Descriptive epidemiology of smothering in Australian commercial free-range layer hen farms.

Since the early 2000 s the practice of free-range egg production has increased in developed countries, partly driven by consumer perception that free-range housing is better for hen welfare. While poultry in free-range systems have more behavioural opportunities compared with poultry in caged systems, free-range systems are associated with greater frequencies of infectious disease, predation and 'smothering', a condition where birds pile on top of one another with death occurring due to suffocation. Although the frequency of smothering deaths in Australian free-range layer poultry is anecdotally high, there is a lack of empirical evidence quantifying smothering cause-specific mortality rates and identifying factors that place birds at higher risk of death from smothering. This was a prospective cohort study of poultry flocks managed by three commercial free-range layer organisations in Eastern Australia. Flocks were enrolled into the study from 1 January 2019 to 29 March 2021 and were followed until the end of lay or until the end of the study on 31 March 2022, whichever occurred first. Throughout the follow-up period flock managers provided production details for each flock and details of smothering events using custom-designed logbooks.A total of 84 flocks were enrolled in the study: 32 from Organisation 1, 35 from Organisation 2 and 17 from Organisation 3. The number of birds per flock ranged from 16,000 to 45,000. The total mortality rate was 1131 deaths per 10,000 bird-years. Smothering mortality rate across the three organisations was 183 (minimum 133, maximum 223) deaths per 10,000 bird-years at risk. Smothering accounted for around 16% (minimum 9%, maximum 22%) of all deaths.We identified no distinctive temporal pattern in daily smothering risk as a function of either the number of days since placement or calendar date. The locations of smothering events in sheds and in the outdoor range were not consistent, with relatively large numbers of smothering events occurring in specific locations for some sheds but not others. To the best of our knowledge, this study is the largest prospective study of smothering mortality in commercial free-range layer flocks conducted to date. Estimates of smothering incidence rate and how that varies within and between flocks and organisations over time provides a critically important benchmark for further investigations into this substantial area of productivity loss.

Effect of different slaughter/stunning methods on stress response, quality indicators and susceptibility to oxidation of large yellow croaker (Larimichthys crocea).

This study aimed to investigate the effects of different slaughter methods (immersion in ice/water slurry, T1; gill cut, T2; CO2 asphyxia, T3; percussion (hit on the head with a stick), T4; Melissa officinalis L. essential oil + CO2, T5) on physiological stress, oxidative stress, and muscle quality in large yellow croaker. In terms of physiological stress, the levels of glucose (GLU), lactate dehydrogenase (LDH), and catalase (CAT) in CO2 asphyxia samples were significantly lower than those in other samples (p < 0.05). The level of cortisol (COR) in T1 sample was 1.25-1.84 times higher than that of other samples. The GLU level of T1 group was 3.2 times higher than that of T3 sample, and significantly higher than that of other samples. The creatine phosphokinase (CPK) and CAT levels of T2 samples were the highest (2.03 ng/mL and 8.34 U/mL, respectively). Furthermore, the superoxide dismutase (SOD) and glutathione peroxidase (GPx) analysis revealed that T3 and T4 samples could maintain good antioxidant enzyme activity during cold storage. The T3 samples maintained the stability of the protein (the lowest carbonyls and surface hydrophobicity) and reduced lipid oxidation (lower TBARS). In addition, the analysis of pH and water-holding capacity (WHC) revealed that T3 samples had better muscle quality. The muscle of T2 samples kept better color due to bloodletting treatment. The samples obtained after addition of Melissa officinalis L. essential oil had poorer indexes in all aspects compared to the T3 samples, which might be caused by the long anesthesia time of the essential oil.

Effect of thiamine pyrophosphate on the characteristics of farrowing and piglet vitality.

