Objective: To describe the clinical characteristics and outcomes in a population of dogs with neg... more Objective: To describe the clinical characteristics and outcomes in a population of dogs with negative-pressure pulmonary edema (NPPE) and to identify the main causes of the disease. To evaluate any associations with morbidity and mortality. Design: Retrospective study. Setting: Three university teaching hospitals and two private referral centers. Animals: Thirty-five client-owned dogs presented with NPPE. Interventions: None Measurements and Main Results: Data collected included patient characteristics, clinical history, clinicopathological abnormalities, radiographic features, treatments and outcome. Median age was 4 months (range 2-90) and median weight was 7.1 kg (range 1.7-37.2). There were many causes of NPPE including leash tugs, near hanging, accidental choking, anatomical obstruction to airflow and purposeful airway obstruction by people. The most common cause of NPPE was accidental choking (40% of cases). Dogs with an anatomical obstruction were older than 24 months. Hypoxemia with an increased alveolar-arterial gradient was common on presentation. The majority of thoracic radiographs (65.7%) showed an alveolar or interstitial pattern in the caudodorsal area as previously described in the literature. Oxygen therapy was administered to 33 (94.3%) dogs. Furosemide was administered to 18 (51.4%) dogs. Median length of hospitalization was 2 days (range 0-14). Twenty-eight (80%) dogs survived to discharge. Seven dogs were mechanically ventilated and only 2 of them (28.6%) 2 survived to discharge. Requirement for mechanical ventilation (p<0.001) was the only parameter associated with mortality. Conclusions: Most cases of NPPE occur in juvenile dogs. Different incidents associated with upper airway obstruction can produce an episode of NPPE. Choking on food or toys and near hanging have not been previously described in the veterinary literature as inciting causes of NPPE. The overall prognosis is good.
Broiler chickens are prone to a range of complex health and welfare issues. To support informed s... more Broiler chickens are prone to a range of complex health and welfare issues. To support informed selection of welfare traits whilst minimising impact on production efficiency and to address a major gap in understanding, we systematically explored associations between health and behavioural indicators of broiler welfare. One conventional (CNV, n = 350) and two slow-growing broiler breeds (SGH and SGN, respectively n = 400) were reared from hatch in pens of 50 birds. Birds were assessed for health (gait, plumage cover and dirtiness, pododermatitis, hockburn, and leg deviations) at 2.2 kg liveweight according to the Royal Society for the Prevention of Cruelty to Animals Broiler Breed Welfare Assessment Protocol. Behaviour and resource-use of 10% of birds per pen, on days 29 (all breeds) and 43 (SGH and SGN), was (i) scan sampled every 60 min between three to six and between twelve to fifteen hours after photoperiod onset; and (ii) continuously sampled sequentially from focal birds for 3 min each in a random order, during 15 min observation periods at three and twelve hours after photoperiod onset. Binary logistic generalized linear models were used, to assess respective associations between pen prevalence of each health outcome and (i) pen mean percentage scans of behaviour, and (ii) pen mean frequency and duration per 3 min focal observation of behaviour. Better growth rate and feed conversion but poorer health outcomes (mortality, gait, pododermatitis, feather cover) were more prevalent in CNV. Strong associations between behaviour and several heath indicators revealed, (i) increases in side-lying inactive, sitting inactive, and use of the litter relative to other resources, as primary and general indicators of poorer health, and (ii) increases in standing inactive, perch use, walking, Comfort, High Energy and Exploratory behaviour as primary and general indicators of better health. Of these, changes in sidelying, standing inactive, walking, Comfort and High Energy behaviour were particularly sensitive to small differences in health outcomes important for breed acceptance in high-welfare schemes. Crucially these behavioural measures additionally represent motivational and affective aspects of welfare not captured by health measures and allow opportunity for earlier intervention. Thus, to provide a comprehensive assessment of broiler experience, behaviour should be incorporated into broiler welfare assessments.
