Effects of dietary spray-dried porcine plasma (SDPP) on growth, digestive capability and diseases resistance of juvenile hybrid grouper Epinephelus lanceolatu x E. fuscoguttatus

Hybrid grouper (E. lanceolatu x E. fuscoguttatus) is a high economic value cultured species in Southeast Asia. There is a dangerous stage during its body length from 7 cm to 15 cm, and rotten fins and enteritis often occur in this period. An 8-week trial was conducted in RAS to investigate the effect of dietary graded SDPP (0, 10, 20, 30, 40 and 50 g/kg) on growth performance, digestive physiology and disease resistance of juvenile hybrid grouper with initial body weight 10.40 +/- 0.15 g. The results showed that both weight gain and specific growth rate were increased firstly and then decreased with the increase in dietary SDPP (p < .05). There were no variations on moisture, crude lipid and crude ash contents in muscle, but crude protein was increased firstly and then kept stable when dietary SDPP higher than 30 g/kg. Both tyrosine and lipase activities were increased by dietary SDPP (p < .05), but there were negative effects on the height and numbers of villus (p < .05). Almost of fish fed with no SDPP were get sick and about two-thirds were deed 48 h after injection with Vibrio Harveyi, and survival rate was significantly increased by dietary more than 20 g/kg SDPP (p < .05). The results illustrated that dietary 20 g/kg SDPP can improve the growth performance, enhance the antioxidant capacity and supply protection against Vibrio Harveyi of hybrid grouper juveniles.