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.

Antioxidant defence in the brain of 1-d-old chickens exposed in ovo to acrylamide.

1. Acrylamide (ACR) is a potent neurotoxicant, although information on its toxic influence on the developing neural system is still limited. The effects of in-ovo-injected ACR on the antioxidant system activity in the brain of newly hatched chickens was examined. This model eliminated the mother's contribution to embryonic development. It was also recognised as an adequate model for animal embryonic development. 2. ACR was injected on d 4 of embryogenesis - in doses of 1.25 and 2.50 mg/egg (n = 40 eggs/group/120 eggs). The doses corresponded well with ACR doses used in other animal studies and their concentrations in certain animal feeds. 3. Mortality and incidences of malformations were not found to increase significantly. Significant depletion of glutathione was detected in the cerebellum, cerebrum and medulla oblongata of specimens exposed to the highest doses of ACR. Enzymatic activity was affected by the highest ACR doses. Glutathione peroxidase (GPx) activity increased significantly in the cerebrum, medulla oblongata and the hypothalamus. Superoxide dismutase (SOD) activity increased significantly in hypothalamus and decreased in cerebellum and cerebrum. A significant depletion of catalase (CAT) activity was detected in cerebellum. In the hypothalamus, the increased SOD/GPx and SOD/CAT ratios suggest the risk of H2O2. 4. It was concluded that ACR significantly influences the antioxidative defence in the chicken brain at doses of 1.25 and 2.50 mg/egg.