Extensive Rearing Systems in Poultry Production: The Right Chicken for the Right Farming System. A Review of Twenty Years of Scientific Research in Perugia University, Italy

Abstract

The demand for poultry meat, being cheaper than red meat, will drive worldwide production of this product. Accordingly, an increase in production up to 16% is expected in 2025, most of which will occur in developing countries. Most poultry meat production is realized with intensive production systems, and extensive rearing systems (ERS) of poultry (organic, free-range, and low-input) represent only a small portion of poultry production in the EU (about 5%). However, there is an increasing interest in such rearing systems to maintain the good image of product and environmental sustainability, improved animal welfare, and meat quality with an annual trend of growth of about 10%. The aims of this work were to summarize the activities and the viewpoint of the researchers of the Department of Agricultural, Food, and Environmental Science of the University of Perugia (Italy). One of the most important goals of the research unit was the challenge of identifying the best poultry genotypes for ERS, which are important not only for the food industry but also for the improvement of human nutrition. Only the definition of the best genotypes adapted to ERS through the measurement of a wide panel of traits-genetic, physiologic, and behavior-and not only relying on daily weight gain will allow us to achieve this goal.

Keywords: extensive rearing systems; management; poultry; quality; sustainability; welfare.

Figure 1

Relationship between evolution of TBARS and liking in Kabir meat (modified by [6]). MDA: Malondialdehyde; TBARS: Thiobarbituric acid reactive substances.

Figure 2

Relationship between evolution of TBARS and liking in Ross 308 meat (modified by [6]). MDA: Malondialdehyde; TBARS: Thiobarbituric acid reactive substances.

Figure 3

Chicken with the, Super Track stick GPS.

Figure 4

Schematic representation of outdoor run use by different poultry genotypes. (R1) Ranger Classic, (R2) Ranger Gold, (R3) Rowan Ranger, (A) Hubbard RedJA, (CY) Gen 5 × JA87, (M) M22 × JA87. In red percentage of time spent outdoor (respect of total opening time of shelter).

Figure 5

Comparison of Pectoralis major muscle cross taken from conventional Ross 308 (CR); conventional Kabir (CK) or conventional Leghorn (CL); and organic Ross 308 (OR), organic Kabir, (OK) or organic Leghorn (OL) chickens; in the circle: α-red fibers (modified by [20]).

Figure 6

Ross 308 Pectoralis major with muscle fibers necrosis (black arrows) and giant fiber (red arrow). H-E, 200×.

Figure 7

Ross 308 Pectoralis major. Presence of hypercontracted atrophic fibers (black arrows) and giant fiber (red arrow). H-E, 200×.

Figure 8

Main oxidative interactions in poultry strains adapted/non-adapted to ERS. GB: grazing behavior, KB: kinetic behavior, ROS: reactive oxygen species, and NOS: reactive nitrogen species PUFA: polyunsaturated fatty acids.

Figure 9

Expression of the genes encoding for the desaturating enzymes in the liver of the three chicken genotypes. (A) FADS1, (B) FADS2, and (C) SCD1 gene expression is reported in the corresponding panel. Data are expressed as median ± range (minimum to maximum). SG: slow growing; MG: medium-growing; and FG: fast growing. Modified by [28].

Figure 10

Schematic representation of the different rearing systems: (A) = no enrichment; (B) = sorghum; (C) = olive trees. (Each pen measured 1000 m² each exclusion pen). Modified by [31].

Figure 11

International Federation of Organic Agriculture Movements principles (modified by https://www.ifoam.bio/why-organic/shaping-agriculture/four-principles-organic, accessed on 27 December 2020).

Figure 12

Schematic layout of the Mobile Poultry Processing Unit (50 chickens/hour): external (a) and internal (b) configuration. Modified by [47].

Figure 13

Main VOC classes (%) in raw (A) and cooked (B) chicken meat. Modified by [47]. VOC: volatile organic compound.

Figure 14

PUFA, VOC, and antioxidant dynamics in poultry meat during cooking process. NOS: reactive nitrogen species; PUFA: polyunsaturated fatty acid; ROS: reactive oxygen species; and VOC: volatile organic compound. Modified by [48].