It is well documented in the international scientific literature that airborne dust in pig houses... more It is well documented in the international scientific literature that airborne dust in pig houses can cause serious health problems for humans as well as for animals. Extensive research has been carried out in different countries during the last few decades to improve the scientific understanding of air quality issues related to intensive animal production. Research and review papers were presented at the international symposium on Dust Control in Animal Production Facilities, held in Denmark in 1999. Different techniques have been used in order to reduce dust burdens in pig confinement buildings, but up to date only the procedure of spraying oil or a mixture of oil and water has contributed to reducing the indoor dust concentrations significantly. This article summarizes the current level of understanding of dust issues in intensive animal production buildings, mainly on the basis of papers presented at the above-mentioned symposium.
Animal : an international journal of animal bioscience, Jan 25, 2015
Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in comme... more Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At 'pulling' (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of ...
Thermodynamic study of incubated eggs is an important component in the optimisation of incubation... more Thermodynamic study of incubated eggs is an important component in the optimisation of incubation processes. However, research on the interaction of heat and moisture transfer mechanisms in eggs is rather limited and does not focus on the hatching stage of incubation. During hatch, both the recently hatched chick and the broken eggshell add extra heat and moisture contents to the hatcher environment. In this study, we have proposed a novel way to estimate thermodynamically the amount of water evaporated from a broken eggshell during hatch. The hypothesis of this study considers that previously reported drops in eggshell temperature during hatching of chicks is the result remaining water content evaporating from the eggshell, released on the inner membrane by the recently hatched wet chick, just before hatch. To reproduce this process, water was sprayed on eggshells to mimic the water-fluid from the wet body of a chick. For each sample of eggshell, the shell geometry and weight, surf...
ABSTRACT Nine hundred and sixty weaner pigs were exposed for 5½ weeks to controlled concentration... more ABSTRACT Nine hundred and sixty weaner pigs were exposed for 5½ weeks to controlled concentrations of airborne dust and ammonia in a single, multi-factorial experiment. Production and health responses were measured. The treatments were a dust concentration of either 1.3, 2.7, 5.1 or 9.9 mg m-3 (inhalable fraction) and an ammonia concentration of either 0.7, 10.0, 18.8 or 37.0 ppm, which are representative of commercial conditions. The experiment was carried out over 2½ years and pigs were used in eight batches, each comprising five lots of 24 pigs. Each treatment combination was replicated once and an additional control group (nominally ˜ 0 mg m-3 dust and ˜ 0 ppm ammonia) was included in each batch to provide a baseline. For the other four lots in each batch, the dust concentration was common while all four ammonia concentrations were used; thus the split-plot design was more sensitive to the effects of ammonia than dust. The pigs were kept in a purpose-built facility. The pollutants were injected continuously into the air supply. An artificial dust was manufactured from feed, barley straw and faeces, mixed by weight in the proportions 0.5:0.1:0.4. The ingredients were oven-dried, milled and mixed and then resuspended in the supply air. Dust concentration was monitored with a tribo-electric sensor, which was calibrated against a TSI aerodynamic particle sizer and gravimetric samplers. Ammonia was supplied under pressure from a bottle bank and its concentration was measured with a NOx chemiluminescent gas analyser after catalytic conversion. Liveweight gain and food intake were measured after 2½ and 5½ weeks of exposure. Exposure to both aerial pollutants depressed performance by an amount dependent upon dust but not ammonia concentration. Both food intake and liveweight gain, but not food conversion efficiency, were lower for weaner pigs exposed to 5.1 and 9.9 mg m-3 dust concentration compared with control and 2.5 mg m-3 treatments.
