Shunzo Miyoshi

Genetic differences in steroid-induced protein synthesis in vivo of the liver and magnum in immature chicks (Gallus domesticus).

1. The present study was conducted to investigate whether or not the rate of steroid-induced protein synthesis measured in vivo in the liver and magnum was different between chicks from different genetic backgrounds. 2. Both protein deposition and synthesis in the liver were enhanced after the administration of beta-estradiol with or without testosterone. In the magnum, the combined administration of beta-estradiol and testosterone resulted in significantly higher protein deposition and synthesis than did beta-estradiol alone. 3. After the administration of beta-estradiol and testosterone, protein deposition in the liver and magnum was lower in broiler than in layer and dual-purpose chicks. Protein synthesis in the magnum tended to be highest, though not significantly, in layer, followed by dual-purpose and broiler chicks in decreasing order. 4. Steroid-induced protein deposition in the liver was not changed between chicks genetically selected for low and high albumen contents. In contrast, steroid-induced protein synthesis in the magnum was significantly higher in high-albumen birds than low-albumen chicks. 5. It was concluded that genetic traits for high egg production were well reflected in increased protein deposition and synthesis in the liver and especially in the magnum of immature female chicks stimulated by steroid hormone treatment.