Utilization of combined extruded soybean and corn gluten meals as feed ingredients for juvenile rainbow trout,Oncorhynchus mykiss diet

In this study, feeding experiment and subsequent digestibility trial were performed to investigate the utilization of extruded soybean meal (SBM) and corn gluten meal (CGM) as feed ingredients for juvenile rainbow trout. Plant ingredients have undergone extrusion at low temperature (100°C, LT) or high temperature (150°C, HT) for 30 s. Four isonitrogenous (44%, crude protein) and isolipidic (14%, crude lipid) diets were formulated. Control diet is fishmeal based while a combined (1:1) non‐extruded SBM and CGM for NE diet, LT SBM and LT CGM for LT diet and HT SBM and HT CGM for HT diet. Two hundred forty rainbow trout juveniles (7.8 g average body weight) were randomly divided into 12 rectangular 60 L glass aquaria and offered four different diets in triplicate. Fish were fed at satiation twice a day, six days a week for 12 weeks. Phosphorus in phytic acid level of extruded ingredients decreased through extrusion cooking. Final weight, weight gain, SGR and PER of fish fed HT diet were significantly (p < .05) higher than those fed with NE diet. Apparent digestibility coefficient for protein of LT and HT diets is significantly higher than of NE diet. The results of this study demonstrated that HT extruded SBM and CGM are suitable feed ingredients for rainbow trout diet without compromising fish growth, feed utilization and fish body composition.     

Apparent digestibility of Asian carp‐ and common carp‐derived fish meals in feeds for hybrid striped bass Morone saxatilis ♀ × M. chrysops ♂ and rainbow trout Oncorhynchus mykiss

Apparent digestibility coefficients (ADCs) of nutrients (crude protein, amino acids, crude lipid, fatty acids, and minerals) were determined for fish meals derived from menhaden, Asian carp (combination of silver and bighead carps), and common carp in feeds for hybrid striped bass and rainbow trout. Extruded test diets were formulated to contain a 70 : 30 mixture of reference diet and test ingredient with yttrium oxide (1 g kg^?1) serving as the inert marker. Diets were randomly assigned to triplicate tanks and fish were fed once per day at 2% body weight. Fecal samples were collected by manual stripping. The ADCs were calculated according to standard procedures. The composition and digestibility of Asian carp and common carp meals was broadly similar to menhaden meal. Protein digestibility ranged from 86.5% (Asian carp meal) to 93.1% (common carp meal). Lipid was highly digestible with ADCs >100% for all ingredients. Although the Asian carp meal was less digestible than the other two fish meals, it was still a highly digestible ingredient. Our data suggest that fish meals derived from Asian or common carp would be valuable feedstuffs in diets for hybrid striped bass, rainbow trout, and possibly other cultured fishes.     

Apparent digestibility coefficients of nutrients in brewer's and rendered animal by-products for rainbow trout (Oncorhynchus mykiss (Walbaum))

Two experiments were conducted to measure the apparent digestibility coefficients (ADCs) of nutrients, dry matter, and energy in by‐products of the brewing industry and in selected animal protein ingredients for rainbow trout. In experiment 1, 500 rainbow trout (average body weight 170.8±5.5 g) were stocked in ten 140‐L digestibility tanks with 50 fish per tank and two tanks per diet. Yttrium oxide was used as an inert marker in the diets. The high fibre content of brewer's dried grains (BDG) affected the ADCs of dry matter but not of protein or amino acids. Brewer's dried yeast had a higher protein content than BDG, but ADC values for protein and amino acids were significantly lower. The ADCs of phosphorus were similar among brewer's dried products. The BDG high‐protein, fraction had marginally higher ADC values for dry matter, protein and amino acids than regular BDG. Conditions in experiment 2 were similar to those in experiment 1. ADC values for spray‐dried porcine plasma were over 98% for dry matter, crude protein, crude fat, and gross energy. ADC values for spent hen meal were higher than those of poultry by‐product meal or feather meal, with the exception of gross energy. However, spent hen meal was unpalatable. The ADCs in these ingredients were variable, and this variability must be taken into account when these ingredients are formulated into feeds for fish.     

