Productive and physiological responses of Japanese quail embryos to light regime during incubation period

Abstract

This study was conducted to investigate the effect of light regime during egg incubation of Japanese quail embryos on growth during embryonic life, hatchability percentage, chick performance post-hatch life, embryo plasma thyroid hormone concentrations and some metabolic parameters. A total of 1400 hatching eggs of Japanese quail were collected at 10thand 14th weeks of age. Eggs were divided into two groups, the first group was set in incubator at dark, and the second group was set at light. White florescent light was used (20 watt) during the incubation period. The light intensity ranged from 620-835 lux at the surface of the fertile eggs. Results showed highly significant differences (P≤0.001) between both incubated groups on most of the studied traits. Relative embryonic weight and hatchability percentage were significantly higher in the light group by 2.05% and 5.63%, respectively than that in the dark group. Chicks hatched under light regime were significantly (P≤0.05) heavier in body weight (one-day old & 6 week old) and weight gain (0-6 weeks) than those hatched under dark regime. The best feed conversion was found for chicks hatched under light regime compared with those hatched under dark regime (3.78 vs. 4.43). Furthermore, light incubation group showed higher (P≤0.0001) plasma triiodothyronine hormone (T3 ) level and T3 /T4 ratio, plasma total protein, albumen, globulin, glucose, cholesterol, triglycerides and total lipids concentrations than those found in the dark incubation group. It was concluded that exposure to light during incubation period increased hatchability percentage and improved growth performance during embryonic life and post-hatch life by enhancing the physiologicalmetabolic processes.