are doing is supplying the natural gas that is used to produce nitrogen that is used to grow feed for livestock, and the petrol to power combines to plant and harvest those grains, and the coal to feed the slaughterhouses and manufacturing plants that prepare the meat, and the petrol to power the trucks that transport the livestock and the meat, and the natural gas used to generate electricity to refrigerate it. 

And that is just the portion of livestock emissions that fall under the 52% rubric represented by those 100 energy companies. Then you've got the direct methane emissions of ruminants like cattle, and the land use changes driven by animal agriculture that are destroying carbon capture and storage in forests.

People aren't going "against livestock" to pick on the little guy, they are pointing out the inherent environmental problems with large-scale animal husbandry and the large contribution this industry makes to overall GHG emissions, water pollution, and land use. 

No one denies that the energy companies are the primary target for global climate change. But the secondary targets are still important, and this is one of several different environmental problems toward which animal agriculture is contributing.