Digestibility of Dry Matter, Protein, Lipid, and Organic Matter of Two Fish Meals, Two Poultry By-product Meals, Soybean Meal, and Distiller's Dried Grains with Solubles in Practical Diets for Sunshine Bass, Morone chrysops ×M. saxatilis

Limited information is available on digestibility of nutrients in various practical ingredients used in diets for commercially important finfish species, such as hybrid striped bass. This information is especially needed for sunshine bass, Morone chrysops × M. saxatilis , to improve least-cost diet formulations and to allow effective substitution of feedstuffs. A study was conducted with large (867 g) sunshine bass to determine the apparent digestibility coefficients (ADCs) for moisture, protein, lipid, and organic matter (OM) in a variety of ingredients in floating, extrusion-processed, diets. The practical ingredients tested were menhaden (MEN) fish meal (FM), anchovy (ANCH) FM, pet-food grade poultry by-product meal, feed-grade poultry by-product meal, dehulled soybean meal (SBM), and distiller's dried grains with solubles (DDGS). Test diets consisted of a 70:30 mixture of reference diet to test ingredient with chromic oxide (1.0%) as the inert marker. Reference and test diet ingredients were mixed and extruded on a Wenger X85 single-screw extruder to produce floating pellets. The digestibility trials were conducted in twelve 1200-L circular tanks. Diets were randomly assigned to tanks of 30 sunshine bass and were fed once daily to satiation. Protein digestibility coefficients were significantly ( P  < 0.05) different among test ingredients and ranged from 86.42% for MEN to 64.94% for DDGS. Lipid ADCs were significantly different ( P  < 0.05) among test ingredients and ranged from 92.14% for MEN to 57.11% for SBM. OM ADCs were significantly different ( P  < 0.05) among test ingredients and ranged from 89.41% for MEN to 16.94% for DDGS. This information will assist in the formulation of more efficient, economical diets for sunshine bass.     

Effects of extrusion processing on digestibility of peas, lupins, canola meal and soybean meal in silver perch Bidyanus bidyanus (Mitchell) diets

Two experiments were conducted to investigate effects of processing on apparent digestibility coefficients (ADCs) of legumes and oilseeds for juvenile silver perch, Bidyanus bidyanus (～49 g). The first experiment evaluated interactive effects of ingredients (lupins or field peas), processing (whole seed; hulls on or hulls off) and extrusion cooking (raw or extruded) on ADCs for juvenile silver perch (～4 g fish^?1). The second experiment was a three‐fixed‐factor anova designed to evaluate interactive effects of ingredients (soybean meal or canola meal), extrusion cooking (raw or extruded) and inclusion content (30% or 50% of the diet) on ADCs for juvenile silver perch (～4 g fish^?1). Lupin protein was more digestible than that of peas (ADC for crude protein 91% vs. 85% for peas) but the organic matter was less digestible (ADC for organic matter 50% vs. 67% for peas). Dehulling lupins significantly improved ADCs for all indices (dry matter, organic matter, energy and crude protein), but extrusion had no effect because lupins do not contain starch or heat‐labile anti‐nutrients. Conversely, for starch‐rich peas that contain heat‐labile trypsin inhibitors, both dehulling and extrusion significantly improved ADCs. Digestibility of soybean meal was much higher than that of canola meal. For soybean meal, neither processing, content nor their interaction affected digestibility but extrusion improved ADCs for dry matter, organic matter and energy but there was an interaction with content. Although higher overall, digestibility for these indices declined with increasing content for extruded product while there were only minor effects of inclusion for raw product. Benefits of extrusion were attributed to reductions in anti‐nutrients, including phytic acid. For canola, there were no interactions between extrusion and content for any ADC. Increasing content reduced ADCs for crude protein, dry matter and organic matter but did not effect energy. Surprisingly, extrusion of canola also reduced digestibility for all ADCs. Dehulling improved both lupins and peas. Crude protein for all ingredients was well digested with ingredients ranked: lupins>soybean meal>peas>canola meal. Energy digestibility was best for soybean meal and worst for lupins. Extrusion greatly improved digestibility of peas and to a lesser extent soybean meal, gave no benefits to lupins and was detrimental for canola.     

