Chiara Rizzi

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

Abstract Hens of 2 hybrid lines (Hy Line Brown - HLB, Hy Line White - HLW) and 2 local breeds (Robusta maculata – RM and Ermellinata of Rovigo – ER) were reared following the organic production procedure and their egg yield and quality were studied at two different ages (30 and 42 weeks). The experimental period was between 26 and 42 weeks of age, starting in summer and lasting until autumn. Age significantly (P<0.01) affected the hen-day egg production and the daily egg mass of the HLB (84 vs. 94% and 44.5 vs. 59.4 g), of the HLW (81 vs. 89% and 42.4 vs. 54.7 g) and of the RM hens (27 vs. 63% and 12.9 vs. 36.7 g), which was the least precocious. Age did not affect the daily egg production of the ER hens (which was maintained around 58%), although it was observed a slight (P<0.05) increase of the daily egg mass (28.6 vs. 32.1 g). Age increased (P<0.01) the egg weight, yolk colour, yolk percentage and yolk:albumen ratio and decreased the albumen percentage in all groups.

Growth patterns of Italian local chicken populations

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.

Chemical composition of meat and egg yolk of hybrid and Italian breed hens reared using an organic production system

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 degrees 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.

Quality of organic eggs of hybrid and Italian breed hens

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.

Slaughter performance and meat quality of three Italian chicken breeds

Abstract A trial was carried out to study the slaughter performance and the meat quality of three Italian dual-purpose chicken breeds: Ermellinata di Rovigo (ER), Robusta lionata (RL) and Robusta maculata (RM). Females were studied from June to October from 47 days of life until slaughtered age, at 138 (I age) and 168 (II age) days of age. Each genotype had access to outdoor and indoor spaces. RL and RM birds showed a higher final body weight, and provided heavier carcass and commercial cuts than ER (P<0.01), at both ages. The dressing-out percentage of RL and RM females was more favourable than ER ones, in particular at II age (P<0.01). Differences in carcass conformation were observed at II age: the ER carcass showed a higher (P<0.01) proportion of leg and wing. The RM carcass had a higher (P<0.01) proportion of breast. The thigh meat/ bone ratio was higher in RL at I age (P<0.01) and II (P<0.05) age. Significant differences in breast colour were observed among the breeds; ER thigh showed the highest (P<0.05) a* value. At II age, lipids were lower (P<0.01) in ER breast; thigh lipids were similar among the groups. Slaughtering at I age seem to be more advantageous for the ER breed since it is more precocious.

Effect of sex on slaughter performance and meat quality of Ermellinata di Rovigo chickens

Abstract In this trial male and female chickens belonging to a dual-purpose Italian breed, Ermellinata di Rovigo (ER), were reared under a free-range production system (June-October) from 47 days of life until slaughter age, at 138 (I age) and 168 (II age) days of age. At both ages, the final body weight, the dressing-out percentage and the ready-to-cook carcass weight were higher (P<0.01) in males. At II age the female carcass showed higher (P<0.01) proportion of breast and lower (P<0.01) proportion of leg. At both ages, the redness index (a*) of breast and thigh were lower (P<0.01) in females, whereas the yellowness index (b*) showed the opposite trend; the females showed higher lipids in breast meat (P<0.05), thigh meat (P<0.01) and skin (P<0.01). The breast tenderness did not change. The results indicate that the ER birds have a different live body weight, slaughter performance and meat quality according to sex, both at I and II age. At 168 days, under the studied environmental conditions, the chickens were in prepubertal period and the sex affected the dressing-out percentage, meat colour and skin lipids in particular.

Carcass characteristics and meat quality traits of the Padovana chicken breed, a commercial line, and their cross

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<0.01) and dressing percentage (+1.38%; P<0.05). Breast skin of BGxPC was darker (-1.74; P<0.05), less red (-0.23; P<0.05), and bluer (-1.54; P<0.01) than the average of BG and PC, and breast muscle was more yellow (+0.64; P<0.05) for BGxPC. Cooking losses were lower (-0.99%; P<0.05) for crossbred than the average of BG and PC chickens. Results confirmed the specificity of meat characteristics of PC local breed and demonstrated the potential benefit of crossbreeding to improve production traits of PC breed without compromising the peculiar quality of its meat.

