Date Full Report Received12/31/2020
Date Abstract Report Received12/31/2020
Funded ByPork Checkoff
|During the Spring of 2020, the US Pork industry experienced unprecedented supply chain interruption because of packing plant closures and slowdowns. While the industry quickly adapted feed rations to slow pigs’ growth rate, some producers ran out of time and space and were forced to euthanize pigs. This crisis revealed the fact that other than sending pigs to harvest, the US was unprepared for humane mass depopulation of pigs on farm. Therefore, humane and approved methods are needed that can operate on-farm with high throughput capacity, that would allow for sites to be depopulated quickly. To this end, we proposed to adapt electrical stunning techniques once utilized in harvest plants into an automated, single step electrical euthanasia system that is fully mobile. The objectives of the project were: 1) To validate an AVMA-approved method of humane euthanasia for on-farm application, to ensure the same standard of welfare is met during mass depopulation events that is provided under federally regulated conditions in slaughter plants. 2) To provide real-time industry assistance with mass depopulation while gathering data that will be used to develop SOPs and infrastructure for future crises. 3) To develop a unit that can be replicated for national preparedness and response to catastrophic events on farm that may be considered for addition to the USDA stockpile. The investigators used an expired patent for an auto-stunner that had been designed for slaughter plant use as the starting point for the project. Under slaughter conditions, electrical stunning is accepted as a humane method of rendering swine immediately unconscious, but a second step is required to prevent return to sensibility and ensure death. The aim of this project was to validate automated electrocution as a humane, single step method for on-farm euthanasia on a large scale.
A brief description of the mobile unit is as follows. A v-belt restrainer was mounted onto a 30′ flatbed gooseneck trailer. At the rear of the trailer is a lead up chute that is chute/dock height. The electric components and the electric drive unit for the hydraulic are mounted to the front of the trailer and powered by connecting to a 3 phase 220-volt power source with 30 amps. A negative contact was positioned to make contact with the left legs of the pigs as the restrainer moved them through the unit. An insulated paddle is lined on one side with a steel contact plate for the hot positive contact point. The pigs enter the unit via the lead up chute, transition into the restrainer which carries them forward to make contact with the negative contact bar followed by the hot paddle. When the pigs are in contact with both the negative contact bar and the hot paddle, head to heart electrical euthanasia occurs with a single step. By introducing the current across the head, instantaneous unconsciousness occurs, and the body contact achieves fibrillation (cardiac arrest). Pigs maintain the contacts for a minimum of 3 seconds. The restrainer carries the pigs to the end of the restrainer where they transition onto the exit slide and are discharged from the trailer.
The unit was not completed in time to assist with depopulation, which was objective #2. Sixty pigs ranging in weight from 125 pounds to ~600 pounds were processed through the unit for validation. 56 of the 60 pigs were euthanized with the single step automated electrocution as designed. The four pigs that required the use of a secondary method to ensure death pointed to size limitations (lower limit) or the need for a lower hold down apparatus, not a design issue with the use of automated single step electrical euthanasia. The investigators were extremely pleased with the ability of the electrical contacts to apply and maintain good electrical contact as the pigs were transported on the restrainer, even on mature Duroc boars with thick coarse hair. The above leads investigators to be extremely pleased with progress towards objectives 1 and 3. Farm staff that observed the use of the mobile unit all preferred its use vs their standard farm protocols of euthanasia.
The most important contribution this project has to pork producers is the validation of hands-free single step electrical euthanasia in a mobile unit on pigs ranging from 125 pound to ~600 pounds. While pork producers now have access to one operation unit, the process that has been undertaken on this project ensures the unit can be copied by other companies/government agencies to make their own unit(s). The fact that it does not require a human to apply the euthanasia holds great promise for worker mental health. Additionally, as it is extremely quick and bloodless, the visual aspects are also of importance for worker mental health. The unit also is designed in such a way to minimize the number of workers needed on site and greatly reduces the need for workers to move animals. All told, this is a safe, highly effective mobile unit that can perform hands free single step electrical euthanasia with minimal staff needed and to perform a necessary task in the most humane and mentally acceptable manner possible.