A study was conducted to evaluate egg weight, yolk weight, yolk % in egg weight and yolk cholesterol content in eggs from 9 Japanese quail lines. The experiment involved fresh eggs from 12 to 18-week-old Japanese quails. 30 to 60 eggs were sampled from each population. Brief characteristics of lines: 1. Line 01: inbred egg-producing quails, agouti plumage colour 2. Line 02: outbred semi-heavy English White quails, white plumage with dark spots (wh/wh) 3. Line 03: outbred semi-heavy quails of agouti plumage 4. Line 04: semi-inbred semi-heavy tuxedo-plumaged quails (E/E, Wh+/wh) 5. Line 05: semi-inbred semi-heavy quails of dark (mahogany plumage coloration (E/E) 6. Line 07: outbred egg-producing quails showing agouti plumage, used in the Intercosmos Space Flight Programme 7. Line 08: inbred meat-type quails with agouti plumage 8. Line 09: semi-inbred meat-type quails showing agouti plumage 9. Line 01 X 07: an egg-producing hybrid The weight of eggs from Japanese quail lines is given in Tab. I. The mean egg weight was highest in Line 03 (semi-heavy) and Line 08 (meat-type), being 10.09 and 9.95 g, resp. the lowest egg weight was recorded in the egg-producing hybrid derived from Line 01 X Line 07 and raised for commercial egg production. The mean egg weight in this hybrid was 9.0 g. Variation coefficient of egg weight ranged from 7.5 to 11.5 %. A significant difference was found between Line 03 and 01 X 07 hybrid (P < < 0.01) and between Line 08 and 01 X 07 hybrid (P <0.05). No literary data on quail egg quality traits in relation to line and breed have been reported. However, the results obtained strongly suggested relationship similar to those in hens, e. g. a marked effect of body weight on egg weight. This conclusion was also confirmed in light egg-producing lines and heavy meat lines. Tab. II presents basic statistical characteristics of yolk weight in quail lines. The mean yolk weight ranged from 2.81 (Line 01, Japanese meat line) to 3.06 g (Line 02, English White and Line 05, semi-heavy mahogany). Between-line differences in yolk weight were not statistically significant. Variation coefficient of this trait fluctuated from 9.83 to 16.02 %. Egg and yolk weights were closely related to yolk % in egg weight but between-line differences were not significant. Basic characteristics of yolk percentage are given in Tab. III. Yolk percentage in quail eggs was higher than in eggs from commercial layer hens. A pronounced decrease in yolk percentage in hen eggs might be attributed to breeding for high egg production. The range of yolk percentage in egg weight was 29.8 (Line 09, meat type) to 33 % (Line 04, tuxedo-plumaged semi-heavy line). Analyses of yolk cholesterol content in quail eggs from different lines (Tab. IV) provided interesting results. Mean yolk cholesterol content ranged from 1620 mg . . 100 g-1 (layer hybrid 01 X 07) to 2051 mg . 100 g-1 of yolk (Line 02, semi-heavy, English White). Variation coefficient of yolk cholesterol content was within the range 11.62-19.92 %. The highest yolk cholesterol content was recorded in Lines 02, 03 and 04 (semi-heavy lines). A highly significant difference was found between Line 02 and 01 X 07 (layer hybrid), 03 and 09, 03 and 01 X 07 and also 04 and 01 X 07 (P < <0.01). A significant difference in yolk cholesterol content existed between Lines 02 and 07, 02 and 09, 03 and 07 (P < 0.05). The lowest yolk cholesterol content was recorded in the hybrid line 01 X 07, raised for commercial egg prodction. This is an important fact from the viewpoint of human diet. Yolk cholesterol content in eggs from individual lines is presented in Fig. 1. It shows differences between semi-heavy lines 02, 03, 04, 05, compared to light (egg-producing) lines 01, 07, 01 X 07 and heavy meat lines 08, 09. The study gives correlations between the traits studied. A highly significant positive correlation was found between egg weight and yolk weight (r = +0.591 to 0.931) and between yolk weight and yolk percentage in egg weight (r = +0.533 to 0.704) in all the 9 lines. The correlations between cholesterol content, egg weight, and yolk weight were mostly insignificant and ambiguous.