Nine hundred and sixty weaned pigs were exposed for five weeks to controlled concentrations of at... more Nine hundred and sixty weaned pigs were exposed for five weeks to controlled concentrations of atmospheric ammonia and dust in a single, multifactorial experiment. The treatments were a mean dust concentration of either 1.2, 2.7, 5.1 or 9.9 mg/m3 (inhalable fraction) and a mean ammonia concentration of either 0.6, 10.0, 18.8 or 37.0 ppm, concentrations representative of commercial conditions. The experiment was carried out over two years and the pigs were used in eight batches, each consisting of five lots of 24 pigs. Each treatment combination was replicated once, and an additional control lot (nominally 0 mg/m3 dust and 0 ppm ammonia) was included in each batch. The dust concentration was the same in the other four lots in each batch in which the four concentrations of ammonia were used; thus, the split-plot design was more sensitive to the effects of ammonia than dust. The groups of pigs were kept separately in five rooms in a purpose-built facility, and the pollutants were injected continuously into the air supply. Ammonia was supplied from a pressurised cylinder, and the endogenous dust in each room was supplemented by an artificial dust manufactured from feed, barley straw and faeces, mixed by weight in the proportions 5:1:4; its ingredients were oven-dried, milled and mixed, and then resuspended in the air supply. The health of the pigs was assessed in terms of general pathology, respiratory tract pathology, and the microbiology of the nasal cavity, trachea and lung. In each batch, postmortem examinations were carried out on 40 pigs after five weeks&amp;amp;amp;amp;amp;amp;#39; exposure to the pollutants and on 30 pigs two weeks later to test for carryover and recovery--a total of 560 pigs. These examinations revealed minimal gross pathology and widespread minor pathological changes of little significance. The pigs&amp;amp;amp;amp;amp;amp;#39; turbinate and lung scores were low and unaffected by exposure to pollutants. All the putative bacterial pathogens, with the exception of toxigenic Pasteurella multocida type D, were isolated from the respiratory tract of the pigs of both ages, but there were no differences between the effects of the different concentrations of pollutants.
The presence of porcine circovirus type 2 (PCV-2) and other pathogens before and during an outbre... more The presence of porcine circovirus type 2 (PCV-2) and other pathogens before and during an outbreak of postweaning multisystemic wasting syndrome (PWMS) in pigs is evaluated in this study. At the time of the outbreak on a large commercial pig farm in the UK, serum samples and data were collected in two independent on-going research projects, one in weaned pigs and the other in sows. Serum samples of growing pigs and sows were PCV-2-antibody and PCR positive before and during the PMWS outbreak. Upon sequencing, PCV-2 isolates collected before the outbreak were identified as PCV-2a, and isolates collected during the outbreak were identified as PCV-2b, suggesting a shift of PCV-2 genotypes present on the farm. Pigs in the weaner study were from sows originating from different breeders and an association of sow origin and PCV-2 serostatus in offspring was found. Further, pigs had higher odds to be PCV-2 antigen positive if the sow was PCV-2 antibody positive around farrowing, the sow was of higher parity, and were less likely to test antigen positive if the sow was sourced from a particular breeder. The findings of this study highlight the potential role of the immune status of the sow on the occurrence of PMWS.
Disease control measures require poultry to be killed on farms to minimize the risk of disease be... more Disease control measures require poultry to be killed on farms to minimize the risk of disease being transmitted to other poultry and, in some cases, to protect public health. We assessed the welfare implications for poultry of the use of high-expansion gas-filled foam as a potentially humane, emergency killing method. In laboratory trials, broiler chickens, adult laying hens, ducks, and turkeys were exposed to air-, N2-, or CO2-filled high expansion foam (expansion ratio 300:1) under standardized conditions. Birds were equipped with sensors to measure cardiac and brain activity, and measurements of oxygen concentration in the foam were carried out. Initial behavioral responses to foam were not pronounced but included headshakes and brief bouts of wing flapping. Both N2- and CO2-filled foam rapidly induced ataxia/loss of posture and vigorous wing flapping in all species, characteristic of anoxic death. Immersion in air-filled, high expansion foam had little effect on physiology or behavior. Physiological responses to both N2- and CO2-filled foam were characterized by a pronounced bradyarrythymia and a series of consistent changes in the appearance of the electroencephalogram. These were used to determine an unequivocal time to loss of consciousness in relation to submersion. Mean time to loss of consciousness was 30 s in hens and 18 s in broilers exposed to N2-filled foam, and 16 s in broilers, 1 s in ducks, and 15 s in turkeys exposed to CO2-filled foam. Euthanasia achieved with anoxic foam was particularly rapid, which is explained by the very low oxygen concentrations (below 1%) inside the foam. Physiological observations and postmortem examination showed that the mode of action of high expansion, gas-filled foam is anoxia, not occlusion of the airway. These trials provide proof-of-principle that submersion in gas-filled, high expansion foam provides a rapid and highly effective method of euthanasia, which may have potential to provide humane emergency killing or routine depopulation.
commercial scale is unaffected by step-wise changes in light intensity and that other husbandry m... more commercial scale is unaffected by step-wise changes in light intensity and that other husbandry measures are needed to raise activity and hence improve leg health.
o r P e e r R e v i e w O n l y Figure 1. Interactive effects of gas mixture and section of gas c... more o r P e e r R e v i e w O n l y Figure 1. Interactive effects of gas mixture and section of gas chamber (windows 1-4) on mean proportion of scans of posture/behaviour observed and based on back-transformed means (n= 143 and 118 scans per window for CO 2 +O 2 and AR+CO 2 , respectively). The transformed means on the logit scale, s.e.d.s, Wald statistics and p-values referring to the transformed data are quoted in the text.
