Effect of dietary vitamin A deficiency on growth performance, feed utilization and immune responses of juvenile Jian carp (Cyprinus carpio var. Jian).

摘要

The aim of this study was to determine the effect dietary vitamin A deficiency on the growth performance, feed utilization and immune response of Jian carp. Two diets were compared in this study. The basal diet was formulated to be vitamin A-deficient. Before the formulation of diets, the vitamin A contents of ingredients were analysed, and vitamin A was found to be absent in the fish meal, rice protein meal, alpha -starch and soya oil. The final level of vitamin A was 3969 IU/g in the vitamin A-supplemented diet (vitamin A acetate). A total of 240 fish were randomly distributed into each of 6 glass tanks with 3 replicates per treatment. Fish fed the vitamin A-deficient diet showed normal behaviour and appearance for about 30 days. Thereafter, slight reduction in appetite, loss of body colouration, exophthalmia, sluggish movement, haemorrhage in the skin, fins and hepatopancreas, spinal deformities and increased mortality were observed. None of these deficiency signs were observed in fish fed the vitamin A-supplemented diet during the experiment. Significant differences in growth performance, feed utilization and erythrocyte and leukocyte counts were observed between the 2 treatments. Fish fed the vitamin A-supplemented diet had higher weight gain (WG), specific growth rate (SGR), survival rate (SR), feed intake (FI), protein retention ratio (PRR) and lower feed conversion ratio (FCR). Condition factor (CF), hepatopancreas index (HI), hepatopancreas vitamin A content, anterior intestinal fold height, posterior intestinal fold height and spleen index (SI) were positively affected by the vitamin A supplement. The survival rate after challenge with Aeromonas hydrophila was significantly reduced in fish fed the vitamin A-deficient diet. It was concluded that vitamin A was necessary for growth and immunity of Jian carp.