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Abstract. The results of this study constitute a part of a project aiming at developing a cross-breed suitable for an extensive rearing system, utilising local biodiversity. Hybrids from mating a commercial broiler's male component (C) with Green-legged Partridgenous (GP) or Sussex (Sx) hens were compared with Cobb broilers. The study included 720 chickens of 3 genetic groups. Up to the third week of age, all birds were fed with balanced mixtures recommended for broiler chickens. From the fourth week, the mixture was weekly reduced by 10 % for the birds kept extensively (E). The deducted part was replaced with wheat bran, and from the seventh week with wheat. E groups had access to runs and received green fodder. Birds were slaughtered in 12th week of life. Carcass yield, giblets and proportion of carcass elements were estimated along with meat traits. The body weight at the 6th, 9th, 12th week of rearing and dissection results indicated a good suitability of Cobb chickens for an extensive rearing system. Hybrids were characterised by a considerably smaller proportion of breast muscle and slightly bigger of thighs and drumsticks, compared with Cobb, which could result from their greater motor activity. Results obtained by C × Sx and C × GP chickens, such as final body weight, proportions of abdominal fat and carcass elements, and appropriate value of meat traits, point at the usefulness of these hybrids as a meat-type chicken under extensive housing conditions. Darker colour of chicken meat, derived from C cocks and Sx or GP hens crossbred, can constitute an indicator for their carcasses' identification on the market.

Purpose The purpose of this paper is to evaluate changes in selected quality traits of chicken table eggs during their storage under standard storage conditions and in refrigeration. Design/methodology/approach The sample consisted of 570 eggs from Hy-Line hens. The eggs were placed on trays of 30 pieces each, and then group C (control) eggs were stored at 14°C temperature and 70 per cent humidity and group F (experimental) eggs were refrigerated at 5°C and 30 per cent humidity. Changes in egg mass and air cell depth were measured on the laying day and, then, after every 7 days for 5 weeks for group C and for up to 24 weeks for group F. Initially for every week and then after every four weeks, the quality of 30 eggs from each group was evaluated. The following traits were analysed: whole egg (mass, specific gravity), shell (conductivity, strength, mass, thickness, and density) and content (proportions, pH, albumen quality and yolk colour). Findings It was shown that due to a significant limitation of qualitative changes (lower water loss, higher specific mass, lower shell conductivity, better albumen quality, lower pH content, more favourable proportions of morphological elements) in eggs stored in refrigeration despite prolonged time, reduced temperature should be considered as a factor allowing for a significant prolongation of egg shelf life during storage. Originality/value The unusually elongated time of the experiment allows for a practical implementation of the results, especially in the case of eggs intended for processing.

Abstract. The aim of the study was to evaluate the usefulness of hybrids derived from Greenleg Partridge cocks and Rhode Island Red (GPR) hens for an extensive rearing system (RS), with special emphasis on high-quality table eggs. Newly created hybrids were compared to Hy-Line Brown (HLB) hens. The experiment was carried out with a total of 2400 hens. Both hybrid types (H's) were divided into two equal groups according to the rearing system: intensive (I) and extensive (E). The traits analysed in hens were body weight at the 8th, 16th, and 33rd weeks of age; laying production; and feed intake. At the 33rd week of a bird's age, egg quality was evaluated. The results of the study showed different reaction of the hybrids to the rearing system. This may confirm better usefulness of GPR for extensive farming and HLB hens for intensive methods of rearing. Furthermore, it can be concluded that the extensive system had a positive impact on the productivity of GPR birds.

the aim of the study was to demonstrate the relationship of egg weight and egg quality traits with storage time and type of cages in which the laying hens were kept. the material consisted of 960 eggs from same age hy-line Brown hens kept in conventional and furnished cages at the same time in one building. the eggs were randomly collected, sorted by weight (s, m, l and Xl), and stored under controlled temperature and humidity conditions. all eggs were weighed on days 1 (day of laying) and 28 of the experiment. during the same time they were candled to determine depth of the air cell, and 60 eggs from each subgroup were chosen to evaluate quality traits (egg weight and egg specific gravity), shell characteristics (shell strength, weight, thickness and density), and interior quality of eggs (albumen height and ph, yolk colour, weight and ph). the eggs (especially those from the heavier weight classes, Xl and l) from hens reared in furnished cages were characterized by significantly smaller quality changes (egg weight loss, yolk proportion, albumen height, haugh units) due to storage time in relation to those from hens kept in conventional cages. this fact could point to their better suitability for consumption. in addition to the housing system, changes occurring in eggs during storage should also be considered in terms of their weight class. economically important egg traits (e.g. egg weight, shell strength) were better in eggs from furnished compared to conventional cages.