Welfare of broilers on farm

Abstract

This Scientific Opinion considers the welfare of domestic fowl (Gallus gallus) related to the production of meat (broilers) and includes the keeping of day-old chicks, broiler breeders, and broiler chickens. Currently used husbandry systems in the EU are described. Overall, 19 highly relevant welfare consequences (WCs) were identified based on severity, duration and frequency of occurrence: 'bone lesions', 'cold stress', 'gastro-enteric disorders', 'group stress', 'handling stress', 'heat stress', 'isolation stress', 'inability to perform comfort behaviour', 'inability to perform exploratory or foraging behaviour', 'inability to avoid unwanted sexual behaviour', 'locomotory disorders', 'prolonged hunger', 'prolonged thirst', 'predation stress', 'restriction of movement', 'resting problems', 'sensory under- and overstimulation', 'soft tissue and integument damage' and 'umbilical disorders'. These WCs and their animal-based measures (ABMs) that can identify them are described in detail. A variety of hazards related to the different husbandry systems were identified as well as ABMs for assessing the different WCs. Measures to prevent or correct the hazards and/or mitigate each of the WCs are listed. Recommendations are provided on quantitative or qualitative criteria to answer specific questions on the welfare of broilers and related to genetic selection, temperature, feed and water restriction, use of cages, light, air quality and mutilations in breeders such as beak trimming, de-toeing and comb dubbing. In addition, minimal requirements (e.g. stocking density, group size, nests, provision of litter, perches and platforms, drinkers and feeders, of covered veranda and outdoor range) for an enclosure for keeping broiler chickens (fast-growing, slower-growing and broiler breeders) are recommended. Finally, 'total mortality', 'wounds', 'carcass condemnation' and 'footpad dermatitis' are proposed as indicators for monitoring at slaughter the welfare of broilers on-farm.

Keywords: animal‐based measures; broilers; end the cage age; husbandry systems; mutilations; on farm welfare; welfare consequences.

Figure 1

The space occupied A by two broiler chickens depicted as two circles with the interindividual space

1. A = total space (area) including a = space covered, with r = being the radius of a broiler chicken and R being the radius added to reflect the interindividual distance D/2 since values for interindividual distances were divided by two birds.

Figure 2

Depiction of the entire flock with the additional space ω between chickens (space covered by chicken plus interindividual distance)

Figure 3

The Patio™ on‐farm hatching system – (A) photo and (B) schematic drawing ©Vencomatic Group

Figure 4

The X‐Treck® on‐farm hatching system – (A) photo and (B) schematic drawing © Vencomatic Group

Figure 5

The Home Hatching™ system for on‐farm hatching where eggs are placed in racks. (A) the hatching process (© Coppens Diervoeding) and the barn before placement of setter egg trays – notice the infrared heaters above the racks (© Peda BV)

Figure 6

The One2Born® system for on‐farm hatching where eggs are placed in hatchholders directly in the litter. (A) the hatching process (Photo credit: Anja Brinch Riber) and (B) the barn after placement of hatchholders (© One2Born)

Figure 7

The NestBorn® on‐farm hatching method where eggs are placed directly in the litter – (A) the hatching process (NestBorn®, Photo Credit: Ceres Media, Netherlands) and (B) placement of eggs using a machine specifically designed for the process (NestBorn®, Photo Credit: HFHC)

Figure 8

Indoor floor housing system without windows (upper picture (A); Photo Credit: Ingrid de Jong), and indoor floor housing system with roof windows, metal round perch and bales as enrichment (B) (de Jong and Gunnink, 2019)

Figure 9

Indoor floor housing with popholes that provide access to the covered veranda (left side) (upper picture) and pophole to covered veranda (lower picture). (Photo credit: Wageningen Livestock Research)

Figure 10

Example of a mobile house, in this case for laying hens (Photo Credit: Flemming Haugaard Haugaarden Aps)

Figure 11

Example of a broiler breeder‐rearing house in northwest Europe (De Jong and van Emous, ; Photo credit: Wageningen Livestock Research)

Figure 12

Broiler breeder‐rearing house © Big Dutchman

Figure 13

Schematic representation of thermal zones as a function of the environmental temperature (From EFSA AHAW Panel (2022a))

Figure 14

Schematic representation of the thermoneutral zone and the comfort zone as a function of the environmental temperature, considered especially relevant for the assessment of animal welfare of broilers on farm (EFSA AHAW Panel, 2022a)

Figure 15

Stepwise linear relationship (pink line) between the stocking density (x‐axis) and % of time walking during day time (y‐axis)

1. Four values (shown in pink with grey certainty ranges) were obtained by EKE. A linear relationship between increasing space allowances (kg/m²) and % time walking is assumed (pink line) to interpolate the EKE results. The red distribution on the right‐hand side of the plot represents the variability in % time walking expected in a population of broilers placed in a barn with highly restricted space (e.g. minimal allowed space or high stocking densities). No data were available to describe the variability in % time walking expected in a population of broilers placed in a barn with unrestricted access to space (low stocking density).

Figure 16

Stepwise linear relationship (pink line) between the stocking density (x‐axis) and the ABM, here the average FPD score

1. Three values (shown in pink with grey certainty ranges) were obtained by EKE. A stepwise linear relationship between increasing space allowances (kg/m²) and average FPD score is assumed (pink line) to interpolate the EKE results. The red, vertical distribution on the right‐hand side of the plot represents the variability in the average FPD score expected in a population of broilers placed in a barn with highly restricted space (e.g. minimal allowed space).

Figure B.1

Relative proportion of walking in comparison to a stocking density of 35 kg/m²

Figure B.2: Scatterplot of % time walking and stocking density of broilers of 3 age classes (Age class: 3= >=42 d; 2= 35–< 42 d; 1= 26–< 35 d 0= < 26 d) and the linear relationship for age class 0–2 and age class 3

Figure B.3

Plot of the extracted data for the relation of stocking density and average FPD score stratified in three age groups. Linear trends are weighted with the sample size

Figure D.1

Flow chart of the process leading to the selection of the ABMs that were considered to best reflect animal welfare in broiler chickens farm