Enthymeme:  Hog factories are environmentally unsound because they pollute the environment. 

• Claim: Hog factories are environmentally unsound.
• Reason: Hog factories pollute the environment.
• Warrant: Farming practices that pollute the environment are environmentally unsound.
• Backing: proof that farming practices that pollute the environment are unsound. I bet my audience will grant me this warrant because we share the underlying belief that polluting the environment is unsound. 
• Grounds: all the evidence and proof that hog factories actually pollute the environment. Factories may contain as many as 5000 individual hogs (find source for this). That many large animals produces as much raw sewage in one building as a small town does over several miles, and without sewage treatment! I plan to research this reason further to produce more evidence.
• Conditions of Rebuttal: To my warrant and backing, some opponents might claim that MANY farming practices leave residues in the environment (plowing, grazing, fertilizing, etc.) and that such residues aren't always pollution. In addition, they might not value the environment as much as they value a profit or jobs.  To my reason and grounds, opponents might say that hog factories use a minimal amount of land and thus are environmentally friendly. 
• Qualifiers:  I think I might qualify my reason since hog factories might be made more ecologically sound in the future: As they are currently operated, hog factories damage the environment. I probably ought to qualify my warrant, too: In most cases, farming practices that damage the environment are environmentally unsound.