Effects of long term feeding diets differing in protein source and pre-slaughter starvation on biometry, qualitative traits and liver IGF-I expression in large rainbow trout

The effects of feeding two complete extruded diets differing in protein source (fish meal-FM vs. vegetable proteins-VP) over 30 weeks and subsequent 30 days of starvation on biometry, fillet composition and liver IGF-I mRNA were studied in large rainbow trout. At the end of the feeding period, the dietary protein source little affected major biometry traits, dressing out yields and overall adiposity (P>0.05) but fish given the VP diet resulted in higher content of PUFA n-6 fatty acids in mus- cle (0.46 vs. 0.22 g/100g fillet, P0.05) and of all fatty acids in fillet (P<0.05), except DHA. Liver IGF-I mRNA content was little affected by the test diet and starvation

Growth performance of sea bass fed increasing levels of pea-wheat protein in diets varying in fish meal quality

A 11-week trial was carried out to compare the growth performance of sea bass (D. labrax) fed six isonitrogenous isocaloric diets where protein from two fish meals of different nutritive value was replaced with graded levels (0, 50 or 75%) of a mixture made up by a pea protein concentrate and wheat gluten. Fish meal quality did not affect (P>0.05) weight gain or feed efficiency in fish fed graded levels of plant protein in the diet. Feed intake decreased (P<0.05) as the level of plant protein was increased in the diet but this did not led to impaired growth or feed conversion rate. Protein efficiency and retention were equally improved (P<0.05) only with diets where a poor quality fish meal was substituted by protein rich-plant ingredients. Calculations based on the mass balance of nutrients of sea bass proven the inclusion of a mixture of highly purified plant-protein derivatives in complete diets for the sea bass, to be beneficial in reducing pollution load

Functional fish: improving nutrition for the elderly

Elder people need highly digestible foods that can also provide health benefits even to those suffering from chronic diseases. Furthermore, such foods should be palatable as well as familiar for elder consumers. Fish is a high-protein, low-fat food that potentially provides a range of health promoting effects which may be further improved with suitable approaches in the production systems. The present mini-review intends to report possible aquaculture interventions to enhance the positive impact of fish on elder health and to promote its function in terms of prevention and recovery of specific diseases. Some fish species during their lifespan experience periods of food restrictions that can be mimicked in aquaculture without affecting fish welfare. Under these circumstances fish can modify the fatty acid profile and increase the use of muscle proteins to fulfill their energy requirements, by activation of muscle endogenous proteases. Degradation of muscle proteins can enhance their digestibility and possibly the release of encrypted bioactive peptides, showing a plethora of biological actions, including the antihypertensive activity. The degree of myofibrillar protein degradation and the fatty acid profile of fish fillet can then be managed by suitable and sustainable feeding protocols in the context of farming conditions

Welfare and quality of farmed trout fed high plant protein diets. 1 Growth performance and quality traits

AbstractThis study was performed to evaluate the effects of high levels of inclusion of plant protein sources to replace fish meal in rainbow trout (O. mykiss) diets on growth performance and quality characteristics. Two isoproteic (44.8%) and isolipidic (19.6%) extruded diets were fed to eight groups of trout (IBW 106.6g) for 103 days. Diet FM, containing only fish meal as protein source, was used as control treatment and compared to diet PV80, where a plant protein mix (pea protein concentrate and wheat gluten) was included to replace 80% of fish meal protein. Growth performance (FBW: 318.5g; SGR: 1.06%) and feed to gain ratio (0.79) of the fish were not affected by dietary treatment (p>0.05). Dry matter and protein ADCs, measured in vivo after stripping, resulted higher in fish fed the high vegetable protein diet relative to the fish meal one (p<0.05). Trout fed diet PV80 were characterised by higher agility index (2.02 vs 1.72, p<0.05), carcass yield (91.95 vs 91.18%, p<0.05), lower hepatosomatic inde..

Replacing maize grain with ancient wheat lines by‐products in organic laying hens’ diet affects intestinal morphology and enzymatic activity

