GBADs Technical Guide

Hughes, Ellen and Gilbert, William and Rushton, Jonathan and Bruce, Mieghan and Larkins, Andrew and Temesgen, Wudu Jemberu and Torgerson, Paul and Li, Yin and Mayberry, Dianne and Schrobback, Peggy and Dennis, Gabriel and Raymond, Kassy and Meyer, Anne and Menezes, Taís C. and Shakil, Golam Saroare and Tozooneyi, Takesure and Countryman, Amanda M. and Pendell, Dustin L. and Marsh, Thomas L. and Chaters, Gemma Louise and Limon, Georgina (2024) GBADs Technical Guide. Working Paper. Zenodo.

Abstract

What is the GBADs Technical Guide? The GBADs Technical Guide: a working document (version 1.0) is a downloadable document containing six chapters: an introduction, followed by five chapters each covering one of the five key methodologies currently used in GBADs analyses: 1.      Introduction 2.      Livestock biomass 3.      The economic value of farmed animals 4.     The Animal Health Loss Envelope 5.      Attribution to species causes 6.      The wider economic impact of animal disease burdens This is version 1.0 of the GBADs Technical Guide. The Guide is a working document that will be updated as methods are developed and refined.   1.      Livestock Biomass Livestock biomass is an estimation of the total liveweight of all animals in the population under investigation. It can be used for per unit (kg) comparisons of disease burdens, livestock value, antimicrobial use, and other characteristics of livestock systems such as inputs (e.g. feed), outputs (e.g. milk), and production losses (e.g. decreased milk production due to disease). This chapter explains how to calculate livestock biomass depending on the availability and quality of appropriate data. 2.      The economic value of farmed animals Knowing the value of animals is crucial for making informed decisions about disease management and investments in livestock health. This chapter describes how to determine the economic value of livestock in the population under investigation. It explains the economic value framework within which farmed animals can be valued, and describes methodologies to calculate their economic value, as well as outlining the data required. 3.      The Animal Health Loss Envelope (AHLE) This chapter introduces a new GBADs metric for measuring the financial losses due to animal diseases through production loss, loss of animals and expenditure on veterinary services and products. It compares the value of livestock, production and expenditure under current conditions to those in an ideal scenario without diseases. The difference between these states is the Animal Health Loss Envelope (AHLE), representing an upper boundary when assessing farm animal disease burdens.  4.      Attribution of losses to disease This chapter describes methods to attribute the overall losses due to disease, as calculated in the AHLE, to specific causes. Losses may be attributed to single causes such as a specific pathogen or to a collection of causes that result in a common outcome, such as lameness. When losses are attributed to multiple causes, this chapter also outlines how to deal with comorbidity (where animals are affected by more than one cause at a time) to prevent over-estimation of losses. 5.      The wider economic impact of animal disease burdens Understanding the economic impact of animal health burdens on both domestic and international markets can provide valuable insights and useful metrics for the individual household up to the policymaker. This chapter introduces the economic models used by the GBADs programme, namely computable general equilibrium (CGE) and partial equilibrium (PE) models. These complex models are used to simulate the broader impacts of animal diseases on markets and trade and help predict how changes in animal health affect different sectors of the economy.