Effect of dietary probiotics on apparent digestibility coefficients of nutrients of white shrimp Litopenaeus vannamei Boone

Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, phosphorus (P), essential amino acids (EAA), non‐essential amino acids (NEAA) and fatty acids were determined for white shrimp (Litopenaeus vannamei). A probiotic (Bacillus sp.) was used at 0% (diet 1), 0.5% (diet 2), 1.0% (diet 3), 3.0% (diet 4) and 5.0% (diet 5) inclusion rates in experiment diets. Apparent digestibility coefficients was determined using 0.01% Y₂O₃ as an indicator. A total of 300 shrimp (initial mean body weight 11.5±0.6 g) were randomly stocked into fifteen 500‐L outdoor concrete tanks. Faeces were collected from three replicate groups of shrimp three times a day. The ADCs of five diets were: DM, 66.1–69.6%; CP, 80.4–84.7%; lipid, 82.2–84.9%; P, 25.4–28.5%; EAA, 82.0–85.4%; NEAA, 81.5–85.1%; saturated fatty acids (SFA), 79.6–82.4%; monounsaturates (MUFA), 81.6–84.2% and polyunsaturates (PUFA)+highly unsaturates (HUFA), 83.4–86.6%. Apparent digestibility coefficients of DM, CP, lipid, P, amino acids and fatty acids in diet 1 were significantly lower than in other diets (P<0.05). Apparent digestibility coefficient of P in diets increased as probiotic increased. Apparent digestibility coefficient of lipid in diet 3 was the highest, but the difference was not significant among diets. In general, ADCs of most amino acids and fatty acids were over 80% in all diets, and PUFA+HUFA>MUFA>SFA. The results showed that ADCs of diets supplemented with 10, 30 and 50 g probiotic kg^?1 basal diet were higher than in other diets except lipid, and the difference was significant.     

Ability of European seabass (Dicentrarchus labrax) to digest rendered animal fats from fish,poultry and mammals

This study evaluates the in vivo apparent digestibility coefficients (ADC) of rendered animal by‐product fats in European seabass (Dicentrarchus labrax) juveniles. Diets contained fish oil (FOd), poultry fat (PFd) or mammal fat (MFd), from rendering animal by‐products, at 140 g/kg. Macronutrient and fatty acids ADCs were evaluated in quadruplicate tanks with fifteen 100 g fish. While total lipids ADCs (88%–90%) were unaffected, individual fatty acids ADC varied significantly among diets. Monounsaturated fatty acids ADCs were similar (94%–95%), saturated fatty acids ADCs were lowest in MFd (85% vs. 91% in PFd and FOd), and polyunsaturated fatty acids (PUFA) ADCs were lowest in PFd (96 vs. 97%–98%). Total n‐3 PUFA were better digested in FOd than in the other diets (98 vs. 96%–97%), while MFd had the highest total n‐6 PUFA ADC. FOd showed significantly higher EPA (20:5n‐3) and DHA (22:6n‐3) ADCs compared to the other test diets. The obtained results suggest that rendered animal fats can be considered feasible alternatives to fish oil in seabass. Nevertheless, that lack of EPA and DHA in land animal fats, combined with the reduced digestibility of these fatty acids, may compromise its dietary inclusion at high levels.     

Aurantiochytrium sp. meal as DHA source in Nile tilapia diet,part II: Body fatty acid retention and muscle fatty acid profile

Nile tilapia juveniles (8.35 ± 0.80 g) were fed on four levels (0.0%; 0.5%; 1.0%; 2.0%, 4.0%) of Aurantiochytrium sp. meal (ALL‐G‐RICH?), a source of docosahexaenoic acid (DHA). The 1% Aurantiochytrium sp. meal diet was compared to a control diet, which contained the same amount of DHA as cod liver oil (CLO) at 1.7% diet. Groups of 25 fish were stocked in 100 L tanks and fed twice daily until apparent satiation, for 57 days, at 28°C. Increasing dietary Aurantiochytrium sp. meal reduced the body retention of DHA and n‐3 polyunsaturated fatty acids (n‐3 PUFA) but increased the body retention of alpha‐linolenic (α‐LNA), linoleic (LOA) and n‐6 polyunsaturated fatty acids (n‐6 PUFA). Fatty acid profile in tilapia muscle was affected by increasing dietary inclusions of Aurantiochytrium sp. meal, with an increase in DHA, α‐LNA, n‐3 PUFA and n‐3 long chain‐polyunsaturated fatty acids (n‐3 LC‐PUFA) but a decrease in monounsaturated fatty acids (MUFA), n‐6 PUFA and n‐6 long‐chain polyunsaturated fatty acids (n‐6 LC‐PUFA). There was a larger body retention of DHA, α‐LNA, LOA, n‐3 PUFA and n‐6 PUFA fatty acids and a higher percentage of DHA, n‐3 PUFA and n‐3 LC‐PUFA in muscle fatty acid profile in fish fed on CLO diets than in those fed on 1% Aurantiochytrium sp. Therefore, Aurantiochytrium sp. meal is an alternative source of DHA for Nile tilapia diets.     