1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively littl... more 1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production. 2. The study was designed to investigate whether chronic exposure to continuous noise (60 dB(A) vs. 80 dB(A)) and/or light intensity (150 lux vs. 5 lux) during the critical period of coming into lay (16-24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens. 3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150 lux; hens in the high noise pens rested more frequently than those in quieter pens. 4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise. 5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.
1. Poultry on farms are sometimes required to be killed in an emergency, such as during a disease... more 1. Poultry on farms are sometimes required to be killed in an emergency, such as during a disease epidemic, yet none of the available methods are ideal. Whole-house carbon dioxide (CO(2)) administration has practical advantages, but gives rise to welfare concerns. 2. The study measured the body temperature, respiration, cardiac and brain activity (EEG) responses of 10 adult hens placed in tiered cages in a deep pit house while the entire flock (28,000 end-of-lay hens) was killed with CO(2). Video and thermographic images were also recorded. Liquid CO(2) was injected into the building producing a gaseous concentration of 45% within 19 min. 3. Those hens nearest the gas delivery site showed delayed respiratory, cardiac and EEG responses compared with those at more distant locations. Although sub-zero temperatures were recorded in the immediate vicinity of some birds, body temperatures indicated that they did not die of hypothermia. 4. EEG characteristics strongly associated with unconsciousness were used to determine an unequivocal time to loss of consciousness; this ranged from 6·0 to 10·5 (average 7·8) min after onset of gas injection. Distinctive cardiac and respiratory responses were seen following gas exposure; in particular, birds responded to inhalation of CO(2) by deep breathing. 5. The primary welfare concern is the duration of unpleasant respiratory effects, such as deep breathing, while the birds were substantively conscious. However, the concentration of CO(2) to which the birds were exposed while conscious would not have stimulated nasal and oral nociceptors. Time to death varied between 12·0 and 22·1 min after gas delivery.
Research is being conducted to develop integrated management systems for the rearing of broilers.... more Research is being conducted to develop integrated management systems for the rearing of broilers. The focus is on real-time dietary control to achieve growth-performance targets according to the prescribed criteria that include pollution emission considerations. Two 'sister' projects are in operation: one studying growthperformance and the other monitoring aerial pollution emission responses to dietary control. Both research projects utilize the same commercial-scale feeding trials on flocks of approximately 34 000 birds. Results are presented from the pollutant-monitoring project for one of a base set of experiments where a different protein level diet was supplied to each of four houses. Male broilers received ad libitum diets with target protein levels (based on lysine content) of 85, 90, 100 or 110% of the normal commercial level. The experimental arrangement is described, and results are presented of the emissions of ammonia, dust and odour monitored from the four houses throughout the 6-week rearing period. Observable correspondences were found between the ammonia emissions from and the actual total protein consumed within each house. Ammonia concentrations were consistently below 15 p.p.m., and dust and odour concentrations were reasonably consistent with previously reported levels. In the longer term, the pollution-monitoring and the birdperformance-monitoring projects aim to enable real-time control of diets to be formulated with regard to both profitability and pollution emissions. #
Journal of Agricultural Engineering Research, 2001
Composting of sheep manure mixed with straw was carried out in a pilot plant using three differen... more Composting of sheep manure mixed with straw was carried out in a pilot plant using three different systems of aeration: pile turning; forced aeration of static pile; and passive aeration of static pile. The aim was to investigate which of these three systems was the most appropriate for the management of the manure and straw. The effects of the such
Journal of Agricultural Engineering Research, 1998
A model for estimating the mean internal temperature of livestock buildings was developed for use... more A model for estimating the mean internal temperature of livestock buildings was developed for use in climate change studies. The model, which calculates a steady-state heat balance every hour, combines wind, artificial ventilation, thermal buoyancy effects and solar ...
