How many farm animals are killed every year by animal cruelty and how many people could they feed?

Such a value cannot be obtained since it is impossible to obtain a statistic without risking serious error and miscalculation. There are beliefs that around 50 to 58 billion animals are either abused or killed on factory farms, but such numbers can be inaccurate and may not even be factual. Thus the question itself is unanswerable.

To the second question, it all depends on what farm animal you are referring to: chickens, hogs, cattle? Please be more specific in this question.