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The optimization of animal welfare, meat quality, environmental impact, and economic sustainability in alternative poultry farming can be achieved by modulating several productive factors and improving the synergy between the chicken genotype and the outdoor environment. The objective of the study was to characterize 4 slow-growing chicken genotypes reared in free range conditions. Eight hundred chickens (SGs; 25 chickens/replicates/genotype/enrichment) belonging to the following genotypes, Red JA57 (RJ), Naked Neck (NN), Lohmann Dual meat-type (LD), and an Italian crossbreed (Robusta Maculata x Sasso, CB). were utilised and slaughtered at 81 d: The grazing areas were alternatively provided with enrichment constituted by strips of sorghum plants (ENR) or only grass (NO ENR). Productive performance (daily weight gain, daily feed intake, feed conversion ratio, live weight) were recorded weekly. Behaviour observations (walking and grass pecking), carcass and meat quality of breast and drumstick were also assessed in 15 chickens/replicate/genotypes/enrichment. Results demonstrated that both LD and CB showed the highest walking activity, but the different strains were differently capable of using the foraging resources (eating grass). The better productive performance was recorded in RJ followed by NN, CB and LD. In LD and CB, the different walking activities also affected the physico-chemical profiles (lower pHu, WHC, and lipids) of the breast and drumstick. The oxidative status was worse in CB than in the other groups (lower tocols, higher carbonyls), in both meat cuts. Fatty acid profile was also related to the genetic strain: a higher amount of n-3 polyunsaturated fatty acids was recorded both in the breast and drumstick of RJ and NN. The Healthy Fatty Index resulted excellent in all the chicken genotypes. In conclusion, the environment/animal interaction resulted as an important factor affecting the adaptability of genotypes to an extensive rearing system. All four genotypes, to different extents, showed good adaptability and production performance, with the exception of LD and CB, which were too light for the commercial supply chain requirements., Competing Interests: DISCLOSURES The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The majority of poultry meat used to be sourced from intensively housed birds. However, consumer preference has since demanded poultry producers develop more sustainable farming systems. Although free-range farming is considered beneficial for animal welfare, it is not as easy to standardize as an intensive system, which makes the choice of bird genotype appear crucial for alternative systems. In this study, we aimed to evaluate the effect of conventional and free-range rearing systems on the immune status, stress parameters, intestinal morphology and mortality in commercial hybrids (Ross 308) and local poultry strains, Bionda Piemontese (BP), Robusta Maculata (RM), BP x Sasso (BPxS), and RM x Sasso (RMxS). RNA was extracted from the jejunum and spleen to assess the mRNA expression of IL-2, IL-6, IL-10, IL-18, IL-1β, inducible nitric oxide synthase (iNOS), toll-like receptor (TLR)-4, and interferon gamma (IFN-γ). The heterophil:lymphocyte (H/L) ratio and intestinal histomorphometric evaluation were also calculated. We found that compared to the conventional system, the rearing system significantly affected the jejunum expression of IL-10, iNOS, IL-2, and IL-6, where these genes were upregulated in free-range system. A significant interaction between the rearing system and the genotype was also shown. More specifically, local breeds showed a significantly higher expression (P < 0.001) of IL-6 in the free-range system compared to the same genotypes in the conventional system. Moreover, IL-6 is constantly upregulated in local breeds within the free-range system compared to Ross hybrids. We also found significantly increased H/L and mortality rates in the latter, compared to the local breeds in the free-range reared system. The jejunum morphology also demonstrated a significantly higher villus height in BP and BPxS compared to the Ross hybrids. Overall, the results of our study confirm that the intense selection for growth in broiler chickens may have reduced their ability to react to the environmental stimuli related to free-range systems, resulting in a lower adaptability to a free-range environment, thus making them inappropriate for any farming system other than the conventional one. On the contrary, local chicken breeds are able to adapt and survive in the free-range system of rearing, and represent a genetic resource especially when adaptability to free-range conditions is required., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The present study aims to validate the Gompertz model to predict the growth performance of chicken crosses according to growth curve parameters of the parental lines and the estimated heterosis for each curve parameter. A total of 252 one-day-old chicks of both sexes belonging to 6 genotypes, including Ross 308, Sassò (SA), Bionda Piemontese (BP), and Robusta Maculata (RM), and the crosses between these local breeds and SA (BP × SA and RM × SA) were randomly allocated in 18 pens (3 pens/genotype) in mixed-sex groups (14 animals/pen; 7 females and 7 males). The individual body weight (BW) of all birds was recorded once a week from hatching until slaughtering (81 d for Ross 308; 112 d for SA, 140 d for the other genotypes). We drew up our final dataset with 240 birds (40 birds/genotype; 20 females and 20 males). The growth curve of each genotype was described using the Gompertz model, and the heterosis for each growth curve parameter was calculated as the difference between F 1 crosses and the average of parental breeds. The predicted growth curve parameters were evaluated by cross-validation. The Gompertz model accurately estimated the growth curves of all the genotypes (R 2 > 0.90). Heterosis was significant for almost all growth curve parameters in both crosses (P < 0.05). Heterosis ranged from -13.0 to +11.5%, depending on parameters, but varied slightly between the crossbreeds (BP × SA and RM × SA). The predicted values of adult BW, weight at the inflection point, and maximum growth rate were overestimated for BP × SA and underestimated for RM × SA, with a mean error between observed and predicted values <│2.7│% for all the curve parameters. In conclusion, the growth performance of chicken crosses between local breeds and commercial strains can be accurately predicted with Gompertz parameters of the parental lines adjusting for heterosis., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)