Evaluation of apparent digestibility coefficients of individual feed ingredients in spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

Apparent digestibility coefficients (ADCs) for dry matter, crude protein, energy and essential amino acids for five commonly used feed ingredients were determined for juvenile spotted rose snapper Lutjanus guttatus (average body weight 90.6 g). ADCs were determined using the stripping technique to collect faeces after fish were fed a reference diet and test diets composed of 700 g kg^?1 reference diet and 300 g kg^?1 test ingredient. Chromic oxide (Cr₂O₃) was used as an inert indicator. Ingredients tested included sardine fishmeal (FM), canola meal (CM), tuna by‐products meal (TBM), poultry by‐product meal pet grade (PBM‐PG) and solvent‐extracted soybean meal (SBM). In general, all ingredients showed high digestibility values for all essential amino acids, although differences were detected among ingredients. ADC values for dry matter, protein and energy ranged 77.0–80.4%, 84.3–82.5% and 89–88.8%, respectively, for marine ingredient and land‐based animal protein sources, and 75.0–74.2%, 81.5–80.9% and 87.4–86.8%, respectively, for the plant‐based protein source. SBM, TBM and PBM‐PG should be further evaluated in feeding trials as partial FM replacements in rose snapper L. guttatus diets. Knowledge of ADC values for these ingredients will allow feed producers to develop nutritionally balanced, low‐cost feed formulations for this species.     

Apparent digestibility of selected feed ingredients in diets for juvenile hybrid tilapia,Oreochromis niloticus×Oreochromis aureus

The apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, ash, phosphorus, gross energy and amino acids of 10 selected ingredients for juvenile hybrid tilapia (7.05 ± 0.09 g) were determined using 0.5% Cr₂O₃ as an inert indicator. The feed ingredients tested in this study were corn gluten meal (CGM), corn byproduct, corn germ meal (CG), soybean meal (SBM), fermented soybean meal (FSM), soy protein concentrate (SPC), soy protein isolate, malt sprouts (MS), fish meal (FM) and earthworm meal (EM). The test diets were prepared by incorporation of 30% test ingredients into the reference diet. Reference and test diets were fed to the fish and the faecal samples were collected using a faecal collection column attached to the fish‐rearing tanks. The ADCs for dry matter, crude protein, crude lipid, ash, phosphorus and gross energy were 41.7–98.9%, 90.6–99.6%, 73.1–98.8%, 34.1–98.6%, 49.5–99.6% and 45.4–99.7% respectively. Soy protein isolate, FM and EM had higher dry matter, crude protein and gross energy ADCs. Corn byproduct and EM had higher crude lipid ADCs, and CG and EM had higher phosphorus ADCs. Corn germ meal had the highest ash ADC, while CGM had the highest value for gross energy. The lowest dry matter, crude protein, lipid and gross energy ADCs occurred in MS, while the lowest ash and phosphorus ADCs occurred in SPC. The amino acid ADCs ranged from 83.3% to 100%, exhibiting a positive correlation with crude protein digestibility for a given test ingredient. The feed ingredient digestibility of this study may provide useful information about nutrient and energy utilization to facilitate formulation of least‐cost practical diets for hybrid tilapia.     

Effect of microbial phytase on apparent nutrient digestibility of barley, canola meal, wheat and wheat middlings, measured in vivo using rainbow trout (Oncorhynchus mykiss)

Microbial phytase (Natuphos 5000G) was supplemented into barley, canola meal, wheat and wheat middlings at 500 FTU kg^–1 diet to test the effectiveness of the phytase on digestibility of crude protein (CP), gross energy (GE) and minerals for rainbow trout. A total of 180 rainbow trout (initial mean body weight 223.8 ± 17.9 g) were stocked into ten 40-L fibreglass digestibility tanks with 18 fish per tank. Duplicate tanks were assigned to a reference diet and a single tank was assigned randomly to each of the eight diets made from these four ingredients supplemented with and without phytase. The collection of faeces lasted for 2 weeks. Faeces collected in each week represented a replicate and they were analysed separately. The mean apparent digestibility coefficients (average of four ingredients) in phytase supplemented and nonsupplemented ingredients were: CP, 97.3% and 96.5%; GE, 62.8% and 53.1%; calcium (Ca), 38.3% and –5.3%; magnesium (Mg), 72.4% and 50.3%; manganese (Mn), 31.0% and –4.2%; total-phosphorus (total-P), 71.1% and 47.6%; phytate-phosphorus (phytate-P), 87.5% and 22.3%; copper (Cu), 38.3% and 26.4%; potassium (K), 97.1% and 97.0%; sulphur (S), 90.2% and 88.6%; zinc (Zn), 12.3% and –16.6%. A two-tailed t -test indicated that phytase supplementation significantly ( P  < 0.05) improved the digestibility of Ca, Mg, Mn, total-P, phytate-P, and GE. The efficacy of phytase on nutrient digestibility also depended on the type of ingredient as measured in rainbow trout.     

