Direct assessment of nutrient resources in free-range and scavenging systems

Abstract

The low-input:low-output scavenging systems in Africa, Asia and Latin America and the pastured and organic farming systems in Europe and North America depend on the free-range. Nutrient resources available in free-range and scavenging systems can be assessed by three parameters: Scavengeable Feed Resource Inventory (SFRI); Range Coverage (RC); and Scavengeable Feed Resource Harvest (SFRH). SFRI is estimated by 4 procedures: determination of the quantity of Household Leftovers (HHL) added to the range and determination of the quantity of scavengeable flora and fauna using Pitfall Traps; Transect Mappings; and Quadrants. RC is assessed by 3 procedures: visual inspection; physical space measurement; and automatic monitoring of birds by telemetry. SFRH, or the intake of scavengeable materials (HHL, plants, insects and metazoans) from the range, is estimated by applying 3 procedures to the content of the crops of scavenging birds: visual identification; physical separation and weighing; and chemical analysis. The assessment methods and parameters are still rudimentary and require a lot of improvement in accuracy and repeatability.