Predictions of growth are important factors that contribute to the profitability of an operation in poultry production. Modern commercial hybrids have a higher body growth in comparison with the local purebreds. However a niche market for meat and egg poultry production needs to be established using local purebreds to promote biodiversity. The aim of this study was to model the growth response of male and female chickens belonging to 5 local Italian populations: a commercial slow-growing hybrid (Berlanda, B), the Padovana pure breed [2 plumage varieties: silver, argentata (PA) and chamois, camosciata (PC)], and their crosses PC×B and PC×PA. A total of 398 one-day-old birds were reared until 180 d of age under indoor conditions. The linear and 3 nonlinear models (logistic, Gompertz, and Richards) were compared to study the growth patterns of these chicken populations. Significant (P < 0.01) differences were observed among the genotypes for several curve parameters. In males, PC×B showed the lowest age at inflection point, B showed the highest age and BW, whereas PA showed the highest age and the lowest weight. In females, the age at the inflection point did not differ among the groups; B showed the highest weight. All the nonlinear models gave a good fit of male and female data with R(2) ranging from 0.992 and 0.999, but the logistic equation had higher value of root mean square error than the Gompertz and the Richards values. Based on residual sum of squares for both sexes, the Richards model was better (P < 0.05) than the logistic but not superior to the Gompertz. The logistic equation showed an overestimation of initial BW for all the groups and sex. For Italian local chicken populations, the Richards model requires a measure of BW recorded at 90 d or after to obtain a good fit of the asymptotic weight. However, the Gompertz model has the advantage that it requires one less parameter than the Richards model.

Slaughtering yields and some meat physical and sensorial parameters of laying hens reared under organic system production were studied. The hens belonged to both Italian dual-purpose breeds [Ermellinata di Rovigo (ER; brown eggshell) and Robusta Maculata (RM; brown eggshell)] as well as hybrid genotypes [Hy Line White 36 (white eggshell) and Hy Line Brown (brown eggshell)]. The birds were reared under organic farming system production from 24 to 44 wk of age, when they were slaughtered. They were reared throughout summer and autumn, and the temperature ranged from about 28 to 3° C. Local breeds presented higher (P < 0.01) live BW and dressing percentage compared with hybrids. The RM and ER carcasses had (P < 0.01) the highest breast and leg (thigh and drumstick) percentage, respectively. The muscle-bone ratio of the Hy Line White 36 drumstick was lower (P < 0.05) than the RM ratio, whereas the other groups were intermediate. The ER breast presented the highest (P < 0.01) lightness value and the lowest (P < 0.01) final pH value compared with the other 3 groups. The breast meat significantly differed according to genotype for almost all the studied sensorial parameters (adhesivity, fibrousness, chewiness, solubility, juiciness, tenderness, shear resistance), with the exception of aroma and odor intensity. In the thigh, genotype significantly affected aroma, adhesivity, fibrousness, solubility, tenderness, and shear resistance.

The quality of eggs laid by 2 hybrid and 2 Italian dual-purpose genotypes of hens reared under organic farming system was studied. Hens belonging to Hy-Line Brown (brown eggshell, HLB), Hy-Line White (white eggshell, HLW), Ermellinata di Rovigo (brown eggshell, E), and Robusta maculata (brown eggshell, R) genotypes were reared from 24 to 43 wk of age. The trial was carried out from July to December, with environmental temperature ranging from 25°C (±5°C, summer) to 13°C (±7°C, autumn). The HLB eggs were heavier (P < 0.01) than HLW (62.9 vs. 60.4 g), and R eggs were heavier (P < 0.01) than E (56.5 vs. 54.4 g). The albumen weight differed (P < 0.01) among HLB, HLW, R, and E (40.7, 38.3, 32.7, 34.1 g, respectively). The E and R yolk weights were similar (16.2 g) and higher (P < 0.01) than hybrids; HLW yolk was higher (P < 0.05) than HLB (15.8 vs. 15.5 g). The HLB showed the highest (P < 0.01, 6.74 g) shell weight and E had the lowest (P < 0.01; 5.43 g). The yolk cholesterol content was higher (P < 0.01) in the Italian eggs than in the hybrids (258 vs. 219 mg/yolk). The HLB yolk had the lowest (P < 0.01) saturated fatty acids (33.8 vs. 34.9%), and R yolks showed the lowest (P < 0.01) monounsaturated fatty acids (36.3 vs. 38.0%) and the highest (P < 0.01) polyunsaturated fatty acids (28.7 vs. 27.4%) than the other groups. The HLW yolk showed the highest (P < 0.01) n-6/n-3 ratio (13.7) in comparison to the other 3 groups (12.8). During 21 d of storage (at 21°C and 62% RH), the E eggs showed the lowest (P < 0.01) quality (albumen height, 4.93 vs. 5.56 mm; Haugh units, 71 vs. 74). A sensory profile of boiled eggs showed differences (P < 0.05) in odor and flavor sensations and in certain yolk and albumen texture properties according to genotype. The quality of organic eggs from different genotypes differs in relation to the strain but also the interaction with the environmental conditions has to be considered.

Organic farming production. Effect of age on the productive yield and egg quality of hens of two commercial hybrid lines and two local breeds

A trial was done to study the chemical composition of meat and egg yolk of laying hens belonging to different genotypes reared using an organic production system. Two commercial hybrid hens (Hy-Line Brown and Hy-Line White 36) and 2 Italian dual-purpose breed hens (Ermellinata di Rovigo and Robusta Maculata) were reared from 25 to 44 wk of age. During the experimental period (July to December), the environmental temperature decreased from about 25 to 13°C and the RH increased from 62 to 73%. The photoperiod was 16L:8D. Meat and egg yolks of 44-wk-old hens were analyzed. The Italian breeds showed higher meat production and lower egg production when compared with the hybrids. Genotype affected protein, lipid, and ash content of breast and thigh meat. Hy-Line White and Ermellinata di Rovigo showed the lowest (P < 0.01) breast lipid and Hy-Line White had the lowest (P < 0.01) thigh lipid. Hy-Line White showed higher (P < 0.05) breast and thigh cholesterol. Genotype affected egg yolk cholesterol, which was higher (P < 0.01) in Italian breeds than in hybrids. The fatty acid profiles of meat and yolk were significantly affected by genotype. The hybrid and Robusta Maculata meat and egg fatty acid composition may be considered to be more favorable to human health. The results indicate that the ability of laying hens to incorporate fatty acids is genetically dependent and a possible interaction between strain and environmental conditions may exist for the absorption and utilization of dietary components.

The objective of this study was to compare the Padovana Camosciata local chicken breed (PC; n=59), the slow-growing line Berlanda-Gaina (BG; n=62), and their cross (BGxPC; n=57) for carcass and meat quality features. Animals were reared under the same experimental conditions and slaughtered at 3 different ages. An analysis of variance was performed on carcass and meat traits using a linear model that included fixed effects of genotype, sex, age at slaughter, and interactions between them. The PC local breed was approximately 1 kg lighter (P<0.001) at slaughter and exhibited greater dressing percentage (+1.50%; P<0.05) than BG. Breast skin of PC was bluer (-2.74; P<0.001), and breast muscle was darker (-2.65; P<0.001) and redder (+0.48; P<0.001) than that of BG. The pH (+0.16; P<0.001), thawing (+0.90%; P<0.01) and cooking (+2.28%; P<0.001) losses determined on breast muscle were higher for PC than BG. Crossbred animals performed better than the average of BG and PC chickens for breast weight (+22.81 g; P<...