Effects of Neutral Phytase Supplementation on Biochemical Parameters in Grass Carp, Ctenopharyngodon idellus, and Gibel Carp, Carassius auratus gibelio, Fed Different Levels of Monocalcium Phosphate

Abstract

Two 8‐wk studies were conducted to evaluate the effects of neutral phytase supplementation on hemato‐biochemical status, liver biochemical parameter, and intestinal digestive enzyme activity of grass carp, Ctenopharyngodon idellus, and gibel carp, Carassius auratus gibelio, fed with different levels of monocalcium phosphate (MCP). The control diet was prepared with 2% MCP but without phytase (P2.0). The other three experimental diets were prepared with the addition of 1.5, 1.0, and 0.5% MCP, respectively, when supplemented with 500 U/kg neutral phytase in each diet and designated as PP1.5, PP1.0, and PP0.5, respectively. The results indicated that the serum alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) activities, as well as the albumin (ALB) content were increased in grass carp (P < 0.05) and gibel carp (P > 0.05) fed with phytase‐supplemented diets. Meanwhile, the serum cholesterol, high‐density lipoprotein, and total protein contents of the two species of fish were increased in comparison to the control. In addition, dietary phytase inclusion did not significantly affect hepatic ALP, ALT, and AST activities in the two species of carp fed with different levels of MCP. Amylase activity increased in foregut and hindgut of both species when fed with the phytase‐supplemented diets while lipase activity was reduced in the foregut and hindgut in both fish. This study suggests that neutral phytase supplementation increases serum ALP, ALT, and AST activities but does not notably affect these enzyme activities in the liver of the two species of carp when fed different levels of MCP. On the other hand, amylase activity increased while lipase activity was reduced in the intestine of the species of carp fed with phytase‐supplemented diets.

The sparing effect of phytase in plant-protein-based diets with decreasing supplementation of dietary NaH2PO4for juvenile yellow catfishPelteobagrus fulvidraco

“…The possible reason might be that phytase can enhance the digestive enzyme activity and subsequently stimulate the nutrients digestion in fish. This hypothesis was verified in tilapia, grass carp Ctenopharyngodon idellus and gibel carp Carassius auratus gibelio that phytase enhanced the amylase, lipase and protease activities (Li, Li & Wu ; Nwanna ; Liu, Luo, Liang, Wang, Wu & Pan ). Furthermore, the hydrolysis of phytate also neutralizes the negative effects of phytate on proteins and on other nutrients utilization (Mitchell et al .…”

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“…Due to increasing demands with the passage of time, plant by-products are being used as the alternative protein sources in fish feeds but unfortunately they have antinutritional factor (Liu et al, 2013). To overcome this problem supplementation of phytase in fish feeds has been generally resulted to improve the bioavailability and utilization of plant minerals by fish (Cao et al, 2007).…”

“…Recent studies have shown that the addition of CA and phytase to the fish feed improved P and Ca content in Beluga (Huso huso) fed with soybean meal diets (Khajepour, Hosseini, & Imanpour, 2012;Liu et al, 2013). Combining a low dose (0.22%) of citric acid to the phytase supplemented diets significantly increased the activity of the enzyme (Phromkunthong et al, 2010).…”

“…There has been considerable research regarding the effect of dietary acidification on mineral utilization in terrestrial animals, yet studies on fish have been very limited. A recent study has shown that the addition of CA and phytase to fish feed improved P and Ca contents in Beluga (Huso huso) fed with SBM diets (Khajepour & Hosseini, 2012b;Liu et al, 2013). Combining a low dose of citric acid with phytase supplemented diets significantly increased the positive effects of the enzyme (Phromkunthong, Nuntapong, & Gabaudan, 2010).…”

“…Plant by-products are the alternative protein sources in fish feeds but unfortunately they have antinutritional factors such as phytate or phytic acid (Liu, Luo, Liang, Wang, & Wu, 2013). Phytate has alarming adverse effects on the fish digestive tract resulting in poor growth performance (Baruah et al, 2004).…”