Apparent Digestibility Coefficients Values Research Articles

Plant-based polymer as a thermoresistant carrier of phytase in Nile tilapia (Oreochromis niloticus) diets

A biodegradable soybean oil-based polymer produced following the Green Chemistry principles, was assessed as a thermoresistant vehicle of phytase aiming to improve the enzyme stability during fish diet processing. Juvenile Nile tilapia (70 ± 4.3 g) were submitted to a digestibility assay designed in a factorial model (3 ×2) to assess the polymer efficiency. The treatments comprised the combination of three phytase inclusion methods with two feed processing methods. The inclusion methods of phytase were: CPP- coating post processing, in which the enzyme was spread on top of pellets after processing, PAE- polymer associated to enzyme, which was adsorbed by the polymer and included in the ingredients mash prior feed processing and NE- no enzyme inclusion, playing a control role as phytase was not included. The feed processing methods were extrusion (120 °C) or pelleting (40 °C), exposing the polymer to different temperatures. Phytase was supplemented at 1500 units kg−1 using the CPP or PAE methods. There was a significant interaction for the apparent digestibility coefficient (ADC) values of phosphorus (P), calcium (Ca) and Ash (P < 0.05). CPP resulted in higher ADC values for P and Ca, compared to PAE and NE in extruded diets (P < 0.05). The PAE method resulted in higher ADC values of P, Ca, and Ash than NE in extruded diets (P < 0.05). In pelleted diets, PAE resulted in higher ADC values for P and Ca, and a similar ADCAsh in comparison to CPP (P < 0.05). As verified in extruded diets data, the polymer partially protected phytase from heat denaturation, resulting in higher ADC values in comparison to NE (P < 0.05). The polymer improved phytase effects in pelleted diets probably by reducing degradation in fish stomach. These results suggest that the polymer may be a potential protective carrier of phytase and other thermolabile additives in extruded and pelleted diets.

Apparent Digestibility Coefficients of Black Soldier Fly (Hermetia illucens), Yellow Mealworm (Tenebrio molitor), and Blue Bottle Fly (Calliphora vicina) Insects for Juvenile African Catfish Hybrids (Clarias gariepinus × Heterobranchus longifilis).

A digestibility trial was conducted with African catfish hybrid juveniles in order to determine the apparent digestibility coefficients (ADCs) of different nutrients. The experimental diets contained defatted black soldier fly (BSL), yellow mealworm (MW), or fully fat blue bottle fly (BBF) meals, in a 70 : 30 ratio between the control diet and the tested insect meals. The indirect method for the digestibility study was performed using 0.1% yttrium oxide as an inert marker. Fish juveniles of 217.4 ± 9.5 g initial weight were distributed in 1 m3 tanks (75 fish/tank) of a recirculating aquaculture system (RAS), in triplicates, and fed until satiation for 18 days. The average final weight of the fish was 346 ± 35.8 g. The ADCs of the dry matter, protein, lipid, chitin, ash, phosphorus, amino acids, fatty acids, and gross energy for the test ingredients and diets were calculated. A six-month storage test was carried out to evaluate the shelf life of the experimental diets, while the peroxidation and microbiological status of the diets were also assessed. The ADC values of the test diets differed significantly (p < 0.001) compared to those of the control for most of the nutrients. Altogether, the BSL diet was significantly more digestible for protein, fat, ash, and phosphorus than the control diet but less digestible for essential amino acids. Significant differences were found between the ADCs of the different insect meals evaluated (p < 0.001) for practically all nutritional fractions analyzed. The African catfish hybrids were able to digest BSL and BBF more efficiently than MW, and the calculated ADC values agreed with those of other fish species. The lower ADCs of the tested MW meal correlated (p < 0.05) with the markedly higher acid detergent fiber (ADF) levels present in the MW meal and MW diet. Microbiological evaluation of the feeds revealed that mesophilic aerobic bacteria in the BSL feed were 2-3 orders of magnitude more abundant than those in the other diets and their numbers significantly increased during storage. Overall, BSL and BBF proved to be potential feed ingredients for African catfish juveniles and the shelf life of the produced diets with 30% inclusion of insect meal retained the required quality during a six-month period of storage.

