In practice, for which species is adjusting records generally considered almost useless?

• A. Cattle
• B. Sheep
• C. Pigs
• D. Poultry

Answer: (D)

Adjusting phenotypic records is about removing non-genetic sources of variation so differences among animals reflect genetics rather than environment. In poultry, environments are highly standardized across houses, flocks, and hatcheries, and you have extremely large numbers of birds contributing data. This combination means the environmental noise is already minimized and the genetic signal is well captured by the sheer volume of records and the many offspring per sire. As a result, making adjustments to individual records adds little to the accuracy of breeding value estimates, so the practice is essentially not worth the effort in poultry.

In species like cattle, sheep, or pigs, management and environment vary more between farms and flocks, so adjusting records for fixed effects (like flock, barn, season, or parity) can meaningfully improve the separation of genetic merit from environmental influence, leading to more accurate genetic evaluations.