Enzymatic hydrolysis of cottonseed protein enhances appetite and intestinal health of Litopenaeus vannamei

This study examined the effects of enzymatic hydrolysis cottonseed protein (ECP) on the appetite and intestinal health of Litopenaeus vannamei (0.16 ± 0.01 g). Based on the control diet (fishmeal 18 %, crude protein 40 %, crude fat 7.5 %), 2 %, 4 %, 6 %, 8 % and 10 % of ECP were added to replace fishmeal in equal amounts to formulate six isonitrogenous and iso-lipidic experimental diets named ECP0 (Control), ECP2, ECP4, ECP6, ECP8, and ECP10, respectively. After an 8-week feeding trial, the serum orexin levels were significantly increased (P < 0.05); and leptin, peptide YY and cholecystokinin were significantly reduced when shrimp ingested diet contained ECP， as well as their genes expression levels (P < 0.05). Compared with the ECP0 group, the weight gain rate of the shrimps in group ECP2 had significantly increased (P < 0.05). Besides, intestinal fold height and muscular thickness of shrimps in group ECP2 were markedly increased, and up-regulated genes expression levels for periplasmic membrane factors (P < 0.05). Significantly increased intestinal amylase, lipase, trypsin and chymotrypsin activities were found in shrimps fed diet ECP2 and ECP4 (P < 0.05). The addition of ECP significantly decreased Vibrio, Photobacterium and Tenacibaculum abundance, and increased Ruegeria and Marivita abundance in shrimp intestine (P < 0.05), especially the supplemented 2 % ECP significantly improved the membrane transport and amino acid metabolism functions of the intestinal flora in shrimps (P < 0.05). Therefore, the addition of 2–4 % ECP by replacing fishmeal at an equal level could enhance growth by improving appetite, intestinal morphology and the composition of gut microbiota for L.vannamei.