Digestibility of Different Plant-derived Oils and their Influence on Fatty Acid Composition in the Liver and Muscle of Juvenile Common Carp (Cyprinus Carpio)

We evaluated the digestibility of plant oils and their influence on the growth of and fatty acid composition in common carp. Apparent digestibility coefficients (ADC) of lipids were determined in carp (200.2 ± 40.0g) fed with cod liver oil (CLO), linseed oil (LO), sunflower oil (SFO), or sesame oil (SO). A 96-day growth trial was then conducted using six isolipidic (from 100 to 101 g/kg diet) diets, namely CLO, LO, SFO, SO, and two blends of plant oils (SLO = SO + LO; SSFO = SO + SFO). Lipid ADC values (0.920-0.972) were similar or slightly lower in the plant oil-based diets than in the CLO-based diet. Growth and feed efficiency (FE) were not influenced by dietary lipids. The fatty acid profile in the liver and muscle reflected those of the dietary lipids. The EPA and DHA proportions were higher in the liver and muscle of the LO and SLO-fed fish than in the other plant oil groups, and lower than in CLO-fed fish (P &lt;0.05). Higher EPA, DHA, and n3/n6 ratio levels in the muscle of fish fed on the linseed oil (LO) diet, as compared to those in fish fed on the other plant oil-based diets, were ideal for human health and suggest that it can be used as a suitable alternative to fish oil.

Apparent digestibility coefficients of selected protein ingredients for juvenile Totoaba macdonaldi

AbstractTwo feeding trials were performed to evaluate the apparent digestibility coefficients (ADCs) of dry matter, protein, and amino acids of three animal‐origin and four plant‐origin ingredients in Totoaba macdonaldi. In the first feeding trial, the animal‐origin ingredients were evaluated using totoaba juveniles with an initial weight of 529.7 ± 104.2 g, and for the second feeding trial 745.9 ± 210.6 g. Evaluated ingredients were: poultry by‐product meal, meat and bone meal, feather meal (FM), soy protein concentrate, soybean meal (SBM), corn gluten (CG), and wheat gluten (WG). Each experimental ingredient was evaluated in triplicate. ADCs of dry matter ranged from 35.9% for FM to 67.9% for poultry by‐product, while the protein ADCs values ranged from 41.7% for CG to 83.2% for poultry by‐product. Fish meal ADC (79.6%) was similar to poultry by‐product but significantly higher than WG and soy protein concentrate (72.5% and 72.6%, respectively). The ADCs for lysine were significantly higher for WG, sardine meal, poultry by‐product, and SMB (94.5%, 79.8%, 79.4%, and 79.4%, respectively). Based on the results from the present study, poultry by‐product, WG, and soy protein concentrate are the most promising alternative ingredients (i.e., to the fishmeal) for the formulation of totoaba grow‐out feeds.

Apparent digestibility coefficients (ADCs) of intact-cell marine microalgae meal (Pavlova sp. 459) for juvenile Atlantic salmon (Salmo salar L.)

