# Effects of different dietary starch sources on growth performance, hepatic antioxidant capacity, and muscle quality of adult grass carp (Ctenopharyngodon idellus)

## TL;DR

This study shows that using sorghum as a starch source in grass carp feed improves growth, liver antioxidants, and muscle quality compared to other starches.

## Contribution

The study identifies sorghum as a sustainable and effective alternative to wheat in grass carp feed.

## Key findings

- Sorghum improved final body weight and feed conversion ratio in grass carp.
- Sorghum enhanced hepatic antioxidant enzyme activities and gene expression.
- Sorghum improved muscle quality by increasing flavor-related amino acids and fatty acids.

## Abstract

Starch is a key component of herbivorous fish feeds, but its utilization efficiency varies across species. This study examines the effects of replacing wheat with different starch sources (barley, corn, sorghum, and broken rice) on the growth performance, hepatic antioxidant capacity, and muscle quality of grass carp (Ctenopharyngodon idellus), aiming to identify suitable starch sources for grow-out feed and provide a theoretical basis for developing efficient, environmentally friendly, and safe feed. Sorghum was chosen due to its superior nutritional profile, strong antioxidant properties, and potential as a sustainable alternative to wheat. The results showed that final body weight (FBW) was significantly higher in the S1 groups than in S2 (P < 0.05), the Feed Conversion Ratio (FCR) of the S2 group was higher than that of the S1 group. Biochemical analyses revealed that triglyceride (TG) and aspartate aminotransferase (AST) activities were similar and higher in S1 and S4 than in other groups. Hepatic superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities in S4 were comparable to S1 and significantly higher than in S2 and S5 groups. Additionally, malondialdehyde (MDA) levels were significantly higher in S2 than in S1, S3, and S4. At the molecular level, S4 showed significantly higher expression of hepatic glutathione peroxidase (gpx), cu/zn-superoxide dismutase (cuznsod), nuclear factor E2-related factor 2 (nrf2), and heme oxygenase 1 (ho-1), while the expression of Kelch-like ECH-associated protein-1 (keap1a) was downregulated. Sorghum promoted the accumulation of flavor-related amino acids and beneficial fatty acids in muscle tissue. In conclusion, compared to barley, corn, and broken rice, sorghum is an ideal and sustainable alternative to wheat in grass carp feed, offering significant potential for improving aquaculture feed formulations.

•Compared to other starch sources, sorghum improved grass carp growth•Sorghum enhanced SOD, GSH-Px, and CAT activity in grass carp over other starch.•Sorghum enhanced gpx, cuznsod, nrf2, and ho-1 expression compared to other starch.•Compared to other starch, sorghum improved the muscle quality of grass carp

Compared to other starch sources, sorghum improved grass carp growth

Sorghum enhanced SOD, GSH-Px, and CAT activity in grass carp over other starch.

Sorghum enhanced gpx, cuznsod, nrf2, and ho-1 expression compared to other starch.

Compared to other starch, sorghum improved the muscle quality of grass carp