Apparent digestibility coefficients of selected feed ingredients for juvenile hybrid tilapia,Oreochromis niloticus×Oreochromis aureus

The apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, gross energy, phosphorus and amino acids in local fish meal (LFM), Peruvian fish meal (PFM), poultry by‐product meal (PMM), meat and bone meal (MBM), tilapia by‐product meal (TM), fermented soybean meal (FSBM), soybean meal (SBM), peanut meal, canola meal (CM), cottonseed meal (CSM) and de‐gossypoled cottonseed meal were determined for juvenile hybrid tilapia (7.18 ± 0.2 g, mean ± SD). A reference diet (RF) and test diets (consisting of 70% RF and 30% of the feedstuff) were used with 0.5% chromic oxide as an external digestibility marker. The juvenile hybrid tilapias were stocked in 500‐L fibreglass tanks at a density of 20 fish per tank. Faeces were collected from triplicate groups of fish using a faecal collection column attached to the fish‐rearing tank. The results indicated that the ADCs of dry matter for juvenile hybrid tilapia ranged 71.88–89.53% for animal products and 65.89–79.98% for plant products. For crude protein, apparent digestibility coefficients of protein (ADCp) exceeding 90% were observed for FSBM, SBM and PFM, and ADCp of MBM was the lowest among all the treatments. Apparent digestibility coefficients of lipid in all the treatments were above 90%; the results indicate that lipids from both animal and plant sources were well digested by hybrid tilapia. The ADCs of phosphorus of animal and plant feedstuffs ranged between 58.04–74.44% and 52.65–64.23% respectively. The lowest ADC of phosphorus was observed in CSM among plant ingredients and in MBM among animal ingredients. The ADCs of energy were similar to those of dry matter and protein; the highest and lowest ADCs of energy were found in PFM and CM respectively. In general, the amino acid availability coefficients tended to reflect the ADCp among highly digestible ingredients. For the animal products, the availabilities of amino acids in PFM, LFM and PMM were generally higher than that in TM and MBM; among all the plant products, the availabilities of amino acids in FSBM and SBM were higher than in CM. These results indicated that juvenile hybrid tilapia is able to utilize different feedstuffs efficiently.     

Digestibility and growth performance of juvenile rainbow trout (Oncorhynchus mykiss) fed with pea and canola products

A digestibility experiment and subsequent 84-day feeding experiment evaluated the use of pea and canola meal products in diets for rainbow trout. The effect of milling and heat treatment on nutrient, dry matter and energy digestibility of raw/whole peas, raw/dehulled peas, extruded/dehulled peas and autoclaved air-classified pea protein was determined. Digestibility of the protein component was uniformly high for all pea ingredients (90.9–94.6%), regardless of the processing treatment. Autoclaving or extrusion increased starch digestibility by 41–75% ( P  ≤ 0.05), which consequently increased energy and dry matter digestibility of whole and dehulled peas. Autoclaved air-classified pea protein had superior protein (94.6%), energy (87.0%) and dry matter (84.0%) digestibility ( P  ≤ 0.05). It was demonstrated that inclusion of 25% dehulled peas, 20% air-classified pea protein or 20% canola meal fines was feasible in trout diets allowing for replacement of soya bean meal. The data showed no difference ( P  ≥ 0.05) in feed intake, final weight and specific growth rate (SGR) measurements, and feed utilization was not compromised with inclusion of pea or canola meal products as the primary plant ingredient. It was concluded that dehulled peas, air-classified pea protein and canola meal fines are suitable ingredients for use in trout diet formulation at a level of 20%.     

Apparent digestibility coefficients of selected feed ingredients for juvenile snakehead,Ophiocephalus argus

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, gross energy, phosphorus and amino acids in Peruvian fish meal, poultry by‐product meal, meat and bone meal, spray‐dried blood meal, hydrolysed feather meal, corn gluten meal, soybean meal, peanut meal, cottonseed meal and rapeseed meal were determined for juvenile snakehead (Ophiocephalus argus) with initial mean body weight of 78.1 g. A reference diet and test diets that consisted of a 70 : 30 mixture of the reference diet to test ingredient were used with 5 g kg^?1 Cr₂O₃ as an external indicator. Fish meal, poultry by‐product meal and corn gluten meal had higher ADCs of dry matter, crude protein, and gross energy among ingredients tested. Dry matter ADCs ranged 61.9–81.5% for animal ingredients and corn gluten meal and ranged 52.2–68.0% for soybean meal, peanut meal, cottonseed meal and rapeseed meal. Energy ADCs of ingredients followed similar trends to differences in dry matter digestibility. Protein ADCs of animal and plant ingredients ranged 73.6–92.8% and 75.3–85.6%, respectively. Amino acid ADCs generally reflected protein digestibility. Lipid ADCs were relatively high for the ingredients tested. Phosphorus ADCs of animal and plant ingredients ranged 39.5–65.2% and 38.7–57.1%, respectively.     

