Rearing, bird type and pre-slaughter transport conditions I. Effect on dead on arrival

Morris Villarroel,Jesús Méndez,Miguel A Ibáñez,Paula Martínez-Guijarro,Carlos De Blas,Almudena Lage,Fernando Pomares

doi:10.5424/sjar/2018162-12013

Abstract

The transport of broilers to slaughter normally results in a small percentage of dead on arrival (DoA) but little is known about the effects of flock thinning or bird weight. A multivariable linear model was used to analyse the incidence of DoA over one year in 1,856 flocks of Ross broilers (9,188 shipments). Each flock was categorized according to broiler type (yellow-skinned females and males, white-skinned females and males and roaster females) and thinning (birds transported after thinning, remaining birds after thinning and non-thinned flocks), in addition to transport distance, waiting time, maximum and minimum daily temperatures, precipitation and maximum wind speed. The overall percentage of DoA was 0.187%. The effect of the daily maximum outside temperature on DoA was quadratic with minimum DoA at 21.5ºC. Arrival time to the slaughterhouse and waiting time increased DoA by 0.0044% and 0.0021% for every 60 min increase, respectively. DoA were higher in males (which were heavier than females), and in the flocks that were previously thinned. An interaction between thinning and bird type was found, so that DoA were higher in previously thinned flocks of male broilers and roaster females. Despite the high incidence of thinning and larger bird weight, the percentage of DoA was comparable to previous studies. This research provides one of the largest detailed analyses of DoA in commercial broiler production in the Iberian Peninsula. The models described allow to quantify how increases in temperature, transport distance, waiting time, bird weight and the practise of thinning can all increase broiler mortality.

Highlights

Transport to slaughter can have negative effects on the welfare of broilers (Mitchell & Kettlewell, 1998), often resulting in a small percentage of dead on arrival (DoA)
The transport of broilers to slaughter normally results in a small percentage of dead on arrival (DoA) but little is known about the effects of flock thinning or bird weight
Each flock was categorized according to broiler type and thinning, in addition to transport distance, waiting time, maximum and minimum daily temperatures, precipitation and maximum wind speed

Summary

Introduction

Transport to slaughter can have negative effects on the welfare of broilers (Mitchell & Kettlewell, 1998), often resulting in a small percentage of dead on arrival (DoA). A relatively low incidence overall, the wide relative variability suggests that several factors are at play. Those may include factors associated with variables on the farm, environmental conditions (e.g., temperature and humidity), transport conditions (e.g., distance travelled; Oba et al, 2009), waiting time, and animal based variables such as genotype, sex and live-weight (Nijdam et al, 2004; Chauvin et al, 2011; Jacobs et al, 2016a, b; Kittelsen et al, 2017). There is little data on the effect of flock thinning, where a first group of birds is removed from the main flock and taken to slaughter a number of days before the second group. Thinning has been linked to increased infection of Campylobacter jejuni in the birds that remain on the farm (Koolman et al, 2014) but few studies have considered its effect on DoA

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