Best not to watch “Eating Animals” right before dinner, or you might find yourself skipping the main course. On the other hand, watching it might encourage you to change your grocery habits permanently, which could be a very good thing.

Christopher Dillon Quinn’s documentary, based on the 2009 book by Jonathan Sofran Foer, who also co-wrote the narration delivered with appropriate sobriety by Natalie Portman, is about the deplorable way in which chickens, turkeys, and pigs are nowadays raised for slaughter in what are euphemistically called COFOs—Concentrated Animal Feeding Operations. They are assembly-line production mechanisms in which the animals suffer cruelly as they’re fatted for slaughter on diets that include heavy doses of antibiotics, which can have adverse impact on human consumers (the avian flu epidemic in China is cited as an example). Their waste matter is also released into rivers and streams, polluting the environment in ways that directly endanger fish, and humans as well.

“Eating Animals” documents how these plants function, despite the growing number of states that have passed so-called Ag-gag legislation criminalizing taking photos what’s going on in them. One of the whistleblowers interviewed is Craig Watts, a contractor raising chickens for Perdue who found himself deeper and deeper in debt to the company and ruefully describes its mercenary policies. Another is James Keen, a scientist whose life was destroyed, both personally and professionally, when he opened up about experiments in genetic engineering at a government-sponsored research center in Nebraska.

Then there is the irate testimony of the members of a North Carolina watchdog group investigating the contamination of a river. They trace the source to a bevy of pork COFOs upstream, where pink reservoirs containing fecal matter from the pigs is released into the water, but such is the stranglehold of the industry on the state government that nothing is done is stop it.

Quinn also takes the time to provide brief histories of some of those involved in the development of such techniques of mass production. One such is Harland Sanders, who started his Kentucky Fried Chicken empire from humble beginnings and was angered to see his emphasis on quality betrayed by the corporations to which he sold his operation. Another is John Tyson, founder of the firm that has become infamous for its chicken factories. The beginnings of Chicken McNuggets at MacDonalds are also sketched.

As a contrast to such mega-agribusiness, the film also provides portraits of farmers who swim against the tide, like poultry man Frank Reese of Kansas, who lovingly raises various breeds of chickens and turkeys the old-fashioned way. But his operation, presented in idyllic, elegiac images, is perpetually on the brink of financial disaster.

The aim of the filmmakers is not to persuade viewers to stop eating meat—indeed, one farmer who raises pigs with the same care that Reese does chickens proudly recalls a knowledgeable fellow who said that the pork from his animals was the best he’d ever tasted. Instead they harbor the hope that such devoted modes of private-farm production might be revived in greater numbers, and that consumers might opt to purchase their products, despite the higher cost.

Of course the documentary doesn’t really address that issue of cost—which would affect relatively well-to-do buyers less than those lower on the wage scale, who must scramble to put meat on their tables at all. Nor does it have much to say about the ever-increasing demand for meat from an exploding global population, many of whom are already barely able to find enough food to survive.

Still, Quinn’s well-made, well-meaning film—expertly shot by Matt Hupfel and edited by Geoff Richman and Mary Lampson—can serve to educate viewers on the truly unsavory way in which most of the meat on our plates is produced, and perhaps encourage them to agitate for greater transparency in the factory-farm business and use their economic clout to demand changes.

Maybe it will even convince some of them to go the vegetarian route, which is certainly another means of solving the problem.