Phase 2.2: University Field Trials
Based on successful laboratory trials of the Zephyr-EXL carried out at the University of Bristol in November 2014, extension to field trials is desired.
Summary: Causality piglets (200) shot with the Zephyr-EXL and assessed for signs of consciousness. Gross pathological analysis of a representative sample will be performed.
Research carried out by Bristol University entitled “The Adaptation of Zephyr Technology to the Single Stage Euthanasia of Compromised Piglets” for Bock Industries. The trial examined the effectiveness of the Zephyr-EXL percussive gun operated at 120 psi, to stun/kill using visual evoked potentials (VEPs a test of residual consciousness) in 60 anesthetized piglets ranging in live weight from <3 – 11 kg.
Methodology:
Statistical advice (Prof Toby Knowles, Chartered Statistician within the Royal Statistical Society) suggests that 100% efficiency can never be absolutely proven. There will always be some small margin for error, however large the study. However, if we demonstrate for example, with the number of animals given in table 1, for n = 150, we would be 95% confident if 100% of 150 animals were effectively stun/killed that the very maximum percentage of animals not immediately stunned/killed would be never more than 2.5%. Based on a confidence level of 95% a sample size of 200 is recommended as a sensible balance between the cost of the study and demonstrating the degree of efficacy. In the event of a piglet surviving this treatment, a higher pressure will be selected and a further 200 animals tested.
Table 1. Statistical justification for the number of animals selected.
Summary: Causality piglets (200) shot with the Zephyr-EXL and assessed for signs of consciousness. Gross pathological analysis of a representative sample will be performed.
Research carried out by Bristol University entitled “The Adaptation of Zephyr Technology to the Single Stage Euthanasia of Compromised Piglets” for Bock Industries. The trial examined the effectiveness of the Zephyr-EXL percussive gun operated at 120 psi, to stun/kill using visual evoked potentials (VEPs a test of residual consciousness) in 60 anesthetized piglets ranging in live weight from <3 – 11 kg.
Methodology:
Statistical advice (Prof Toby Knowles, Chartered Statistician within the Royal Statistical Society) suggests that 100% efficiency can never be absolutely proven. There will always be some small margin for error, however large the study. However, if we demonstrate for example, with the number of animals given in table 1, for n = 150, we would be 95% confident if 100% of 150 animals were effectively stun/killed that the very maximum percentage of animals not immediately stunned/killed would be never more than 2.5%. Based on a confidence level of 95% a sample size of 200 is recommended as a sensible balance between the cost of the study and demonstrating the degree of efficacy. In the event of a piglet surviving this treatment, a higher pressure will be selected and a further 200 animals tested.
Table 1. Statistical justification for the number of animals selected.
The effect of the percussive blow will be subjectively assessed for the presence of rhythmic breathing and other brain stem and cranial reflexes, within 3 minutes of the application on 200 piglets by experienced personnel.
Effective percussive stunning results in tonic and clonic activity that is characterised by immediate loss of posture, unconsciousness, the absence of rhythmic breathing and uncontrolled motor activity (kicking). Post stun convulsions were considered to be aesthetically unacceptable by a number of producers, particularly when accompanied by gasping. Therefore the degree of post stun convulsions will be recorded.
It is likely that casualty piglets will be either moribund or suffering from disease or trauma and will therefore require less restraint than healthy pigs. Their condition will be recorded as it may affect the degree of post stun/kill convulsions. Post stun/kill convulsions will be scored using the scoring system outlined in table 2.
Table 2. Scoring system used to assess post stun/kill movement
Effective percussive stunning results in tonic and clonic activity that is characterised by immediate loss of posture, unconsciousness, the absence of rhythmic breathing and uncontrolled motor activity (kicking). Post stun convulsions were considered to be aesthetically unacceptable by a number of producers, particularly when accompanied by gasping. Therefore the degree of post stun convulsions will be recorded.
It is likely that casualty piglets will be either moribund or suffering from disease or trauma and will therefore require less restraint than healthy pigs. Their condition will be recorded as it may affect the degree of post stun/kill convulsions. Post stun/kill convulsions will be scored using the scoring system outlined in table 2.
Table 2. Scoring system used to assess post stun/kill movement
Following the assessment of the effect of the application of the Zephyr the heads will be removed, they will be tagged and bagged and returned to a laboratory (Bock Industries) where they will be frozen and subsequently split by band saw for gross pathological examination to determine the degree of structural brain damage.
In addition, a survey form (annex 1) will be designed and distributed to those farmers who have either purchased or will purchase the Zephyr percussive gun within the life of this project, to enable their feedback on the gun’s performance to be included in this evaluation.
Research Personnel:
Steve Wotton & Andy Grist
University of Bristol
School of Veterinary Sciences
Langford
N. Somerset, UK
BS40 5DU
In addition, a survey form (annex 1) will be designed and distributed to those farmers who have either purchased or will purchase the Zephyr percussive gun within the life of this project, to enable their feedback on the gun’s performance to be included in this evaluation.
Research Personnel:
Steve Wotton & Andy Grist
University of Bristol
School of Veterinary Sciences
Langford
N. Somerset, UK
BS40 5DU