Initial investigations on the biochemical composition and in vitro protein digestibility indicated that dry intact-cell meals produced from Pavlova sp. CCMP strain 459 (henceforth referred to as Pav459) marine microalgae have good potential in novel low trophic aquafeeds. This study established in vivo apparent digestibility coefficients (ADCs) of essential nutrients and energy from Pav459 meal using the substitution digestion assay with juvenile (~25 g) Atlantic salmon, Salmo salar L. The Pav459 meal contained 10% ash, 54% crude protein (CP), 42 g total amino acids (AA) 100 g of meal−1, 11% crude lipid, 25% carbohydrate, 22 MJ kg−1 gross energy and 4% combined of essential n3 long chain polyunsaturated fatty acids (LC PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Pav459 meal had a high essential AA (EAA) to non-EAA ratio (1.0), EAA index (0.9), n3:n6 LC PUFA ratio (4.5), essential fatty acid (FA) index (4.9), PUFA:saturated FA ratio (2.6), fish lipid quality index (36.4) and a low index of thrombogenicity (0.1). Single ingredient Pav459 meal ADCs are established for protein (83%), lipid (91%), carbohydrate (72%) and energy (71%). Pav459 meal ADC values for EAAs are high for arginine (97%), histidine (94%), isoleucine (93%), leucine (93%), lysine (93%), methionine (95%), phenylalanine (92%), threonine (96%), tryptophan (92%) and valine (95%) and FA groupings saturates (76%), monounsaturates (80%), PUFA (97%), n6 PUFA (94%), n3 PUFA (99%) and EPA + DHA (99%). High values (average 1.8; range 1.04–3.58) are reported for the first time for Pav459 meal for digestible indispensable amino acid scores (DIAAS); which demonstrate Pav459 meal to be a complete protein when fed to Atlantic salmon. Dietary EPA + DHA levels and n3:n6 LC PUFA ratio were enhanced (by 19–31%), feed intake was significantly increased (by 8%) and carbohydrate ADC was significantly improved (by 41%) with 20% dietary Pav459 meal. Inclusion of 20% Pav459 meal had no effect on ADC of dietary dry matter, ash, monounsaturates, n3 PUFA or n6 PUFA and only trace reductions (less than 4%) for ADC of dietary protein, energy, EAAs, lipid, PUFA and EPA + DHA compared to the Reference diet. Cumulative study results suggest a recommended dietary inclusion level of Pav459 meal in salmonid feeds of up to 20% of the diet. At this level, Pav459 meal alone may satisfy NRC (2011) n3 LC PUFA requirements for Atlantic salmon and help restore EPA + DHA losses in current farmed salmon feeds; provided that similar growth performance, nutrient utilization and fish health can be demonstrated in Atlantic salmon fed nutritionally balanced diets containing Pav459 meal.

Effect of feeding level on the digestibility of alternative protein-rich ingredients for African catfish (Clarias gariepinus)

Apparent digestibility coefficients (ADC) of nutrients and individual amino acids (AA) for 13 feed ingredients as affected by feeding level were determined for African catfish, a species of economic importance in Africa. Results from two trials are reported. In each trial, ADC were determined using a reference diet and test diets with yttrium oxide as indicator. Juvenile African catfish (averaging 53.9 g, trial 1; 40.4 g, trial 2) were stocked in tanks connected to a common recirculation aquaculture system. Ingredients tested included hydrolysed feather meal (HFM), fishmeal (FM), insect meal (IM), soybean meal (SBM), sunflower meal (SFM), poultry meal (PM), corn dried distillers grains with solubles (CDDGS), faba beans (FB), lupine meal (LM), pea protein (PP), guar meal (GM), canola meal (CM) and yeast meal (YM). The effect of feeding level on ADC was determined by feeding fish restrictively (80% satiation) for 5 weeks and subsequently to apparent satiation for 2 weeks. Inclusion of yeast meal at 30% resulted in low palatability. ADC of nutrients were significantly affected by feeding level (except for fat and carbohydrate), but the effect was ingredient-dependent. African catfish was able to digest protein very effectively in almost all tested ingredients with ADC values ranging from 85.6 to 105.1% across feeding periods. Several ingredients tested, including animal protein ingredients and YM had similar high ADC for dry matter as FM. However, the ADC of AA differ among ingredients, indicating a need for digestible amino acid profile data. Methionine (Met) was the first limiting essential amino acid in HFM, FB, and LM with values ranging from 5−6 g/kg, expressed as digestible Met (dMet) per unit of digestible protein (DP), compared to FM (27 g dMet/kg DP). IM had comparable and sometimes higher overall digestible essential AA values compared to FM, except for methionine and lysine. For oilseeds and legumes, SBM tended to be the best quality AA source, as it had the highest digestible essential amino acid profile. These data provide information concerning nutrient and digestible AA values, which will allow a more efficient use of alternative ingredients in African catfish diets. Formulating diets based on the digestible AA in ingredients will aid precise feed formulation, thereby minimising economic losses and reducing the environmental footprint of aquaculture production.