Asphyxia is considered the main non-infectious cause of prepartum mortality in swine, as well as an important factor that negatively affects neonatal vitality and can trigger physiological and metabolic disorders. Hence, the search for pharmacological protocols to reduce the harmful effects of asphyxia is a key area of research. Recent observations show that administering thiamine pyrophosphate (TPP) prior to a hypoxic event in certain species (rabbits, rats) has a neuroprotector effect that preserves energy metabolism under hypoxic conditions. Given this, the objective of this study was to evaluate a prophylactic protocol in high- and low-vitality neonate piglets based on TPP's effect on physiological and metabolic responses, body temperature, and weight. A total of 149 piglets born from 15 multiparous sows were used. The dams were randomly divided into two groups: control (NaCl 0.9%) and TPP (25 ml of TTP) administered 24 and 12 h before the expected farrowing date. The following reproductive variables of the sows were recorded: duration of farrowing, total number of piglets born per litter, number of liveborn piglets per litter, number of stillbirths and mummified fetuses at birth, and number of live piglets at weaning. In addition, the expulsion interval and vitality of all neonates were evaluated, body temperatures were recorded at ten intervals, and physiological profiles (blood gases, electrolytes, glucose) were registered for each neonate. Results show that the TPP-treated sows had shorter farrowing duration (P = 0.0060) and higher percentage of high-vitality neonates (60%). Moreover, their offspring exhibited greater vitality, fewer imbalances in their physiological and metabolic profiles, and greater weight gain at weaning (P < 0.0001). Findings suggest that administering TPP exerts a protective effect when hypoxic events occur, though this differs from results obtained with rat pups, where applying TPP after such events did not provide protection from asphyxia-induced damage. These differences may be due to the moment at which TPP was applied. The application time we selected was distinct from the procedure followed with rats because it was based on a dataset that describes the influence of administering TPP as a prophylactic treatment before a hypoxic event. Prophylactic administration of TPP to sows at the end of gestation exerted a neuroprotective effect on neonatal vitality and gas exchanges and energy metabolism in the offspring that were reflected in the greater weekly weight gain in those piglets.

Serum sRAGE and sE-selectin levels are useful biomarkers of lung injury and prediction of mortality in calves with perinatal asphyxia.

The objective of the present study was to evaluate the biomarkers specific to lung endothelial and epithelial damage in the determination of lung injury and its severity in calves with perinatal asphyxia and to evaluate their prognostic importance among survivors and non-survivor calves. Ten healthy calves and 20 calves with perinatal asphyxia were enrolled in the study. Clinical examination and laboratory analysis were performed at admission. Serum concentrations of soluble advanced glycation end-product receptor (sRAGE), soluble E-selectin (sE-selectin), clara cell secretory protein (CC16), and soluble intercellular adhesion molecule-1 (sICAM-1) were measured to assess lung injury. Venous pH, sO2, HCO3, and BE of calves with perinatal asphyxia were significantly lower than the healthy calves. sRAGE, sE-selectin, pCO2, and lactate were significantly high in calves with asphyxia. ROC analysis showed that sRAGE, sE-selectin, pCO2, lactate, and respiratory rate were higher while HCO3 and BE were lower in the nonsurvivor calves than survivors. In conclusion, serum sRAGE and sE-selectin concentrations highlight the utility of these biomarkers in determining lung injury in calves with asphyxia. Also, pH, pCO2, lactate, HCO3, BE, and respiratory rate along with serum sRAGE and sE-selectin were useful indicators in the prediction of mortality.

Use of cardiac troponin I (cTnI) levels to diagnose severe hypoxia and myocardial injury induced by perinatal asphyxia in neonatal dogs.

