الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
SUMMARY AND CONCLUSION
The present study was carried out in Poultry Physiology Research Lab at Faculty of Agriculture, Ain Shams University, from April 2021 to July 2021 under the Egyptian environmental conditions.
The study aimed to decrease the detrimental effects of long broiler breeder eggs storage period by using Short Period of Incubation During Egg Storage Period (SPIDES) technique, with or without late prenatal thermal conditioning on egg quality, hatchability, post-hatch productive and immune performance, some physiological traits, some histocytological observation of breast muscles and exploring the molecular mechanism of the hepatic expression of heat shock proteins (hsps), antioxidant enzymes and mitochondrial related genes of broiler under heat stress conditions.
Eight hundred Ross broiler eggs were divided into four main groups control kept in the storage room conditions, the 1st (S0) group was maintained under the optimal egg storage room conditions for 20 d, while The 2nd (S1),3rd (S2) and 4th (S3) were subjected in a separate room to SPIDES for 5 h at 37.8○C ± 0.1 once at day 5 , two times at day 5 and 10; and three times at day 5, 10 and 15 d after egg collection, through same period of storage.
At the 14th day of incubation, the main groups were randomly divided into two equal main subgroups, the control kept under the optimal conditions (TC0) and the thermal conditioned exposed to prenatal thermal conditioning (TC1) at 39.5 ○C ± 0.1 for 6h/ d from the 14th to the 18th embryonic day resulting finally in eight experimental sub-groups (S0TC0, S1TC0, S2TC0, S3TC0, S0TC1, S1TC1, S2TC1 & S3TC1).
The egg quality, embryo temperature, hatchability percentage, early, mid and late embryonic mortalities, post-hatching performance, post-hatching immunocompetence, some blood biochemical constituents, T3 plasma level, mRNA expression of Heat shock proteins’ gene of liver, mRNA expression of mitochondrial related genes and mRNA expression of hepatic antioxidant enzymes related genes in liver, histocytological measurements of pectoral muscles and liver histology were estimated.
The results obtained can be summarized as follows:
1. SPIDES did not affect external egg quality however, it enhanced the internal egg quality.
2. Averages egg weight loss% during storage period was significantly higher at SPIDES groups compared to non preincubated ones.
3. Prenatal thermal conditioning increased egg weight loss% during incubation compared to control.
4. Prenatal thermal conditioning caused a highly significant increase in eggshell temperature comparable to the control groups.
5. SPIDES for 3 times increased hatchability percentage and decreased embryonic mortalities rates in general.
6. Late embryonic TC increased hatchability percentage and decreased late embryonic mortality rate.
7. The best LBW, BWG and FCR values were conducted for group of three times SPIDES group followed by prenatal thermal conditioning S3TC1 or three times SPIDES with non-thermal conditioning group S3TC0, while control group (S0TC0) had the worst data at 35 DOA.
8. Mortality rate significantly reduced under heat stress conditions affected by SPIDES and TC.
9. At 35 DOA HDL were significantly increased by both SPIDES and prenatal thermal conditioning on contrast to triglycerides plasma levels.
10. Plasma concentrations of total protein, albumin and globulin were significantly increased at 35 DOA at prenatal thermally conditioned groups compared to the non-thermal conditioning group.
11. Plasma liver function enzymes were significantly decreased by SPIDES treatment compared with control.
12. Concentration of calcium was significantly decreased in chicks hatched from normally incubated eggs, compared prenatal thermally conditioned chicks while phosphorus plasma level was not significantly affected.
13. Pectoral muscles relative weights were significantly increased by prenatal thermal conditioning while SPIDES had no significant effect.
14. Heart relative weights at 35 DOA were significantly affected by raising under heat stress conditions and had the higher value for the control groups compared to the prenatal thermally ones.
15. T3 plasma levels at hatch were significantly higher at thermally conditioned groups compared to control reverse to its rates on 35 DOA.
16. Rectal temperatures were not significantly affected by SPIDES or prenatal thermal conditioning at hatch and at 2 WOA but under heat stress conditions at 35 DOA were significantly reduced at TC group compared to control.
17. (IgM) and (Ig Y) plasma levels were increased in SPIDES and TC groups at both hatch and at marketing age.
18. Hshp70, 60, 90B and 90A expression was significantly decreased in thermally conditioned groups compared to control.
19. Hshp9A, SOD2 and NOX4 expression also were significantly decreased by prenatal thermal conditioning
20. NOX4, SOD, CAT and CPT1A expression at 35 DOA were significantly decreased by prenatal thermal conditioning group.
21. Myocytes number of major pectoralis muscles/field was significantly increased at thermally conditioned group and at 3 times SPIDES group.
22. Liver histocytological observations improved by SPIDES and TC compared to control groups under the same heat stress conditions.
from the results reported herein, it could be concluded that:
Pre incubation SPIDES every 5 day after egg collection and Prenatal TC enhanced chick performance at 35 DOA by increasing LBW, breast muscles relative weights and breast myocytes number. SPIDES treatments enhanced chick immunocompetence by decreasing lysozyme activity and C-reactive protein concentrations and increasing immunoglobulin’s plasma levels. Furthermore, prenatal thermal conditioning treatments increased thermotolerance acquisition from hatch till 35 DOA by decreasing hsp70. 60. 90A and 90B gene expression, decreasing heat production through reduction of thyroid hormones plasma levels, as well as lowering rectal temperature and decreasing gene expression of mRNA heat shock proteins, mitochondrial related genes as well as hepatic antioxidant enzymes.