Pollan argues in Chapter 17 that utilitarian philosophy is concerned with the "sum of happiness and suffering" (page 327). He believes that the killing of an animal who can't understand death does not involve suffering. He also argues that if an animal lives comfortably on what he calls a "good farm" (a concept borrowed from Peter Singer), that animal will enjoy life and will add to the sum of total happiness. The suffering perhaps caused by killing one animal can be, through his calculus, overcome by replacing that animal with another that lives on a "good farm."
As Singer comments, it would be difficult to translate Pollan's ideas into practice. Carrying out this type of animal calculus would be impossible on a large scale, but it does point to Pollan's larger idea that "what's wrong with eating animals is the practice, not the principle" (page 328). In other words, utilitarians could argue that consuming animals that are raised and killed with humanity and respect can be justifiable. Animals are killed in the United States in unjust industrialized fashions, but Pollan argues, using utilitarian theory, that it could be ethical to eat animals that are killed with respect. This is because their suffering would be minimal, so the joy people get from eating them would outweigh their suffering.