Effects of phytase on vertebral shapes and non-specific immune related enzymes activities in channel catfish (Ictalurus punctatus)
Various plant proteins such as soybean meal and canola meal were considered promising protein sources as substitutes for fishmeal. However, they would enhance the presence of ant-i nutritional factors like phytate. Phytate (myo-inositol-hexaphosphate phosphohydrolase) was the main storage form of ph...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Zhejiang University Press
2014-01-01
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| Series: | 浙江大学学报. 农业与生命科学版 |
| Subjects: | |
| Online Access: | https://www.academax.com/doi/10.3785/j.issn.1008-9209.2013.04.035 |
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| Summary: | Various plant proteins such as soybean meal and canola meal were considered promising protein sources as substitutes for fishmeal. However, they would enhance the presence of ant-i nutritional factors like phytate. Phytate (myo-inositol-hexaphosphate phosphohydrolase) was the main storage form of phosphorus (P) in plant proteins and not available for fish due to the lack of intestinal phytase for efficient phytate hydrolysis during digestion. Therefore, most of the phytate-P was excreted into the water which contributed to eutrophication effects. Phytase could be added to plant-based diets to hydrolyze non-digestible phytate into available-P during passing through the fish gut and improve the P availability, which reduced P excretion and its loss into the environment in fish diets. Furthermore, phytase could also improve protein digestibility by hydrolyze the form of phytate-protein complexes that are resistant to proteolytic digestion. In the present, most researches on phytase were directed toward determining its effect on bioavailability of nutrients (P and protein) and the growth performance of fish. Based on the fact that nutrients (P and protein) were essential to maintain bone health and non-specific immune responses in fish, it was necessary to explore the effects of phytase on the bone health and non-specific immune responses in fish.This experiment was conducted to evaluate the effects of different levels of liquid phytase on vertebral shapes and non-specific immune responses in channel catfish (Ictalurus punctatus). Six isonitrogenous (37.50% crude protein) and isocaloric (17.00 kJ/g gross energy) diets were formulated, a negative control (NC) diet: a basal diet was supplemented with 1% dicalcium phosphate (CaHPO<sub>4</sub>), a positive control (PC) diet: the NC diet was supplemented with another 1% dicalcium phosphate (CaHPO<sub>4</sub>), in addition, four phytase supplementation groups: the NC diets with graded levels (250, 500, 1 000, 2 000 U/kg) of phytase were assigned and fed channel catfish (5.78±0.07) g/individual with 5 replicates for 60 days after a foster period.Results showed that the mass gain rate and feed conversion ratio were significantly improved by phytase supplementation compared with NC group (P < 0.05). Especially in 1 000 U/kg group, the mass gain rate reached the most positive value by 117.42% compared with PC group (P < 0.05). The protein retention efficiency was significantly improved by phytase supplementation compared with NC group (P < 0.05) and no significant differences were observed between phytase addition group and PC group (P > 0.05), and the P retention efficiency was increased significantly (P < 0.05) with the level of phytase supplementation increasing. The curvature and scoliosis in the middle part of vertebrae were observed in NC group. In addition, the activity of lysozyme (LSZ) in liver was significantly higher than PC group when phytase was supplemented with 500 U/kg (P < 0.05) and the activity of LSZ in head-kidney was highest in 2 000 U/kg group (P < 0.05). A significant improvement (P < 0.05) in PC group on the activity of superoxide dismutase (SOD) in liver was observed. For the activity of alkaline phosphatase (AKP) in liver, no significant differences were observed between 500 U/kg group and PC group (P > 0.05).In conclusion, the optimum level of phytase supplementation is 1 000 U/kg and phytase supplementation increas growth performance and protein retention efficiency, ameliorate vertebral malformations and improve nonspecific immune related enzymes in channel catfish. |
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| ISSN: | 1008-9209 2097-5155 |