Elisabete Matos

Dietary tools to modulate glycogen storage in gilthead seabream muscle: glycerol supplementation.

The quality and shelf life of fish meat products depend on the skeletal muscles energetic state at slaughter, as meat decomposition processes can be exacerbated by energy depletion. In this study, we tested dietary glycerol as a way of replenishing muscle glycogen reserves of farmed gilthead seabream. Two diets were tested in duplicate (n = 42/tank). Results show 5% inclusion of crude glycerol in gilthead seabream diets induces increased muscle glycogen, ATP levels and firmness, with no deleterious effects in terms of growth, proximate composition, fatty acid profile, oxidative state, and organoleptic properties (aroma and color). Proteomic analysis showed a low impact of glycerol-supplementation on muscle metabolism, with most changes probably reflecting increased stress coping capacity in glycerol-fed fish. This suggests inclusion of crude glycerol in gilthead seabream diets (particularly in the finishing phase) seems like a viable strategy to increase glycogen deposition in muscle without negatively impacting fish welfare and quality.

Life cycle assessment of aquafeed ingredients

PurposeThis study performs an exploratory comparative evaluation of various animal and vegetable protein and lipid sources, used as feed in the aquaculture industry. The ingredients studied include fishmeal (FM) and fish oil (FO) from fisheries by-products, meal and fat by-products from poultry slaughter, FM and FO from Peruvian anchovy capture, and soybean meal and oil. The boundaries studied include the production or capture, the ingredient processing unit and the transport to the unit that processes the ingredients into aquafeeds in Portugal.MethodsThe LCA impact assessment method is the CML-IA baseline V3.04/EU25 and the results were obtained for the characterisation step. Some of the inventory data were collected from a Portuguese company (Savinor) that processes both by-products from local fisheries and by-products from poultry production. Savinor provided data specifically associated with the ingredients’ production. Obtained data were complemented with literature data from: fish capture and poultry production. Inventory data for the production of ingredients from Peruvian anchovy and soybeans were retrieved from literature. It was assumed that the transport of the ingredients produced from Peruvian anchovy, between Lima and Rotterdam, is made in a transoceanic vessel, and it is considered a transport by truck between Rotterdam and Ovar, for soybean ingredients and FM/FO produced from Peruvian anchovy.Results and discussionThis paper shows that poultry meal and poultry fat from poultry slaughter by-products have the larger contribution to all environmental impact categories evaluated, being the production of poultry the life cycle stage that contributes most to the overall categories. On the other hand, FM and FO from Peruvian anchovy were the ingredients with a lower contribution to all impact categories, except for abiotic depletion category, for FM from Peruvian anchovy, and abiotic depletion, abiotic depletion (fossil fuels) and ozone layer depletion for FO from Peruvian anchovy. For these categories, soybean meal and oil had lower impacts, respectively. The ingredients were compared by classes (protein and lipid sources).ConclusionsA general conclusion is that soybean meal and oil and FM/FO from Peruvian anchovy appear to be very interesting options for aquafeeds from an LCA perspective. However, some limitations identified for this study, as, for instance, that it does not account for the environmental benefits associated with the use of the mentioned by-products, that would otherwise be considered wastes (i.e. by-products from the fish canning sector and poultry slaughter) shall be evaluated in future studies.

Mineral composition of dry dog foods: impact on nutrition and potential toxicity

Detailed mineral profile of a selection of commercially available complete dry dog foods was determined using ICP-MS (Se, Cu, Mn, Zn, and nonessential trace elements), flame photometry (Na and K) and atomic and molecular spectrophotometry (Ca, P, Mg, and Fe). The contribution of ingredients to the mineral composition was correlated to the food market segment. Results showed an oversupply of essential elements due to the energy density effect on feed intake. Additives contributed from 40.8 to 55.1% to the total trace elements contents. With the exception of Se, all trace elements were supplied above the nutritional requirements of adult dogs. Legal limits of Cu, Se, and Zn were surpassed. The content of nonessential trace elements included values in the range of nanograms to micrograms per kg, without surpassing safe upper limits. This work brings awareness to the need to find supplementation strategies that ensure nutritional adequacy and avoid waste.

Proteomics as a tool to understand fish stress in aquaculture

Physiological and psychological stress are important concerns in economic sectors that rely on animal husbandry, particularly in finfish aquaculture, as impaired fish welfare often implies worse fish health, productivity and final product quality traits. Moreover, this also brings obvious ethical implications.