Digestibility of nutrients and amino acids of different protein sources in practical diets by largemouth bass Micropterus salmoides (Lacepéde, 1802)

This study evaluated the apparent digestibility coefficients (ADCs) of dry matter, protein, lipid, energy, calcium, phosphorus, and essential and non‐essential amino acid availability of animal and plant protein sources in practical diets for the carnivorous fish, largemouth bass Micropterus salmoides (8.0±0.5 g; 10.0±0.3 cm). Fish were conditioned to accept artificial feed and those stocked in plastic cages were fed pelleted test diets. Diets contained 30% of the ingredient tested mixed with 70% of a reference ration (RD) containing 40 g 100 g^?1 of crude protein, 19.85 kJ g^?1 crude energy, and 0.5% of chromic oxide. Cages were then transferred to cylindrical, conical‐bottomed aquaria (200 L) where the faeces were collected by sedimentation in a refrigerated container. All the tested ingredients had high ADCs for protein and lipid; ADCs of amino acids of varying protein sources showed significant differences (P<0.01). Plant protein sources did not significantly influence the ADCs of diets. The results allow the inference that the availability of amino acids in plant and animal protein sources varies considerably.     

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.     

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.     

Apparent digestibility of soybean coproducts in extruded diets for Nile Tilapia,Oreochromis niloticus

Soybean coproducts are important protein sources in aquaculture because of their amino acid profile. Tilapia can be reared on soybean coproducts as the only source of dietary protein without compromising growth. This study estimated apparent digestibility coefficients for five soybean coproducts for juvenile Nile tilapia, Oreochromis niloticus, fed with extruded diets. A reference diet and test diets consisting of 70% reference diet and 30% coproduct ingredient were formulated, along with 5.0 g kg^?1 chromic oxide (Cr₂O₃) as a marker. Apparent digestibility coefficients (ADC) for dry matter (ADCDM), gross energy (ADCGE) and crude protein (ADCCP) for soybean coproducts were estimated as 84.2–88.4%, 86.9–91.1% and 96.8–97.9%, respectively. ADCDM and ADCCP values did not vary among the ingredients, but low‐protein soybean meal exhibited lower ADCGE values than did soybean protein concentrate. ADCs of all amino acids were >95%, and mean ADCs for amino acids were similar to the values observed for ADCCP. Soybean coproducts had good nutritional value in extruded diets fed to tilapia. Methionine, histidine and valine were the limiting amino acids in all evaluated ingredients.     

芽孢杆菌对斑节对虾饲料表观消化率的影响

研究了斑节对虾(Penaeus monodon)饲料中添加不同剂量的芽孢杆菌制剂(Bacillus sp.,109 CFU/g)对饲料干物质、粗蛋白、脂肪、磷、氨基酸和脂肪酸的表观消化率的影响.饲料1(对照组)、饲料2、饲料3、饲料4、饲料5和饲料6中芽孢杆菌制剂的添加量分别为0、1.0 g/kg、2.0 g/kg、3.0 g/kg、4.0 g/kg和5.0 g/kg饲料.养殖实验在室外水泥池进行,每池养虾40尾,每组实验设3个重复.以Y2O3为指示剂,添加量为0.01%,连续收集粪便20 d.6个实验组中,对饲料中各营养素的表观消化率分别为:干物质,74.35%～77.89%;粗蛋白,87.29%～89.01%;脂肪,86.46%～89.67%;磷,35.83%～44.17%;必需氨基酸,93.01%～94.04%;非必需氨基酸,91.05%～92.42%;饱和脂肪酸,86.88%～89.95%;单不饱和脂肪酸,90.39%～93.40%;多不饱和脂肪酸 高不饱和脂肪酸,87.97%～91.32%.对照组的脂肪表观消化率高于饲料2、饲料5和饲料6组,但低于饲料3和饲料4组.饲料3组的脂肪和部分脂肪酸的表观消化率最高.对照组的干物质、粗蛋白、氨基酸和磷的表观消化率最低,芽孢杆菌添加量在1.0～3.0 g/kg饲料范围内,随着芽孢杆菌添加量的增加,表观消化率逐渐上升,饲料4组的表观消化率最高,与其他组相比差异显著(P＜0.05),添加量超过3.0 g/kg的各组,随着芽孢杆菌添加量的增加,表观消化率又逐渐下降.实验结果表明,在饲料中添加适量的芽孢杆菌可以显著的提高干物质、粗蛋白、氨基酸和磷的表观消化率.     

