Improvement of growth and antioxidant status in Nile tilapia,Oreochromis niloticus,fed diets supplemented with mushroom stalk waste hot water extract

Mushroom stalk waste (MSW) generated from the oyster mushroom industry is drastically increasing and safe disposal of MSW is becoming a critical issue worldwide. Mushrooms are an established, excellent source of nutraceuticals and antioxidants, and therefore MSW may confer similar effects when consumed. The severe deterioration of aquatic habitat may compromise the homoeostasis of antioxidative metabolism of Nile tilapia, Oreochromis niloticus, which resulted in a reduced total production. Based on this paradigm, hot water extracts (HWE, 2‐ and 5‐h) of MSW were evaluated as a supplement in fish feed and determined the effect on growth performance and the antioxidant status of Nile tilapia, O. niloticus, in vivo. The HWE 5‐h contained significantly higher amounts of nutrient and β‐glucan than HWE 2‐h (P < 0.05). Four standardized in vitro antioxidant assays showed that HWE 5‐h was a better antioxidant agent than HWE 2‐h (P < 0.05). Tilapia fingerlings fed 5 g kg^?1 HWE supplemented feed produced better (P < 0.05) growth and higher antioxidant enzyme activities than 10 g kg^?1 HWE, CD and BD. Thus, HWE of MSW included at 5 g kg^?1 may be beneficial to tilapia farming and may also provide a way of disposing the waste created by mushroom farming.