The effects of replacement of maize grain with ancient wheat by‐products on intestinal morphometry and enzymatic activity in laying hens was studied. Eighty hens were divided into two groups (40 each, 8 replicates, 5 hens/replicate) fed two isoproteic and isoenergetic diets. In the treated group, part of the maize was replaced by a mix of ancient grains (AGs) middling, in a 50:50 ratio of Triticum aestivum L. var. spelta (spelt) and Triticum durum dicoccum L. (emmer wheat). The AG diet affected the weight of all the large intestine tracts, decreasing the weight of caeca (p < 0.01) and increasing those of colon (p < 0.01), rectum and cloaca (p < 0.05). Villus height in the AG group was higher (p < 0.01) than the control for the duodenum and jejunum, while for the ileum, the control group showed the highest values (p < 0.01). The submucosa thickness was higher (p < 0.01) in the control group for the duodenum and ileum, while the jejunum for the AG group showed the highest (p < 0.05) submucosa thickness. The crypts depth was higher (p < 0.01) in the control group for the duodenum and ileum. Enzyme activity was enhanced by AGs (p < 0.01) in the duodenum. Regarding the jejunum, sucrase‐isomaltase and alkaline phosphatase had higher activity (p < 0.05 and p < 0.01, respectively) in the AG group. In the ileum, sucrase‐isomaltase showed higher activity (p < 0.01) in the control group, while alkaline phosphatase showed the highest values (p < 0.05) in the AG group. Overall, results suggested that the dietary inclusion of AGs exerted positive effects in hens, showing an improved intestinal function

Chemical composition and apparent digestibility of a panel of dried microalgae and cyanobacteria biomasses in rainbow trout (Oncorhynchus mykiss)

Despite a growing interest in microalgae and cyanobacteria as potential sources of nutrients in aquafeeds, little information is presently available on their nutritive value for carnivorous fish species. The aim of this study was to evaluate chemical composition and nutrient digestibility of a panel of microalgae and cyanobacteria dried biomasses (MACB), using rainbow trout (Oncorhynchus mykiss W.) as a fish model. Nine test diets were obtained by mixing 80 parts of a reference diet, added with 20 g/kg of acid insoluble ash as an indigestible marker, to 20 parts of each of the following dried whole-cell biomass: Arthrospira platensis, Nostoc sphaeroides, two strains of Chlorella sorokiniana, Nannochloropsis oceanica, Tisochrysis lutea, Phaeodactylum tricornutum, Porphyridium purpureum and Tetraselmis suecica. The digestibility measurements were conducted with rainbow trout (52.4 \ub1 1.5 g) kept in six tank units each including three 60-L vessels singularly stocked with 12 fish and fitted with a settling column for faecal recovery. Per each diet, faeces were collected over three independent 10-day periods. Apparent digestibility coefficients (ADCs) of dry matter, crude protein (CP), organic matter and gross energy (GE) of single MACB were calculated by difference relative to those of the reference diet. The MACBs had heterogeneous chemical composition (CP, from 20 to 69%; Lipid, 5\u201327%; GE, 12.5-\u201322.6 MJ/kg dry matter basis) reflecting their overall biodiversity. Most of them can be considered as virtually good sources of minerals and trace elements and exhibit an essential amino acid profile comparable or even better than that of soybean meal commonly used in fish feeds with P. purpureum showing the best protein profile. The digestibility results obtained with rainbow trout allowed ranking the MACBs into two major groups. A first one, including C. sorokiniana, N. oceanica and T. suecica, resulted in markedly lower (P < 0.05) crude protein and energy ADC (64\u201373%; 51\u201359%, respectively) compared to a second group including P. purpureum, T. lutea and cyanobacteria (CP-ADC, 83\u201388%; GE-ADC, 74\u201390%) while P. tricornutum resulted in intermediate values. Overall, the present study confirms the consistently reported role of cell-wall structure/composition in affecting accessibility of nutrients to digestive enzyme. Based on the overall outcomes, only T. lutea and cyanobacteria actually meet the requirements for being used as protein sources in aquafeeds provided their mass production becomes more feasible and costeffective, hence attractive for the feed-mill industry in the near future

The use of stable isotope ratio analysis to trace European sea bass (D. labrax) originating from different farming systems

This study aimed to determine whether isotopic ratio mass spectrometry (IRMS) can discriminate farmed European sea bass according to different farming systems and geographic origins. Dicentrarchus labrax of commercial size from three different rearing systems (concrete tank inland, sea cages, and extensive methods in valleys or salt works) were collected at the trading period (autumn\u2013winter). For each farming type, different locations spread over Italy were monitored. Once the fish were harvested, the muscle and feed were sampled. For both muscle and feed, \u3b413C and \u3b415N were measured by continuous flow elemental analyzer isotope ratio mass spectrometry (CF-EA-IRMS) with the goal of discriminating samples based on the rearing system. Additional \u3b42H and \u3b418O measurements of fish samples were performed by continuous flow total combustion elemental analyzer isotope ratio mass spectrometry (CF-TC/EA-IRMS) to track the geographical origin. The measurements of \u3b413C and \u3b415N made it possible to discriminate cultured sea bass from different farming systems (extensive vs. intensive) reared at different geographical sites in Italy. Additional information was obtained from \u3b418O and \u3b42H, which enabled the geographical areas of origin of the sea bass farmed extensively and intensively (in cages) to be distinguished