Weaning European glass eels (Anguilla anguilla) with plant protein-based diets and its effects on intestinal maturation

Weaning glass eels with compound diets (36% proteins, 16% lipids) differing in their fishmeal (FM) level (50, 75 and 100% FM replaced by a blend of plant proteins, PP) was compared to a group fed cod roe. Weaning lasted for 20 days and then, eels were fed compound diets for 70 days, whereas the other group was only fed cod roe (90 days). Diets were tested with four replicates and evaluated in terms of growth, survival, glass eels metamorphosis into elvers, oxidative stress status and activity of digestive enzymes. Although glass eels are traditionally fed with fish roe and progressively weaned onto compound diets, results revealed that this strategy should not be prolonged for a long time, since feeding glass eels with cod roe for 90 days negatively affected their growth (2 times lower than fish fed compound diets), delayed their metamorphosis, as well as the maturation of their digestive function as the ratio of alkaline phosphatase and leucine-alanine peptidase indicated. Weaning glass eels onto compound diets differing in their FM levels did not affect their growth, metamorphic stage nor the activity of pancreatic enzymes (total alkaline proteases, trypsin, bile salt-activated lipase and α-amylase), although 75% FM replacement by PP sources delayed the level of intestinal maturation in eels. In comparison to glass eels fed the 100% FM diet, survival was negatively affected in groups fed diets with 50 and 75% FM replacement by PP ingredients, which indicated that further improvement is needed in diet formulation for this stage of development.info:eu-repo/semantics/acceptedVersio

Legumes, Sustainable Alternative Protein Sources for Aquafeeds

Aquaculture produce a great portion of aquatic derived proteins for human in the world. It has the highest and the fastest growth rate among the protein producing industries. Fish meal (FM) is the main and the most expensive ingredient for aquafeeds production. It provides protein, essential amino acids, energy, minerals and vitamins in aquafeeds. Given the current rapid development of aquaculture industry the competition for limited global supplies of FM may reduce its availability and elevate its price. Thus, finding high quality, economic and environmentally friendly alternative protein sources (APS) for aquafeeds production is vital for sustainability of the aquaculture industry. Among various APS, legumes have been proved to be promising APS because they have medium protein content with suitable amino acid profile, high digestible protein and energy levels, and appropriate minerals and vitamins for the most cultured aquatic species. They also are cost-effective and highly accessible. However, they contain various anti-nutritional factors that may reduce feed palatability and may negatively affect growth and health of cultured aquatic animal species. This chapter provide information regarding legumes and their derivatives as APS, their nutritional quality and their potential drawbacks. In addition, strategies for increasing the efficiency of legumes in aquafeeds are reviewed and discussed

Nutritional effects of additives containing organic acids, cinnamaldehyde and permeabilizer on some growth indices and intestinal structure of whiteleg shrimp, Litopenaeus vannamei

This study investigated the effects of feed additive containing organic acids, cinnamaldehyde and permeabilizers on growth rate and intestine structure of whiteleg shrimp (Litopenaeus vannamei). So, five isoproteic (∼38%) diets containing different levels of 3, 6, 9 and 12 g/kg (T3, T6, T9 and T12, respectively) commercial additive Biotronic Top 3 were formulated and a diet without this additive were considered as a control. Shrimps (2.7 g in average weight) were randomly placed in fifteen 300-liter fiberglass tanks containing sea water (20 shrimps in each tank) and each experimental treatment was in triplicate. Shrimps were fed at the rate of 7% of their body weight three times a day. At the end of the experiment, the average final weight in shrimps fed with diets containing additives was significantly higher than the control group (p0.05). The food conversion ratio in the treatments fed with additives, (except for T9) was significantly lower than the control group (p<0.05). Examining the shrimp intestine showed that using this additive elevated the height of the intestinal villi. In general, according to the findings of this study, dietary supplementation of Biotronic Top 3 at 3 g/kg can enhance the growth rate and intestine histology of whiteleg shrimp

Macronutrient Requirements of Silvery-Black Porgy (Sparidentex hasta): A Comparison with Other Farmed Sparid Species

Silvery-black porgy (Sparidentex hasta) is recognized as one of the most promising fish species for aquaculture diversification in the Persian Gulf and the Oman Sea regions. In this regard, S. hasta has received considerable attention, and nutritional studies focused on establishing the nutritional requirements for improving diet formulation have been conducted during recent years. Considering the results from different dose–response nutritional studies on macronutrient requirements conducted in this species, it can be concluded that diets containing ca. 48% crude protein, 15% crude lipid, 15% carbohydrates and 20 KJ g−1 gross energy are recommended for on-growing S. hasta juveniles. In addition, the optimum essential amino acid profile for this species (expressed as g 16 g N−1), should be approximately arginine 5.3, lysine 6.0, threonine 5.2, histidine 2.5, isoleucine 4.6, leucine 5.4, methionine + cysteine 4.0 (in a diet containing 0.6 cysteine), phenylalanine + tyrosine 5.6 (in a diet containing 1.9 tyrosine), tryptophan 1.0 and valine 4.6. Moreover, the optimum dietary n-3 long chain polyunsaturated fatty acids and soybean lecithin are recommended to be 0.8% and 6%, respectively. The maximum replacement of fish meal with soy protein is recommended to be between 16.5% and 27.3%. In addition, different vegetal oil sources are also recommended for partial and almost complete replacement of fish oil in diets. Although the nutritional requirements in terms of macronutrients have been established under laboratory conditions, the analysis of the available literature indicate that future studies need to be conducted using a more holistic approach under intensive farming conditions in which different nutrients or additives need to be tested under different rearing conditions for refining nutrient requirements in this species.info:eu-repo/semantics/publishedVersio

