Effects of diets on the growth performance and shell pigmentation of Pacific abalone

This study investigated the effects of natural and artificial diets on growth performance and shell pigmentation of cultured abalone. A 7-month feeding trial was conducted on 12 000 Pacific abalones (Haliotis discus hannai) with four diets including two extruder-processed test diets (with & without addition of oleopaprika carotenoids), Pacific dulse (Palmaria mollis) and a combination of Pacific dulse and a test diet. The results showed that the two test diets resulted in higher survival of abalone, but with a lower growth rates when compared with Pacific dulse alone (P < 0.05). The combination diet achieved the highest survival and growth rates. The Pacific dulse resulted in abalone with dark-brown shells, which are preferred by Asian markets. The test diets led to 52% and 55% of the animals with pink coloured shells and the supplementation of oleopaprika did not affect shell pigmentation. The aqueous acidic extracts from both dark-brown and pink shells showed blue colour; HPLC-MS chromatography revealed that the pigments in the extracts were consistent with a biliverdin and a cysteine-biliverdin. These results are valuable for the development of abalone feed and the control of abalone shell colouration.