If you've ever watched a fresh-caught trout flopping on the river bank, disemboweled a deer, or frozen in a duck blind, you will notice something missing from "The First Washington Exhibit of Conservation Art," now on view at the Art Barn, 2401 Tilden St. NW. Sugar coats these images of geese and duck and elk. They ought to stink of gore.

They are handsome, but not honest. They do not dare to show the shadow of the killer, with his shotgun or his rod, but he is there in spirit. Edward J. Bierly's oil, which shows a mother doe licking at her fawn, is titled "Happy Hour," but it might have been called "Venison." Jim Sprankle's carved and painted ducks have every pinfeather in place, but look like decoys still.

This stuff was once called Sporting Art. Conservation Art is Sporting Art sans death. The Disney-pretty animals we meet in this exhibit may be portrayed as woodland pals, but not so very long ago they were trophies of the chase.

The eight local artists in this show represent an army. Artists by the thousands, most meticulous and patient, now paint pictures such as these. Art world snobs ignore them. They rarely get exhibits in national museums. But they see themselves as comrades. They compete with one another joyfully and often. And together they've developed a vast and growing market.

Duck art is big business. If you want to shoot a duck, you first must buy a duck stamp from the U.S. government. The money goes for wetlands. The colored picture on the stamp is picked anew each year in a vast competiton. More than 2,000 entries are expected nowadays. He who wins the contest is almost certain to grow rich.

Albert Gilbert won it in 1977, and grossed more than $1 million by selling to collectors perhaps 100,000 prints of his design. Winning the Federal Duck Stamp Contest, he noted at the time, "is like breaking the bank at Monte Carlo. . . . It's the biggest art prize in the world."

Bierly, whose sweet and well-made oils are included in this show, has won that contest thrice. More than 15,000 photolithographs of 25 Bierly images are offered to the public in his latest catalogue. Most are inexpensive -- many of them sell for only $45 or $50 -- but if he sells them all he will gross more than $1 million. His secret is numbers. He will reproduce a painting of tigers or of foxes perhaps 950 times, in editions he regards as "relatively small." His Duck Stamp prints cost more. And their editions are much larger.

The Federal Duck Stamp Contest has spawned scores of competitions. Roger Bucklin, whose works are on display, won the 1982-83 Maryland Duck Stamp Contest. He was last year's winner of the Maryland Trout Stamp Contest. This year that award went to Carla Huber, whose paintings and prints are included here.

Art that portrays wildlife popularly and accurately is, of course, not new. Antoine Louis Barye, the 19th-century French sculptor, produced bronzes by the thousands, of bulls and snakes and lions. Queen Victoria's favorite painter, one Sir Edwin Landseer -- he is perhaps best known for his "Monarch of the Glen" -- was even more successful. But Barye's beasts attack and snarl, Landseer's bleed and suffer. Once he was regarded as far too sentimental. His critics used to sniff that his noble dogs and deer looked as if they thought the thoughts of human beings. Then Disney came along.

The artists in the Art Barn show have learned from the Victorians, and from J.J. Audubon, the porcelains of Edward Boehm, and the paintings of the Wyeths. Like Andrew Wyeth, they approve of weathered wood, dead grass and rust. Like Audubon and Boehm they specialize in birds -- grouse and geese and pheasant, bald eagles, wild turkey and all sorts of duck. There are more than 70 birds portrayed in the 37-object show. It calls to mind a trophy room, but trophy rooms are scary and this show is always sweet. Bierly's bitch fox at her den seems devotedly maternal. Warren Cutler's charming wolf is not more ferocious than say, Lad A Dog.

The friendly little Art Barn, snug in Rock Creek Park, has walls of rustic wood and stone, and seems a perfect setting for the present exhibition. Wholly free of grief and doubt, this art is conservative, accessible, enjoyable, well-made. No wonder that it sells.

These artists and their peers do not fear the public. They have so much in common that they welcome competition. The National Parks and Conservation Association, and Trout Unlimited, who organized the show, have sportingly included a ballot-box and ballots so that each visitor may vote for the object he likes best. The winner gets a pewter bowl designed by Don Miller. I cast mine for Sprankle's splendid wooden duck, and I hope he wins, but the votes will not be counted until "The First Washington Exhibit of Conservation Art" closes Aug. 29.