Apparent digestibility of common feed ingredients by juvenile haddock, Melanogrammus aeglefinus L.

The digestible energy (DE) content and the apparent digestibility coefficients (ADCs) of nutrients in common feed ingredients available in Atlantic Canada for haddock, Melanogrammus aeglefinus, feed formulations were determined. Juvenile haddock (mean weight, 93.9±2.1 g) were held in tanks equipped with fecal collection columns and fed practical fish meal‐based diets for 5 weeks. The experimental diets consisted of a reference diet and six test diets, each containing 30% test ingredient, with all diets being supplemented with chromic oxide (Cr₂O₃, 5 g kg^?1) as the inert digestion indicator. Three marine fish by‐products, herring meal (HM), shrimp meal (SM) and crab meal (CRM) and three plant protein supplements, dehulled soybean meal (SBM), canola meal (CAM) and corn gluten meal (CGM) were the test ingredients. The DE content of HM, SBM, CGM, CRM, CAM and SM were 18.3, 18.0, 17.8, 12.4, 10.9 and 8.8 MJ kg^?1 respectively. Protein ADCs were 95.9%, 92.2%, 92.3%, 82.0%, 83.0% and 73.5% respectively. Organic matter ADCs were 95.9%, 89.0%, 72.6%, 68.9%, 58.9% and 54.9% respectively. Lipid ADCs were 97.9%, 83.0%, 57.4%, 62.0%, 87.2% and 55.8% respectively. Based upon its high crude protein content and nutrient ADC and DE content, properly processed dehulled SBM was found to be a good plant protein supplement to partially replace HM in haddock feeds.     

Nutrient Digestibility of Common Feedstuffs in Extruded Diets for Sunshine Bass Morone chrysops♀×M. saxatilis ♂

The digestibility of nutrients and energy in various ingredients to fish is affected by a variety of factors including ingredient quality and processing. Limited information is available regarding the digestibility of nutrients in feedstuffs for sunshine bass Morone chrysops♀×M. saxatilis♂. This information is particularly needed to improve the accuracy of diet formulations and allow appropriate substitution of feedstuffs. Therefore, a study was conducted with advanced sunshine bass fingerlings (50–75 g) to determine the apparent digestibility coefficients (ADCs) for protein, lipid, carbohydrate, gross energy, and organic matter in a variety of feedstuffs in extrusion‐processed diets. Included in the study were low‐temperature processed menhaden fish meal (Select®), meat and bone meal, fish meal analog (PROPAK?) dehulled soybean meal, cottonseed meal, corn grain, sorghum, wheat flour, wheat middlings, and rice bran. Test diets consisted of a 70:30 mixture of reference diet to test ingredient with chromic oxide (0.8%) as the inert marker. Reference and test diet ingredients were mixed in a commercial ribbon blender, preconditioned and extruded on a Wenger X‐20 to produce a neutrally buoyant pellet (5 mm). The digestibility trials were conducted in six 600‐L rectangular tanks connected as a closed recirculating brackish (5–7 ppt) water system. Diets were randomly assigned to tanks of 45–50 sunshine bass and fed twice daily to satiation. Feedstuffs of high‐protein and high‐lipid content were better digested by sunshine bass than feedstuffs of high carbohydrate or high fiber content. Organic matter digestibility ranged from 42% for both sorghum and corn to 96% and 98% for meat and bone meal and Select? menhaden fish meal, respectively. Select? menhaden fish meal and meat and bone meal appeared to be the best Ingredients for sunshine bass diets in terms of overall nutrient profiles and digestibility of nutrients. The fish meal analog did not perform as favorably as the other two animal products. Protein and lipid of cottonseed meal were highly available to sunshine bass with ADCs of 85% and 92%, respectively. Protein digestibility was high for soybean meal (77%), whereas the digestibility of organic matter (51%), lipid (54%), carbohydrate (25%) and energy (56%) in this feedstuff was moderately low. Energy in wheat middlings and wheat also was moderately available at 67% and 59%, respectively. Energy in sorghum and corn was much less available at 44% and 40%, respectively. Digestibility of nutrients and energy in rice bran exceeded 90%. Use of this information should aid the development of more efficient and economical diet formulations for sunshine bass.     

