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This review article highlighted the effects of different rearing systems on egg quality parameters and the welfare of laying hens. Different housing systems for laying hens continue to cause controversy among consumers, researchers, environmentalists, and producers. The main concern and issue is the effect of these systems on bird health, behavior, and egg quality. In the European Union, public concern has increased about animal welfare in the poultry sector, since 2012 conventional battery cages (CC) for laying hens have been banned and replaced by other alternative housing systems: enriched cages (EC) and non-cages systems, such as aviaries (AV), and free-range system. The rearing systems and maintenance technologies of the laying hens can also influence the quality parameters of the egg. Conventional rearing systems can involve overcrowding of hens, poor hygiene conditions, or lack of access to space and natural light, which can lead to stress and disease in the birds and, by implication, reduced egg quality. The use of modern technologies in the breeding of laying hens can contribute to the improvement of egg quality parameters and the well-being of laying hens. These technologies include automated systems for feeding and watering, temperature and humidity control in rearing houses, artificial lighting, and the use of food supplements to ensure adequate nutrient intake. [ABSTRACT FROM AUTHOR]

Eggs are a great source of animal protein that are rich in fatty acids, selenium, B vitamins, provitamin A, amino acids, and folic acid. Egg quality and yolk colour are important attributes for consumers. They associate a higher intensity colour of yolk with a healthy egg which its rich in nutrients. Because hens are unable to synthesise pigments, they must come from feed mixtures. Furthermore, the synthetic colourants are added to laying hens diets to improve the yolk colour intensity. However, human health received more attention in the last time, so, the consumers are attracted by natural-coloured eggs. Carotenoids are the most numerous and widespread group of pigments in nature. They are a class of widely distributed pigments that include red, yellow, and orange colour. Numerous studies have examined the use of carotenoids, particularly yellow carotenoids, in animal feed, which aid to make egg yolks more orange in colour. They are found in different plants, microalgae, bacteria, fungi and have various biological functions, including increasing production, antioxidant, anti-inflammatory, antibacterial and immunomodulator role. For practical purposes, the cost of carotenoids from natural sources needs to be considered. The objective of this review was to summarise the recent findings in available literature data on the supplementation with natural pigments based on marigold and calendula flowers and paprika extracts for egg quality and yolk colour pigmentation which are preferred over pigments of synthesis, due to their costs and biodisponibility. [ABSTRACT FROM AUTHOR]

An experiment was conducted to assess the impact of vitamin D3, on laying hens' performances, egg yolk fatty acid profile (FA), antioxidant compounds and vitamin transfer in the eggs. For that, one hundred twenty, 34 weeks old Lohmann Brown laying hens, were allocated to completely randomized block arrangement of three dietary treatments: T1, control (C) with 2500 IU/kg vitamin D3; T2 with 3000 IU/kg vitamin D3 and T3, with 3200 IU/kg vitamin D3. All diets had identical basal diet structure containing 17.50% crude protein and 2780 kcal/kg, metabolizable energy, being isocaloric and isonitrogenous. Feed intake and feed conversion ratio were significantly (p<0.05) lower in T2 and T3 groups compared to T1, without any impact on average egg weight. Egg production was significantly (p<0.05) higher only in T2 group, compared with T1 and T3. No significant (p>0.05) contribution of vitamin D3 supplementation was observed on total saturated fatty acids (SFA), unsaturated fatty acids (UFA) or monounsaturated fatty acids (MUFA) classes determined in egg yolk. From the sum of cis FA, significantly (p<0.005) higher was palmitoleic FA in T1 egg yolk compared with T2 and T3 egg yolks. On the other hand, from the total trans group, nervonic FA was significantly (p<0.05) higher in eggs belonging to higher vitamin D3 supplement groups. Total polyunsaturated fatty acids (PUFA), were significantly (p<0.05) higher in T2 and T3 egg yolks compared with T1 egg yolk. However, n-3 increase significantly only in T3 yolks being with 43.92% higher compared with T1 yolk and with 35.51% higher compared with T2 yolk. From the antioxidant compounds, total polyphenol content, total antioxidant capacity, lutein and zeaxanthin, vitamin A and vitamin E registered slightly higher values in T2 and T3 eggs versus T1 eggs, but without significant (p>0.05) effect. Vitamin D3 transfer in eggs increased significantly (p<0.05) in T3 compared with T1 and T2 eggs, as a main effect of supplemental vitamin D3 in laying hens' diets. [ABSTRACT FROM AUTHOR]

