Which biosecurity measures are specific to free-range poultry? Insights from a scoping review

In poultry farms, the assessment of biosecurity is usually based on checklists designed for production systems that do not allow access to a free-range area. However, providing outdoor access may increase the risk of contamination by certain pathogens (e.g., soil borne pathogens or those transmitted by wild birds). Therefore, in free-range systems, biosecurity assessment should specifically cover practices related to this particular environment. In this scoping review, we aimed to (1) identify and categorize specific biosecurity measures (BSMs) that could be assessed in free-range poultry farms in high-income countries based on published protocols, and (2) describe the context in which these studies were carried out. A systematic search was conducted in four databases (PubMed, Scopus, Agricola, and Web of Science) and reports were screened according to PRISMA-ScR guidelines. Studies were first deduplicated in EndNote™ and then screened in Rayyan. After screening 481 records, 15 studies were retained as eligible for the extraction of contextual data and the list of BSMs specific to free-range poultry systems. The studies relied on the assessment of a heterogeneous number of BSMs, and a total of 52 unique BSMs were identified and subsequently classified into 8 categories and 23 subcategories. Most measures were related to the presence of other species on the outdoor range-mainly wild birds (including attraction, interaction and direct observation), followed by effective range use by poultry. However, some aspects of biosecurity were seldom or only superficially addressed, such as access to the range by workers and equipment, the characteristics of the range, or methods for wild birds scaring. The proposed list and classification of BSMs should provide additional insights into how biosecurity assessment could be adapted and applied in free-range poultry production systems.