In cooking, the process of clarification entails straining out extraneous muck from liquids so that they might be pure, clear and ideal for consumption. With this series on food terminology and issues we're attempting to do the same.

This little piggie is bred for market. This little piggie can't turn her body around. That's about to change.

The term "gestation crates" has been trotted out across news media and social networks over the course of the last few months as major corporations declared plans to phase out their use, but what exactly are they and why is their use so controversial?

What are gestation crates?

There are approximately 5.8 million breeding sows living on pig farms across the United States, according to the USDA, and 60 to 70 percent of them spend the majority of their lives in metal-sided stalls that are two feet wide and seven feet long. They are pregnant for most of their lifespan and then moved to a farrowing stall to give birth.

Food and water is provided to the sows while they're in the stalls, but they have a very limited range of motion. The animal may flop down on her side, but she cannot turn around.

Op-ed: Jane Velez-Mitchell – Get rid of gestation crates NOW

Why are gestation crates used?

The industry began moving from group pens to individual sow housing in the 1960s, but it wasn't until the 1990s that it became standard practice. Dr. Paul Sundberg, the National Pork Board's Vice President of Science and Technology says that sows are aggressive, competitive animals, and if they are made to live in a contained group situation, they will fight for food, shelter and space.

Twenty to thirty years ago, producers keeping their pigs in group housing had to have a certain skill set, financial resources and quantity of land and personnel to manage their herd. Producers found that individual housing negates the issue of aggression, and the physical structure of the crates makes it easier to manage the herd, and requires fewer resources while allowing the animals to thrive, says Sundberg. Other studies contest that theory.

How do sows fare under those circumstances?

Dr. Sundberg says that science is on the side of the farmers. The industry uses three major measures in combination to assess animal welfare: an assessment of her physiology (white blood cell activity, hormone levels), behavior (interaction with her environment) and production (number of times giving birth and pigs per litter).

The evaluation method was developed by scientists at Texas Tech University and in Australia, and scientists and veterinarians at the American Veterinary Medical Association. By their standards, the welfare of sows in gestation crates is equal to that of those raised in group pens that do not inhibit mobility.

Matthew Prescott, Food Policy Director for the Humane Society of the United States, argues that these measures are not enough. He says, "It doesn't take a scientist to look at a situation where an animal is crammed in such a tight space, they can't even turn their own body around - just maybe shift a little to the left or the right. We know that farmers can do better."

While these circumstances aren't necessarily seen as egregious an abuse as the piglet throwing, wound neglect and anesthetic-free castration and tail amputation that the Humane Society uncovered and recorded at a pig farm in Wyoming, Prescott believes that the housing is symptomatic of a "culture of cruelty" within a segment of the pork industry. He believes that their resistance to outside input is based on an "archaic philosophy" that the only people who should have any say in how animals are treated are those who have the animal.

"24 hours a day, seven days a week for your whole life adds up to a lot of suffering," he says.

Famed animal scientist Temple Grandin likens tenure in a gestation crate to a life-long sentence in a first-class airplane seat. "You could maybe turn over on your side," she says, "and there's someone bringing you food and water and everything you need, but you can't move." The pigs not emerge unscathed, she says, "They can feel fear and pain."

Grandin agrees with Prescott - and with Sundberg - that innovative solutions should and will come from farmers.

What are major food corporations asking of pig farmers?

Since February, major fast food chains like McDonald's, Burger King, Denny's and Wendy's as well as the nation's two largest grocery story chains, Safeway and Kroger have publicly announced that they will join earlier adopters including Chipotle, Whole Foods and Wolfgang Puck in phasing out gestation crate pork from their supply chains. The change will not be immediate; most plans call for suppliers to adhere to a ten-year transition timeline.

Smithfield and Hormel, two of the country's leading pork producers, have pledged to end the use of gestation crates at their company-owned facilities by 2017, and Cargill is already 50 percent crate-free.

Eight states, have passed laws to ban the use of gestation crates. Massachusetts, New York and Rhode Island have bills pending, and earlier this week, New Jersey state senators proposed a bill that would prohibit, "crating, confining or tethering a gestating sow in order to prevent the free range of motion."

The change, Sundberg, Prescott and Grandin agree, is inevitable - and some worry it will come at a cost.

What will the burden be on the farmers?

A transition to group housing could be cost-prohibitive to a farmer, fears Sundberg, and it's very producer-specific. The price of conversion to a different system is based on a number of factors: the depreciation schedule of the equipment a farmer has; cost of facilities, land, management, production and labor; and changes in feed and productivity.

"It could cost millions to convert an average-sized farm," he says. "It could cost less and it could cost much more. It's economics - not emotional."

Sundberg balks at the notion of an outside marketing entity coming in and imposing their structure on farmers who he believes "know best" and are constantly trying to innovate.

Prescott cites a two-and-a-half year-long economic analysis by Iowa State University in which researchers found that group housing of gestation sows resulted in a weaned pig cost that was 11 percent less than the cost of one produced within an individual stall. Additionally, the study notes that group housing does not require more labor than a crate - possibly even less - but that the skill sets may be different and require training.

Grandin advises that farmers might lessen the sting of equipment purchase if they make the switch at the natural replacement intervals for worn-out equipment. While she admits that the group housing may take 15 to 30 more space, the cost of steel barriers would be greatly reduced.

What does the future hold?

While Sundberg and the Pork Board are opposed to the change, he agrees, along with Prescott and Grandin that the shift away from gestation crates is inevitable. The economic pressure from large food corporations is too great, and public opposition to the current system only grows, as evidenced by online petitions, social media campaigns and polls.

Grandin believes that the resistance comes mainly comes from farmers in their 40s, who have only ever known the crate system. She has observed animal breeding facilities all over the world, and points to Murphy-Brown LLC, the world’s largest producer of pork products (and a subsidiary of Smithfield Foods) as an example of adaptation and innovation.

After a comprehensive study, the facility committed to phasing out gestation crates in favor of group housing, and sought to breed hybrid pigs with temperaments that were less aggressive and more suitable to communal living. And not only were the sows' living facilities improved - there was also a great benefit to the consumer. A slowdown in the breeding process in order to introduce new hybrids allowed the pigs to develop more fat, rather than quick-growing, but lean meat. It was, to Grandin's palate, "Much juicier and tastier."

That may be what makes change easier for everyone to swallow.

Read - Op-ed: Jane Velez-Mitchell – Get rid of gestation crates NOW and A day two pigs would die