In this experiment the effects of different housing systems on physical indicators of egg yolk and egg albumen quality of table eggs were studied. Hens of laying hybrid Lohmann Brown Lite were housed in two different housing systems, in enriched cage or on floor housing system. In both systems, the hens were kept under standard bioclimatic conditions. Eggs (n = 1080) were collected from the first phase of the laying cycle, at monthly intervals, at the age of laying hens 30-42 weeks. Egg weight (g), egg specific weight (g.cm-3), egg shape index (%), eggshell weight (g), eggshell percentage (%), and average eggshell thickness (µm) were evaluated. In the indicators of the whole egg quality was statistically significantly higher (P<0.001) the average weight of eggs produced by laying hens kept in enriched cage (66.3 ± 3.6) mean ± SD in comparison with the eggs from laying hens housed on litter (64.3 ± 4.0) mean ± SD. Similarly, in eggshell quality indicators (weight, proportion, average thickness) there were significantly higher differences in favor of the eggs from caged breeding. The values of the average egg shell thickness (µm) in the order of groups (392 ± 24.6; 377 ± 24.3) (mean ± SD). The results obtained show that the eggs from caged breeding achieved better results in more quality indicators compared to the eggs from litter breeding. [ABSTRACT FROM AUTHOR]

In this experiment the effects of different housing systems on physical indicators of egg yolk and egg albumen quality of table eggs were studied. Hens of laying hybrid Lohmann Brown Lite were housed in two different housing systems, in enriched cage or on floor housing system. In both systems, the hens were kept under standard bioclimatic conditions. Eggs (n = 540) were collected from the first phase of the laying cycle, at monthly intervals, at the age of laying hens 30-42 weeks. Egg albumen weight (g), egg albumen percentage (%), egg albumen index, Haugh units (HU), egg yolk weight (g), egg yolk percentage (%), egg yolk index, egg yolk color (HLR) were evaluated. The results showed that in egg albumen quality indicators the differences in egg albumen weight (40.5 ± 4.3; 41.4 ± 3.5 mean ± SD) and egg albumen percentage (62.4 ± 3.9; 63.8 ± 6.1 mean ± SD) were significantly higher (P <0.05) for hens housed on the floor. In Haugh's units and the egg albumen index, the differences were statistically insignificant (P ≥ 0.05). Yolk quality indicators, namely the percentage of yolk (27.1 ± 2.4; 25.8 ± 3.1 mean ± SD) and the yolk index (47.4 ± 3.1; 43.5 ± 5.7 mean ± SD) found statistically significant differences in favor of eggs from hens housed in enriched cages. In egg yolk weight and egg yolk color, differences between eggs from both systems were noticeable. The results obtained show that the quality indicators of the internal egg content of both housing systems were comparable. [ABSTRACT FROM AUTHOR]

The aim of this study was to determinate the effect of the clove (Syzygium aromaticum) essential oil to the egg production parameters and egg quality of laying hens. A total of 40 Isa Brown laying hens were divided into 4 groups (n=10). The laying hens were fed 20 weeks ad libitum. The control group was fed with complete feed mixtures without additives. The first group of hens was fed a diet with complete feed mixtures with 0.3 ml.kg-1 of clove essential oil. The second group of hens was fed a diet with complete feed mixtures with 0.6 ml.kg-1 of clove oil and the third group of hens was fed a diet with complete feed mixtures with 1 ml.kg-1 of clove oil. Egg production, egg weight (g), specific egg weight, albumen weight (g), albumen index, Haugh Units (HU), yolk weight (g), yolk index, yolk colour (HLR) were studied. The results show that the addition of clove oil, especially in the group of laying hens with the addition of 1 mg.kg-1 clove oil had no significantly different (P>0.05) to the egg production (the order of the groups: 90.3; 91.8; 91.3; 92.6%). In egg weight were found no significant differences between groups. The addition of 1 ml.kg-1 clove oil had significant (P>0.05) influenced the albumen index and the addition of 0.6 ml.kg-1 and 1 mg.kg-1 clove oil had significant (P>0.05) influenced Haugh units. In the control group was found not significant (P>0.05) different in yolk weight compared with other groups. In the other parameters of egg quality (albumen weight, yolk index, yolk colour) with the addition of clove oil were found no significant differences between groups. [ABSTRACT FROM AUTHOR]