Dietary fatty acid profiling in plant protein‐rich diets affects the reproductive performance, egg fatty acid profile and haematological parameters in female rainbow trout (Oncorhynchus mykiss)

The influence of dietary fish oil (FO) substitution with blends of vegetal oils (VO: canola, linseed, olive, sunflower, corn and coconut oils) in plant protein‐rich diets on reproductive performance and fatty acid dynamics of embryos was evaluated in female rainbow trout (Oncorhynchus mykiss) brooders (1.8 ± 0.1 kg). Four diets were formulated in which 20% (FO80/VO20), 50% (FO50/VO50), 75% (FO25/VO75) and 100% (VO100) of FO were replaced by mixture of VO. The above‐mentioned diets were administered for a short period prior to spawning (3 months). Fish fed the VO100 had the lowest fertilization rate (81.3 ± 2.3), whereas brooders fed the FO80/VO20 diet had the lowest survival rates at eyed embryo stage (83.7 ± 1.6%) and hatching rate (79.9 ± 3.1%). The fatty acid dynamics of embryos were not only affected by embryonic developmental stages, but also they were influenced by the dietary fatty acid profile. Our study confirmed that using blends of different VO sources and FM residual fat in the FO25/VO75 for the short‐term period prior to spawning seemed to be a good strategy in terms of successful reproduction for sparing high levels of FM and FO in diet of O. mykiss brooders.info:eu-repo/semantics/acceptedVersio

Optimal stocking density for beluga, Huso huso, and ship sturgeon, Acipenser nudiventris during the grow‐out phase

The influence of three different initial stocking densities (SD) in flowthrough systems was evaluated on growth performance and feed utilizaition in beluga, Huso huso, and ship sturgeon, Acipenser nudiventris, juveniles in three different grow‐out phases for 228 days. In each grow‐out phase, fish were randomly distributed in 18 concrete square tanks (2.0 × 1.0 × 1.2 m3; 2 m3 of volume) according to the experimental SD. At the first phase, both fish species were subjected to three SD including 1.5, 3 and 6 kg/m2 for 60 days. In the second phase, fish were submitted to three SD including 3, 6 and 9 kg/m2, whereas in the third phase, beluga were stocked at 6, 9 and 12 kg/m2 and ship sturgeon were stocked at 6, 8 and 10 kg/m2 and each phase lasted for 12 weeks. In both species, the growth performance and feed intake (FI) significantly decreased with increasing SD at the end of the first phase (p < 0.05). In the second phase, growth performance and FI in beluga decreased with increasing SD, whereas in ship sturgeon neither growth nor FI were affected by SD. Interestingly, the growth performance and feed utilization in both species were not decreased with increasing SD in the third phase indicating adaptability of these species to high stocking density during grow‐out period. According to the result of this study, the appropriate initial SD for beluga within the range of 100–500, 500–2,000 and 1,500–3,000 g were at 1.5, 6 and 12 kg/m2, respectively in an open flow‐throw system. Regarding to ship sturgeon, initial SD at 1.5 and 10 kg/m2recommended for fish within the range of 100–300 and 300–1,200 g, respectively in an open flow‐throw system.info:eu-repo/semantics/acceptedVersio

Hemato-Immunological and plasma biochemical responses of silvery-black porgy (Sparidentex hasta) fed protein and essential amino acid deficient diets

A six-week feeding trial was conducted to evaluate the effects of protein free (PF) and essential amino acid deficient (EAAD) diets on the physiological responses of silvery-black porgy (Sparidentex hasta) juveniles. Three experimental diets were formulated: a control diet in which 60% of dietary nitrogen was provided by intact protein (fish meal) and 40% by crystalline AA [(blends of essential amino acids (EAA) and none essential amino acids (NEAA)]; an essential amino acid deficient diet in which 60% of dietary N was provided by intact protein, whereas the rest was provided by NEAA; and a protein free (PF) diet, which based on carbohydrate sources. Fish fed the PF and EAAD showed signs of anemia including lower red blood cells counts, hemoglobin and hematocrit levels than control group. Plasma lysozyme activity and complements C3 and C4, as well as total immunoglobulin levels were drastically reduced in fish fed PF and EAAD diets. Plasma and liver alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatase were significantly increased, but superoxide dismutase was decreased in fish fed PF and EAAD diets. Plasma total protein, albumin, high density lipoprotein, calcium and inorganic phosphorous significantly decreased in fish fed PF and EAAD diets. The information obtained from this study testing to extreme diets (EAAD and PF diets) may serve for better understanding the impact of protein nutritional imbalances in fish.info:eu-repo/semantics/acceptedVersio