Prolonged perinatal asphyxia and subsequent severe hypoxia are the main causes of mortality in neonatal dogs in the first days of life. In medicine, specific cardiac biochemical markers, such as troponin I, are used to diagnose ischemic and nonischemic myocardial injury in asphyxiated newborns after birth. Thus, the objectives of this study were to compare the levels of cardiac troponin I (cTnI) between asphyxiated and nonasphyxiated newborn dogs and evaluate the correlations of cTnI levels with the modified Apgar score, the levels of oxygen saturation, blood glucose, and lactatemia, and blood gas parameters. This study aimed to determine the possible use of cTnI as a marker of severe hypoxia and myocardial ischemic injury in neonatal dogs. Fifteen animals in a eutocic vaginal delivery group (VG), 15 animals in a cesarean section group (CG), and 13 animals in a hypoxia (asphyxiated) group (HG) were evaluated. The animals in the asphyxiated group were from dystocic deliveries and born by vaginal delivery or cesarean section. All groups were evaluated at birth and after 60 min. The newborns in the VG and CG exhibited mixed acidosis (respiratory acidosis due to increased partial pressure of CO2 (pCO2) and metabolic acidosis due to reduced pH and bicarbonate (HCO3) levels, base excess/deficit in the extracellular fluid compartment (BEecf), and increased lactate levels) due to transient physiological hypoxemia at birth. The cTnI levels in the VG and CG were within the reference standards for healthy dogs. No correlations between cTnI level and the other parameters were observed in the VG and CG. Newborns in the HG exhibited prominent mixed acidosis (p < 0.05) due to severe hypoxemia. The Apgar score and blood gas parameters showed that these dogs were born asphyxiated, and they presented low vitality and the need for resuscitation maneuvers. The cTnI levels in the HG were significantly higher than those in the VG and CG (p < 0.05) and above the reference standards for healthy dogs, which indicated ischemic myocardial injury. The cTnI level was negatively correlated (p < 0.05) with the parameters Apgar score, heart rate, peripheral oxygen saturation (sO2) level, reflex score, and total carbon dioxide (TCO2) level and positively correlated (p < 0.01) with lactate level. This study showed that asphyxiated newborn dogs have higher serum cTnI levels than nonasphyxiated newborn dogs; thus, the cTnI can be used as a marker of severe hypoxia and ischemic myocardial damage in newborn dogs.

Effects of airway management and tidal volume feedback ventilation during pediatric resuscitation in piglets with asphyxial cardiac arrest.

To compare the effect on the recovery of spontaneous circulation (ROSC) of early endotracheal intubation (ETI) versus bag-mask ventilation (BMV), and expiratory real-time tidal volume (VTe) feedback (TVF) ventilation versus without feedback or standard ventilation (SV) in a pediatric animal model of asphyxial cardiac arrest. Piglets were randomized into five groups: 1: ETI and TVF ventilation (10 ml/kg); 2: ETI and TVF (7 ml/kg); 3: ETI and SV; 4: BMV and TVF (10 ml/kg) and 5: BMV and SV. Thirty breaths-per-minute guided by metronome were given. ROSC, pCO2, pO2, EtCO2 and VTe were compared among groups. Seventy-nine piglets (11.3 ± 1.2 kg) were included. Twenty-six (32.9%) achieved ROSC. Survival was non-significantly higher in ETI (40.4%) than BMV groups (21.9%), p = 0.08. No differences in ROSC were found between TVF and SV groups (30.0% versus 34.7%, p = 0.67). ETI groups presented lower pCO2, and higher pO2, EtCO2 and VTe than BMV groups (p < 0.05). VTe was lower in TVF than in SV groups and in BMV than in ETI groups (p < 0.05). Groups 1 and 3 showed higher pO2 and lower pCO2 over time, although with hyperventilation values (pCO2 < 35 mmHg). ETI groups had non significantly higher survival rate than BMV groups. Compared to BMV groups, ETI groups achieved better oxygenation and ventilation parameters. VTe was lower in both TVF and BMV groups. Hyperventilation was observed in intubated animals with SV and with 10 ml/kg VTF.

Extreme crowding in laying hens during a recurrent smothering outbreak.

BACKGROUND: Piling, a behaviour where hens crowd together, is referred to as smothering if mortalities result. Smothering is a considerable concern for the egg industry, yet is vastly understudied. METHODS: During an outbreak of recurrent smothering, continuous video footage captured a commercial, free-range flock over 35 days. We describe the piling behaviour observed and potential associations with productivity and flock health indicators. RESULTS: Forty-eight piles were filmed, with a maximum density of 187.93 birds/m2 and up to 1204 birds in one pile. Piling occurred in the same house location on 33 of 34 observation days, the first evidence of regularity in piling behaviour. Despite extreme bird densities, we did not find associations between piling extremity and productivity but did find associations with water:feed ratio and temperature range. CONCLUSION: This study describes the most extreme level of piling reported in literature and offers new insights into this problem behaviour and its consequences.

Syngamus asphyxiation in a captive ring-necked pheasant.

A deceased ring-necked pheasant (Phasianus colchicus) presented for necropsy following a history of chronic wasting. Necropsy revealed nematodes consistent with the genus Syngamus partially obstructing the trachea. Phylogentic analysis failed to reveal conclusive results regarding the species. Syngamus spp. can cause obstruction of the trachea in several different hosts. Additional genetic data from this taxon would aid in the more precise identification of diagnostic specimens.