Apparent Digestibility of Gross Nutrients from Feedstuffs in Extruded Feeds for Rainbow Trout,Oncorhynchus mykiss

Abstract.— The current experiment was performed to determine apparent protein and energy digestibility coefficients of feed ingredients by the fecal stripping technique using extruded diets. The ingredients tested included five fish meals, three terrestrial animal by‐products, five plant protein concentrates, four plant meals, and seven low‐protein plant ingredients. Protein digestibility differed among fish meals and ranged from 90% for fair and average quality menhaden meal to 97% for anchovy meal. Protein apparent digestibility coefficients (ADCs) in plant concentrates ranged from a low of 89% for rice protein concentrate to a high of 100% for wheat gluten meal. Apparent protein digestibility was lower in plant meals than fish meals with a low of 70% for flaxseed meal to a high of 89% for soybean meal. Low‐protein plant meals had generally lower protein ADC from 64% for rice bran to 85% for whole wheat. A similar pattern for energy ADCs was observed; ADCs ranged from 106% for anchovy meal to 32% for whole wheat. In the current trial, divergent protein and energy ADC values were obtained most notably in ingredients known to be high in fiber or have very high starch content. The comparability of ingredients/diets processed by cold pelleting or extrusion thus appears questionable at this juncture.     

Incorporation of Whole Lupin,Lupinus albus,Seed Meal in Commercial Extruded Diets for Rainbow Trout,Oncorhynchus mykiss: Effect on Growth Performance,Nutrient Digestibility,and Muscle Fatty Acid Composition

Whole lupin seed meal was evaluated as partial replacement for fishmeal in extruded diets for rainbow trout, with particular emphasis on the effect on growth performance and apparent digestibility coefficient (ADC) of protein, lipids, carbohydrates, and energy. Effect on muscle fatty acid composition was also evaluated. All diets were formulated to be isonitrogenous and isoenergetic and to contain approximately 45% crude protein and 5.5 kcal energy g/diet. Diets were formulated to include whole lupin seed meal at 0, 10, 15, and 20%. Triplicate groups of fish weighing 65.9 ± 15.1 g on average were fed twice a day until apparent satiation during 12 wk. Growth, feed intake, hepatosomatic index, hepatic histology, proximate composition of whole body, and muscular fatty acid profile were determined. Growth and feed utilization were similar in all treatments and whole‐body composition did not vary among treatments. Polyunsaturated fatty acids of the n‐6 and n‐3 series remained constant in muscle as the amount of lupin in diets increased. Furthermore, the ADCs were similar among all diets. These results suggest that inclusion of whole lupin seed meal up to 20% in extruded diets for rainbow trout do not have any negative effect on growth, feed performance, or flesh quality.     

Apparent Digestibility Coefficients of Selected Feed Ingredients for Yellowfin Seabream, Sparus latus

The apparent digestibility coefficients (ADC) of dry matter (DM), crude protein (CP), gross energy (GE), and amino acid in seven feed ingredients were determined with juvenile yellowfin seabream (initial body weight, 41 ± 2 g; means ± SD) through two digestibility trials. The ingredients consisted of white fish meal (WFM), Peruvian fish meal (PFM), brown fish meal (BFM), rapeseed meal (RM), soybean meal (SBM), extruded soybean meal (extruded SBM), and peanut meal (PM). In each of the two trials, a casein–gelatin reference diet was mixed with test ingredients in a ratio of 70:30 to produce a series of diets, and yttrium oxide was used as the inert marker. The reference and test diets were fed to yellowfin seabream reared at 27.5 ± 1 C, and fecal samples were collected by siphoning. The derived DM, CP, and GE ADCs (means ± SD) for the test ingredients were, respectively, WFM – 72.3 ± 3.87, 86.4 ± 1.06, and 93.6 ± 2.63; PFM – 54.1 ± 15.45, 80.5 ± 7.81, and 77.4 ± 11.9; BFM – 57.7 ± 2.34, 82.8 ± 3.07, and 84.5 ± 5.77; RM – 33.5 ± 5.50, 84.7 ± 2.83, and 56.3 ± 9.87; SBM – 58.7 ± 4.42, 92.6 ± 3.94, and 58.1 ± 2.91; extruded SBM – 65.1 ± 16.52, 89.7 ± 1.68, and 64.8 ± 6.23; and PM – 70.6 ± 1.43, 97.3 ± 3.52, and 59.8 ± 4.78. The ADC of CP of both plant and animal feed ingredients was high, whereas DM and GE values varied greatly. Apparent DM digestibility coefficients of ingredients decreased as ash or fiber contents of ingredients increased, and the variation of apparent GE digestibility coefficients of ingredients is similar to that in DM, with the exception of the value for PM.     

