Christmas, Fla. — Old MacDonald he's not, but Herman Brooks is a farmer. His barnyard is a steamy green 28-acre swamp and his livelihood is 3,000 alligators.
While other people grow chickens or hogs or cattle, a handful of Florida ''crackers,'' says Mr. Brooks, are pouring cash and sweat into swampland here nurturing the alligator industry they see as a financial bonanza.
Although the image of traditional reptile farms still exist - where the alligator tamer keeps one hand on the animal and sells souvenir ashtrays with the other, these farmers are forging a new image. Several factors - both scientific and legal - have changed the thrust of their business from tourism to serious farming of alligators for their hides and meat, says Mr. Brooks, president of the Florida Alligator Farmers Association.
* Avenues for government-controlled trade in hides and meat were cleared when the American alligator was removed from the endangered species list in 1977.
* Farmers, who envision a multimillion-dollar industry in Florida alone, are sinking thousands of dollars into experimental alligator breeding and nutrition. University of Florida researchers and owners of Orlando's Gatorland succeeded in producing the world's first artificially inseminated hatchings last September - following up with a similar project last week. And in Louisiana, researchers have found that by varying incubation temperatures slightly up or down, farmers can control the sex of the offspring.
* The financial promise of alligator farming has placated some environmentalists who see it as an incentive to preserve endangered wetland. And others view it as a way to take the hunting pressure off the wild and more endangered members of the crocodilian family around the world.
These factors have unleashed a wave of enthusiasm among people like Brooks, who claims a fascination with alligators that stretches years back - before the promise of big profits.
Today, Mr. Brooks estimates capital investments to start an alligator farm run to about $200,000.
''You can't just sink a bathtub in your backyard and call it an alligator farm,'' he says. There is considerable sophisticated research being poured into the process of raising alligators from their inches-long infancy to 8-to-12-foot maturity.
Gatorland, south of Orlando, has perhaps the most extensive facilities in Florida - an incubator for eggs, a hothouse for newborn, and separate pens for experimental subjects.
''The (profit) figures we have on paper have encouraged us to go ahead and try this,'' says Mel Gentry, Gatorland assistant manager. A researcher at Univeristy of Florida at Gainesville, who helped Gatorland hatch the world's first artificially inseminated eggs, estimates that there is a potential $200 million annual business in alligator farming if farmers can utilize research findings and growth and selective breeding. He says Florida's farming output could be 400,000 gators a year at today's going rate of $500 apiece.
Already, research has enabled Gatorland to double its alligator growth rate by manipulating environmental and dietary conditions, says Mr. Gentry, adding that successful hatches have increased to over 75 percent. Toothy babies from last September's hatch are already two feet long - normally they would only be 1 foot at this time.
It takes four to five years to bring an alligator to sellable size - a prime hide would offer 22 belly inches - so as yet there is only a trickle of farmed hide and meat on the market. Mr. Brooks, for example, is building his brood stock while last year's hatchings grow.
While there are tough restrictions in Florida on hunting the animal in the wild, the state's ''nuisance'' program, in which licensed hunters are permitted to hunt wild alligators that have become a nuisance in a neighborhood, produced 2,000 hides last year - still more than the farmers have produced yet, explains Don Ashley, a lobbyist for the National Alligator Association.
Although the issue of taking alligators from the wild is still hotly debated among wildlife defenders and hunters - there is a general acceptance of the farming industry. ''There is already a big market for alligator hides and if alligator farming is successful we would have less pressure'' on endangered crocodillian species, says Marjorie Carr, president of Florida Defenders of the Environment.