Modern welfare assessment focuses on animal-based outcome measures like behavior, body condition, and fear response rather than just resource inputs like space and enrichment.
The evolution from input-based to outcome-based welfare assessment represents a major advance in welfare science. Checking that a farm has the required space per animal tells you relatively little about the welfare of the animals; measuring whether those animals show fear responses, stereotypic behaviors, or injuries tells you far more. Outcome measures also provide a more honest accountability system: farms can game resource-based audits by meeting minimum space requirements while maintaining practices that cause poor outcomes. Animal-based outcomes reveal welfare quality regardless of how inputs are managed.