Table 27.

Sources of uncertainty (in a non‐prioritised order) associated with the assessment methodology and inputs (extensive literature search, expert’s opinions) for the identification and assessment of the most relevant WCs and ABMs

Source of Uncertainty	Nature or cause of the uncertainty	Impact of the uncertainty on the assessment
Literature search – Language	The search was performed exclusively in English. More studies could have been identified by including references in languages other than English.	WCs might have been selected that in reality belonged to another category than highly relevant, and WCs that in reality were highly relevant might have missed to be selected.
Literature search – Publication type	The studies considered included primary research studies identified through the extensive literature search and grey literature (fact sheets, guidelines, conference papers, EU reports, book chapters, etc.) known to the EFSA Experts, but an extensive search of the grey literature was not conducted. Therefore, there may be reports and other guidance documents on animal welfare of which the EFSA Experts were not aware off.	Underestimation of the published relevant studies.
Literature search – Search strings	Although the search criteria were thoroughly discussed, some synonyms may have not been used in the search strings, and thus less hits might have been retrieved. In addition, literature from non‐transport conditions, that may still have been relevant for the assessment, may also not have been found.	The understanding of the relation between hazards and ABMs may not be complete due to having missed data.
Literature search – data sources	The search was limited to Web of Science. Although the search was complemented by internet searches and manual searches of the publicly available literature, no data were retrieved from other sources (e.g. industry, NGO or authority data). More information could have been retrieved by applying a different methodology (e.g. public call for data).	The understanding of the relation between hazards and ABMs may not be complete due to having missed data.
Literature search – inclusion and exclusion criteria	The screening phase might have led to the exclusion of certain studies that could have included relevant information.	Underestimation of the published relevant papers.
Expert group – number of experts, type of experts	This SO was carried out by a working group of 12 EFSA Experts, of whom 3–5 were species‐specific experts. The approaches underlying the SO is based on expertise from the whole working group, whereas the vast majority of the text within the SO has been written by the species‐specific experts. Experts had to show they have no conflict of interest due to, e.g. involvement with the pig industry or NGOs. This may have resulted in reduced level of technical and applied expertise.	As the highly relevant welfare consequences were selected by expert opinion, the experts might have selected WCs that in reality belonged to another category than the highly relevant ones, and might have missed to select WCs that were in reality highly relevant.
Transport conditions of the studies retrieved in the extensive literature search	The transport conditions of the studies retrieved might have differed from the ones currently used in the EU, thus requiring an extrapolation exercise from the experts.	Under‐ or overestimation of the level of magnitude of the welfare consequences and related ABMs.
Husbandry practices and pig breeds and categories of the studies retrieved in the extensive literature search	The studies retrieved may have involved husbandry practices and pig breeds and categories differing from EU‐standards. Thus, experts had to extrapolate findings to the EU relevant conditions in some cases.	Under‐ or overestimation of the level of magnitude of the welfare consequences and related ABMs.
Transport conditions of the studies retrieved in the extensive literature search	Transport conditions (e.g. driving style, ventilation capacity of the vehicle, external temperature) were not always specified in all the studies retrieved.	Under or overestimation of the effects of the transport conditions on the WCs selected.
Time allocation	The time and resources allocated to this SO were limited and additional time for reflection would have facilitated a more in‐depth discussion of some of the aspects.	Inclusion, under‐ or overestimation of the level of magnitude of the WCs and related ABMs.
Lack of ABMs that are documented to be useful during transport in terms of feasibility, sensitivity or specificity	Based on the available knowledge, it was not possible to use single ABMs to assess the effect of exposure variables and transport conditions on welfare consequences.	Under‐ or overestimation of the level of magnitude of the WCs.
Transport being a complex stressor, for which animal welfare has been studied much less than animal housing	The complexity of animal transport with the many interacting hazards and thus WCs, means that many WCs are relevant, and thus that some can be missed in the selection of the highly relevant.	WCs that are in reality highly relevant are missed and thus underestimated.
Lack of available studies done under the recommended conditions	The number of studies available involving the conditions recommended in this SO is very limited. In addition, there are very few recent European studies. Thus, in some cases, and especially for the assessment of the journey time, experts had to extrapolate findings from studies done under different conditions.	Under‐ or overestimation of the level of magnitude of the welfare consequences.