Based on my research and some shifty deleted scenes, it turns out that the chicken and oxen, like Lt. Ellen Ripley, had their DNA samples taken by Weyland-Yutani personnel for evaluation. Runner obviously fed on some of the colony's livestock for nutritional requirements. The slight traces of xenomorph DNA now bounded to the genetic material of Gallus gallus domesticus and Bos primigenius were just as vital for the future resurrection of aliens as were the alien queen DNA infused into Ripley's own "blood samples on ice."
Look at Jean Pierre Jeunet's film once more and you will see a lot of homages and nods towards this not-very-well-known information. Remember the crazed chestburster ripping through Wren's head? Since oxen and bulls are known to charge violently through people, it is often speculated by super alien analysts ("alienists") that this was a trait inherited from the oxen DNA used to help clone the xenomorphs on the Auriga. Why else would the adult drones present on that ship have double jointed, digitigrade legs while all other human spawned drones seen in the other films had human-like legs? The beaky looking chin and snout? The explanation of those surprising traits happens to be simple. Traces of chicken DNA. The mutated aliens on the Auriga were not only an amalgamated dynamic infusion (ADI's) of human and xenomorph DNA, but also oxen and chicken DNA.
Duh!