Objective: To describe the clinical characteristics and outcomes in a population of dogs with neg... more Objective: To describe the clinical characteristics and outcomes in a population of dogs with negative-pressure pulmonary edema (NPPE) and to identify the main causes of the disease. To evaluate any associations with morbidity and mortality. Design: Retrospective study. Setting: Three university teaching hospitals and two private referral centers. Animals: Thirty-five client-owned dogs presented with NPPE. Interventions: None Measurements and Main Results: Data collected included patient characteristics, clinical history, clinicopathological abnormalities, radiographic features, treatments and outcome. Median age was 4 months (range 2-90) and median weight was 7.1 kg (range 1.7-37.2). There were many causes of NPPE including leash tugs, near hanging, accidental choking, anatomical obstruction to airflow and purposeful airway obstruction by people. The most common cause of NPPE was accidental choking (40% of cases). Dogs with an anatomical obstruction were older than 24 months. Hypoxemia with an increased alveolar-arterial gradient was common on presentation. The majority of thoracic radiographs (65.7%) showed an alveolar or interstitial pattern in the caudodorsal area as previously described in the literature. Oxygen therapy was administered to 33 (94.3%) dogs. Furosemide was administered to 18 (51.4%) dogs. Median length of hospitalization was 2 days (range 0-14). Twenty-eight (80%) dogs survived to discharge. Seven dogs were mechanically ventilated and only 2 of them (28.6%) 2 survived to discharge. Requirement for mechanical ventilation (p<0.001) was the only parameter associated with mortality. Conclusions: Most cases of NPPE occur in juvenile dogs. Different incidents associated with upper airway obstruction can produce an episode of NPPE. Choking on food or toys and near hanging have not been previously described in the veterinary literature as inciting causes of NPPE. The overall prognosis is good.
Broiler chickens are prone to a range of complex health and welfare issues. To support informed s... more Broiler chickens are prone to a range of complex health and welfare issues. To support informed selection of welfare traits whilst minimising impact on production efficiency and to address a major gap in understanding, we systematically explored associations between health and behavioural indicators of broiler welfare. One conventional (CNV, n = 350) and two slow-growing broiler breeds (SGH and SGN, respectively n = 400) were reared from hatch in pens of 50 birds. Birds were assessed for health (gait, plumage cover and dirtiness, pododermatitis, hockburn, and leg deviations) at 2.2 kg liveweight according to the Royal Society for the Prevention of Cruelty to Animals Broiler Breed Welfare Assessment Protocol. Behaviour and resource-use of 10% of birds per pen, on days 29 (all breeds) and 43 (SGH and SGN), was (i) scan sampled every 60 min between three to six and between twelve to fifteen hours after photoperiod onset; and (ii) continuously sampled sequentially from focal birds for 3 min each in a random order, during 15 min observation periods at three and twelve hours after photoperiod onset. Binary logistic generalized linear models were used, to assess respective associations between pen prevalence of each health outcome and (i) pen mean percentage scans of behaviour, and (ii) pen mean frequency and duration per 3 min focal observation of behaviour. Better growth rate and feed conversion but poorer health outcomes (mortality, gait, pododermatitis, feather cover) were more prevalent in CNV. Strong associations between behaviour and several heath indicators revealed, (i) increases in side-lying inactive, sitting inactive, and use of the litter relative to other resources, as primary and general indicators of poorer health, and (ii) increases in standing inactive, perch use, walking, Comfort, High Energy and Exploratory behaviour as primary and general indicators of better health. Of these, changes in sidelying, standing inactive, walking, Comfort and High Energy behaviour were particularly sensitive to small differences in health outcomes important for breed acceptance in high-welfare schemes. Crucially these behavioural measures additionally represent motivational and affective aspects of welfare not captured by health measures and allow opportunity for earlier intervention. Thus, to provide a comprehensive assessment of broiler experience, behaviour should be incorporated into broiler welfare assessments.
It is well documented in the international scientific literature that airborne dust in pig houses... more It is well documented in the international scientific literature that airborne dust in pig houses can cause serious health problems for humans as well as for animals. Extensive research has been carried out in different countries during the last few decades to improve the scientific understanding of air quality issues related to intensive animal production. Research and review papers were presented at the international symposium on Dust Control in Animal Production Facilities, held in Denmark in 1999. Different techniques have been used in order to reduce dust burdens in pig confinement buildings, but up to date only the procedure of spraying oil or a mixture of oil and water has contributed to reducing the indoor dust concentrations significantly. This article summarizes the current level of understanding of dust issues in intensive animal production buildings, mainly on the basis of papers presented at the above-mentioned symposium.
