Broiler egg storage induces cell death and influences embryo quality

Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, T6G 2P5, Canada.
Poultry Science (Impact Factor: 1.67). 08/2011; 90(8):1749-57. DOI: 10.3382/ps.2011-01361
Source: PubMed


It is well known that egg storage reduces embryo performance, but the fundamental reasons for reduced embryo quality remain unclear. The objective of this study was to investigate possible cellular and molecular mechanisms that might reduce embryo quality after egg storage. Broiler hatching eggs were obtained from the Ross 308 broiler strain, divided into 2 groups, and stored (4 and 14 d) under the same temperature and humidity conditions. Samples of the eggs were used to assess embryo quality by determining daily embryo weight (wet and dry) from 4 to 21 d of incubation. To understand possible cellular and molecular mechanisms that might affect embryo quality, blastoderms (unincubated embryos) were isolated from a sample of eggs from each storage group, dissociated into single cells, and subjected to flow cytometry analysis to differentiate between viable, apoptotic, and necrotic cell populations. Quantitative real-time PCR analysis was used to compare the expression of selected apoptotic genes (Bcl-2 homologous antagonist/killer gene, Bcl-2-associated X gene, Bcl-2-related ovarian killer gene, B-cell lymphoma 2 gene, and B-cell lymphoma xL gene) in blastoderms and embryos (6 d old after incubation). Data were analyzed by the MIXED model procedure of SAS (SAS Institute, Cary, NC), with significance set at P ≤ 0.05. After covariance analysis of initial egg weights, the results showed decreased daily embryo weights (wet and dry), an indication of decreased embryo quality that could affect hatch quality. In addition, a decrease in blastodermal cell viability was associated with an increased percentage of apoptotic cell deaths (P < 0.0001). Expression of pro-apoptotic genes (Bcl-2 homologous antagonist/killer gene, Bcl-2-associated X gene, and Bcl-2-related ovarian killer gene) were upregulated at the blastodermal level as the storage duration increased, but all genes were downregulated after 6 d of incubation. This suggests that an increase in egg storage duration could activate mechanisms of apoptotic cell death at the blastodermal level, which may be one of the molecular mechanisms that leads to reduced daily embryonic weight during incubation. Experimental controls capable of reducing the cellular and molecular mechanisms of egg storage should be used to increase embryo quality.

