The study was performed to evaluate the effect of organic chromium (Cr), organic selenium (Se) or vitamin C (vit. C) alone or in combination on reproductive performance, and egg quality of Dokki-4 laying hens under hot summer conditions of Egypt. A total number of 240 hens plus 48 cocks from Dokki-4 strain at 30 weeks of age were randomly selected and distributed into eight groups with 3 replicates ( 10 hens + 1 cock) each. The remaining 24 cocks were also divided into 8 groups of 3 cocks each and housed separately for semen evaluation experiment. Treatments groups were fed a basal diet (control group) or the basal diet supplemented with either 400 μg Cr/kg diet (Cr group), 250 mg of L-ascorpic acid /kg diet (vit. C. group), 0.2 mg Se/kg diet (Se group), 400 μg Cr plus 250 mg of L-ascorpic acid/ kg diet (Cr + vit. C group), 400 μg Cr plus 0.2 mg Se/kg diet ( Cr + Se group), 2 mg Se plus 250 mg L-ascorbic acid/kg diet ( Se + vit. C. group) and 400 μ Cr plus 0.2 mg Se plus 250 mg ascorbic acid /Kg diet (Cr + Se + vit.C group). All groups were put under observation for 12 weeks. Results obtained can be summarized as follows: Supplementation of Cr, Se or vitamin C alone or in combinations significantly increased (P < 0.05) shell thickness, haugh units, albumin and shell to egg weight, sperm motility, ejaculate volume, sperm concentration, total sperm output, total motile sperm, live spermatozoa, semen quality factor and significantly decreased (P < 0.05) dead spermatozoa and seminal malondialdehyde (MDA) as compared with control group. The best result was obtained for layers fed diet containing the combinations of the three supplements (Cr, Se or vitamin C) as compared to other groups.
In conclusion, combinations of Cr, Se and vitamin C improved the most reproductive traits and egg quality of Dokki-4 strain under Egyptian hot summer.