Digestibility of energy,lipids and fatty acids of vegetable oils and poultry fat by pacu Piaractus mesopotamicus (Holmberg 1887)

Evaluation of vegetable oils and poultry fat digestibility is the first step to elicit their use in aquafeeds. This work aimed at determining apparent digestibility coefficients (ADCs) of energy, lipids and fatty acids of oil sources for pacu, a widely farmed neotropical Characin. A semipurified, omnivorous fish diet (344.2 g kg^?1 crude protein; 18.16 MJ kg^?1 gross energy) was used as reference diet. Test diets were obtained by adding 2 g kg^?1 chromium III oxide and replacing 15 g kg^?1 reference diet with fish, soybean, colza, corn and flaxseed oils and poultry fat. Juvenile pacu (64 ± 10.8 g; 14.6 ± 1.1 cm) were fed to apparent satiety, four times a day, and then transferred to cylindrical–conical aquaria for collection of faeces by sedimentation (n = 3). Apparent digestibility coefficients of energy and lipids were high for all tested oils (P > 0.05); ADCs of saturated fatty acid (SFA) were lower than monounsaturated fatty acids (MUFA) and polyunsaturated fatty acid (PUFA). Essential fatty acids (18:2n‐6 and 18:3n‐3) had high ADC (>93%), colza oil and poultry fat yielding the lowest ADC for 18:2n‐6 (P = 0.01) and 18:3n‐3 (P < 0.01), respectively. Corn oil, soybean oil and flaxseed oil were interesting sources of 18:2n‐6 and 18:3n‐3 dietary fatty acids for pacu.     

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.     

Effects of dietary palm oil source on growth,tissue fatty acid composition and nutrient digestibility of red hybrid tilapia,Oreochromis sp., raised from stocking to marketable size

A 20-week feeding trial was carried out to investigate the influence of three palm oil products as the principal dietary lipid source on the growth performance, proximate composition, tissue fatty acid composition and nutrient digestibility of red hybrid tilapia (Oreochromis sp.) fed these diets from stocking to marketable size. Four isonitrogenous (30% crude protein) and isoenergetic (16.5 kJ g^− 1) practical diets were formulated with 8% of added fish oil (FO), crude palm oil (CPO), palm fatty acid distillate (PFAD) or refined, bleached and deodorized palm olein (RBDPO), respectively. Each diet was fed to triplicate groups of 30 fish of 31.24 ± 0.05 g mean initial body weight. The tilapia were raised at 29 ± 1 °C in 12 round 1000 L fiberglass tanks with a continuous water flow rate of about 1.8 L/min.Results showed that the source of added lipid did not significantly influence (P > 0.05) final body weight, specific growth rate, feed conversion ratio, survival, body indices, hematocrit and production yield of tilapia. There was no significant difference in the fillet proximate composition of fish fed the various diets, except that fish fed the PFAD diet showed lower lipid deposition. The deposition of fatty acids in fish tissues was generally influenced by the fatty acid profile of the diets. Fillet fatty acid profiles of tilapia fed palm oil-based diets had significantly higher concentrations of saturated and monounsaturated fatty acids, but lower levels of polyunsaturated fatty acids (PUFA) compared to the fish fed the FO diet. Fillet of fish fed the FO diet had significantly higher concentrations of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) compared with fish fed palm oil-based diets. Dietary lipid source did not significantly affect dry matter and protein digestibility (62.1–64.8% and 83.5–85.0%, respectively). The inclusion of dietary palm-origin oils significantly reduced the total lipid digestibility of the diets due mainly to the decreased digestibility of the saturated fatty acids. In all treatments, the apparent digestibilities of both n − 3 and n − 6 PUFA were the highest, followed by monoenes, while the lowest were the saturated fatty acids. Despite the high free fatty acid content of PFAD (92.2%) compared to CPO (4.8%) and RBDPO (0.1%), the different free fatty acid content did not significantly affect the nutrient digestibility of the palm oil-based diets. Results obtained confirmed the feasibility of feeding tilapia with palm oil-based diets with a 100% substitution of added dietary fish oil throughout the grow-out cycle until marketable size.     

