ABSTRACT
The present study aimed to investigate the effect of different molting procedures on the post molt egg quality and some plasma blood constituents. Two hundred and seventy Hy-Line laying hens aged 60 weeks were randomly chosen from a large commercial flock. All hens were approximately of an equal body weight and similar performance.
Birds were divided into three groups. Birds of the first group (30 birds) were fed ad-libitum and considered as control. The second group (120 birds) was force molted by adding 1% zinc oxide on diet for 14 days. While birds of the third group (120 birds) were force molted by feed restriction (25%) for 7, days then fasting fore subsequent 7 days.
At the end of the force molting treatments (14 days) when hens completely ceased egg production, the 2nd and 3rd groups were equally divided into 4 subgroups each (30 birds each) and injected as follows:-1-Distilled water (1 ml) for 6 days. 2- Estradiol 17 ß (10 mg/ml) for 6 days. 3- Indomethacin (10 mg/ml) for 3 days then Bromocriptine (10 mg/ml) for 3 days. 4- Human Chorionic Gonadotrophin (HCG) 50 IU for 6 days.
Results indicated that: Injecting fast molted hens with either estradiol 17β or HCG increased shell thickness, yolk index, plasma albumen and plasma cholesterol. Fast molted hens injected with HCG improved Haugh units score and increased plasma total lipids and calcium. However, injecting fast molted hens with estradiol 17β increased the levels of plasma total protein, globulin and inorganic phosphorus. From this study, it could be recommended to use fasting to force laying hens to rest and injected with either estradiol 17 ß (10 mg/ml) or HCG (50 IU) to improve internal egg quality of laying hens during the second laying cycle.
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