Which sequence best explains how a persistent environmental stressor can reduce livestock growth?

An animal must respond to environmental demands to preserve internal stability. For example, cold exposure can require additional metabolic heat production, diverting energy that might otherwise support growth or production. Heat stress may also depress appetite, reducing nutrient intake. The other options incorrectly claim that stress necessarily improves efficiency, eliminates all thermoregulation, or changes genetic potential. **Key takeaway:** Productivity falls when adaptation consumes resources or reduces intake needed for production.\n\n**Glossary:**\n- **Adaptation**: Responses that help an animal cope with changed conditions.\n- **Metabolic heat**: Heat produced by the animal’s metabolism.\n- **Feed efficiency**: Production obtained relative to feed consumed.