Practical oxygen therapy for newborn piglets.

Aims: To evaluate the effect of a novel method of practical oxygen therapy on physiological parameters related to survival, weaning weight and preweaning mortality of neonatal piglets under commercial farm conditions. Methods: Piglets from hyperprolific sows born with signs of asphyxia, (n = 109; <6 on a score of respiration, meconium staining and activity) or very low birth weight (VLBW; n = 112; <1.05 kg) were selected for the study. Approximately half of each group (n = 55 VLBW piglets and n = 57 piglets with asphyxia) received 100% oxygen immediately after birth using a specially designed facemask for 45 seconds (VLBW) or 1 minute (asphyxiated). Physiological parameters (peripheral blood oxygen saturation (SpO2) blood glucose concentration and rectal temperature) were measured before oxygen treatment 5 minutes after birth (SpO2) and 24 hours later (SpO2, blood glucose concentration, temperature). Weight at birth, at 24 hours and at 21 days of age, preweaning mortality, and estimated colostrum intake were also recorded. Results: A significant treatment effect on SpO2 was observed (p = 0.013 and p < 0.001 for VLBW and asphyxiated piglets respectively). VLBW and asphyxiated piglets that received oxygen treatment had higher SpO2 after treatment (measured 5 minutes after birth, 97.7 and 97.8% respectively) compared to immediately after birth (93.3 and 86.8% respectively) while untreated piglets showed no variation. Blood glucose concentrations increased in all piglets between birth and 24 hours of age (p = 0.003 and p < 0.001 for asphyxiated and VLBW piglets respectively) and this was higher in asphyxiated piglets that received oxygen than those that did not (5.6 (SE 0.2) mmol/L; p < 0.05). Estimated colostrum intake was higher in asphyxiated (401.6 (SD 24.4) g/kg) and VLBW (374.9 (SE 23.4 g/kg) piglets that received oxygen than those that did not (273.2 (SE 24.1) g/kg; p < 0.001 and 249.0 (SE 22.5) g/kg; p < 0.001 respectively). Similarly weight at weaning was higher in asphyxiated (5.8 (SE 0.2) kg) and VLBW (4.9 (SE 0.2) kg) piglets that received oxygen therapy than control animals (4.9 (SE 0.2) kg; = 0.005 and 4.1 (SE 0.2) kg; p = 0.008 respectively). Furthermore, oxygen treatment markedly reduced preweaning mortality from 9/52 (17%) untreated to 1/57 (1.7%) oxygen-treated piglets suffering asphyxia at birth (p = 0.006). Conclusions: Oxygen therapy improves physiological and productive parameters in piglets born with signs of asphyxia or VLBW. The incorporation of this strategy as part of the farrowing routine enhances the advantages of rearing hyperprolific sows.

Anoxia Effects in Asphyxiated Green Sea Turtles (Chelonia mydas) Caught in an Artisanal Fishing Net on the Coast of Brazil.

Among studies of drowning in green sea turtles (Chelonia mydas), none have associated drowning with injuries of organs other than the lung. We describe the gross and microscopical findings in 23 green sea turtles found dead in a fishing net. Deprived of air, these animals experienced hypoxia and anoxia before dying, which caused congestion, hydropic degeneration and necrosis in several organs. There was no evidence of an alternative cause of death. These findings demonstrate a pattern characteristic of death by asphyxia caused by drowning.

Brief asphyxial state following immediate cord clamping accelerates onset of left-to-right shunting across the ductus arteriosus after birth in preterm lambs.

