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The study was carried out with 11 purebred groups of chickens at 48 weeks of age, laying eggs with white, tint, blue-green and brown shell pigmentation to investigate the colour characteristics of eggshells in the CIE L*a*b* colour system. On the basis of L*, a* and b* values, С* (Chroma), Hue o (the angle between b* and a* colour coordinates) and SCI (eggshell colour index) values were calculated. L* values decreased statistically significantly (Р<0.001) from 92.7 in white-shelled eggs to 40.2 in dark brown eggs. Brown eggs had a* values between 1.9 and 22.5, which increased from cream-coloured to dark brown shells. In bluegreen and tinted eggs, L* and b* values were similar. In blue-green eggs, the values of the a* colour coordinate were negative. There was a substantial variation in the colour of eggs not only within the groups, but also within the breed. The shell colour index (SCI) is suitable for reliable colour identification only in brown and non-pigmented eggs. SCI values lower than 70 could be recommended as reference values for brown pigmented shells whereas SCI values over 85 -for white-shelled eggs. Spectrophotometric analysis is appropriate for use in eggs with uniform pigmentation of the shell. The Hue о angle is not suitable for colour analysis of eggshells due to the extremely large variations and the possibility to obtain similar values but with different sign in eggs with similar colour.

Fresh garlic contains natural phytobiotics, whereas garlic powderseveral biologically active substances with prebiotic activity. The purpose of the study was to evaluate the effect of feed supplementation with garlic powder on growth performance, carcass yield and meat quality in broiler chickens. The experiment was conducted with 120 male broiler chickens divided into 4 groups: group Icontrol; groups II, III and IVsupplemented with 0.2% ; 0.4% and 0.8% garlic powder, respectively. The experiment lasted up to the 56 th day of age. Growth performance of birds was determined, and at 56 days of ageslaughter analysis was performed for evaluation of slaughter traits, pH, water holding capacity (WHC) and colour (L*, a*, b*) of Musculus pectoralis superficialis, Musculus pectoralis profundus and Musculus femorotibialis medialis. The results demonstrated a steady tendency towards increase in live body weight throughout the fattening period proportionally to the level of dietary garlic powder supplementation. After feed supplementation with increasing doses of garlic powder, feed conversion ratio (kg/kg) maintained a stable positive tendency up to the 7 th week of age. Garlic powder supplementation did not influence the proportion of edible offal and meat cuts, except for abdominal fat percentage. Added to poultry feed at levels up to 0.8%, garlic powder had no adverse effect on chicken meat quality, but an increased tenderness of Musculus pectoralis superficialis was established.

At 35 days of age, meat quality analysis was done as well as proximate analysis of breast and thigh muscles of 72 male quails from heavy Pharaoh line. Lightness values (L*) depended both on the time of post mortem analysis and of topographic site – lateral or medial muscle surface of the pectoral muscle. The L* value of lateral M. pectoralis superficialis (MPS) was higher. Redness and yellowness of meat increased proportionally to post mortem ageing, with peak values on the 24th post mortem hour. The chroma was more expressed on the medial MPS surface. With regard to determination of a common index of meat colour based on CIE L*a*b* coordinates, we propose the calculation of Meat Colour Index (MCI) according to the formula: MCI = (L* - C*). The meat of Japanese quails had high protein and low fat content. Gross energy of breast meat was within 5.03 - 6.13 MJ*kg-1, and that of thigh meat between 4.90 and 5.75 MJ*kg-1. The processing mode of carcasses by removing the skin made quail meat an exceptionally dietetic product with fat content < 3%.

The aim of the study was to evaluate egg quality traits in three heavy Japanese quail populations created and reared in the Poultry Breeding Unit of the Trakia University – Bulgaria, marked as WG, GG and GL. In the experiments, 160 female birds from populations WG and GG, and 96 birds from population GL were tested up to the 6th production month. The main egg quality traits were controlled. The highest average egg weight was registered in WG group and the lowest in GL group, 14.04±0.32 g and 12.79±0.29 g respectively (p<0.05). The highest average Shape index was observed in group GG (78.31±0.53%), vs the lowest in WG quails (77.55±0.62%). Albumen proportion is almost 2/3 of egg mass, with average values from 57.14% in group WG tо 59.90% in group GG. Yolk proportion was about 30%, with smaller differences between the groups. The shell share from all tested groups comprised between 10.95 and 12.58% of egg weight. Average shell thickness was the greatest in eggs of WG quails (223.53±5.52 μm), and the lowest – in GG quails (216.91±6.83 μm). Egg quality traits were typical for the meat productive type of Japan quails.

During the past decade, consumers in some regions of the world evidenced a marked interest to eggs with non-traditional shell colour. The aim of the present study was to investigate the productive traits of Easter eggers, obtained by crossbreeding of Araucana and Schijndelaar roosters with White Leghorn layer hens. For this purpose, a total of five groups of hens were used: three control: group L (White Leghorn), group A (Araucana), group S (Schijndelaar) and two experimental: group AWL (F1 Araucana×White Leghorn) and group SWL (F1 Schijndelaar×White Leghorn). During the production cycle which continued up to 65 weeks of age, the following traits were evaluated: live weight at 20% and 50% egg production; economic maturity; average weekly feed intake and feed conversion, egg production and egg weight. At the age of 50% egg production, Araucana had the highest live body weight (1408.25 ±19.25 g), and Leghorns -the lowest (1297.45 ±10.25 g) (p<0.05). The best economic maturity was exhibited by White Leghorn group (135 days of age), whereas the Schijndelaar group attained economic maturity at 205 days of age. The most efficient feed conversion (p<0.001) for production of one egg and 1 kg egg mass was observed in group L (133.46±1.94 g and 2.19±0.05 kg/kg respectively). The highest hen-day egg production was recorded in group L and the lowest -in Schijndelaar (group S) and Araucana (group A). The weight of White Leghorn eggs was substantially higher (р<0.001) compared to eggs laid by Schijndelaars and Araucanas. The traits characterizing the economic efficiency of layer hens (feed conversion per egg produced and per 1 kg egg mass) in experimental groups were comparable to traits recorded in heavy egg-laying hybrids.

The aim of the study was to evaluate egg production in three heavy Japanese quail populations created and reared in the Poultry Breeding Unit of the Trakia University – Bulgaria, marked as WG, GG and GL. In the experiments, 160 female birds from populations WG and GG, and 96 female birds from population GL were tested up to the 6th production month. The main egg production traits were controlled. The highest egg production for the period was demonstrated in group GL (79.84±4.46%), followed by group GG (76.33±3.40%) and group WG (72.11±4.16%). Quails from the WG group were outlined with least efficient feed conversion per egg (74.49±1.21 g feed), while those from the GL group: with the most efficient one – 64.93±1.41 g (p<0.01). The highest average egg weight in descending order was observed in the WG group (14.04±0.32 g), GG group (13.65±0.27 g) and GL group (12.79±0.29 g). The Japanese quail populations created and maintained at the Trakia University showed a potentially good egg production for the production type they belonged to, which makes them attractive for use in interline hybridisation schedules, including for production of autosexing stock layers.