Utilization of different raw and pre-gelatinized starch sources by juvenile yellowfin seabream Sparus latus

Abstract

Raw corn starch (RCS), raw tapioca starch (RTS), raw potato starch (RPS), pre-gelatinized corn starch (PCS), pre-gelatinized tapioca starch (PTS) and pre-gelatinized potato starch (PPS) were evaluated as starch sources in diets for yellowfin seabream Sparus latus in a 56-day growth trial. Seven isonitrogenous semi-purified diets comprising a non-starch cellulose control diet and the six different starch sources holding 200 g kg−1 starch each were prepared and fed to triplicate groups of juvenile yellowfin seabream S. latus. Fish were fed for 8 weeks. Weight gain (WG) and specific growth rate (SGR) for fish fed RCS, RTS and RPS diets were equal, as well as for fish fed PCS, PTS and PPS diets, but values in groups fed the raw starch sources were significantly higher compared with fish fed the pre-gelatinized starches. Feed efficiency and protein efficiency ratio in fish fed different starch source diets showed no significant differences but were significantly higher than those fed a non-starch control diet. Protein productive value was improved by starch incorporation to diets. PCS, PTS or PPS groups showed lower feed intake compared with RCS, RTS or RPS groups, and the differences were significant between PCS, PPS and RCS, RPS groups. Whole-body protein and ash contents and muscle compositions were not affected by different starch sources. Whole-body and liver lipid contents, liver moisture and glycogen contents were significantly affected by starch source. Values of hepatosomatic index, intraperitoneal fat ratio, viscerosomatic index and condition factor did not vary between experimental treatments. Plasma total protein concentration for RCS, RTS or RPS fed fish was significantly higher than that for PCS, PTS or PPS fed fish, but significantly lower than that for non-starch fed fish. Plasma cholesterol and triacylglycerol concentrations were unaffected by starch source, but were significantly higher in fish fed the non-starch control diets. Plasma glucose concentrations in all dietary groups were relatively stable. In conclusion, raw corn, tapioca and potato starches at a 200 g kg−1 inclusion level were well utilized as energy sources by yellowfin seabream, which was evidenced by better WG and SGR. Pre-gelatinization of the starches had no positive effect on starch utilization.