Reversal of shunting across the ductus arteriosus from right-to-left to left-to-right is a characteristic feature of the birth transition. Given that immediate cord clamping (ICC) followed by an asphyxial cord clamp-to-ventilation (CC-V) interval may augment left ventricular (LV) output and central blood flows after birth, we tested the hypothesis that an asphyxial CC-V interval accelerates the onset of postnatal left-to-right ductal shunting. High-fidelity central blood flow signals were obtained in anesthetized preterm lambs (gestation 128 ± 2 days) after ICC followed by a nonasphyxial (∼40 s, n = 9) or asphyxial (∼90 s, n = 9) CC-V interval before mechanical ventilation for 30 min after birth. Left-to-right ductal flow segments were related to aortic isthmus and descending aortic flow profiles to quantify sources of ductal shunting. In the nonasphyxial group, phasic left-to-right ductal shunting was initially minor after birth, but then rose progressively to 437 ± 164 ml/min by 15 min (P < 0.001). However, in the asphyxial group, this shunting increased from 24 ± 21 to 199 ± 93 ml/min by 15 s after birth (P < 0.001) and rose further to 471 ± 190 ml/min by 2 min (P < 0.001). This earlier onset of left-to-right ductal shunting was supported by larger contributions (P < 0.001) from direct systolic LV flow and retrograde diastolic discharge from an arterial reservoir/windkessel located in the descending aorta and its major branches, and associated with increased pulmonary arterial blood flow having a larger ductal component. These findings suggest that the duration of the CC-V interval after ICC is an important modulator of left-to-right ductal shunting, LV output and pulmonary perfusion at birth.NEW & NOTEWORTHY This birth transition study in preterm lambs demonstrated that a brief (∼90 s) asphyxial interval between umbilical cord clamping and ventilation onset resulted in earlier and greater left-to-right shunting across the ductus arteriosus after birth. This greater shunting 1) resulted from an increased left ventricular output associated with a higher systolic left-to-right ductal flow and increased retrograde diastolic discharge from a lower body arterial reservoir/windkessel, and 2) was accompanied by greater lung perfusion after birth.

Effects of maternal dietary nitrate supplementation on farrowing and placental characteristics, level of asphyxiation at birth and piglet vitality.

We investigated whether maternal dietary nitrate supplementation, leading to nitric oxide (NO) formation, would affect duration of farrowing, levels of asphyxiation, vitality of piglets at birth and/or loss of potential viable piglets in the form of stillbirth and pre-weaning mortality. Data were collected from 190 crossbred (Yorkshire x Dutch Landrace) sows, which were allocated, balanced for parity, to six dietary nitrate levels (0, 0.03, 0.06, 0.09, 0.12 or 0.15% of nitrate). Sow received the lactational diet containing nitrate from approximately 7 days before farrowing until 5 days after farrowing. Blood acid-base parameters (pH, pO2, pCO2, BEecf, HCO3, sO2 and lactate) and nitrate concentration were determined in umbilical cord blood. The farrowing process was video recorded and later analysed for total duration of farrowing, piglet birth interval, piglet vitality was scored and piglet latency to stand right after birth. Placentas were collected after expulsion during and after farrowing. Placenta length and width were measured and placental color scores were assessed based on redness of the placenta. The probability of a higher vitality score of piglets (being more vital) linearly increased with increasing levels of maternal dietary nitrate. This higher vitality score however, was not reflected by changes in the blood acid-base parameters in umbilical cord blood, except for a tendency for a higher pO2 with increasing levels of nitrate, which could have been caused by a quicker onset of respiration or an increased blood flow to the piglets during birth. Placenta width increased with increasing levels of maternal dietary nitrate, but no effect on placenta length and redness was found. Neither duration of farrowing nor birth interval were affected by maternal dietary nitrate level. In conclusion, maternal nitrate supplementation may affect piglet vitality via vasodilatation (placental characteristics) rather than an increase in exercise efficiency (duration of farrowing).

Thermal and asphyxia exposure risk to freshwater fish in feral-pig-damaged tropical wetlands.

Acute thermal and asphyxia exposure risks for freshwater fish occupying three tropical wetland typologies were examined. Field water-quality data revealed that fish in wetlands grazed by pigs had the highest exposure risks, because they are shallow and heavily damaged by pig activities. In contrast, with the exception is dissolved oxygen (which still reached critical conditions because of aquatic vegetation respiration), deeper permanent and pig-managed wetlands provides the best opportunity for the same fish species to survive in a heavily pig-modified tropical landscape.

Smothering in UK free-range flocks. Part 2: investigating correlations between disease, housing and management practices.

