Strategies for preventing heat stress in poultry

Lin, Hai; Jiao, Hongchao; Buyse, Johan; Decuypere, Eddy

doi:10.1079/wps200585

Cited by 400 publications

(405 citation statements)

References 114 publications

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“…Slow exposure to hypoxia has been associated with increased heart rate responses in laying hens [4], and exposure to altitude in man also causes tachycardia [53]. The bradycardia observed here in broilers may relate to their compromised cardiovascular physiology [28] but in any case is consistent with exposure to relatively rapid hypoxia, as also seen during controlled atmosphere stunning in broilers [45,[36][37][38].…”

Section: Accepted M Manuscriptmentioning

confidence: 48%

“…The baseline heart rate of birds killed at temperature setting 4 was higher than those killed at setting 3 -these birds were killed earlier in the day and underwent a holding period in crate in cold conditions. The effect of temperature on heart rate is well established; thermoregulatory effort increases heart rate and oxygen consumption [21,51] and there is evidence that modern broilers have compromised thermoregulatory capacity compared to laying hens [28]. These factors suggest that responses to LAPS will be related to ambient temperature in a non-linear way, since thermoregulatory effort and potential alterations in metabolic rate and respiratory control outside the thermally neutral zone will be altered in both hot and cold conditions.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

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Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Martin

Christensen

Vizzier-Thaxton

et al. 2016

Physiology & Behavior

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A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280 s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regards to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2 s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50-60 s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness.Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6 s into LAPS), often associated with arrhythmia, until around 60 s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60 s. There were some effects of temperature A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTadjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort. Highlights A novel stunning system uses hypobaric hypoxia to render poultry unconscious  We measured electroencephalogram, electrocardiogram and...

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Section: Accepted M Manuscriptmentioning

confidence: 48%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

Martin

Christensen

Vizzier-Thaxton

et al. 2016

Physiology & Behavior

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“…Chickens between 24 and 28 weeks of age respond differently to environmental weather conditions as older birds are heavier, and therefore, their heat exchange with environment is more difficult as compared to younger birds (Campos, 2000;Furlan & Macari, 2002). In addition to body weight, 28-w-old layers are achieving the peak of lay, according to most genetic line manuals (Dekalb, 2009;Hy-Line, 2009;Lohmman, 2009), which means that they have higher metabolic activity, and require more nutrients, particularly amino acids (Rocha, 2006;Lin et al, 2006) and energy (Rostagno et al, 2005), generating more metabolic heart, and presenting lower capacity of responding to heat stress.…”

Section: Resultsmentioning

confidence: 99%

Estimating mortality in laying hens as the environmental temperature increases

Pereira

Vale

Zevolli

et al. 2010

Rev. Bras. Cienc. Avic.

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Layer mortality due to heat stress is an important economic loss for the producer. The aim of this study was to determine the mortality pattern of layers reared in the region of Bastos, SP, Brazil, according to external environment and bird age. Data mining technique were used based on monthly mortality records of hens in production, 135 poultry houses, from January 2004 to August 2008. The external environment was characterized according maximum and minimum temperatures, obtained monthly at the meteorological station CATI in the city of Tupã, SP, Brazil. Mortality was classified as normal (≤ 1.2%) or high (> 1.2%), considering the mortality limits mentioned in literature. Data mining technique produced a decision tree with nine levels and 23 leaves, with 62.6% of overall accuracy. The hit rate for the High class was 64.1% and 59.9% for Normal class. The decision tree allowed finding a pattern in the mortality data, generating a model for estimating mortality based on the thermal environment and bird age.

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“…Higher production performance and superior feed efficiency have increased today's chickens susceptibility to heat stress (Lin et al, 2006). In this study, the association between densities of contour feather with heat tolerance was examined as a means to provide a phenotypic marker for heat tolerance that can be used in breeding chickens for appearance and heat resistance.…”

Section: Introductionmentioning

confidence: 99%