Replacement of dietary kelp meal with three macroalgae sources on the growth performance, immune responses and anti-stress capacity of abalone Haliotis discus hannai

A 120-day feeding trial was conducted to evaluate the effects of replacement of dietary kelp Saccharina japonica by Ulva prolifera (previously known as Enteromorpha prolifera), Ulva lactuca, and Gracilaria lemaneiformis on the growth performance, immune responses, and anti-stress capacity of abalone Haliotis discus hannai Ino (initial body weight: 11.00 +/- 0.07 g). The control diet was designed to contain 30% of kelp, and named as Diet-S. On the basis of the control diet, the kelp was 50% replaced by U. prolifera, U. lactuca, and G. lemaneiformis, and named as Diet-SE, Diet-SU, and Diet-SG, respectively. Results showed that the specific growth rate of abalone was not significantly influenced by the replacement of dietary kelp (P > 0.05). Dietary inclusion of U. lactuca and G. lemaneiformis significantly increased the feed efficiency but significantly decreased the feed intake of abalone (P < 0.05). Compared with those in the Diet-S group, the activities of catalase, superoxide dismutase, the total anti-oxidative capacity and lysozyme had the significantly higher values in cell-free haemolymph of abalone fed with Diet-SE, Diet-SU, and Diet-SG (P < 0.05). In addition, the expressions of tumor necrosis factor alpha and nuclear factor kappa B in gill and digestive gland were reduced in the Diet-SE, Diet-SU, and Diet-SG groups. The expressions of heat shock proteins in digestive gland were increased significantly in Diet-SG group (P < 0.05). Moreover, the cumulative mortality of abalone after the heat stress was decreased significantly in the Diet-SG group (P < 0.05). In conclusion, replacement of dietary kelp by U. prolifera, U. lactuca, and G. lemaneiformis did not significantly influence the growth performance, but significantly increased the anti-oxidative capacity and immune response of abalone.

Automated summary

Replacing dietary kelp with Ulva lactuca and Gracilaria lemaneiformis significantly increased feed efficiency but decreased feed intake of abalone, while also improving their antioxidative capacity and immune response.