We are aware of this distinction; but believe you may be misreading it. The above sentence was intended to separate parenthetical elements used in the series giving some specific examples of such. How about commercially made dog and cat food? Perhaps that could be comprised largely of spare animal byproducts that go through the slaughterhouse? Or ever have a hamburger or steak perhaps? You unfortunately provide opinions, but not any solid facts or arguments that can be supported by the relevant historical and statistical records surrounding the captive keeping of these animals.