<P> A single pedigree - level hen might have 25000 parent stock bird descendants, which in turn might produce 3 million broilers . </P> <P> Numerous techniques are used to assess the pedigree stock . For example, birds might be examined with ultrasound or x-rays to study the shape of muscles and bones . The blood oxygen level is measured to determine cardiovascular health . The walking ability of pedigree candidates is observed and scored . </P> <P> The need for high levels of R&D spending prompted consolidation within the primary breeder industry . As of 2017, only two sizable breeding groups remained: </P> <Ul> <Li> Aviagen (with the Ross, Hubbard, Arbor Acres, Indian River and Peterson brands) </Li> <Li> Cobb - Vantress (with the Cobb, Avian, Sasso and Hybro brands) </Li> </Ul>

Which is not a p of the three ps of feed efficiency