Swine industry stakeholders' perception on the use of water-based foam as an emergency mass depopulation method.

The U.S. pork supply chain is vulnerable to various internal and external threats and in need of prompt, comprehensive response plans. Under urgent circumstances, for example in the case of foreign disease incursions, swine farms will have to perform on-farm animal depopulation to prevent disease spread. Several animal depopulation methods including water-based foam (WBF) have been proposed and are under evaluation for feasibility in the field. However, the psychological/emotional impacts of applying depopulation methods for personnel managing and carrying on the tasks are not currently well understood. Thus, this study aimed to investigate WBF as an alternative for depopulation compared to existing methods approved by the American Veterinary Medical Association. Swine industry stakeholders were invited to voluntarily observe a WBF depopulation trial and to provide their self-reported perspectives before and after the observation. A survey was designed to explore key areas on expected and perceived method effectiveness, efficiency, and animal welfare considerations, as well as to evaluate short-term post-observation psychological impacts. Among 42 recruited stakeholders, 31.0% (13/42) were educators/researchers followed by animal health officials (26.2%, 11/42) and veterinarians (23.8%, 10/42), with an average of 11.7 ± 12.6 (n = 39) years of work experience. After the trial, respondents' positive perception of WBF depopulation increased specifically regarding the animal loading process being less stressful than restrained in-barn depopulation options (P = 0.003) and by the observation of fewer swine escape attempts and vocalizations than expected (P < 0.001). Respondents' positive perception of WBF also increased regarding to the time required to fill the trailer with foam, to stop hearing animal vocalization, and stop hearing animal movement, as the observed trial times were faster than their pre-observation estimates (P < 0.001). Additionally, 79.5% (31/39) of respondents agreed that the rapid destruction of animal populations had priority over animal welfare under urgent scenarios. Minor post-traumatic stress disorder-like (PTSD-like) symptoms from the observed trials were reported (26.7%, 4/15 respondents) one month after the observation. This study showed that the WBF depopulation process was perceived positively by swine stakeholders and may have limited short-term psychological impacts on personnel involved in animal depopulation.

Refinement of water-based foam depopulation procedures for finisher pigs during field conditions: Welfare implications and logistical aspects.

Water-based foam (WBF) depopulation is currently being researched as an alternative for rapid destruction of swine populations under emergency circumstances. Appropriate guidelines are needed to maintain method reliability and depopulation efficacy while minimizing animal distress under field conditions. Finisher pigs were depopulated using WBF with a 7.5-minute dwell time in two trials to evaluate the effect of; trial 1) foam fill level (1.5, 1.75, or 2.0 times the pig's head height) and trial 2) foam fill rate (slow, medium, or fast) on aversive pig responses (surface breaks, vocalization, and escape attempts) and time to cessation of cardiac activity. Activity and cardiac activity were recorded using subcutaneous bio-loggers for swine in trial 2. The average time to cessation of movement (COM) from the start of foam filling was compared for the foam fill rate groups using a generalized linear mixed effect model under Poisson distribution. Foam rate group was used as an independent variable, and replicates as a random effect. For trial 1, the average (mm:ss ± SD) time to fill completion was 01:18 ± 00:00, 00:47 ± 00:05, and 00:54 ± 00:05, for 1.5, 1.75, and 2.0 times the pig's head height, respectively. For trial 2, the average time to fill completion was 03:57 ± 00:32, 01:14 ± 00:23 and 00:44 ± 00:03, and the average time (mm:ss ± SE) to COM was 05:22 ± 00:21, 03:32 ± 00:14, and 03:11 ± 00:13 for slow, medium, and fast fill rate groups, respectively. A higher number of aversive pig responses were observed for the lowest foam fill level and slowest foam fill rate compared to increased fill levels and faster fill rates. For trial 2 the median (mm:ss ± IQR) time to fatal arrhythmia was 09:53 ± 02:48, 11:19 ± 04:04, and 10:57 ± 00:47 post-foam initiation for fast, medium, and slow foam rate groups, respectively. Time to cessation of cardiac activity was significantly shorter for the fast foam rate group compared to medium and slow foam rates groups (P = 0.04). For both trials, vocalizations were absent, and all pigs were unconscious following the 7.5-minute dwell time and no pigs needed a secondary euthanasia method. This WBF study showed that slower fill rates and low foam fill levels may extend the time until cessation of cardiac activity in swine during depopulation. A conservative recommendation with consideration of swine welfare during an emergency scenario would be a minimum foam fill level twice the pig's head height and a foam fill rate capable of covering pigs in foam within 60 s to minimize aversive responses and expedite cessation of cardiac activity.

