Economic Risk Assessment by Weather-Related Heat Stress Indices for Confined Livestock Buildings: A Case Study for Fattening Pigs in Central Europe

Abstract

In the last decades farm animals kept in confined and mechanically ventilated livestock buildings are increasingly confronted with heat stress (HS) due to global warming. These adverse conditions cause a depression of animal health and welfare and a reduction of the performance up to an increase of the mortality. To facilitate sound management decisions, livestock farmers need relevant arguments, which quantify the expected economic risk and the corresponding uncertainty. The economic risk was determined for the pig fattening sector based on the probability of HS and the calculated decrease in the gross margin. The model calculation for confined livestock buildings showed, that HS indices calculated by easily available meteorological parameters can be used for assessment quantification of indoor HS, which is so far difficult to determine. These weather-related HS indices can be applied not only for an economic risk assessment but also for a weather-index based insurance for livestock farms. Based on the temporal trend between 1981 and 2017, a simple model was derived to assess the likelihood of HS for 2020 and 2030. Due to global warming, the return period for a 90-percentile HS index is reduced from 10 years in 2020 to 3-4 years in 2030. The economic impact of HS on livestock farms was calculated by the relationship between an HS index based on the temperature-humidity index (THI) and the reduction of the gross margin. From the likelihood of the HS and this economic impact function, the probability of the economic risk could be determined. The reduction of the gross margin for a 10 year return period was determined for 1980 with 0.27 € per year and animal place and increased by the 20-fold to 5.13 € per year and animal place in 2030.

Reduction of the Economic Risk by Adaptation Measures to Alleviate Heat Stress in Confined Buildings for Growing-Fattening Pigs Modelled by a Projection for Central Europe in 2030

“…In France, about 4 million broilers died [2]. For fattening pigs, Schauberger et al [15] determined the loss in gross margin for a 10-year return period in an Austrian case study with 0.27 € per year and animal in 1980 and a 20-fold increase to 5.13 € per year and animal in 2030. These economic losses are caused by an increase of the feed conversion ratio, a lower growth rate, and other productivity traits like increasing mortality [3,[16][17][18][19].…”

“…Adaptation measures (AMs) have been proven effective to reduce HS in confined livestock buildings [15,20,21]. They can be grouped into measures adapting (1) the ventilation system to modify the thermodynamic properties of the inlet air (air temperature and humidity), (2) the building (e.g., insulation, orientation) [22], (3) the indoor equipment at the animal level to modify the indoor climate on a small scale (e.g., sprinkling and fogging systems, forced ventilation), and (4) the livestock management (e.g., thermotolerant breeds, feeding, design values of the ventilation system) [20].…”

“…The scale of the operating figures is beyond everyday experiences of farmers. Neither the reported HS parameters for animals [14] nor the projections for the near future [15] can be directly used by farmers to adopt AMs. Livestock specific information on the likelihood and severity of future HS and the costs and benefits of AMs support investment decisions in new livestock housing systems and reduce the economic risks of stranded assets in the field of livestock farming.…”

“…We use the weather-VaR to describe the ER caused by HS on the gross margin of growing-fattening pigs. With this tool, the expected mean value of the reduction of the gross margin caused by global warming can be calculated but also the return period (10 or 20 years), taking into account the stochastic weather behaviour [15]. This paper describes a three-step process.…”

“…In the last step, the likelihood of HS and the impact function are combined to determine the likelihood of the ER for the near future (i.e. 2030) on the basis of the weather-VaR concept for the reduction of the gross margin per animal place [15,24]. The reduction of the ER due to the application of AMs is the relevant output to support farmers' management decisions for the planning of new or the adaptation of existing livestock buildings.…”