Growth, filtration and ingestion rate of the rotifer Brachionus plicatilis fed with large (Asteromonas gracilis) and small (Chlorella sp.) celled algal species

The rotifer Brachionus plicatilis was fed in experimental conditions with a small celled (2–5 μm) Chlorella sp. and a large celled (16–22 μm) Asteromonas gracilis algae. The specific growth rate (SGR) of rotifers fed Asteromonas (maximum 0.79) was statistically higher than that for rotifers fed Chlorella (maximium 0.61). The filtration and ingestion rates using different rotifer and algal densities exhibited certain maxima depending on the species, the cell density and the condition of the rotifers. The filtration rate was higher with Asteromonas and, although ingestion rate was lower than with Chlorella, the ingestion in terms of cell volume was 10‐fold higher. It seems that B. plicatilis ingests the larger cell diameter algal species more efficiently than the smaller species that is usually used for its mass culture.     

Comparative fatty acid composition of eggs from wild and captive black sea bass, Centropristis striata L.

Lipid content, lipid class and fatty acid compositions were determined in eggs from wild and captive black sea bass, Centropristis striata L., from northern (New England) and southern (South Carolina) regions to determine the effects of diet on egg composition and fertilization success. The formulated diets fed to the northern captive (NC) fish were higher in total lipids (22%) compared with the cut fish and squid diet fed to the southern fish (SC; 3.3% lipid) and had a higher relative amount of linoleic acid (LA) and lower relative amounts of docosahexaenoic acid (DHA) and arachidonic acid (AA). These dietary differences were broadly reflected in the egg lipid composition. The LA levels were higher in all lipid classes in eggs of NC fish while AA levels were lower. The DHA was higher in the major polar lipids (PL) (phosphatidylcholine and phosphatidylethanolamine) of SC eggs compared with NC. Compared with wild fish, both captive groups produced eggs with PLs richer in LA and lower in DHA and AA. Over all fish groups, fertilization success was directly correlated with levels of DHA and AA in the PLs and was inversely correlated with LA levels.     

Amino acids composition difference and nutritive evaluation of the muscle of five species of marine fish, Pseudosciaena crocea (large yellow croaker), Lateolabrax japonicus (common sea perch), Pagrosomus major (red seabream), Seriola dumerili (Dumeril's amberjack) and Hapalogenys nitens (black grunt) from Xiamen Bay of China

A study was conducted to investigate the muscle amino acid profiles of five species of marine fish, Pseudosciaena crocea (large yellow), Lateolabrax japonicus (common sea perch), Pagrosomus major (red seabream), Seriola dumerili (Dumeril's amberjack) and Hapalogenys nitens (black grunt). These carnivorous fishes, all of which belong to the Perciforms, were sampled from Xiamen Bay. Chemical analysis shows significant difference (P < 0.01) among the five species in the muscle total amino acids (TAA). Lateolabrax japonicus has the highest level of TAA in muscle tissues. Significant difference in muscle total essential amino acid (TEAA) and total non‐essential amino acid (TNEAA) were also found among the five species. Lateolabrax japonicus has the highest TEAA level, and H. nitens has the highest level of TNEAA level. Significant difference (P < 0.01) existed in specific EAA except for lysine (P > 0.05). The significant difference (P < 0.05) of the A/E ratios [(each essential amino acid content/total essential amino acid content including cystine and tyrosine) ×1000] based on the essential amino acid composition of muscle tissue from the five species were found in lysine, histidine, methionine, cystine, valine, leucine, isoleucine, and arginine, except for threonine, phenylalanine and tyrosine. These differences indicate that the amino acids profile is species specific for the five species and their essential amino acid requirements are greatly different although they were fed similar feed. In contrast to the reference amino acid profile recommended by FAO/WHO, muscle proteins of each fish were all rich in lysine, the S‐containing amino acids and threonine, but histidine, valine, leucine, isoleucine, phenylalanine and tyrosine were deficient for children's diets. The first limiting amino acid was histidine for P. crocea and L. japonicus, valine for P. major and H. nitens, leucine for S. dumerili. The amino acid score was 66.8, 76.7, 78.4, 84.0 and 95.7 for P. crocea, L. japonicus, P. major, H. nitens and S. dumerili, respectively. In the adult human diet the muscle protein of the five species of marine fish can almost fulfil the requirements of all essential amino acids except for the histidine of P. crocea and L. japonicus and thus can serve as supplemental source of protein in cereal‐based adults diets if we reinforce the histidine correspondingly. Therefore, increasing the proportion of marine fish in the diet of the people in the area where paddy rice and wheat are the main protein sources is an effective way to enhance the nutrition value of food and improve the nutrition status of the developing countries. Moreover, all of five marine fish species contained a comparatively high content of glutamic acid and arginine, which are beneficial to the patients under such conditions as trauma, burn injury, massive small‐bowel resection and renal failure.