Animal : an international journal of animal bioscience, Jan 25, 2015
Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in comme... more Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At 'pulling' (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of ...
Thermodynamic study of incubated eggs is an important component in the optimisation of incubation... more Thermodynamic study of incubated eggs is an important component in the optimisation of incubation processes. However, research on the interaction of heat and moisture transfer mechanisms in eggs is rather limited and does not focus on the hatching stage of incubation. During hatch, both the recently hatched chick and the broken eggshell add extra heat and moisture contents to the hatcher environment. In this study, we have proposed a novel way to estimate thermodynamically the amount of water evaporated from a broken eggshell during hatch. The hypothesis of this study considers that previously reported drops in eggshell temperature during hatching of chicks is the result remaining water content evaporating from the eggshell, released on the inner membrane by the recently hatched wet chick, just before hatch. To reproduce this process, water was sprayed on eggshells to mimic the water-fluid from the wet body of a chick. For each sample of eggshell, the shell geometry and weight, surf...
ABSTRACT Nine hundred and sixty weaner pigs were exposed for 5½ weeks to controlled concentration... more ABSTRACT Nine hundred and sixty weaner pigs were exposed for 5½ weeks to controlled concentrations of airborne dust and ammonia in a single, multi-factorial experiment. Production and health responses were measured. The treatments were a dust concentration of either 1.3, 2.7, 5.1 or 9.9 mg m-3 (inhalable fraction) and an ammonia concentration of either 0.7, 10.0, 18.8 or 37.0 ppm, which are representative of commercial conditions. The experiment was carried out over 2½ years and pigs were used in eight batches, each comprising five lots of 24 pigs. Each treatment combination was replicated once and an additional control group (nominally ˜ 0 mg m-3 dust and ˜ 0 ppm ammonia) was included in each batch to provide a baseline. For the other four lots in each batch, the dust concentration was common while all four ammonia concentrations were used; thus the split-plot design was more sensitive to the effects of ammonia than dust. The pigs were kept in a purpose-built facility. The pollutants were injected continuously into the air supply. An artificial dust was manufactured from feed, barley straw and faeces, mixed by weight in the proportions 0.5:0.1:0.4. The ingredients were oven-dried, milled and mixed and then resuspended in the supply air. Dust concentration was monitored with a tribo-electric sensor, which was calibrated against a TSI aerodynamic particle sizer and gravimetric samplers. Ammonia was supplied under pressure from a bottle bank and its concentration was measured with a NOx chemiluminescent gas analyser after catalytic conversion. Liveweight gain and food intake were measured after 2½ and 5½ weeks of exposure. Exposure to both aerial pollutants depressed performance by an amount dependent upon dust but not ammonia concentration. Both food intake and liveweight gain, but not food conversion efficiency, were lower for weaner pigs exposed to 5.1 and 9.9 mg m-3 dust concentration compared with control and 2.5 mg m-3 treatments.