Smothering, when birds group together in a way that results in death from suffocation, is a welfare and economic concern for the egg industry. This questionnaire-based study explored correlations between disease, housing, management practices and smothering on free-range farms. A binomial logistic regression approach was used to test whether question responses predicted occurrence of nest box smothers (NBS) and panic and recurring smothers (PSRS) on farms. Breed (P=0.008) and nest box manufacturer (P=0.014) predicted NBS. Breed and nest box design have been previously reported to affect nesting behaviour. The affect of nest box manufacturer found in this study may illustrate the effect of nest box design features or house layouts. Nest box manufacturer (P=0.009), feeding oyster grit or grain on the litter (P<0.001) and range use on a sunny day (P<0.001) also predicted PSRS. Implementing some management practices to encourage desirable behaviours (eg ranging) may contribute to smothering, whereas some management practices such as those aimed at occupying birds may be beneficial, illustrating the delicate balance of factors involved in free-range egg production. It is hoped that these results will stimulate further work exploring the suitability of housing design and management of laying hens in light of smothering.

Nondrowning Asphyxia in Veterinary Forensic Pathology: Suffocation, Strangulation, and Mechanical Asphyxia.

Asphyxia in a forensic context refers to death by rapid cerebral anoxia or hypoxia due to accidental or nonaccidental injury. Death due to nondrowning asphyxia can occur with strangulation, suffocation, and mechanical asphyxia, each of which is categorized based on the mechanism of injury. Individuals dying due to various types of asphyxia may or may not have lesions, and even those lesions that are present may be due to other causes. The interpretation or opinion that death was due to asphyxia requires definitive and compelling evidence from the postmortem examination, death scene, and/or history. Beyond the postmortem examination, pathologists may be faced with questions of forensic importance that revolve around the behavioral and physiological responses in animals subjected to strangulation, suffocation, or mechanical asphyxia to determine if the animal suffered. While there is no prescriptive answer to these questions, it is apparent that, because of physiological and anatomical differences between humans and animals, for some mechanisms of asphyxia, consciousness is maintained for longer periods and the onset of death is later in animals than that described for people. Veterinary pathologists must be cognizant that direct extrapolation from the medical forensic literature to animals may be incorrect. This article reviews the terminology, classification, mechanisms, and lesions associated with asphyxial deaths in companion animals and highlights significant comparative differences of the response to various types of asphyxia in animals and people.

The protozoan parasite Trichomonas gallinae causes adult and nestling mortality in a declining population of European Turtle Doves, Streptopelia turtur.

Studies incorporating the ecology of clinical and sub-clinical disease in wild populations of conservation concern are rare. Here we examine sub-clinical infection by Trichomonas gallinae in a declining population of free-living European Turtle Doves and suggest caseous lesions cause mortality in adults and nestlings through subsequent starvation and/or suffocation. We found a 100% infection rate by T. gallinae in adult and nestling Turtle Doves (n = 25) and observed clinical signs in three adults and four nestlings (28%). Adults with clinical signs displayed no differences in any skeletal measures of size but had a mean 3.7% reduction in wing length, with no overlap compared to those without clinical signs. We also identified T. gallinae as the suggested cause of mortality in one Red-legged Partridge although disease presentation was different. A minimum of four strains of T. gallinae, characterized at the ITS/5.8S/ITS2 ribosomal region, were isolated from Turtle Doves. However, all birds with clinical signs (Turtle Doves and the Red-legged Partridge) carried a single strain of T. gallinae, suggesting that parasite spill over between Columbidae and Galliformes is a possibility that should be further investigated. Overall, we highlight the importance of monitoring populations for sub-clinical infection rather than just clinical disease.

Humane harvesting and slaughter of farmed fish.

The overwhelming majority of farmed fish produced throughout the world are killed with little or no consideration for their welfare. Fasting periods can be excessive, transport stressful and killing inhumane. At the time of writing, the salmon industry is the only sector in which consideration of the welfare of the fish at slaughter has resulted in significant improvements throughout most of the industry. There are signs of interest in the use of more humane slaughter methods for some other fish species. This is mostly initiated by the demand for higher standards from European fish retailers. For most species, the humane killing options are limited to percussive stunning and electrical stunning. However, even these methods can have a poor welfare outcome if insufficient consideration is given to the needs of the fish or if the equipment has not been properly designed. The use of food-grade anaesthetics to assist with the harvest has significant potential for improving welfare and their wider use should be investigated further.