Effect of four forms of zinc on growth performance, antioxidant activity and mineral retention in juvenile hybrid grouper (Epinephelus fuscoguttatus♀×E. lanceolatu♂)
1. Experimental Design
Three hundred and sixty of juvenile groupers with initial average weight of 11.00±0.12 g was randomly allocated to 12 glass fiber plastic barrels (0.5m3) with 30 groupers each. Four treatment diets were prepared by adding55 ppm Zn equivalent of zinc sulfate (ZnSO4), zinc hydroxy sulfate (Zn4(OH)6SO4), zinc glycine chelate (Zn-Gly) or zinc hydroxy methionine analogue chelate (Zn-MHA) to a basal diet formulated based on Zn requirement of E. coioides. (Samples are supplied by Xingjia Bio-Engineering Co., Ltd ) The actual total Zn content of 4 treatment diets were 118.85, 116.92, 120.66 and 119.23 mg/kg, respectively. Each treatment diet was fed to 3 barrels for 8 weeks.
Table 1. Effect of supplemented Zinc forms on growth performances in juvenile hybrid grouper (Epinephelus fuscoguttatus♀×E. lanceolatu♂)
Table 2. Effect of supplemented Zinc forms on MDA content and enzymatic activity in liver in juvenile hybrid grouper (Epinephelus fuscoguttatus♀×E. lanceolatu♂)
Table 3. Effect of supplemented Zinc forms on histomorphology of the foregut in juvenile hybrid grouper (Epinephelus fuscoguttatus♀×E. lanceolatu♂)
Compared with ZnSO4, Zn4(OH)6SO4 significantly improved the growth performance and SOD activity in the liver of the juvenile groupers; Zn-Gly and Zn-MHA significantly improved the growth performance of the juvenile groupers, reduced the content of malondialdehyde in the liver, increased the height of the foregut folds and promoted the intestinal development. The bioavailability of Zn4(OH)6SO4, Zn-Gly and Zn-MHA relative to ZnSo4 were 119, 118 and 122%, respectively, for weight gain ratio (WGR), and were 111, 114 and 131%, respectively, for CuZn-SOD activity. In overall, Zn-MHA is the best Zn source among the four forms of zinc in promoting growth, feed conversion and survival rate, therefore, is high beneficial in aquaculture.
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Article made possible through the contribution of Bin YIN et al.