lairage management

• Poultry production losses


  • Relationship with lairage time effects
  • Thermodynamic study under tropical conditions
• The current challenges of poultry production are summarized in the reduction of losses during the production process
• This stage requires a study of critical control points, especially on the pre-slaughter operations
• Few researches recommend ideal intervals of time, especially in warm and wet regions
• Lairage time


  Time animals spend waiting at the abattoir before slaughter
• This trial was conducted in a commercial abattoir in the State of Sao Paulo, Brazil, in the year of 2006
• The historical data set from more than 13,000 trucks, about broiler mortality during pre-slaughter operations, was given by the abattoir
• Factors that influence the welfare of the birds were collected, such as the lairage time in abattoir and hourly dry-bulb temperature
• Statistical analysis was performed using the Double Generalized Linear Models
• During the periods the animals were in heat stress conditions, it was just on a few days throughout the afternoon, considering both the temperature and relative humidity
• In the morning, concerning temperature values, the whole days were found within the range comfort, but it was not verified in relation to the relative humidity, because some days exceeded this limit

  
• During the night, the chickens were in the stress range by cold in a few days, increased by high humidity in most of the year
• The temperature of the environment determines the best treatment given to the birds during the pre-slaughter operations, with emphasis on the condition of lairage on abattoirs
• The effect of lairage internal temperature could not be examined due to the feature of this work about the study of the historical data provided by the company

  
• Analysis of the variability of external temperature offers a legitimate approach to assess the internal environment due to the influence of the external environment inside the lorry

  
• ŷ


  Expected number of dead broilers
• e


  Lairage time
• The effect of the air environment of the lairage is quite significant in the range of lethal temperature (above 28 ºC, with lairage relative humidity around 75%)

  
• Birds are submitted to the external environment, especially in the loading and transport, aggravated with the high density per cage, where recorded temperatures are often greater than the external environment
• The condition of heat stress by severe heat is reduced on the lairage with environmental control, where it is expected that the temperature is less than the external temperature

  
• Holding birds on an environmentally controlled lairage for a longer period is essential due to the heterogeneity between the internal and external layer of boxes in the truck
• In thermal comfort band, efficiency of environmental control is reduced gradually until they reach a level as to the variation in lairage time, on situation of thermal comfort for the birds (below 21 °C, relative humidity around 75 %)

  
• Due the transport under comfort situations, the mortality rates are not influenced by the thermal condition of lairage module
• Lairage time intervals


  • Short: less than 1 hour
  • Moderate: 1- 2 hours
  • Medium: 2 - 3 hours
  • High: more than 3 hours
• Temperature ranges


  • Comfort: less than 21 ºC
  • Alert: 22 – 24 ºC
  • Critical: 25 – 28 ºC
  • Lethal: more than 28 ºC

  
• The environmental temperature has great influence on mortality at the stage of lairage, which increases the concern by the adoption of environmental control, through a waiting time that allows the birds to return to thermal balance, and therefore enhance the survival of the load
• Improving on this point, Furlan et al. (2000) found satisfactory results in the first 10 minutes, concerning the broilers body temperature, with the gradual increase wind speed, when the temperature was high (above 29 ºC) and average relative humidity of 66 %

  
• The enthalpy in this case was 75.6 kJ / kg of dry air, considered critical (Barbosa Filho et al, 2007) for the chickens of the 6th weeks old
• Even in heat stress, the authors related that the use of forced ventilation promotes a cooling towards the core to the periphery of the body of the bird, promoted by the loss of latent heat
• Extending such results for the expected pre-slaughter, the chickens are thermally advantaged in an environment adequate air, within a space of time allowing for such heat exchange and thus reducing body temperature
• Recommended lairage times related with each temperature interval and expected mortality rates

  • Comfort: Moderate (0.29%)
  • Alert: Medium (0.32%)
  • Critic: Medium (0.32%)
  • Lethal: High (0.32%)

  
• The first author is supported through a scholarship by FAPESP – Fundação de Amparo à Pesquisa do Estado de São Paulo