A dynamic framework for calculating the biomass of fattening pigs with an application in estimating the burden of porcine reproductive and respiratory syndrome in the Netherlands

Gaining insight into the size and composition of national pig populations can support decisions on disease control, welfare, and environmental sustainability. However, if one needs to draw meaningful comparisons between the performance of various production systems or countries, a method for standardization is required. One approach to achieve this is by means of biomass estimation. The objective of this study was to develop a biomass estimation framework that can provide detailed and reliable estimates of fattening pig biomass disaggregated by pig life stage (suckling, weaning and fattening), while accounting for the dynamic nature of pig populations. The framework was developed on publicly accessible data pertaining to pig production in the Netherlands, and we additionally assessed availability of required data for several other European countries (Spain, Germany, and Great Britain). Three distinct life stages—suckling piglets, weaning pigs, and fattening pigs—are considered in the framework. Demographic and movement data, including yearly imports, exports, and slaughter numbers, along with standing populations, were collected from official governmental sources. Required production parameters were sourced from representative surveys, with missing parameters supplemented by private industry reports or expert elicitation. The results from the framework for the Netherlands yield insights into the Dutch pig sector. In 2020, 156 million kg, 552 million kg, and 1654 million kg of biomass were produced in the suckling, weaning, and fattening stages, respectively. The evaluation against census data indicated the framework's reliability, with deviations mostly below 10 %. Data availability assessments for Spain, Germany and Great Britain reveal variations in data completeness and underscore the importance of local contacts and language expertise when extending the framework to other countries. The framework's relevance was further demonstrated through an illustrative application, assessing the impact of porcine reproductive and respiratory syndrome on pig biomass in the Netherlands. In the most severe disease scenario, the produced biomass decreased by 13 %, 17 %, and 66 % in the suckling, weaning, and fattening stages, respectively. Beyond disease burden estimation, the biomass estimates can be used as a denominator for various purposes to provide efficiency metrics, such as the amount of antibiotics used or the volume of greenhouse gases emitted per kilogram of pig biomass produced. While the framework could benefit from further refinement regarding resource use and economic values, its current iteration provides a robust and unique foundation for estimating biomass disaggregated by pig life stage, aiding decision-makers in the agricultural and veterinary sector.