Use of technological processing of seaweed and microalgae as strategy to improve their apparent digestibility coefficients in European seabass (Dicentrarchus labrax) juveniles

Algae are natural sources of nutrients, but the presence of anti-nutritional factors often compromises nutrient apparent digestibility coefficients (ADCs) in several fish species. In this study, physical-mechanical and enzymatic technological processing was applied to two seaweeds (Gracilaria gracilis and Ulva rigida) and three microalgae (Nannochloropsis oceanica, Chlorella vulgaris, and Tetraselmis sp.) in order to evaluate its effectiveness in improving nutrient ADC values in diets for European seabass. A practical commercial-based diet was used as reference (REF) and experimental diets were prepared by replacing 30% of REF diet with each test alga used either intact or after processing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fast performance liquid chromatography (FPLC) analyses revealed that enzymatic processing was more effective than the physical one in changing the protein and peptides composition, increasing the amount of low-molecular-weight compounds in seaweeds and N. oceanica microalgae. Protein digestibility was significantly affected by algae species and in the case of the microalgae by the technological process. Gracilaria gracilis is better digested than U. rigida and physical processing enhanced protein and energy ADC values. Nannochloropsis oceanica and C. vulgaris are better digested than Tetraselmis sp.; the highest protein and energy ADCs were observed in diets containing enzymatically processed N. oceanica (NAN-ENZ) and physically processed C. vulgaris (CHLO-PHY), followed by the diet with physically processed Tetraselmis sp. (TETR-PHY). Results clearly showed that it is possible to increase nutrient accessibility and digestibility of algae by fish, by selecting the most adequate method to disrupt the cell wall. Moreover, the physical-mechanical and enzymatic technological processes used in this study are scalable to the industrial level.

Dietary use of Spirulina (Arthrospira) and Chlorella instead of fish meal on growth and digestibility of nutrients, amino acids and fatty acids by African catfish

Growth performance and apparent digestibility coefficient (ADC) of fatty acids, amino acids and macronutrients for diet containing fish meal, Chlorella vulgaris or Spirulina platensis (=Arthrospira platensis) by African catfish (Clarias gariepinus) were assessed in a 42-day feeding trial using a fishmeal-based control diet (REF) and two other test diets containing Spirulina or Chlorella replacing fishmeal in the control diet. The Spirulina-based diet exhibited higher ADC of crude protein than the Chlorella-based diet. The Spirulina- and Chlorella-based diets exhibited higher ADC for all essential amino acids (EAA) when compared with the control diet. High methionine and lysine ADC of Spirulina and Chlorella diet were also observed. The Chlorella diet was significantly higher in ADC of histidine, arginine, valine, isoleucine and tryptophan. Chlorella diet had the highest ADC values for n_6 and n_3 PUFA, lipid. The Spirulina diet exhibited significantly higher lysine, crude fibre, energy, dry matter carbohydrate and docosahexaenoic acid (DHA)ADCs than the Chlorella diet. EPA of reference diet was however, significantly more digestible than Chlorella but not in Spirulina.

Dietary ingredient composition alters faecal characteristics and waste production in common carp reared in recirculation system

