The face of the Hardin residence -- a sprawling, light blue, ranch-style home in south Napa County -- offers few clues about the hog hierarchy that thrives on the three-acre property.

But teen brothers Greg and Doug Hardin of Hardin Hog Farms say the basis for the animals' social ladder is no secret. "Whoever is bigger wins," Doug Hardin said.

The brothers, who breed and sell show pigs and market hogs, kick-started their hobby approximately 10 years ago when they began raising pigs as members of 4-H. Initially building their stock by buying pigs from local breeders, they later traveled to Modesto and Reno, Nev., to acquire more animals at pig shows.

Today, they're charged with the care and maintenance of 16 animals -- Yorkshire and Duroc swine kept on their parents' property. The brothers said they keep one boar and three sows as breeding stock. However, many of their animals are sold annually at the Napa Town & Country Fair, and year-round their beasts are sold to local buyers for meat.

Doug Hardin, 18, said running a hog farm requires a good head for numbers . In addition, the brothers -- through regularly caring for and feeding their animals -- are also familiar with the personal idiosyncrasies of their charges.

A 2-year-old Duroc sow called 645, so named for the ear tag number she wore when the Hardin brothers bought her at Modesto Junior College, is the alpha female of the group. There is also a trickster in the bunch -- Big Red, another 2-year-old Duroc who usually catches the brothers off-guard by surprising them with litters. Lucky, a gentle soul, is the sole survivor of the first litter born at Hardin Hog Farms. The animal is "docile, calm and friendly," perhaps as a result of being bottle-fed as a piglet, according to Doug Hardin.

Lucky and her 15 penmates -- Duroc and American Yorkshire hogs that reach about 500 pounds at maturity -- go through a staggering 300 pounds of feed each week. Adults eat four pounds of food each day, while pregnant sows can eat up to twice as much; the brothers said they fork out about $400 for feed each month at Wilson's Feed & Supply in Napa.

Much of this money passes through the hands of 15-year-old Greg Hardin. Since his older brother's recent enrollment at Boise State University, Greg is now responsible for the lion's share of the animals' upkeep. The Vintage High School student feeds the animals twice daily, worms them each month and makes sure that they get antibiotic shots if they become ill.

In addition to care and feeding, he said, the animals' pens and sheds require constant repairs -- the pigs have broken loose in the front yard, eliciting a visit from the California Highway Patrol. On another occasion, he said, they ventured into a neighbor's strawberry patch.

In spite of the animals' occasional shenanigans, they can usually be depended upon to deliver litters each summer and winter, said Doug Hardin, adding that a sow's gestation is three months, three weeks and three days. "Two of the sows are due to have litters in February. ... They know when it's time; they head over to the birthing shed."

Sadly, litter runts die occasionally from bacterial infections, or when they are unintentionally smothered by a sow. In addition, the piglets sometimes don't get enough of their mother's milk to survive.

"We do our best to keep them all alive, but it doesn't work sometimes," said Doug Hardin.

While the cycle of birth and death is a constant of the farm life, other facets of the brothers' business -- such as market trends -- are a source of constant change. The brothers must keep abreast of what's up and coming in the pork industry.

"There's something new all the time. ... We like going to shows and breeding the new, desired characteristics and being in the loop of the pork industry," Doug Hardin said. Currently, he added, trends favor show animals with wide, muscular bodies, while a few years back, they sought out longer, lean-bodied animals.

In addition to introducing the brothers to the business world, running a hog farm also requires veterinary knowledge, handyman skills and a keen sense of responsibility.

Lori Hardin, the brothers' mom, said her sons' hobby requires time-management skills and teaches them important life lessons. "They really know money management, and how to market the animals. They've also learned about the genetics of raising them. ... It's been a real learning experience."