Testicular growth and comb and wattles development in three Italian chicken genotypes reared under freerange conditions

Male chickens belonging to three Italian purebreds – Ermellinata di Rovigo (ER), Robusta lionata (RL) and Robusta maculata (RM) – were studied. All the birds were reared under the same rearing conditions (from May until autumn). Chickens were reared under infra-red lamps from birth until 4 weeks of age with a 24L:0D photoperiod. Then they were kept outdoor: the photoperiod changed according to the season (from 16L:8D to 12L:12D). At 138 and 168 days of age 20 birds/breed were weighed and then slaughtered. Testicular samples were collected, after evisceration, processed and embedded in paraffine wax. Sections were stained for morphological observations, observed with light microscope, and then classified according to the testis maturation stage. Ermellinata di Rovigo chickens showed the lowest (P<0.01) body weight and the highest (P<0.01) testes weight; testes maturity was higher (P<0.01) in ER than in RL, whereas RM was intermediate. For each genotype testes weight and testes maturity did not significantly differ with aging. Correlations between testes weight and body, comb, and wattles weight, according to the breed, were calculated at 168 days of age. For ER no significant correlation was found, whereas RL showed a significant (P<0.01) positive relationship between testes weight and body weight, and sexual secondary characters. Robusta maculata showed a significant correlation between testes weight and comb (P<0.01) and wattles weight (P<0.10). Our results suggest that under the studied environmental conditions ER showed the highest testes development according to its more precocious achievement of adult body weight, whereas RL was the least precocious purebred.

Plumage colour in Padovana chicken breed: growth performance and carcass quality

Abstract Padovana female chickens of two plumage varieties, chamois (PC) and silver (PS) and their cross (PC male × PS female) were reared from 1 d until 200 d of age, when they were slaughtered. PC has light brown feathers with white edge (chamois), PS has white feathers with black edge (silver); PCxPS has silver plumage (cross-S) or completely white plumage (cross-W) at a ratio, at hatching, of 1:2 as cross-S:cross-W. The chickens were kept in a breeder house from May until December. In a population of Padovana chickens, it seems to be a relationship between the colour plumage and body weight until the sexual maturity: from 2 weeks until 6 weeks of age the PC females exhibited a higher daily growth (p < .001) than PS, as well as body weight (p < .01) at 28 weeks. At 200 d, PC showed higher carcase (p < .05) and thigh (p < .05) weight than PS, but similar ready-to-cook carcase conformation and pH, colour, water losses and shear force of breast muscle; no difference was checked between the other groups. Under the environmental conditions of the trial, heterosis had a positive effect (p < .05) on the daily growth until 70 d of age for cross-S. The results shows a sexual dimorphism for body dimensions increasing until the pubertal age for all the groups; therefore, the females should be slaughtered about 8 weeks later than the males for achieving similar body weight and slaughtering performance and carcase quality.

A morphometrical study on the skull of Padovana chicken

Abstract A trial was carried out to study the head and skull characteristics in a crested chicken breed with cerebral hernia located in a frontal bony protuberance, an uncrested chicken hybrid strain and their relative crosses. Males and females from five genotypes were used: two Padovana breed varieties (two colour plumages: Padovana argentata, silver -PA- and Padovana camosciata, chamois -PC-), the relative cross (PCxPA), a commercial single comb medium-growing strain (Berlanda gaina [B]) and the cross between PC and B (PCxB). As regards skull dimensions B showed heavier, longer, and wider skull than Padovana group (p < .001); the cross PCxB had skulls heavier than Padovana purebreds (p < .05). In the Padovana purebreds the frontal bone height varied from 9.2 to 16.2 mm, whereas in the groups with B component the height ranged from 4.2 to 6.8 mm. The frontal bone height was higher in PC and PCxPA than in PA (p < .01), whereas B and PCxB did not show any bony protuberance. No correlation resulted in Padovana groups between the frontal bone height and the skull length and width. A positive relationship between frontal bone height and skull height was significant only in PCxPA. For the skull characters of PCxPA both the two genotypes seems to be involved and no predominant and relevant effect of only one genotype was seen. The PCxB cross showed relevant differences in the skull morphometry, particularly in the absence of frontal bony protuberance and in the presence of comb.