Search

Camelina meal ( Camelina sativa) ( CM) is a potential protein source for aquaculture feeds, on account of its crude protein level (380 g kg−1) and inclusion of most indispensable amino acids. Two experiments were conducted with rainbow trout ( Oncorhynchus mykiss) and Atlantic salmon ( Salmo salar). Rainbow trout (44.9 g fish−1) were fed diets with CM at 0 g kg−1 (0% CM), 70 g kg−1 (7% CM), 140 g kg−1 (14% CM) or 210 g kg−1 (21% CM) for 12 weeks at 14 °C in freshwater, and salmon (241.8 g fish−1) were fed diets with CM at 0 g kg−1 (0% CM), 80 g kg−1 (8% CM), 160 g kg−1 (16% CM) or 240 g kg−1 (24% CM) for 16 weeks at 14 °C in sea water. Growth, lipid and amino acid tissue compositions were compared between species. Trout could tolerate up to 14% CM diets without affecting the growth compared to the control, while salmon fed ≥8% CM gained less weight than the control ( P = 0.008). The feed conversion ratio in trout fed 21% CM was higher than the control ( P = 0.002), and feed intake in salmon fed ≥8% CM was lower than the control ( P = 0.006). Trout fatty acid and amino acid composition showed minimal differences between CM-fed and control-fed fish, while salmon showed significant alterations after feeding CM diets. Multivariate analyses emphasized differences in tissue composition between species fed CM diets. [ABSTRACT FROM AUTHOR]

Abstract: Fluctuations in mussel (Mytilus edulis) growth have been attributed to large-scale fluctuations in temperature, salinity and the abundance of phytoplankton. This study examined the effect of fatty acids on the growth (wet weight) of cultured mussels during 2000 and 2001 in Notre Dame Bay, Newfoundland. Mussels were socked in June 2000 and harvested in October 2001. On a monthly basis, the mussels grew at variable rates (mean 10.73±6.86, range 5.9–18.8 mg d−1 in 2000 and 10.09±8.91, range 5.1–22.9 mg d−1 in 2001) with the highest growth rate in September of each year. The growth, however, did not demonstrate localized differences. The proportion of polar lipid (PrL) as a percent of total lipid was much higher in mussel samples (mean 71.1±4.8%) than the phytoplankton (mean 44.3±21.2%), and the opposite was observed for the neutral lipid (NL: mean 30.2±4.4% in mussels and 45.3±11.7% phytoplankton). The fatty acid profiles of phytoplankton and mussels were, in general the same, except that the pentaenoic fatty acid, 18:5ω3, was not detected in mussels, and no C22 non-methylene interrupted dienes (NMIDs) were detected in phytoplankton. However, proportions of 22:2NMIDs (as percent of total identified fatty acids) in mussels were relatively high (range 2.5–3.5%) particularly in 2000. The 22:6ω3, 20:5ω3, 16:0, 14:0, 16:1ω7 and to some extent 16:4ω3 were the most abundant fatty acids in the phytoplankton and mussel samples. Of these fatty acids, 20:5ω3 was the only fatty acid in both phytoplankton and mussels that showed a significant positive correlation with growth, while correlations with other fatty acids varied in magnitude or direction (positive or negative) depending on the source of the acid being either phytoplankton or mussel. An interesting observation within the essential fatty acids was that neither 22:6ω3 nor 20:4ω6 was significantly correlated with growth, but when their levels were combined with 20:5ω3 to give the total essential fatty acid in phytoplankton or mussels, the result was a significant positive correlation with growth for both phytoplankton and mussel essential fatty acids. Moreover, the coefficients of correlation for the other physiologically important acids in bivalves, namely the 20:2NMIDs were by far the most significant ones, but only with the mussel NMID, and their correlation with growth was negative. Approximately 140 variables from mussels and phytoplankton were tested in order to construct a model to predict the growth of mussels. Of these variables, four were found to be significant (r 2 =0.725): 20:2NMID1, 18:2ω4 and 22:5ω6 in mussels and 16:1ω9 in phytoplankton. [Copyright &y& Elsevier]

Developing an optimal heterotrophic feeding regime has the potential to improve the growth and overall health of captive corals. This study evaluated the efficacy of seven unique feeding strategies for Acropora loripes , Acropora millepora , and Acropora tenuis nubbins: a novel, micro-bound diet (ATF), a novel, dissolved diet rich in long-chain polyunsaturated fatty acids (LC-PUFA) (LONG), a novel, dissolved diet lacking in LC-PUFA (SHORT), a phytoplankton diet of Isochrysis galbana (ALG), co-feeding of LONG and ALG (COMB), unfiltered seawater (RAW), and an unfed treatment of filtered seawater only (CTL). After 90 days, all species showed the highest growth in the ALG treatment. There was a negative correlation between growth and total lipid concentration, indicating that Acropora corals have a low tolerance for lipid-rich diets. Coral appeared to perform best in the relatively natural treatments, namely the ALG, CTL, and RAW, which recorded higher growth and increased proportions of high-energy lipid compounds such as wax esters, triacylglycerols, and the fatty acids, 16:0 and 22:6n-3. Meanwhile the formulated diets (ATF, LONG, SHORT) promoted greater proportions of structural lipids and indispensable, membrane-bound fatty acids including 20:5n-3 and 20:4n-6. Despite the SHORT diet being low in LC-PUFA, corals fed this diet showed few significant differences in several individual LC-PUFA compared to most other treatments, suggesting that these were obtained via de novo synthesis, or selectively retained from initial reserves. Ultimately, this study showed that phytoplankton represents a promising vehicle of nutrient delivery for captive Acropora corals. • Captive Acropora coral respond favourably to continuous feeding. • Formulated diets are not well accepted by captive Acropora corals. • High dietary lipid contents depress captive Acropora coral growth. • Continuous feeding of Isochrysis galbana promotes improved growth and nutritional composition in captive Acropora corals. • Low growth is also associated with high levels of structural lipid classes in captive Acropora corals. [ABSTRACT FROM AUTHOR]