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Pol. J. Food Nutr. Sci. 2007;57(Special issue 4B):371–375
The objective of this study was to evaluate the chemical composition and sensory characteristics of eggs collected in three periods of the laying cycle from quails fed with feeds supplemented by organic selenium and vitamin E. Quail females were randomly divided into two groups (48 birds each): control (CG) and experimental (EG). From the first day of live to the end of laying cycle birds of the CG were fed the basic feeds, appropriate to age, while of the EG, with feeds supplemented with 0.3 mg/kg selenium (as 300 mg of selenium yeast - Sel-Plex®, Alltech LTD, USA) and 100 mg/kg vitamin E (200 mg/kg of E-50 Adsorbate - Rolimpex S.A). From each group 20 randomly selected eggs were collected at the beginning (1st month of production), peak (4th month) and from the end of the laying cycle (10th month) and subjected to analysis. The following traits were evaluated: contents of albumen, fat, ash and dry matter in relation to egg weight; contents of selenium, cholesterol, albumen and retinol in the yolk; lysozyme and cystatin activity in the egg white. Moreover, the eggs were subjected to sensory evaluation in five-grade consumer scale: overall appearance, taste, flavour, consistency of egg white and yolk, and yolk colour were examined. Chemical analysis of egg essence revealed that fat content in the eggs collected from the CG was, at the peak (11.5%) and entire laying period (11.4%) significantly (p≤0.05) higher than from the EG (10.8% and 10.7%, respectively). Differences in percentage of albumen, minerals and dry matters were not significant. Feed supplementation with organic selenium and vitamin E increased significantly (p≤0.05) selenium content in egg yolk both, collected at the peak and the end of laying cycle. Average value for entire period amounted 0.47 g/10 mL in the EG and 0.37 g/10 mL in the CG. Also albumen content in the eggs of EG (average for entire cycle - 96.4 mg/mL) was higher (p≤0.05) than in the CG (92.2 mg/mL). Feed supplementation with organic selenium and vitamin E increased significantly (p≤0.05) cholesterol level in the yolk. For the entire laying cycle it averaged 13.1 mg/g in EG and 11.8 mg/g in CG. Activity of biological substances in the egg white was changing in the analyzed periods of the laying cycle. At the beginning of cycle the lysozyme activity in the eggs of the EG was higher (p≤0.05), while cystatin activity was lower (p≤0.05) when compare with the CG. However, at the peak of laying lysozyme activity in the egg white of CG increased (p≤0.05) while in eggs of EG decreased, therefore for the entire laying cycle existing difference was not significant. Similar variations were observed in relation to cystatin. At the beginning and peak of cycle its activity in CG (3.4 U/5 mg and 3.3 U/5 mg) was higher (p≤0.05) than in EG (3.0 U/5 mg and 2.7 U/5 mg, respectively) while at the end was opposite (3.3 U/5 mg in EG and 3.0 U/5 mg in CG; p≤0.05). For all evaluated periods the taste, flavour, consistency of egg white and yolk, and yolk colour of eggs from CG were higher (p≤0.05) comparing to EG.