Feed is a common factor influencing both fish growth and waste production in aquaculture. We examined the effect of different feed ingredients on the quantitative and qualitative aspects of faecal waste produced by common carp. Ingredients rich in (i) starch (field peas, PEA); (ii) protein (feather meal, FeM); (iii) insoluble non-starch polysaccharides, NSP (sunflower cake meal, SFM); or (iv) soluble NSP (wheat dried distillers grain with soluble, WDG) were studied. Five experimental diets were produced, a control diet produced from a basal mixture (CON) and four other diets (PEA, FeM, SFM and WDG) were prepared by replacing 30% of the basal mixture in CON with the respective test ingredient (70:30). Common carp juveniles (95 g, 15 fish per tank) were fed (restrictively, 22 g/kg0.8/d) the experimental diets for 7 weeks, in triplicate groups. Growth, body composition, energy and nutrient balances were significantly different; with highest growth recorded in CON and WDG; lowest in the FeM and SFM groups. Apparent digestibility coefficient (ADC) of dry matter, nutrients (protein, fat, carbohydrate, ash and phosphorus) and energy in the diets and ingredients were significantly altered between the groups (p < .001). PEA had the best ADC for macro-nutrients and energy, while ash and phosphorus were highest with WDG; SFM had the lowest ADC values for DM, fat, carbohydrate, energy, and phosphorus. The quantity, proximate composition and recovery percentage of the feaces (collected by settling) was significantly different between treatments (p < .001). Faeces recovery and solid removal efficiency were the highest in WDG, comparable to CON; and lowest in SFM. Physical characteristics of the feaces (stripped) indicated by dry matter content and stability were significantly affected by the ingredients only at day 26 and 29, respectively. However, changes in dry matter and stability over time (days) were significant in SFM and WDG (for DM); and all groups except SFM (stability). Osmolality and viscosity of the stripped faeces was unaffected. In summary, SFM resulted in significantly lower performance, low DM and nutrient digestibility, increased faecal loss, lower stability and removal efficiency. FeM lowered growth, protein and fat digestibility; with altered faecal chemical composition. WDG and PEA performed on par with control, if not better in certain aspects with respect to mineral availability and faecal recovery. Overall, 30% inclusion of the test ingredients not only affected growth, but also the waste production and removal efficiency by altering the physical and chemical characteristics of the faeces in common carp.

Apparent nutrient and fatty acid digestibilities of microbial raw materials for rainbow trout (Oncorhynchus mykiss) with comparison to conventional ingredients

Determination of apparent digestibility coefficients (ADC) of ingredients has a central importance in formulation of aquaculture diets. Heterotrophic and phototrophic grown microalgae are considered as one of the best eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) as well as protein alternatives for fish oil and fish meal (FM) to sustain further growth in aquaculture production. This study aimed to determine nutrient and fatty acid ADCs of microbial materials including Nannochloropsis oceanica, Phaeodactylum tricornutum and two thraustochytrid strains (T29 and T66) with comparison to commonly used ingredients such as two batches of FMs, poultry-by product meal (PBM), soybean meal (SBM), corn gluten meal (CGM), wheat gluten meal (WGM) and whole wheat flour (WF) in rainbow trout, Oncorhynchus mykiss. Each ingredient was tested using Cr2O3 as an indigestible marker in triplicated cylindro-conical tanks for 2 weeks. Protein ADCs of microbial ingredients ranged between 77.6% in T66 and 84.4% in P. tricornutum and were close to those of FMs and PBM. N. oceanica had generally significantly lower lipid and fatty acid ADCs than those of P. tricornutum, thraustochytrids and the conventional feed ingredients probably due to their thick cell walls. Between the thraustochytrids strains, the T66 appeared to have slightly lower lipid, energy, organic matter, saturated, monounsaturated, long chain n-6 and long chain n-3 fatty acid ADCs than T29. P. tricornutum showed comparable nutrient ADC values to the two FMs used in the study. The results suggest that even if the microbial ingredients were used at 30% in reference diet without exposition to a pretreatment process, they can be utilized at acceptable rates by rainbow trout.

Apparent digestibility coefficients of selected protein ingredients for pirarucu Arapaima gigas (Teleostei: Osteoglo ssidae)

Apparent digestibility coefficients (ADCs) of nine protein ingredients were determined for pirarucu Arapaima gigas , a Neotropical fish species with great aquaculture potential in the Amazon. ADCs of crude protein, energy and dry matter were determined by feces sedimentation in cylindrical-conical tanks. Experimental diets were composed of 795 g kg -1 of the reference diet, 5 g kg -1 of chromic oxide and 200 g kg -1 of the following test ingredients: fish by-product meal, salmon by-product meal, poultry by-product meal, hydrolyzed feather meal, meat and bone meal, blood meal, soybean meal, corn gluten meal and corn gluten feed. Blood meal, meat and bone meal and corn gluten feed resulted in low ADCs for pirarucu, whereas corn gluten meal, poultry by-product meal and soybean meal were better digested, indicating that these ingredients may be potential protein sources in feed formulations for pirarucu. The other animal protein ingredients presented intermediate ADCs values and, together with blood meal and meat and bone meal, they demonstrate that the nutritional quality of the animal by-products tested could be improved, especially by enhancing the processing methods of this group of ingredients.

