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During the pre-slaughter phase broiler chickens may experience thermal stress. We aimed to assess the impact of thermal conditions on, and identify potential risk factors for, thermal stress. Per transported flock (n=50), 1-3 temperature-humidity loggers were placed in-crate. Additionally, data were collected on weather conditions, truck curtain configuration (open/half-open/closed), stocking density, transport and lairage duration, ventilation and wetting during lairage. Transport microclimate was documented with a temperature-humidity-index (THI; 0.85*dry-bulb-temperature + 0.15*wet-bulb-temperature). Thermoregulatory indicators were assessed before transportation and after lairage: body temperature, body weight, panting and huddling prevalence. The abattoir provided mortality% and rejection% data. Transports were categorized in four groups (hot n=18, medium n=13, neutral n=13, cold n=6) based on mean THI, maximum THI, and the duration of THI>20°C. Both before transportation (P=0.028) and after lairage (P=0.009), body temperature (mean±SE) was or tended to be higher under hot and medium compared to neutral and cold conditions (Before: hot 41.34±0.06°C, medium 41.29±0.07°C, neutral 41.15±0.07°C, cold 41.00±0.10°C; After: hot 40.64±0.07°C, medium 40.51±0.09°C, neutral 40.34±0.08°C, cold 40.21±0.12°C). Panting prevalence was higher under hot conditions compared to medium, neutral or cold conditions before transportation (hot 3.80±1.11%, medium 0.20±0.14%, neutral 0.03±0.02%, cold 0.0±0.0%; P<0.001) and higher than under neutral conditions after lairage (hot 2.85±0.99%, neutral 0.19±0.10%; P=0.007). Group (hot, medium, neutral, cold) mortality%, rejection%, huddling prevalence and body weight did not differ. Outside temperature (hot 16.5±1.1°C, medium 10.9±1.2°C, neutral 8.3±1.2°C, cold 5.0±1.8°C), wind speed (hot 3.0±0.3m/s, medium 3.2±0.4m/s, neutral 4.1±0.4m/s, cold 5.2±0.5m/s), and truck configuration (open: hot 77.8%, medium 46.2%, neutral 30.8%, cold 0%) differed between thermal groups (P≤0.003), indicating those as potential risk factors for thermal stress. Panting occurred under hot conditions, but body temperature remained within normal range. This may indicate that thermoregulatory behaviours helped the birds to cope with the studied hot conditions. Open curtain configuration seemed to alleviate heat stress.
|Titel||Proceedings of the Xth Symposium on Poultry Welfare|
|Publicatiestatus||Gepubliceerd - 2017|
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