The aim of our experiment was to evaluate the influence of propolis extract on internal egg quality parameters of laying hens' hybrid Hy-Line Brown. For housing hens (n=40) three storey enriched battery cage was used in which hens were divided in groups (n=10). In the control group of hens complete feed mixtures without any additions were fed. In the first experimental group complete feed mixture was enriched with propolis extract in a dose of 0.1 g.kg-1. In the second experimental group propolis extract was added to the feed mixture at a dose of 0.25 g.kg-1. The third experimental group was enriched with propolis extract in a dose of 0.4 g.kg-1. All groups were fed ad libitum. Complete analysis of the table egg quality was used to evaluate quality parameters: egg weight (g), albumen weight (g), albumen index, Haugh Units (HU), yolk weight (g), yolk index, yolk colour (HLR). The results show that supplementation of feed mixture with propolis extract in a doses 0.25 g.kg-1 and 0.4 g.kg-1 significantly increased egg albumen index and Haugh Units (p≤0.05) (values of Haugh Units of albumen in the order of the groups (mean±S.D): 79.87±7.23, 80.58±7.60, 82.11±8.36, and 81.66±9.16 HU). However, the addition of propolis extract in a same doses significantly decreased yolk weight (p≤0.05). The values of the other eggs quality indicators were comparable with the control group (p>0.05). [ABSTRACT FROM AUTHOR]

The aim of our experiment was to evaluate the influence of probiotic preparation based on lactobacillus; probiotic preparation based on enterococci or humic acid on egg production and selected internal egg quality parameters of laying hens' hybrid Lohman Brown Lite. For housing hens (n=60) three storey enriched battery cage was used in which hens were divided in groups (n=15). In the control group of hens complete feed mixtures without any additions were fed. In the first experimental group complete feed mixture was enriched with probiotic enterococci based preparation in a dose of 0.5 g x kg-1. In the second experimental group probiotic lactobacilli based preparation was added to the feed mixture at a dose of 0.5 g x kg-1. The third experimental group was enriched with 0.5% concentration of humic acid. All groups were fed ad libitum. Egg production and egg weight were recorded daily. Complete analysis of the table egg quality was used to evaluate quality parameters: yolk weight (g), yolk index, yolk colour (HLR), albumen weight (g), Haugh Units (HU), and albumen index). The results show that supplementation of feed mixture with both kind probiotics as well as humic acid increased egg production (p>0.05) (values of average intensity of laying in the order of the groups: 90.3; 92.0; 91.6 and 92.4%). The addition of probiotics or humic acid only slightly influenced egg weight (p>0.05). The addition of both kind of probiotics influenced non-significant positive albumen index (p>0.05). The supplement of probiotics on lactobacilli based statistically significantly increased Haugh Units (p≤0.05). The supplement of humic acid statistically significantly increased albumen index and Haugh Units (p≤0.05). The others qualitative parameters of egg internal content were with probiotics or humic acids addition insignificantly influenced (p>0.05). Doses of supplements used in this study did not significant negatively influenced monitored egg quality parameters. Based on these findings and the beneficial effects of substances on the poultry health confirmed by other authors we recommend use of these substances as supplements to the feed mixtures for laying hens. [ABSTRACT FROM AUTHOR]

In this experiment the effects of supplementing of the diet for laying hens with sodium selenite (SS) or selenized yeast (SY) on the quality and content of some minerals of eggs were studied. Hy-Line Brown chickens were randomly divided on the day of hatching into 4 groups (12 birds per group). The birds were fed from day 1 of life till 9 months of age with diets differing in amounts and/or forms of selenium. The control group received a basal diet (BD) containing selenium naturally occurring in feeds (0.1 mg Se/kg of dry matter (DM)). The first and second experimental groups were fed by the same BD enriched with Se at a dose of 0.4 mg/kg DM from sodium selenite or selenized yeast, respectively. The feed for the third experimental group consisted of BD supplemented with selenized yeast to a final selenium content of 1.0 mg/kg DM. The results showed that supplementation of SY to the diet significantly affected egg weight and Haugh units. The Haugh units in both hybrids were higher in all experimental groups of hens fed with feed supplement of selenium in both forms, with significant differences only in the groups with addition of organic forms at both doses compared to the control group (84.52±3.87, 86.60±3.80, 87.21±4.10*, 86.93±3.56*, P<0.05), respectively. Freshness of eggs was positively influenced by the addition of selenium, but with no statistically significant difference (P>0.05). Higher values were recorded in each of the four analyzes in the groups with the addition of selenium in the form of selenized yeast. Analyzing after three weeks of storage showed an obvious decrease of Haugh units in relation to the decreasing quality of the internal contents of eggs (75.39±3.07, 76.15±2.97, 78.77±4.32, 78.24± 4.84, P>0.05) but still retained a tendency to higher values in groups with the addition of selenium, especially organic form. [ABSTRACT FROM AUTHOR]