Effects of dietary inorganic phosphorus levels on growth, liver and intestinal morphology and digestive enzymes in fingerling obscure puffer (Takifugu obscurus)
2021
Liu, Qingying | Wan, Fen | Liu, Yang | Liu, Ruoshuang | Tang, Qipei | Wang, Anli | Ye, Chaoxia
Phosphorus (P) is involved in extensive metabolism and fish attain most of P from their diets. However, little is known about the optimal supplemented amount of P in diet for Takifugu obscurus (obscure puffer). To explore the effects of P on growth performance, tissues mineralization, digestive organs structure, and digestive capability, six diets supplemented with at 0, 2, 4, 6, 8 and 12 g/kg P were prepared and fed to obscure puffer (11.92 ± 0.19 g) for 56 days. The results showed that the highest final body weight, specific weight gain rate and protein efficiency ratio were observed in puffer fed diet supplemented with 6, 8 and 12 g/kg P. Dietary inorganic P supplements markedly increased P and calcium concentrations of the whole-body, muscle and vertebrae. The crude lipid content of whole body and muscle, plasma cholesterol and triglyceride content were reduced with increasing inorganic P supplement. For digestive capability, hepatic and intestinal structure and villi length of intestine were also significantly improved in puffer fed 6, 8 and 12 g/kg inorganic P diet. Moreover, hepatic and intestinal lipase activities were significantly enhanced in fish with raising inorganic P supplement in diet. Hepatic and intestinal amylase activities were markedly increased in puffer fed 8 g/kg inorganic P diet. The present study indicated that optimal dietary inorganic P level could promote growth by improving liver and intestinal morphology, vertebrae mineral deposition and increasing digestive capability in obscure puffer, which suggested that the range of supplemental inorganic P is estimated to be 4.5–6.4 g/kg based on the broken-line analysis of whole body and vertebrae P content.
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