Dietary chromium enhances carbohydrate utilization and metabolic gene expression while alleviating cold stress in Labeo rohita fingerlings

Abstract

The winter months pose challenges for the growth and survival of L. rohita by reducing the metabolism and feed intake. L. rohita naturally thrives on herbivorous diet and effectively utilizes carbohydrates to meet the energy demand, but their efficiency diminishes at low temperatures during winter seasons in culture ponds. To address this issue, chromium picolinate, an organic compound known to enhance carbohydrate utilization and thermogenesis, was incorporated into the diet and fed to L. rohita fingerlings reared under low water temperature (18.24 ± 0.18°C) for a 60-day feeding trial. 180 fingerlings (Average weight 10.30 ± 0.15 g) were randomly stocked into six treatment groups. The first three groups were given semi-purified diets containing 400 g carbohydrate/kg diet with varying doses (0.4, 0.8, and 1.2 mg/kg diet) of chromium picolinate. The next three groups received a 430 g carbohydrate/kg diet with similar doses of chromium picolinate. The result indicated that the dietary carbohydrate (430 g/kg diet) showed significantly better growth performance like weight gain (WG), weight gain percentage (WGP), specific growth rate (SGR), protein efficiency ratio (PER), and lipid efficiency ratio (LER), with the lowest feed conversion ratio (FCR). Additionally, the combination of dietary carbohydrate (430 g/kg) and chromium (1.2 mg/kg) improved the growth performance and reduced FCR (p < 0.05). Moreover, the digestive enzymes (amylase, protease, and lipase) increased significantly with the dietary carbohydrate (430 g carbohydrate/kg diet) and cumulative performance in synergetic with chromium. The dietary carbohydrate and chromium have individual effect on metabolic enzyme activities, which increased significantly (p < 0.05). Conversely, superoxide dismutase activity in liver and gill tissues was reduced significantly under these dietary treatments. The gene expression study revealed that the dietary carbohydrate 430 g/kg diet and 1.2 mg/kg chromium picolinate significantly upregulated the expression of genes associated with energy metabolism and stress response. In conclusion, the study suggests that supplementing rohu fish diets with 1.2 mg chromium picolinate/kg diet can significantly enhance carbohydrate utilization (430 g carbohydrate/kg diet) and overall growth performance at low temperature.