Nine hundred and sixty weaned pigs were exposed for five weeks to controlled concentrations of at... more Nine hundred and sixty weaned pigs were exposed for five weeks to controlled concentrations of atmospheric ammonia and dust in a single, multifactorial experiment. The treatments were a mean dust concentration of either 1.2, 2.7, 5.1 or 9.9 mg/m3 (inhalable fraction) and a mean ammonia concentration of either 0.6, 10.0, 18.8 or 37.0 ppm, concentrations representative of commercial conditions. The experiment was carried out over two years and the pigs were used in eight batches, each consisting of five lots of 24 pigs. Each treatment combination was replicated once, and an additional control lot (nominally 0 mg/m3 dust and 0 ppm ammonia) was included in each batch. The dust concentration was the same in the other four lots in each batch in which the four concentrations of ammonia were used; thus, the split-plot design was more sensitive to the effects of ammonia than dust. The groups of pigs were kept separately in five rooms in a purpose-built facility, and the pollutants were injected continuously into the air supply. Ammonia was supplied from a pressurised cylinder, and the endogenous dust in each room was supplemented by an artificial dust manufactured from feed, barley straw and faeces, mixed by weight in the proportions 5:1:4; its ingredients were oven-dried, milled and mixed, and then resuspended in the air supply. The health of the pigs was assessed in terms of general pathology, respiratory tract pathology, and the microbiology of the nasal cavity, trachea and lung. In each batch, postmortem examinations were carried out on 40 pigs after five weeks&amp;amp;amp;amp;amp;amp;#39; exposure to the pollutants and on 30 pigs two weeks later to test for carryover and recovery--a total of 560 pigs. These examinations revealed minimal gross pathology and widespread minor pathological changes of little significance. The pigs&amp;amp;amp;amp;amp;amp;#39; turbinate and lung scores were low and unaffected by exposure to pollutants. All the putative bacterial pathogens, with the exception of toxigenic Pasteurella multocida type D, were isolated from the respiratory tract of the pigs of both ages, but there were no differences between the effects of the different concentrations of pollutants.
The presence of porcine circovirus type 2 (PCV-2) and other pathogens before and during an outbre... more The presence of porcine circovirus type 2 (PCV-2) and other pathogens before and during an outbreak of postweaning multisystemic wasting syndrome (PWMS) in pigs is evaluated in this study. At the time of the outbreak on a large commercial pig farm in the UK, serum samples and data were collected in two independent on-going research projects, one in weaned pigs and the other in sows. Serum samples of growing pigs and sows were PCV-2-antibody and PCR positive before and during the PMWS outbreak. Upon sequencing, PCV-2 isolates collected before the outbreak were identified as PCV-2a, and isolates collected during the outbreak were identified as PCV-2b, suggesting a shift of PCV-2 genotypes present on the farm. Pigs in the weaner study were from sows originating from different breeders and an association of sow origin and PCV-2 serostatus in offspring was found. Further, pigs had higher odds to be PCV-2 antigen positive if the sow was PCV-2 antibody positive around farrowing, the sow was of higher parity, and were less likely to test antigen positive if the sow was sourced from a particular breeder. The findings of this study highlight the potential role of the immune status of the sow on the occurrence of PMWS.
Disease control measures require poultry to be killed on farms to minimize the risk of disease be... more Disease control measures require poultry to be killed on farms to minimize the risk of disease being transmitted to other poultry and, in some cases, to protect public health. We assessed the welfare implications for poultry of the use of high-expansion gas-filled foam as a potentially humane, emergency killing method. In laboratory trials, broiler chickens, adult laying hens, ducks, and turkeys were exposed to air-, N2-, or CO2-filled high expansion foam (expansion ratio 300:1) under standardized conditions. Birds were equipped with sensors to measure cardiac and brain activity, and measurements of oxygen concentration in the foam were carried out. Initial behavioral responses to foam were not pronounced but included headshakes and brief bouts of wing flapping. Both N2- and CO2-filled foam rapidly induced ataxia/loss of posture and vigorous wing flapping in all species, characteristic of anoxic death. Immersion in air-filled, high expansion foam had little effect on physiology or behavior. Physiological responses to both N2- and CO2-filled foam were characterized by a pronounced bradyarrythymia and a series of consistent changes in the appearance of the electroencephalogram. These were used to determine an unequivocal time to loss of consciousness in relation to submersion. Mean time to loss of consciousness was 30 s in hens and 18 s in broilers exposed to N2-filled foam, and 16 s in broilers, 1 s in ducks, and 15 s in turkeys exposed to CO2-filled foam. Euthanasia achieved with anoxic foam was particularly rapid, which is explained by the very low oxygen concentrations (below 1%) inside the foam. Physiological observations and postmortem examination showed that the mode of action of high expansion, gas-filled foam is anoxia, not occlusion of the airway. These trials provide proof-of-principle that submersion in gas-filled, high expansion foam provides a rapid and highly effective method of euthanasia, which may have potential to provide humane emergency killing or routine depopulation.
commercial scale is unaffected by step-wise changes in light intensity and that other husbandry m... more commercial scale is unaffected by step-wise changes in light intensity and that other husbandry measures are needed to raise activity and hence improve leg health.
o r P e e r R e v i e w O n l y Figure 1. Interactive effects of gas mixture and section of gas c... more o r P e e r R e v i e w O n l y Figure 1. Interactive effects of gas mixture and section of gas chamber (windows 1-4) on mean proportion of scans of posture/behaviour observed and based on back-transformed means (n= 143 and 118 scans per window for CO 2 +O 2 and AR+CO 2 , respectively). The transformed means on the logit scale, s.e.d.s, Wald statistics and p-values referring to the transformed data are quoted in the text.
