On September 7, 2000, at 1945 mountain daylight time, a Cessna 340A, N844YT, sustained substantial damage when it collided with two antelope during takeoff roll at Big Piney, Wyoming. The airline transport certificated pilot and his three passengers were not injured. No flight plan was filed for this Title 14 CFR Part 91 business flight en route to Casper, Wyoming. Visual meteorological conditions prevailed. According to the pilot, the aircraft was at about 95 knots indicated airspeed during takeoff roll on runway 31 when it struck two antelope that were crossing the runway from left to right. The pilot said both animals missed the left engine and were struck by the nose landing gear assembly and the right engine propeller. Damage was sustained to the right propeller, nose landing gear assembly, and the keel beam in the nose wheel well was buckled. Following the collision, the takeoff roll was successfully aborted. Both antelope were fatally injured. Following the collision, the pilot taxied the aircraft back to the ramp and later notified the FAA via the Casper, Flight Standards Field Office. Light conditions at the time of the accident were dusk conditions with slight haze and the recorded visibility was 10 miles. A review of airport data at the Big Piney Airport revealed that the airport is not controlled and no animal protective fencing or other animal control devices are installed.