Water-based medium-expansion foam depopulation of adult cattle.

Current options for depopulation of adult cattle are limited, have logistic constraints, and may not be practical on a large scale. Aspirated water-based foam (WBF) has been shown to be successful in depopulating poultry and swine but has yet to be tested in cattle. WBF is advantageous because necessary equipment can be readily available, easy to use, and presents minimal personnel risk. With the use of a modified rendering trailer in a field setting, we evaluated the efficacy of aspirated WBF for depopulation of adult cattle. Water-based medium-expansion foam was added to the trailer holding cattle to a depth of approximately 50 cm greater than head height. The study was conducted as a gated design and the initial trial was conducted using six anesthetized and six conscious animals for verification of the process and followed by four replicates each containing 18 conscious cattle. A total of 84 cattle were used, with a subset (n = 52) implanted with subcutaneous bio-loggers that recorded activity and electrocardiograms. Cattle were loaded onto the trailer and three gasoline-powered water pumps delivered foam into the trailer followed by a 15-min foam dwell period. Average (± SD) time to completely fill the trailer with foam was 84.8 ±â€…11.0 s. No animal vocalizations were heard during foam application or the dwell period, and all cattle were confirmed dead upon removal from the trailer after 15 min of immersion. Necropsies of a subset of cattle revealed foam extending to at least the tracheal bifurcation in all cattle and distal to this level in 67% (8/12) animals. Time to cessation of movement, which served as a proxy for loss of consciousness, was 2.5 ±â€…1.3 min and time to cardiac death was 8.5 ±â€…2.5 min as determined by data from animals carrying subcutaneous bio-loggers. The results of this study indicate that WBF is a rapid and effective method for depopulation of adult cattle with potential advantages in speed and carcass handling and disposal over current methods.

Energy restriction and housing of pregnant beef heifers in mud decreases body weight and conceptus free live weight.

Average temperatures in the Midwest, USA are predicted to increase 2-9°C by the end of the century; resulting in muddy pastures for spring calving beef heifers as they enter late gestation. The objective of this study was to evaluate the effects of muddy conditions on heifer body weight (BW), body condition score (BCS), conceptus free live weight (CFLW), and fetal growth when heifers were energy restricted during late gestation. Eighteen Angus heifers (n = 9/treatment) were paired based on initial BW. One heifer from each BW pair was randomly allocated to either the mud (MUD) or control (CON) treatment on day 196 of gestation. Pens in the CON treatment were bedded with wood chips, while pens in the MUD treatment were filled with mud (average depth of 19.5 ±â€…7.9 cm). Heifers were housed individually and fed the same diet that consisted of a limit-fed total mixed ration from day 196 to 266 of gestation that was formulated to meet 66% of the net energy for maintenance, growth, and gestation requirements. Requirements and the amount of the diet offered were adjusted weekly, and heifers were weighed and sampled for blood metabolites weekly. Data were analyzed as a randomized complete block design with repeated measurements. There was a treatment × day of gestation interaction, such that heifers had similar BW, BCS, and CFLW on day 196 of gestation. By day 266 of gestation; however, heifers in the MUD treatment weighed 43.5 kg less (P < 0.01) and were 1.8 BCS units less (P < 0.01) than heifers in the CON treatment. This is further supported by the treatment × day effects we observed for back fat (BF) and rump fat (RF) thickness, such that the MUD heifers had less BF (P = 0.02) and RF (P < 0.01) by day 266 of gestation. There was a marginally significant difference for gestation length (P = 0.06), such that heifers in the MUD treatment calved approximately 3.1 days before the heifers in the CON treatment. Though heifers in the MUD treatment decreased their BW and CFLW during the treatment period, we did not observe a difference in calf birth weight (P = 0.34), calf plasma IgG concentration (P = 0.37), or calf weaning weight (P = 0.63). Despite heifers in the MUD treatment having greater BW, CFLW, and BCS losses compared with the heifers in the CON treatment, the heifers in the MUD treatment seemed to prioritize fetal growth, as they mobilized their body tissues to meet the energetic demands of pregnancy.