Apparent digestibility of dry matter, organic matter, protein and energy of native Peruvian feedstuffs in juvenile rainbow trout (Oncorhynchus mykiss)

Trout production is a growing activity in recent years but requires new alternative sources of feed to be sustainable over time. The objective of this research was to determine the apparent digestibility coefficient (ADC) of dry matter (DM), organic matter (OM), crude protein (CP) and digestible energy (DE) of kañiwa (Chenopodium pallidicaule Aellen), kiwicha (Amaranthus caudatus L), quinoa (Chenopodium quinoa Willd), beans (Phaseolus vulgaris L.), sacha inchi, (Plukenetia volubilis L) and jumbo squid (Dosidicus gigas) meal in juvenile rainbow trout. The experimental diets were composed of a 70% basal diet and 30% of any raw materials. The ADC was determined by the indirect method using insoluble ash as a non-digestible marker. Jumbo squid, sacha inchi and quinoa showed the highest values of ADC (%) of DM (84.5, 73.5 and 69.7), OM (89.1, 78.4 and 72.9), CP (93.2, 98.0 and 90.3), and DE (4.57, 4.15 and 2.95 Mcal/kg DM), respectively. The ADC values for kañiwa, kiwicha and bean were significantly lower. In conclusion, quinoa meal and jumbo squid meal have an acceptable digestibility but sacha inchi meal is a potential alternative for rainbow trout feeding in the future.

A bioenergetic and protein flux model to simulate fish growth in commercial farms: Application to the gilthead seabream

A model for fish growth simulation based on the bioenergetic factorial approach is presented. This work presents a novel approach that extends the traditional bioenergetic model by explicitly including the Energy and Protein fluxes (EP model). This is a valuable feature that allows the dynamic simulation of fish proximate composition. For the aquaculture industry it represents a trade-off between detailed process simulation and feasibility of model implementation, namely regarding data gathering on an operational setting. The EP model is targeted to simulate fish production in commercial farms. Farm data for feed intake, feed composition (energy and protein content), temperature over time and the initial fish body weight are the only required data to run the model. Furthermore, apparent digestibility coefficient (ADC) values of the feed used in the farm must be known or else ADC values of feeds with similar composition can be used. The EP model implementation is illustrated for the gilthead seabream (Sparus aurata) based on published experimental data. The model was validated (r = 0.997, p < 0.05, n = 12) using a published experimental data set for gilthead seabream reared in a range of temperatures that reproduce the conditions in most countries producing this species. For the entire growth period (488 days) the estimated mean absolute error (MAE) is 8.8 g.fish−1 and the mean absolute percentage error (MAPE) is 8.3%. Simulation of fish growth in real operational conditions is evaluated with three datasets from a commercial farm that operates in earthen ponds with temperatures ranging between 12.6 °C and 24.8 °C. Overall the model outputs match well with the production data in the 3 batches. Initial weight ranged between 2.8 g and 3.7 g. The deviation between the data and simulated final weights is below 15 g, for a final weight around 435 g. The maximum absolute error is 21.1 g per fish (MAE) and in percentage 8.3% (MAPE).

Apparent Digestibility of Minerals from Several Ingredients for Tambaqui, Colossoma macropomum, Juveniles

AbstractBased on the importance of tambaqui, Colossoma macropomum, for Latin American aquaculture and the digestibility of minerals for the production of sustainable aquafeeds, we designed a series of trials to determine the apparent digestibility coefficients (ADCs) of phosphorus, calcium, magnesium, manganese, and zinc from six protein sources: soybean meal (SBM), corn gluten meal 60 (CGM60), cottonseed meal 40, fishmeal (FM), poultry byproduct meal (PBM), and meat and bone meal (MBM); four cereal grain products: corn, wheat middlings, broken rice (BR), and rice bran (RB); and dicalcium phosphate (DCP). Considerable variation in the ADCs of minerals was observed among the feed ingredients. In general, CGM60, PBM, and RB tended to show the highest ADC values, while SBM, MBM, DCP, and BR showed the lowest ADC values. ADC‐P was markedly lower in animal protein sources and the phosphate source (DCP), while high P digestibility was observed for plant protein sources and cereal grain products. Interestingly, tambaqui seems to be able to digest and absorb minerals from plant ingredients more efficiently than animal proteins and DCP. In light of the correlation between nutrient levels and the ADCs of minerals, physiological mechanisms that regulate mineral uptake, and the nutritional ecology of the species, we hypothesize that tambaqui are able to digest minerals from plant proteins with high efficiency.

