Police were investigating the theft of $10,000 worth of frozen bull semen and embryos from Cal Poly Luis Obispo, a school spokesman said. Stolen was a container holding six one-ounce vials of semen and 25 embryos, all frozen by liquid nitrogen to 100 degrees below zero, spokesman Don McCaleb said. No arrests have been made and the dairy building burglary was not believed to be a prank, he said. The semen and embryos were registered to prove they breed champion Holstein and Jersey cattle, making the material difficult to sell, officials said. Campus police investigator Ray Berrett said a $1,500 reward has been posted for information leading to an arrest and conviction in the case.