Physiological responses of broilers to pre-slaughter lairage: Effects of the thermal micro-environment?

Silva

2014

Agraria

The aim of this study was to estimate parameters and design models for mortality prediction of broiler chickens in different preslaughter conditions, using the double generalized linear models. Preslaughter data from 13,937 broiler flocks were recorded daily during 2006, in a commercial slaughterhouse in Brazil. Several factors which influenced mortality rate were analysed, such as daily mean drybulb temperature and relative humidity, lairage time, daily periods, density of broilers per crate and season of the year. The data were analysed using a Double Generalized Linear Model, an extension of Generalized Linear Models (GLM), which provides a framework for modeling the dispersion in generalized linear models as well as the mean. As results, the double generalized linear models showed high accuracy for broiler mortality estimation, through interactions between the main factors which have influence on preslaughter operations.Key words: poultry production, preslaughter operations, stochastic models Modelización de la mortalidad previo al sacrificio de pollos con modelos lineales generalizados doble RESUMEN El objetivo de este estudio fue estimar parámetros y diseñar modelos para predecir la mortalidad de pollos de engorde en distintas condiciones de pre abate, utilizándose de un modelo linear generalizado doble. Datos del pre abate de 13.937 pollos fueron colectados diariamente durante el año de 2006 en un matadero comercial en Brasil. Distintos factores que tienen influencia sobre la tasa de mortalidad fueron analizados, como la media de temperatura de bulbo seco y humedad relativa del aire, tiempo de estabulación, periodos diarios, densidad de los pollos por caja y estaciones del año. Los datos fueron analizados utilizándose del Modelo Linear Generalizado Doble, una extensión del Modelo Linear Generalizado (MLG), que proporciona un marco para el modelado de la dispersión en los modelos lineares generalizados y también la media. Como resultado, el modelaje linear generalizado doble demostró una alta precisión para estimar la tasa de mortalidad de pollos de engorde, a través de las interacciones entre los principales factores que influyen en las operaciones antes del abate de los animales.Palabras clave: modelos estocásticos, operaciones previas al sacrificio, producción avícola

Section: Resultssupporting

confidence: 82%

Modeling preslaughter mortality of broiler chickens using double generalized linear models

Silva

2014

Agraria

“…To improve broiler welfare and reduce thermal stress after broiler transportation, holding areas with environmental control at the processing plants associated with a suitable lairage time interval can permit distribution of cooled air inside the crates before arrival at the slaughter line (Quinn et al, 1998). Several authors have recommended short lairage times (less than 2 h) because of low energy availability in fasted, metabolically active birds (Hunter et al, 1998;Warriss et al, 1999;Nijdam et al, 2004). Bianchi et al (2005) found no significant effect of lairage time on mortality rate and suggested a controlled fasting time preslaughter to reduce deaths before slaughter.…”

Section: Introductionmentioning

confidence: 96%

Preslaughter mortality of broilers in relation to lairage and season in a subtropical climate

et al. 2011

The preslaughter handling and transport of broilers are stressful operations that might affect welfare and meat quality and could increase numbers of deaths before slaughter. However, the influence of thermal factors during transportation and lairage at slaughterhouses is complex in subtropical regions, where increasing temperature and high RH are the major concerns regarding animal survival before slaughter. In this study we assessed the influence of a controlled lairage environment on preslaughter mortality rates of broiler chickens that were transported during different seasons of the year and had varying lairage times in the subtropical climate. Preslaughter data from 13,937 broiler flocks were recorded daily during 2006 in a commercial slaughterhouse in southeastern Brazil. The main factors that influenced daily mortality rate were mean dry bulb temperature and RH, lairage time, daily periods, density of broilers per crate, season of the year, stocking density per lorry, transport time, and distance between farms and slaughterhouse. A holding area at the slaughterhouse with environmental control was assessed. Using a double GLM for mean and dispersion modeling, the seasons were found to have significant effects (P < 0.05) on average mortality rates. The highest incidence was observed in summer (0.42%), followed by spring (0.39%), winter (0.28%), and autumn (0.23%). A decrease of preslaughter mortality of broilers during summer (P < 0.05) was observed when the lairage time was increased, mainly after 1 h of exposure to a controlled environment. Thus, lairage for 3 to 4 h in a controlled lairage environment during the summer and spring is necessary to reduce the thermal load of broiler chickens.

“…Thus, the controlled environment makes a decisive role in the desirable duration of lairage time. In environments with little or without ventilation, previous research recommended time intervals less than 2 hours (HUNTER et al, 1998) and between 1 and 2 hours (WARRISS et al, 1999). In climatized environments, the time intervals ranging over 2 hours (QUINN et al, 1998) and BRESSAN & BERAQUET (2002), through a trial conduced in Brazil, recommended that the ideal time is between 2 and 4 hours, targeting the thermal comfort of birds and consequently a reduction loss.…”

Section: Introductionmentioning

confidence: 99%

“…However, as evidenced by HUNTER et al (1998), the waiting time in the slaughterhouse can vary from 0 to 7 hours. Thus, the controlled environment makes a decisive role in the desirable duration of lairage time.…”

Section: Introductionmentioning

confidence: 99%

Thermal stress related with mortality rates on broilers' preslaughter operations: a lairage time effect study

et al. 2011