Improved digestibility of plant ingredient-based diets for European seabass (Dicentrarchus labrax) with exogenous enzyme supplementation

This study evaluated the effect of supplementation of a plant ingredients-based diet with two levels of commercially digestive enzyme products: Synergen™ and Natugrain® on the apparent digestibility coefficients (ADCs) of nutrients and on digestive enzyme activities in European seabass (Dicentrarchus labrax) juveniles. A control diet was formulated with 450 g/kg CP (200 g/kg from fish meal + 800 g/kg from plant protein) and 180 g/kg CL (fish oil), and four other diets were made similar to the control but supplemented with 0.2 g/kg or 0.4 g/kg of Synergen™ and Natugrain®. Digestive enzyme activities were not affected by dietary treatments. Nevertheless, chyme pH along the intestine of fish fed the Natugrain®-supplemented diets was reduced. The ADC of nutrients increased with exogenous digestive enzyme supplementation, with the highest ADC values being observed for the 0.4 g/kg Natugrain® diet. The ADC of dry matter, protein, lipids, energy and phosphorus in this diet were 26%, 6%, 4%, 16% and 63% higher, respectively, than in the control diet. Overall, diet supplementation with exogenous enzyme complexes seems to have high potential for improving the utilization of plant feedstuff-rich diets for seabass juveniles. This study revealed that Natugrain® was more effective than Synergen™ in improving the ADC of nutrients and energy in European seabass juveniles.

Fish protein hydrolysate in diets for Nile tilapia post-larvae

Abstract: The objective of this work was to determine the apparent digestibility coefficient (ADC) of crude protein, crude energy, fat, and dry matter of fish protein hydrolysate (FPH), made of by-products of Nile tilapia (Oreochromis niloticus) and whole sardines (Cetengraulis edentulus), and to evaluate the productive performance and muscle fiber growth of Nile tilapia post-larvae. Two trials were conducted, the first one to determine the digestibility in 120 fingerlings (70.0±2.0 g), and the second one to evaluate the productive performance of 375 post-larvae, with three days of age, which were distributed in 25 aquaria with 30 L of useful volume. Five diets were prepared based on vegetable ingredients, to which fish were included at 0, 2, 4, 6, and 8% FPH. For the evaluation of muscle growth, eight fish of each experimental unit were used. The ADC values found were: 98.29% for dry matter; 99.28% for crude protein; and 99.13% for gross energy. The best zootechnical response for the productive performance resulted from the treatment with the inclusion of fish hydrolysate at 4.75%. The diets affected the frequency of the muscle fiber diameters, mainly the growth by hyperplasia. FPH can be efficiently used, and its inclusion at 4.75% is indicated in the diets for Nile tilapia in the post-larvae stage.

Apparent digestibility coefficients of European grain legumes in rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus)

Two trials were carried out to evaluate the apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipids, starch and gross energy (GE) of six European varieties of grain legumes, namely chickpea-type Kabuli (CHK), chickpea-type Desi (CHD), field pea (FP), faba bean (FB), white lupin (WL) and chickling vetch (CV), in rainbow trout and Nile tilapia juveniles. The ADCs were measured using a reference diet and six experimental diets (700 g/kg of the reference diet and 300 g/kg of each raw grain legume) containing 10 g/kg chromic oxide as inert marker. Additionally, grain legumes were analysed for the organic acids profile. In rainbow trout, FP presented the highest ADCs of DM, CP and GE, whereas chickpeas and FB had the lowest DM, GE and starch ADC values. In Nile tilapia, the lowest values of nutrients (except starch) and energy ADCs were found for FP and CV. Nutrients and energy of chickpeas, WL and FB were better digested by tilapia, whereas FP was better digested by trout. Overall results reveal raw grain legumes as promising feed sources for both fish species.

