Document Type : Original Article
Authors
1
Cell Biology Department, National Research Centre, Giza, Egypt
2
1Cell Biology Department, Biotechnology Research Institute, National Research Centre, 33 El-Bohouth Street, P.O:12622, Dokki, Giza, Egypt.
3
Department of Animal Production, Agricultural and Biology Institute. National Research Centre, 33 El-Bohouth Street, P.O:12622, Dokki, Giza, Egypt.
4
Department of Cell Biology, Biotechnology Research Institute, National Research Centre, Dokki, Giza, 12622, Egypt
5
Hydrobiology Department - Veterinary Research Institute. National Research Centre, Egypt.
6
Department of Animal Production, Agricultural and Biology Institute. National Research Centre, Dokki, Giza, 12622, Egypt.
7
Department of Animal Production, Agricultural and Biology Institute. National Research Centre, Dokki, Giza, 12622, Egypt. research centre
Abstract
This study investigated the effects of dietary dried yeast on growth performance, blood constituents, and gene expression in the Nile tilapia fries reared under different water temperatures. A total of 180 fries (initial average weight 146.17 ± 0.845 g per aquarium) were distributed into 18 aquaria (10 fries each) and assigned to six treatments: G1, G2, and G3 consisted of a basal diet at 28, 31, and 34°C, respectively, while G4, G5, and G6 received the basal diet supplemented with 1.2% dried yeast for 60 days, followed by exposure to 28, 31, and 34°C, respectively, for 15 days to simulate thermal stress. Growth parameters including final weight (FW), total body weight gain (TBWG), average daily gain (ADG), specific growth rate (SGR), relative growth rate (RGR), feed intake (FI), crude protein intake (CPI), and protein efficiency ratio (PER) were significantly improved, while feed conversion ratio (FCR) was reduced in yeast-fed groups (G4–G6). Serum biochemical analysis revealed reduced AST and cholesterol levels with yeast supplementation under elevated temperature, while ALT and albumin showed significant variations. Gene expression analysis showed that 34°C with yeast supplementation was the most favorable condition for upregulating IGF1, IGF2, and GH in liver tissues and GH in gills, whereas 28°C with yeast promoted IGF1 and IGF2 in gills. Additionally, 31–34°C with yeast improved liver and kidney functions. Overall, yeast supplementation, particularly at 34°C, enhanced growth, blood biochemistry, and growth-related gene expression, supporting its application in aquaculture under thermal stress.
Keywords
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