Evaluation of a Water-Based Medium-Expansion Foam Depopulation Method in Suckling and Finisher Pigs.

The threat of foreign animal disease introduction through contaminated animal products, feed ingredients, and wildlife vectors have highlighted the need for additional approved methods for mass depopulation of swine under emergency scenarios, especially methods that can be applied to pigs across all production phases. The market disruption within the swine industry due to the SARS-CoV-2 pandemic has demonstrated this lack of preparation. The objective of this study was to validate water-based foam as a mass depopulation method for suckling (18 to 24 days of age) and finisher stage (63 to 100 days of age) pigs. Finisher pigs (n = 31, originally 32 but one finisher pig died prior to foaming), allocated as 9 triads and 1 set of 4 pigs, in 10 total replicates, and suckling pigs (n = 32), randomly allocated to two replicates, were completely covered in water-based medium-expansion foam for a 15-min dwell time in a bulk container. Container fill time for the trials were 6.5 ± 0.68 s and 5.3 ± 0.03 s for finisher and suckling pig replicates, respectively. Average (± SD) time for cessation of movement was 105 ± 39.1 s (s) for finisher pigs and 79.5 ± 10.5 s for suckling pigs. After completion of the 15-min dwell time in the foam, all pigs were confirmed dead upon removal from the container. The results from the present study suggest that the use of water-based foam can be an effective means of mass depopulation for suckling and finisher stage pigs, supporting previous research on the application to adult swine.

Technical Note: Validation of the effectiveness of electric stunning for euthanasia of mature swine (Sus scrofa domesticus).

Electrocution and the use of a penetrating captive bolt gun (PCBG) are both acceptable methods of euthanasia for market weight swine. Research has demonstrated that a PCBG is effective in both growing and mature swine. Given limited to no published research base on electrocution in mature swine, the objectives of the present study were to evaluate the efficacy of a two-stage (head only followed by head to heart, 10 s contact for each) mobile electric stunner (E-STUN, Hubert HAAS TBG 96N) and to assess euthanasia outcomes when comparing E-STUN with the frontal placement of a heavy-duty PCBG (Jarvis, In-line Cylinder Style) when applied to heavy-weight (>200 kg) mature boars and sows. Effectiveness of the E-STUN and PCBG was evaluated first in unconscious anesthetized mature swine (n = 7 boars and sows per treatment; average weight 282 ± 48 kg, n = 28) to reduce the risk of failure in a conscious animal and then in conscious mature swine (n = 3 boars and sows per treatment; average weight 282 ± 63 kg, n = 12). Data from both stages were combined for analyses. Treatment efficacy was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. A three-point traumatic brain injury score (0 = normal; 1 = some abnormalities; and 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible with E-STUN and PCBG, and no difference was noted between treatments for the detection of corneal reflex following treatment application (P = 0.11). Rhythmic breathing was absent following the administration of either E-STUN or PCBG. When evaluating the time to last heartbeat, there was a significant interaction between sex and treatment. Boars euthanized via E-STUN had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via PCBG (P < 0.001), and females euthanized via E-STUN had a 479.3-s decrease in time to last heartbeat compared with females euthanized via PCBG (P < 0.001). Intracranial hemorrhage was common for both methods, and visible disruption of neural tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN system is as effective as a heavy-duty PCBG in inducing insensibility and death and shows promise as an alternative method for euthanizing mature pigs on-farm.

Euthanasia is a moral obligation of all individuals working in the swine industry. A majority of acceptable methods have been validated for market weight pigs, while less attention has focused on heavy-weight mature boars and sows. The objectives of the current study were to evaluate the effectiveness of a mobile electric stunner (E-STUN) as a method of humane euthanasia in heavy-weight mature boars and sows and to assess the outcomes when compared with a penetrating captive bolt gun (PCBG) method. The efficacy of the treatment was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. The amount of traumatic brain injury was evaluated across the brain, and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible, and rhythmic breathing was absent following either treatment application. Boars and sows had a decreased time to last heartbeat with the E-STUN when compared with the PCBG method. Intracranial hemorrhage was common for both methods, and visible disruption of brain tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN is as effective as a PCBG for humane euthanasia of heavy-weight mature swine.