Larval rearing and ontogeny of digestive enzyme activities in yellowfin seabream (Acanthopagrus latus, Houttuyn 1782)

The present research was conducted to provide insight into digestive larval capacity in Acanthopagrus latus larvae from hatching up to 30 days after hatching (DAH). Newly hatched larvae were stocked into six 300-L cylindrical polyethylene tanks at a density of larvae 50 larvae/L and reared by means of the green water system using Nannochloropsis oculata (0.5 × 106/mL). After mouth opening, larvae were fed with rotifers (5–16 individual/mL) from 2 to 20 DAH; then, Artemia nauplii (0.5–3.0 individuals/mL) were offered to larvae from 18 to 30 DAH, meanwhile a commercial microdiet was offered to larvae from 25 to 30 DAH. Larval performance in terms of growth and survival, and the assessment of the activity of selected digestive enzymes ontogeny of digestive enzymes activities was evaluated in larvae sampled at 0 (hatching), 7, 15, 22 and 30 DAH. Larvae showed an exponential growth characterized by two different growth stanzas, a first one characterized by slow growth rates comprised between hatching to 15 DAH (4.7 ± 0.2 mm), followed by a period of faster growth rates between 16 and 30 DAH (7.5 ± 0.6 mm). The activities of the brush border (alkaline phosphatase, ALP) and cytosolic (leucine-alanine peptidase, LAP) enzymes, as well as those of the pancreatic ones like total alkaline proteases, bile salt-activated lipase and α-amylase were detected from the mouth opening stage. Total activities of pancreatic and gastric enzymes increased with larval growth showing an enhancement of digestive capacities with larval age and size. The intestinal maturation in A. latus as assessed by the ratio of AP to LAP did not occur as expected by end of the first month of life suggesting the complete establishment of digestive luminal processes may take place at older ages. This study related to the growth patterns and ontogenic changes in activity of pancreatic, gastric and intestinal enzymes in A. latus and their nutritional regulation may be considered as the first step for improving the larviculture, as well as assessing and refining the nutritional requirements during the larval and early juvenile stages of this sparid species.info:eu-repo/semantics/acceptedVersio

Growth Performance, Hemato-Immunological Responses, and Digestive Enzyme Activities in Silvery-Black Porgy (Sparidentex hasta) Fed Dietary Bovine Lactoferrin

An 8-week study was conducted to evaluate three different diets supplemented with bovine lactoferrin (LF) at 0 (control), 800, and 1200 mg LF kg−1 diet on somatic growth, hemato-immunological parameters, antioxidant status, and digestive enzyme activities in silvery-black porgy (Sparidentex hasta) juveniles. Fish fed the 800 mg LF kg−1 diet had higher growth performance and feed utilization parameters than the other groups. Hematological and liver antioxidant parameters were not affected by dietary LF supplementation. Fish fed the 800 mg LF kg−1 diet had higher plasma lysozyme activity values than the other groups. Total protease activity was higher in fish fed LF-supplemented diets than the control group. Results indicated that diet supplemented with 800 mg kg−1 for 8 weeks enhanced somatic growth performance, lysozyme activity, and proteolytic digestive enzyme activities in S. hasta, as well as improving feed efficiency parameters like the protein efficiency and feed conversion ratios.info:eu-repo/semantics/acceptedVersio

Ontogeny of the digestive enzyme activity of the Amazonian pimelodid catfish Pseudoplatystoma punctifer (Castelnau, 1855)

The aim of the study was to evaluate the functional ontogeny of the digestive system of Pseudoplatystoma punctifer through the analysis of the activity of the main intestinal (alkaline phosphatase, aminopeptidase N, maltase and leucine-alanine peptidase), pancreatic (trypsin, chymotrypsin, total alkaline proteases, bile-salt activated lipase and amylase) and gastric (pepsin) enzymes. Larvae were raised in triplicate in a recirculation system from 4 to 27 days post fertilization (dpf) at an initial density of 90 larvae L−1, 27.8 ± 0.7 °C and 0 L: 24D photoperiod. Larvae were fed from 4 to 17 dpf with Artemia nauplii and weaned onto an experimentally formulated feed (crude protein content ~ 45%; crude fat content ~ 10%; crude carbohydrate ~ 8%) within 3 days, then continued with the same diet until the end of the trial. P. punctifer showed an exponential growth pattern with two different growth rates: a slower one from hatching to 12 dpf followed by a faster one from 12 to 27 dpf. The specific and total activities of the pancreatic and intestinal enzymes were detected from hatching. The digestive system was functional at 12 dpf, indicating the transition from the larval to the juvenile stage (alkaline to acid digestion). Therefore individuals could be weaned from that day onwards. The variations observed in the enzymatic activity from 17 dpf reflected the adaptation of the enzymatic machinery to the new diet supplied. P. punctifer larvae showed a fast digestive system development with an enzymatic profile typical of a tropical and carnivorous species.info:eu-repo/semantics/acceptedVersio