Investigation of the nutritional requirements of Australian snapper Pagrus auratus (Bloch & Schneider, 1801): apparent digestibility of protein and energy sources

Two experiments were carried out to determine the apparent crude protein (CP), organic matter (OM), fat and gross energy (GE) digestibility coefficients (ADCs) of several protein and energy sources (ingredients) for Australian snapper using the indirect method of determination and collection of faeces by passive settlement. The first experiment determined ADCs for one level of fishmeal (500 g kg^?1 diet), three levels of extruded wheat (200, 300 or 400 g kg^?1 diet) and two levels of fish oil (150 or 250 g kg^?1 diet). The second experiment determined ADCs for two levels each of meat meal or poultry meal (300 or 500 g kg^?1 diet), one level each of haemoglobin powder or blood meal (150 g kg^?1 diet) and one level each of solvent extracted soybean meal or a low‐allergenic, cold‐pressed soybean meal (300 g kg^?1 diet). Similar ingredients and where appropriate, different inclusion levels were compared using one‐ or two‐way analysis of variance (anova ). Fishmeal was almost completely digested and ADC values ranged between 94.3% and 99.2%. Fish oil was also well digested, with ADC values ranging between 97.6% and 106.0% and was not significantly affected by inclusion level. Linear regression analysis indicated that there was no relationship between the inclusion level of extruded wheat and either CP (ADCs ranged from 100.1% to 105.4%) or fat digestibility (ADCs ranged from 89.1% to 104.4%). However, there was a significant negative linear relationship between the inclusion level of extruded wheat and GE digestibility (GE_ADC=86.51?0.031 × inclusion level; R²=0.49). Two‐way anova indicated that CP, OM and GE ADCs of poultry meal (i.e. 85.9%, 89.7% and 91.3% respectively) were significantly higher than those determined for meat meal (i.e. 63.8%, 63.4% and 71.3% respectively), but ADCs were not affected by inclusion level or the interaction between inclusion level and ingredient type. The fat digestibility coefficients of meat and poultry meal were not significantly different (ADCs ranged from 92.3% to 95.0%). The CP digestibility of haemoglobin powder (95.1%) was significantly higher than that of ring‐dried blood meal (81.6%), but there was no difference between the digestibility of OM (77.0%) or GE (80.4%) from these products. There was no difference between the CP (88.9%), OM (56.9%) and GE (65.6%) digestibility of the solvent extracted soybean meal and the low‐allergenic, cold‐pressed soybean meal. These coefficients will be useful in formulating both practical and research‐based diets for this species.     

Apparent Digestibility Coefficients of Nutrients and Nutritional Value of Poultry By-product Meals for Rainbow Trout Oncorhynchus mykiss Measured in vivo Using Settlement

