European Food Safety Authority (EFSA) BSE/TSE risk assessment of the use of bovine dried blood products in feeds destined for farmed fish (BIOHAZ Panel)
In its Opinion of 21 October 2004 on BSE risk from dissemination of brain particles in blood and carcass following stunning, the EFSA concluded that the brain damage caused by both penetrating and non-penetrating captive bolt stunning in cattle, as well as that caused by penetrating captive bolt in sheep can result in occurrence of central nervous system tissue in venous blood draining the head. The risk could however not be quantified.
In its Opinion of 28 April 2005 on the assessment of the health risks of feeding of ruminants with fishmeal in relation to the risk of TSE the EFSA concluded that if there is any risk of TSE in fishmeal, this could arise from the mammalian feed being fed to fish which are then included in fishmeal or through fishmeal contaminated by Meat and Bone Meal (MBM). The risk of TSE in fish, either being fed directly or by amplification of infectivity is remote.
Against this background, the European Commission has requested to the Scientific Panel on Biological Hazards to deliver a scientific opinion on a TSE risk assessment of the use of bovine blood in feeds for fish, in consideration of a report produced by the European Animal Protein Association (EAPA).
The EFSA opinion considers that the EAPA report is well written and comprehensive. However, its qualitative approach does not fully take into account the uncertainties surrounding several of its risk parameters. Consequently, its conclusions may be overly optimistic.
A human or animal health risk may arise if recycling of BSE-contaminated bovine SDRC occurs directly (bovine SDRC fed to cattle) or indirectly (fishmeal made from fish recently fed with BSE contaminated bovine SDRC given to cattle) because this would be equivalent to feeding cattle by-products to cattle (intra-species recycling).
The assessment of the BSE related-risk of bovine SDRC from slaughtered bovine animals considered fit for human consumption to be included in aqua feed is theoretically feasible both semi-quantitatively and quantitatively by developing a probabilistic risk assessment model.
However, key parameter limits of this model (i.e. endogenous bovine blood BSE infectivity and degree of contamination with CNS by current stunning and slaughter methods) can only be developed from expert opinion and judgement, as there is currently not experimental data available. Both the degree of uncertainty of this type of data (which would reduce the robustness of any risk estimates) and the extensive work that would be needed to produce such model makes its development unrealistic in the frame of this opinion.
On the other hand and considering the current implementation of the EU feed-ban, the inclusion of bovine blood products in the authorized list of ingredients in fish feed would potentially limit the suitability of current available tools, to detect the presence of prohibited bovine by-products (i.e. SRM) Following this, the BIOHAZ panel recommends to develop and assess the outcome of a semi-quantitative or quantitative risk model of the BSE risk of bovine SDRC employed in aquafeed.
In order to enhance the robustness of that risk assessment with experimental data which is currently not available, it is further recommended to quantitatively evaluate different risk parameters. These would include the evaluation of the endogenous blood infectivity levels in incubating and terminally BSE affected cattle, the evaluation of the current allowed methods for cattle stunning for the potential to produce embolism and the quantitative assessment of the CNS contamination risk posed by different blood collection methods.
Finally, a combination of tests capable of detecting, with a high level of sensitivity, the species and tissue origin of the animal proteins included in fish feed should be developed and validated.