Monola oil versus canola oil as a fish oil replacer in rainbow trout feeds: effects on growth, fatty acid metabolism and final eating quality

Monola oil, a high oleic acid canola cultivar, and canola oil were evaluated as replacers of 26 fish oil at three levels of inclusion (60, 75 and 90%) in rainbow trout diets. After a 27-week 27 grow-out cycle, the diet-induced effects on growth, fatty acid metabolism and final eating 28 quality were assessed. Overall, no effects were noted for growth, feed utilisation or fish 29 biometry, and the fatty acid composition of fish fillets mirrored that of the diets. Dietary 30 treatments affected fillet lipid oxidation (free malondialdehyde), pigmentation and flavour 31 volatile compounds, but only minor effects on sensorial attributes were detected. 32 Ultimately, both oils were demonstrated to possess, to differing extents, suitable qualities 33 to adequately replace fish oil from the perspective of fish performance and final product 34 quality. However, further research is required to alleviate on-going issues associated with 35 the loss of health promoting attributes (n-3 long chain polyunsaturated fatty acids) of final 36 farmed products

Short-term food deprivation does not improve the efficacy of a fish oil finishing strategy in Murray cod

Two groups of fish (Maccullochella peelii peelii) were fed for a 90-day conditioning period on a canola oil diet (CO) or a fish oil diet (FO). Canola oil diet fed fish were then shifted to the FO diet for a 90-day finishing period. A variable period of  starvation (0, 5, 10 and 15 days) was introduced to reduce the initial lipid level of CO fed fish at the beginning of the finishing period and therefore accelerate the rate of recovery of FO-like fatty acids. During starvation, fish did not show  significant reduction in total lipid content, either in the fillet or whole body. At the end of the conditioning period, fatty acid composition of the diet was mirrored in fish tissues. These differences came close to levelling out following re-feeding, with the exception of n - 6 polyunsaturated fatty acids (PUFA). However, no  effects of the starvation periods on the final fatty acid make-up of fish were recorded. The results of this trial show that Murray cod, when subjected to a starvation period of up to 15 days, does not lose an appreciable quantity of lipid and, therefore, the tested starvation approach to reduce the initial level of lipid has to be considered unsuccessful.&nbsp

Caratterizzazione chimica e biometrica di crostacei marini e d'acqua dolce

In this study the main biometric parameters, the proximate composition, the nutritional value, and the chemical qualities of four different crustaceans species, commonly available on the Italian market, were evaluated. In spite of some differences in the chemical and fatty acids composition of the flesh of the target species, all the studied crustaceans showed very good nutritional characteristics. This in particular thanks to the high contribution in protein, the very low percentage of total lipids and the very low atherogenicity and thrombogenicity. The analysis of the volatile compounds showed interesting differences among the four species; in particular the crustaceans from marine origin showed an overall higher amount of these compounds