Which of the following is a physical device used to achieve barrier-sustained colonies?

Specialized ventilation systems are crucial for achieving barrier-sustained colonies, particularly in laboratory settings where maintaining a specific environmental and microbial status is essential. These systems help regulate airflow and filter out potential contaminants, thereby creating a controlled environment that minimizes exposure to pathogens. By providing a clean, stable atmosphere, specialized ventilation systems enhance the welfare of the animals and ensure the integrity of research outcomes. This is especially important in barrier facilities where animals are often bred and housed in isolation from external contamination.

The other options, while beneficial for animal welfare or health, do not address the specific requirement of maintaining a barrier-sustained colony. Environmental enrichment items enhance the psychological well-being of animals, containment cages facilitate safe housing, and prebiotic additives improve gut health, but none of these directly function to maintain the physical and microbial barriers needed in such specialized research colony environments.