Brief communication: Plasma cortisol concentration is affected by lactation, but not intra-nasal oxytocin treatment, in beef cows.

In mammals, including sheep and mice, lactation attenuates the hypothalamo-pituitary-adrenal axis and plasma cortisol concentration. Oxytocin, one neuropeptide present in the blood during lactation, may contribute to such stress attenuation. Providing oxytocin intra-nasally increases plasma oxytocin concentration in cattle and can be used in non-lactating cows to mirror plasma oxytocin concentration of lactating cows. Therefore, our hypothesis was that there would be no difference in plasma cortisol between non-lactating beef cows intra-nasally administered oxytocin and lactating beef cows intra-nasally treated with saline. Twenty Bos taurus cows were randomly allocated by lactational status to one of four treatments, in a 2×2 factorial arrangement: 1) Non-lactating, saline (NL-S; n = 5); 2) Non-lactating, oxytocin (NL-OXT; n = 5); 3) Lactating, saline (L-S; n = 5); and 4) Lactating, oxytocin (L-OXT; n = 5). Two hours pre-treatment, cows were catheterized, moved to their appropriate chute and baseline blood samples were collected at -60, -45, -30, and 0 minutes before treatments were administered. Directly following the 0-minute sample, cows were administered their intra-nasal treatment via a mucosal atomization device. Subsequently, blood was collected at 2, 4, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 minutes. Non-lactating cows had greater (P = 0.02) plasma cortisol concentration compared with lactating cows. There was no lactation by treatment interactions for either plasma cortisol (P = 0.55) or oxytocin (P = 0.89) concentration. Although a treatment by time interaction was identified for oxytocin (P < 0.0001), there was no main effect of lactation on plasma oxytocin concentration (P = 0.34). Similar oxytocin and dissimilar cortisol concentration in lactating and non-lactating cows indicate that oxytocin alone cannot be responsible for reduced plasma cortisol in lactating ruminants. Further investigations are needed to elucidate alternative mechanisms that may be involved in the stress hypo-responsive condition of lactating mammals.

Validating the effectiveness of alternative euthanasia techniques using penetrating captive bolt guns in mature swine (Sus scrofa domesticus).

Euthanasia of mature swine is challenging. Temporal and behind-the-ear locations are two sites that have been identified as alternatives to the more commonly used frontal placement. In stage one, the effectiveness of two penetrating captive bolt gun styles (cylinder or pistol) was evaluated using frontal, temporal, and behind-the-ear placement in anesthetized mature swine (n = 36; weight: 267 ± 41 kg). For stage one, when evaluating treatment efficacy by sex, the cylinder-style equipment was 100% effective in achieving death when applied to all cranial locations (frontal, temporal, and behind-the-ear) for sows; however, the pistol-style equipment was only 100% effective when applied at the behind-the-ear location for sows. For boars, the cylinder-style equipment was 100% effective when applied to the frontal and behind-the-ear location, but the pistol-style equipment was not effective for any cranial location in boars. Therefore, the pistol-frontal, pistol-temporal, pistol-behind-the-ear, and cylinder-temporal were not included for boars, and pistol-frontal and pistol-temporal were not included for sows in stage two. In stage two, commercial, mixed-breed, mature swine (n = 42; weight: 292 +/- 56 kg) were randomly assigned to one of four treatments based on the inclusion criteria described in stage one. A three-point traumatic brain injury (TBI) score (0 = normal; 1 = some abnormalities; 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of hemorrhage was also noted. All treatments were 100% effective in stage two. A significant interaction between gun style and placement was determined on predicting total TBI as the cylinder style produced a higher total TBI score compared with the pistol type of the magnitude of +2.8 (P < 0.01). The cylinder style tended to produce a greater TBI score than the pistol in the temporal location (+1.2; P = 0.08). No difference was noted for TBI score behind-the-ear between the cylinder- and pistol-style gun (P > 0.05). TBI tended to be less in boars compared with sows (-0.6; P = 0.08). Hemorrhage was observed in frontal, parietal, occipital, and temporal lobes. This study demonstrated that the cylinder-style captive bolt gun more effectively resulted in brain trauma and death compared with a pistol-style gun and the behind-the-ear and temporal placement showed promise as an alternative placement site for euthanizing mature pigs on-farm.