الفهرس 
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Abstract
The study was carried out using two commercial layer flocks, the Bovans Brown and Lohman Brown located on the farms of Sharkia
province. The study consisted of the evaluation and analysis of fresh egg production and egg quality as well as the effect of exposure to various storage periods and temperatures. The purpose was to provide data on which breed is more suitable for our local environments and which storage environment is more appropriate to keep high quality table egg.
The results indicated that:
1- Bovans Brown excelled significantly Lohman Broil for fresh egg weight, percentage of HHEP; but the reverse was true for the percentage of HDEP (61.56 gm, 57.81% and 61.39% versus 60.18 gm, 56.62% and 61.91%, respectively).
- Bovans Browns had superior values for albumen height, albumen weight, Haugh units, yolk weight, yolk index, shell weight percentage and shell thickness was compared to those recorded for Bovans Brown (7.69 mm, 37.48 gm, 86.26, 16.75 gm, 0.41, 10.15% and 0.35 mm Vs. 6.99 mm, 37.08 gm, 81.26, 16.19 gm, 0.39, 9.66% and 0.33 mm; respectively).
- Lohman Brown had high values of percentage of albumen weight, egg index and weight loss and percentage compared to that recorded for Bovans Brown (61.59%, 77.12%, 1.17 gm, 1.84% Vs. 60.72%, 77.06%, 1.06 gm and 1.74%, respectively).
2-The Winter season was characterized by high estimated values of egg weight, percentage of FIDEP and percentage of I IHEP (63.26 gm, 67.60% and 63.80%). These values are comparable to those recorded in Autumn for egg weight and HMI) (56.68 gm and 56.38%) and in Summer for MEP (49.92%).
The winter season was characterized by having maximal values of Haugh units, albumen height, albumen weight and percentage, yolk index and shell weight (87.31, 7.78 mm, 39.45 gm, 62.30%, 0.45 and 6.25 gm; respectively) in comparison with other seasons, but minimal values of egg weight loss and percentage (0.65 gm and 1.03%).
- The summer seasons was of lower significant values for Haugh units, albumen height, yolk index, shell weight and percentage, shell thickness and egg shape index (74.58, .43 mm, 0.31, 5.76 gm, 9.60%, 0.32 mm and 75.49%; respectively). Maximal weight loss and percentage were also, recorded in Summer (2.03 gm and 3.06%).
3-Age intervals of laying hens affected significantly egg production and quality parameters. Age interval 33-42 wks, had the records, 63.08 gm, 68.12% and 64.61% for egg weight, HDEP% and 1-IHE11%, respectively. Age interval 22-32 wks had the records 56.48 gm and 55.71% for egg weight and HDEP%.
- Also, age interval 33-42 wks had the maximal value of albumen weight and percentage, albumen height, yolk index and shell weight (39.50 gm, 62.57%, 7.79 mm, 0.45 and 6.24 gm; respectively) and minimal value of weight loss and percentage (0.60 gm and 0.96%). Maximal Haugh units (87.24) were recorded at age interval 22-33 wks.
- Maximal egg weight loss and percentage were found at the period 53-63 wks. They were 1.91 gm and 2.96%.
4-Storage period influenced significantly the quality of table eggs. Maximal values of Haugh units, albumen height, albumen weight and percentage and yolk index were estiatmed for fresh eggs. These values were (91.29, 8.39 mm, 38.71 gm, 63.65% and 0.47; respectively). Stored eggs for ten and twenty days had the lower values, but maximal egg weight loss;
5-Storage temperature influenced significantly the quality of table eggs. Higher values of Haugh unit scores, albumen height, albumen wieight and percentage and yolk index (88.09, 7.83 mm, 38.06 gm, 62.06% and 0.45; respectively), and minimal weight loss and percentage (0.52 gm and 0.87%) were recorded for eggs kept at refrigeration temperature (5°C). Small values (82.79, 7.18 min, 37.02 gm, 60.83% and 0.38;
respectively) and higher weight loss and percentage (1.27 gm and 2.10%) were recorded for eggs kept at room temperature.
6-Bovans Brown hens had non significantly higher serum calcium level (22.22 mg/dL) and significantly higher serum phosphorus level (5.35 mg/dL) as compared with those of Lohman Brown (21.05 and 4.01 mg/dL).
7-Peak egg production had non significant higher serum calcium (22.36 mg/dL) and significant higher serum phosphorus (5.23 mg/dL) as compared with that of low production level (20.92 and 4.13 mg/dL).
In conclusion, Bovans Brown eggs obtained during different
seasons, age intervals and exposed to different storage periods and temperatures were superior for egg quality parameter when compared with those of Lohman Brown. Bovans Brown eggs are more suitable for longer storage periods at room temperature.
Refrigeration and short period of storage were the best methods to maintain optimum egg quality under the Egyptian environmental conditions. Albumen height, yolk index and shell thickness are the recommended measures for egg quality and freshness.