I live in deep South Texas and certainly kill more hogs on an annual basis that any other animal due to their sheer numbers in the locale and based upon the ease by which local landowners will allow me to hunt them. In my opinion (and I say this having hunted Africa), a feral hog exceeding 150 pounds is one of the hardest animals in the world to kill. The pictures featured above illustrate the sheer amount of fat you must cut through to penetrate vitals, the bones are as dense and unforgiving as anything I have ever seen and the hair will literally dull a knife with a single swipe. They are some tough, tough critters. Moreover, their vitals are situated forward and are protected by the dense foreleg.
With the foregoing stated, and assuming you place your shot well, a 45 pound bow with a sharp COC head placed close to the shoulder on an animal quartering away will achieve adequate penetration for a kill. I would recommend more in the event your arrow does drift a little forward and strikes bone, however. With pigs more than with any other game roaming North America it is critically important to pick your shots. The room for error is miniscule, even with higher poundage bows and heavy arrows. A well-shot pig will bleed like geiser and will expire rapidly. An inch either way and you will find very little blood and no porker.