Influence of the genotype of the hen (Gallus gallus domesticus) on main parameters of egg quality, chemical composition of the eggs under uniform environmental conditions

The objective of this study was to identify and compare the quality characteristics and concentrations of various compounds in eggs from several pure breeds and lines of hens reared under the same environmental conditions and fed a commercial feed. A total of 280 hens aged 52 to 56 wk belonging to 14 different breeds or lines of hens worldwide were included in this study. Their eggs were characterized by wide differences in various egg quality parameters. Breeds and lines of hens with a higher lutein content in eggs were characterized by a lower beta-carotene content (e.g. Hy line brown, Cochin miniature, Ayam Cemani) (P < 0.001). Additionally, vitamin D, cholesterol, and fatty acid contents were also different between eggs, from 1.51 to 1.79 μg/100g; from 14.1 to 15.4 mg/g fat, PUFA from 19.6 to 22.8 g/100g fat, and SFA from 32.8 to 37.8 g/100g fat respectively (P < 0.001). Lysozyme content also exhibited significant variation among breeds, with some showing a 2-fold higher content in eggs compared to others (0.31% - cochin miniature, 0.66% Faverolle) (P < 0.001). Our study demonstrated that intensively selected hen breeds like Hy-line Brown Hybrid had an improved egg quality seen by the increase in many parameters (e.g., egg weight, Haugh unit, Lutein, vitamins D, MUFA) compared to pure breed hens. In conclusion, genetic differences between breeds and lines of hens have a significant impact on the quality of eggs.

Effect of weight and storage time of broiler breeders' eggs on morphology and biochemical features of eggs, embryogenesis, hatchability, and chick quality

The transfer of hatchability results obtained under experimental conditions to the commercial ground with a positive financial effect proves the value and usefulness of these data. On the other hand, finding results on commercial processes of broiler breeders' egg incubation in the literature is challenging. The presented study aimed to determine the effects of egg weight and storage time on the physical, biochemical characteristics of hatching eggs, embryogenesis and hatchability in Ross 308 broiler breeders. On the laying day, the eggs were divided into four weight groups: S - small eggs (57-61 g), M - medium eggs (62-66 g), L - large eggs (67-71 g), and XL - extra-large eggs (72-76 g). The eggs were then stored for 3, 7, 14, and 21 days under controlled conditions. As the egg storage time increased, a decrease in the yolk quality (lower index) was observed. The highest Haugh units were found in eggs from the S and M groups. The cholesterol content of the M, L, and XL groups was lower on days 7, 14, and 21 as compared to that of eggs only stored for 3 days. Egg weight loss during incubation decreased with an increase in the egg weight. An extension of the egg storage time caused an increase in the loss of egg weight. On the 14th and 18th days of hatching, an increase in the eggshell temperature was noted with an increase in the weight of the egg. The eggs stored for 7 days were characterised by the highest shell temperature on each day. The highest hatchability percentage was recorded for the M group. The hatchability rate decreased with the prolongation of the storage time, while the number of crippled chicks after hatching increased. The results confirmed that the increased weight of the eggs and prolonged storage time (14 and 21 days) increased the weight and decreased the length of the newly hatched chicks, respectively. Chicks from the heaviest eggs and those stored for 14 and 21 days showed poor results on the Pasgar score® test. The observations indicate the need to adopt various (of those available) methods to assess the quality of newly hatched chicks in hatcheries in order to produce high-quality broiler chickens. The results also indicate that prolonged egg storing beyond 14 days may affect the thyroid hormone economy during the hatching of chicks, especially in the XL group.

Effect of age of Japanese quail on physical and biochemical characteristics of eggs

The aim of the study was to investigate the effects of age of birds on egg quality in Japanese quail. The eggs were randomly selected from among all eggs laid on the same day when the birds were 15, 23 and 31 weeks old. At each time point, 90 fresh eggs were evaluated for their physical and biochemical characteristics. Egg weights were similar over time. At 23 and 31 weeks, the eggs had less shell than at 15 weeks. Crude fat and ash contents of the eggs increased with the age of the birds. Crude protein was also highest in eggs of the oldest quail. At 31 weeks old, the eggs were lowest in pH of yolk and white. Quail that were 23 and 31 weeks old laid eggs with significantly higher polyunsaturated fatty acid (PUFA) and lower saturated fatty acid (SFA) contents. The lowest cholesterol content was in egg yolks from 23-week-old quail. The oldest birds had the highest contents of sodium, potassium, zinc, selenium, copper, and manganese. The content and activity of lysozyme decreased with ageing of the birds. From the consumers’ point of view, eggs from older birds appeared to be the most valuable. At the same time, as the quail ages, the antibacterial properties of eggs deteriorate, which may indicate a shorter shelf life.