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Available from: Jacob Alhassan Hamidu, Jul 02, 2014
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    • "The higher levels of O 2 , CO 2 and embryonic heat production in embryos of 4 days stored eggs are indications of higher or adequate metabolism which could have resulted in the higher embryonic weight and chick weights observed in our previous study. Thus slower metabolism in 14 days stored eggs may have resulted in slower metabolism of embryonic cells, the whole embryo and subsequent delayed of pipping and hatching as observed in our previous study (Hamidu et al., 2011). An important consequence of this could be higher number of dead in shell embryos or increased late embryo mortality. "
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    ABSTRACT: The research investigates the effects of prolonged storage of hatching eggs on eggshell conductance (G) and embryonic metabolism of Ross 308 broiler breeder eggs. Hatching eggs were collected, weighed and stored for 10 days. After 10 days, a second group of eggs was collected as in the first, weighed and stored for additional 4 days to set up two pre-incubation storage treatments (4 days and 14 days). A sample of eggs (n=30) were placed in desiccator to determine the G value. Additional eggs (n=24) were incubated in metabolic chambers to monitor daily embryonic O2 consumption and CO2 production for the calculation of embryonic heat production (EHP), a parameter used to indicator embryonic metabolism. All data were analyzed using SAS Proc Mixed procedure at P ≤ 0.05. Egg storage had no effect on initial egg weight before and after egg storage and G. The O2 consumption, CO2 production and EHP were significant particularly during the mid and late periods of incubation in 4 days compared to 14 days storage. Reduction in embryonic metabolism of 14 days stored eggs during late incubation period in can negatively affect embryonic growth, hatching process and chick quality.
    07/2014; 4(7):973-977. DOI:10.5455/jasa.20140713053547
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    ABSTRACT: A hypothesis was tested that providing buffer solutions or antioxidants during egg storage may help embryos in combating the harmful effect of longer holding periods. Hatching eggs were obtained from a breeder flock (35 wk) and stored for 13 d before setting. In experiment 1, the eggs were injected (d 4) with bicarbonate buffer solution (BBS) or PBS. For experiment 2, l-carnitine (LC), vitamin E (VE), and vitamin C (VC) were injected (d 7) at 3 different doses. The egg internal quality characteristics were evaluated at 2-d intervals after injection and the remaining eggs were incubated for 21 d under standard conditions. At 21 d, hatchability was recorded and unhatched eggs were broken open to assess the fertility and stage of embryonic mortality. No differences were noted in albumen pH due to using buffer solutions or antioxidants except for a decreased pH at 2 d postinjection of the high dose of VC (75 mg). In ovo injection of BBS increased the albumen index and Haugh unit at d 6 postinjection; however, the response to PBS was not different from that in the control group. In ovo injection of antioxidants did not influence the albumen index, Haugh unit, and yolk index; however, the yolk percentage was partly affected. Irrespective of the dosage, hatchability was greatly decreased following in ovo injection of buffers or antioxidants (as low as 4.3 vs. 87.5% in control), with the highest mortality percentage recorded at early embryonic stages (d 0 to 6). Data suggested that, despite improvement in certain egg internal qualities, preincubational in ovo injection of BBS, PBS, LC, VE, or VC was associated with a profoundly decreased hatchability for which the underlying mechanism(s) remain(s) to be clarified.
    Poultry Science 11/2012; 91(11):2970-6. DOI:10.3382/ps.2012-02246 · 1.67 Impact Factor
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    ABSTRACT: 1,680 eggs were used to investigate the effect of egg storage time (EST) on egg quality, hatchability and chick quality traits of Hubbard (HU), Cairo B-2 (B2) and Fayoumi (FA) broiler breeders (48 wk of age). The HU are commercial broiler breeders, B2 is a new Egyptian broiler cross-line between Arbor Acres males and Egyptian native White Baladi females in the 8th generation and FA is an Egyptian native breed. There were 12 groups (4 replicates per group) arranged factorially with 3 broiler breeders (HU, B2 and FA) and 4 ESTs (0, 3, 7 and 10 d). Fertility rates were 94.6, 89.2, and 84.8% for HU, B2, and FA, respectively. No interaction effects were detected for all traits except for Haugh units that were of HU´s eggs in between FA's eggs values (the highest) and B2's eggs values (the lowest) for all ESTs except for 10 d that, the values decreased faster in HU´s eggs than other breeders' ones. Results indicated that HU fresh egg and chick weights (71.8 and 46.6 g) were higher than FA (52.1 and 33.4 g) and B2 (67.1 and 43.4 g) were intermediate, respectively (P<0.0001). The same trend was observed in hatchability (88.5 vs. 82.3 vs. 74.2%) for HU, B2 and FA, respectively. Increasing EST to 7 or 10 d negatively (P<0.0001) affected egg weight (63.8, 63.0, 61.7 and 60.9 g), hatchability rate (84.2, 83.3, 80.3 and 78.9%) and chick weight (42.2, 41.6, 40.6 and 40.0 g) for 0, 3, 7 and 10 d ESTs, respectively. However, egg shape index, yolk color, shell thickness, clear eggs, piping eggs, embryonic mortality, mortality rate at hatch, percentage of culled chicks at hatch and chick navel quality were not affected by increasing EST up to 10 d. To conclude, HU, B2 and FA breeds were different in egg weights, egg Haugh units, yolk index, yolk color, shell thickness, fertility, hatchability, late embryonic mortality (19-21 d of incubation), one-d-old chick weights and chicken mortality rates at hatch. Also, EST for 7 d or more was not recommended for these breeds.
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