Effect of dietary cholecalciferol levels and gibberellic acid on productive and reproductive traits, serum profile and bone mineralization of laying quail

Abstract

n experiment was conducted to investigate the effect of supplemental cholecalciferol (CC) separately or in combination with gibberellic acid (GA3) on the productive and reproductive traits, bone mineralization and serum profile of aged female japanese quail. 128 females and 64 males (at 42 weeks of age) were assigned to eight experimental groups. For ten weeks, each of the first four groups was fed one of the following four graded levels of CC: 450, 900, 1350 or 1800 IU/kg diet. The other four groups received the same CC levels plus 5 ppm GA3. It was shown that egg production percentage and egg mass were negatively affected by supplemental CC at 450 IU/kg. However, addition of GA3 improved egg production and egg mass at all levels of CC. Feed conversion ratio (g feed/g egg) improved linearly with increasing CC levels and the improvement was more remarkable with supplemental GA3. Feed consumption values affected neither by CC levels nor by GA3. Gibberellic acid supplementation significantly reduced serum concentration of albumin. Similarly, values of albumin to globulin (A/G) ratio indicated a better immune response. Serum globulin was not affected. Serum concentrations of both calcium and phosphorus significantly increased, as well as in the tibia of GA3 groups. Hatchability percentage was reduced but early and late embryo mortality increased due to feeding suboptimal level of CC (450 IU/kg), while GA3 supplementation improved hatching traits. Egg shell percentage improved with adding GA3 into the diets. This may be related to increasing calcium solublization. Tibia weight improved by increasing CC level and GA3 administration. Tibia ash percentage was adversely affected by low CC level, while GA3 addition caused a slight increment. In conclusion, supplemental 1350 IU CC with GA3 is needed for better productive and reproductive performance of old japanese quail hens.