Dietary protein/carbohydrate ratio in low-lipid diets for Senegalese sole (Solea senegalensis,Kaup 1858) juveniles. Influence on growth performance, nutrient utilization and flesh quality

Four isoenergetic (21 kJ/g dry matter, DM) and isolipidic (65 g/kg DM) diets containing different crude protein/total carbohydrate (CHO) ratios: 60/26, 56/30, 52/34 and 48/38, were tested in 22 g Senegalese sole for 104 days. Apparent digestibility coefficients (ADC) were not affected by the treatments, and all groups presented extremely low starch ADC values (22.8%–36.5%). Replacement of dietary protein by CHO did not affect daily growth index (0.9–1.0), but significantly increased voluntary feed intake of fish. Regression analyses demonstrated that digestible protein content, rather than digestible energy, was the main dietary factor influencing such feeding activity (R2 = .952). A significantly increased feed conversion ratio was observed in sole fed increasing CHO contents. The dietary protein/CHO ratio did not influence whole-body composition. Sole fed the 48/38 diet showed the lowest efficiency in terms of N and energy utilization. PUFA were the most represented fatty acid fraction in fillet, regardless of the dietary protein/CHO ratio, mainly due to the high content of DHA. Senegalese sole increase feed intake under low dietary protein/CHO ratios to ensure an adequate N intake. Such compensatory mechanism seems to be triggered to satisfy a specific protein metabolic requirement for energy purposes as tissue accretion remained unchanged.

Reduction of Particle Size of Rhizoclonium riparium Protein Concentrate Improves Digestibility, Growth, and Feed Efficiency of Penaeus vannamei Post Larvae

The present study evaluated the effect of particle size (PS) of Rhizoclonium protein concentrate (RPC) on apparent digestibility coefficients (ADC) as well as on growth and feed efficiency of Pacific white shrimp (Penaeus vannamei) for a period of 30 days. Results showed that white shrimp could effectively digest Rhizoclonium protein concentrate in their diet. Average ADC values for dry matter (ADMD), crude protein (ADCP), and crude lipid (ADCL) were 71.1%, 84.4%, and 94.6%, respectively. A significant inverse relationship (p&lt;0.05) was estimated between PS and ADMD (r=-0.66, p= 0.02). Particle size of 150 µm resulted in the highest final body weight (FBW), weight gain (WG), specific growth rate (SGR), feed conversion efficiency (FCE) and protein efficiency ratio (PER). All response parameters exhibited significant inverse correlations with particle size (p&lt;0.05). In conclusion, digestibility of seaweed protein concentrate and its nutritive value could be improved by grinding it to an optimum size of 150 µm before dietary inclusion.

Reduction of Particle Size of Rhizoclonium riparium Protein Concentrate Improves Digestibility, Growth, and Feed Efficiency of Penaeus vannamei Post Larvae

The present study evaluated the effect of particle size (PS) of Rhizoclonium protein concentrate (RPC) on apparent digestibility coefficients (ADC) as well as on growth and feed efficiency of Pacific white shrimp (Penaeus vannamei) for a period of 30 days. Results showed that white shrimp could effectively digest Rhizoclonium protein concentrate in their diet. Average ADC values for dry matter (ADMD), crude protein (ADCP), and crude lipid (ADCL) were 71.1%, 84.4%, and 94.6%, respectively. A significant inverse relationship (p&lt;0.05) was estimated between PS and ADMD (r=-0.66, p= 0.02). Particle size of 150 µm resulted in the highest final body weight (FBW), weight gain (WG), specific growth rate (SGR), feed conversion efficiency (FCE) and protein efficiency ratio (PER). All response parameters exhibited significant inverse correlations with particle size (p&lt;0.05). In conclusion, digestibility of seaweed protein concentrate and its nutritive value could be improved by grinding it to an optimum size of 150 µm before dietary inclusion.