1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively littl... more 1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production. 2. The study was designed to investigate whether chronic exposure to continuous noise (60 dB(A) vs. 80 dB(A)) and/or light intensity (150 lux vs. 5 lux) during the critical period of coming into lay (16-24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens. 3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150 lux; hens in the high noise pens rested more frequently than those in quieter pens. 4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise. 5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.
1. Poultry on farms are sometimes required to be killed in an emergency, such as during a disease... more 1. Poultry on farms are sometimes required to be killed in an emergency, such as during a disease epidemic, yet none of the available methods are ideal. Whole-house carbon dioxide (CO(2)) administration has practical advantages, but gives rise to welfare concerns. 2. The study measured the body temperature, respiration, cardiac and brain activity (EEG) responses of 10 adult hens placed in tiered cages in a deep pit house while the entire flock (28,000 end-of-lay hens) was killed with CO(2). Video and thermographic images were also recorded. Liquid CO(2) was injected into the building producing a gaseous concentration of 45% within 19 min. 3. Those hens nearest the gas delivery site showed delayed respiratory, cardiac and EEG responses compared with those at more distant locations. Although sub-zero temperatures were recorded in the immediate vicinity of some birds, body temperatures indicated that they did not die of hypothermia. 4. EEG characteristics strongly associated with unconsciousness were used to determine an unequivocal time to loss of consciousness; this ranged from 6·0 to 10·5 (average 7·8) min after onset of gas injection. Distinctive cardiac and respiratory responses were seen following gas exposure; in particular, birds responded to inhalation of CO(2) by deep breathing. 5. The primary welfare concern is the duration of unpleasant respiratory effects, such as deep breathing, while the birds were substantively conscious. However, the concentration of CO(2) to which the birds were exposed while conscious would not have stimulated nasal and oral nociceptors. Time to death varied between 12·0 and 22·1 min after gas delivery.
Research is being conducted to develop integrated management systems for the rearing of broilers.... more Research is being conducted to develop integrated management systems for the rearing of broilers. The focus is on real-time dietary control to achieve growth-performance targets according to the prescribed criteria that include pollution emission considerations. Two 'sister' projects are in operation: one studying growthperformance and the other monitoring aerial pollution emission responses to dietary control. Both research projects utilize the same commercial-scale feeding trials on flocks of approximately 34 000 birds. Results are presented from the pollutant-monitoring project for one of a base set of experiments where a different protein level diet was supplied to each of four houses. Male broilers received ad libitum diets with target protein levels (based on lysine content) of 85, 90, 100 or 110% of the normal commercial level. The experimental arrangement is described, and results are presented of the emissions of ammonia, dust and odour monitored from the four houses throughout the 6-week rearing period. Observable correspondences were found between the ammonia emissions from and the actual total protein consumed within each house. Ammonia concentrations were consistently below 15 p.p.m., and dust and odour concentrations were reasonably consistent with previously reported levels. In the longer term, the pollution-monitoring and the birdperformance-monitoring projects aim to enable real-time control of diets to be formulated with regard to both profitability and pollution emissions. #
Journal of Agricultural Engineering Research, 2001
Composting of sheep manure mixed with straw was carried out in a pilot plant using three differen... more Composting of sheep manure mixed with straw was carried out in a pilot plant using three different systems of aeration: pile turning; forced aeration of static pile; and passive aeration of static pile. The aim was to investigate which of these three systems was the most appropriate for the management of the manure and straw. The effects of the such
Journal of Agricultural Engineering Research, 1998
A model for estimating the mean internal temperature of livestock buildings was developed for use... more A model for estimating the mean internal temperature of livestock buildings was developed for use in climate change studies. The model, which calculates a steady-state heat balance every hour, combines wind, artificial ventilation, thermal buoyancy effects and solar ...
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Papers by T. Demmers