Fish meal production is not growing worldwide, therefore, it is important to search for alternative protein sources. Three types of poultry by-product meals (feed grade, prime, and refined) and two fish meals (herring and menhaden) were mixed into a casein-gelatin purified reference diet at 30% to measure apparent digestibility coefficients (ADCs) for rainbow trout Oncorhynchus mykiss . A total of 90 fish (initial mean body weight 294.6 ± 10.7 g) were stocked into six 140-L fiberglass digestibility tanks at 15 fish per tank. Individual tanks were assigned randomly to each of the five experimental diets and the reference diet. Fecal collection by settlement lasted for 2 wk. Feces collected in each week represented a replicate, and they were analyzed separately. The ADCs of nutrients for herring meal, menhaden meal, feed grade poultry by-product meal, prime poultry by-product meal, and refined poultry by-product meal were: dry matter, 81.3, 70.9, 70.9, 71.5, and 74.5%, respectively ( P = 0.0168); crude protein, 89.8, 85.8, 83.1, 84.8, and 87.1%, respectively ( P = 0.0032); crude fat, 91.5, 90.7, 79.7, 82.7, and 79.9%, respectively ( P = 0.0004); ash, 76.6, 66.2, 74.1, 77.4, and 79.6%, respectively ( P = 0.2880); phosphorus, 58.2, 46.9, 49.4, 45.8, and 56.0%, respectively ( P = 0.0143); gross energy, 88.2, 84.0, 81.9, 83.4, and 79.8%, respectively ( P = 0.2466). Significant differences in ADCs of essential amino acid existed only for arginine, leucine, and tryptophan when comparing refined poultry by-product meal with herring meal. Results showed that refined poultry by-product meal had similar ADC values to herring meal, thus, it has a similar nutritional value and can replace portions of herring meal in rainbow trout feeds. Furthermore, differences exist in ADC values among grades of poultry by-product meals that should dictate appropriate use levels in rainbow trout feeds.     

Apparent digestibility coefficients of selected protein feed ingredients for loach Misgurnus anguillicaudatus

Apparent digestibility coefficients of dry matter, crude protein, lipid and energy, and amino acids availability in white fish meal, brown fish meal, meat meal, fermented soybean meal, soybean meal and rapeseed meal were determined for loach (Misgurnus anguillicaudatus) (12.05 ± 0.21 g), using a reference diet with 5 g kg^?1 chromic oxide and test diets that contained 700 g kg^?1 reference diet, by weight, and 300 g kg^?1 of the test feed ingredients. The juvenile loach was held in 300‐l tanks at a density of 30 fish per tank. White fish meal, brown fish meal, meat meal and fermented soybean meal had highest apparent digestibility coefficients (ADCs) of dry matter, crude protein and gross energy among ingredients tested, ranged from 50.4% to 60.9% for dry matter, from 64.6% to 88.4% for crude protein and from 57.9% to 79.0% for gross energy. The apparent digestibility coefficients of dry matter ranged from 61.0% to 66.9% for animal products and 50.4% to 60.7% for plant products. For crude protein, apparent digestibility coefficients of protein exceeding 80% were observed for white fish meal, brown fish meal, meat meal and fermented soybean meal, and the apparent digestibility coefficients of protein in rapeseed meal were the lowest among all the treatments. Lipids from both animal and plant feedstuffs were poorly digested by loach, ranging from 64.0% to 77.6%. The apparent digestibility coefficients of energy were similar to those of dry matter and protein, and the highest and lowest ADCs of energy were found in WFM and RM, respectively. The loach used dietary phosphorus from the animal feedstuffs more efficiently than from plant feedstuffs (soybean meal and rapeseed meal), with ADC‐values ranging from 42.3% to 53.1% and from 25.1% to 32.7%, respectively. For the animal products, the availabilities of amino acids in white fish meal and brown fish meal were higher than that in meat meal, expect for Met, Asp, Pro, Gly, and Cys. Among all the plant products, the availabilities of amino acids in fermented soybean meal were higher than in soybean meal and rapeseed meal, and thus had a greater potential to be used as a dietary replacement of fish meal in loach diets.     

Evaluation of Soybean Meal-Red Blood Cell Coextruded Feed Ingredient in Diets Fed to Rainbow Trout Oncorhynchus mykiss

Abstract.— Fish meal is one of the predominant sources of crude protein used in practical feeds for most cultured species. However, with overfishing and increasing demand for protein feedstuffs, new competitively priced sources of dietary protein are needed. A coextruded soybean meal-red blood cell (SBM-RBC) ingredient was evaluated as a source of crude protein for rainbow trout Oncorhynchus mykiss . The SBM-RBC ingredient was incorporated at either 0, 21, 42 or 63% of the dietary protein, replacing an isoni-trogenous amount of fish meal. All diets were fed for 8 wk to triplicate groups of juvenile rainbow trout (average initial weight 49.5 g) stocked into a recirculating system consisting of 48, 114-L aquaria. There were no significant differences in weight gain, feed conversion ratio, protein efficiency ratio, apparent crude protein digestibility, apparent gross energy digestibility, dress-out percentage, or fillet protein and fat concentrations in fish fed any of the experimental diets. Based on these data, extruded SBM-RBC appears to be a suitable ingredient in diets fed to rainbow trout.