Apparent digestibility of protein, energy, and amino acids in some selected feed ingredients for pacu Piaractus mesopotamicus

The apparent digestibility coefficients (ADCs) of amino acids (AA), protein, and energy in six feed ingredients (Brazilian fish meal, soybean meal, corn gluten meal, alcoholic yeast, corn, and wheat bran) we evaluated for pacu juveniles. In general, all ingredients showed high digestibility values for all AA, and differences among ADCs of individual amino acid were detected ( P  < 0.01). Corn gluten, soybean, and fish meals had the highest ADCs of AA. The ADCs of protein in fish meal, yeast, and corn gluten meal should not be used as AA digestibility indicators, because those showed differences up to 6.7% between the ADCs of protein and AA. All ingredients had lower ADCs of energy than corn gluten meal ( P  < 0.01). Lysine was the first limiting amino acid in fish meal, corn gluten meal, wheat bran, and corn, and the second limiting amino acid in soybean meal, as methionine was the first limiting amino acid in soybean meal and yeast. However, the soybean meal was the best quality protein source, as it had the highest digestible essential amino acid index. This demonstrated that digestible amino acid values can be used to formulate practical diets for pacu, preventing potential deficiencies or excess that might cause environmental and economic losses.     

The Apparent Digestibility Coefficients of 13 Selected Animal Feedstuff for Cobia,Rachycentron canadum

The apparent digestibility coefficients (ADCs) of crude protein, lipid, phosphorous, and amino acids, as well as energy, of 13 animal feedstuffs were determined for cobia, Rachycentron canadum (initial weight 130.0 g). The feedstuffs tested included five types of fishmeal, two of blood meal, one of poultry meat meal, two of meat‐and‐bone meal, two of feather meal, and one type of shrimp meal. A reference diet was formulated and the test diets contained 70% of the reference diet and 30% of each feedstuff. The ADCs of crude protein, lipid, energy, phosphorous, and amino acids of the test ingredients ranged from 68.97 to 92.5%, 69.3 to 95.7%, 77.5 to 98.3%, 58.2 to 80.1%, and 72.5 to 97.0%, respectively. The ADCs of crude protein of white fishmeal, steam‐dried brown fishmeal, imported flame‐dried fishmeal, spray‐dried blood cells, poultry byproduct meal, meat‐bone meal, and meat meal were significantly higher than those of dried blood meal, fermented feather meal, and hydrolyzed feather meal (P < 0.05). The ADCs of lipid of dried blood meal and hydrolyzed feather meal were significantly lower than those of other feedstuffs (P < 0.05). The ADCs of energy of fermented feather meal and hydrolyzed feather meal were significantly lower than those of other feedstuffs (P < 0.05) and the ADCs of phosphorus of white fishmeal, steam‐dried brown fishmeal, and imported flame‐dried fishmeal were significantly higher than those of the other ingredients (P < 0.05).     

Digestibility of the defatted microalgae Nannochloropsis sp. and Desmodesmus sp. when fed to Atlantic salmon,Salmo salar

The aim of the study was to investigate the apparent digestibility coefficient (ADC) of defatted biomass derived from microalgae Nannochloropsis sp. and Desmodesmus sp. when fed to Atlantic salmon postsmolts in seawater. Two experiments, one employing cold‐pelleted and the other employing extruded pellets, were carried out to determine the ADC of dry matter (DM), protein, ash and energy. The test feeds consisted of a fishmeal‐based reference feed and the algal biomass, at a ratio of 70:30, and yttrium oxide as the inert marker. The ADC of DM and protein in fish fed microalgae‐incorporated cold‐pelleted feeds were significantly higher for Nannochloropsis sp. compared with Desmodesmus sp. The Nannochloropsis sp. inclusion in extruded feeds also led to higher ADCs of DM and energy compared with Desmodesmus sp. The extrusion processing significantly increased the ADC of ash in both defatted microalgae biomass, as well as ADCs of DM in Nannochloropsis and protein in Desmodesmus sp. In conclusion, the microalga Nannochloropsis sp. was more digestible than Desmodesmus sp., and extrusion processing can be used as a means to improve digestibility of certain nutrients.     

Apparent digestibility of alternative plant‐protein feedstuffs for channel catfish,Ictalurus punctatus (Rafinesque)

A study was conducted with channel catfish, Ictalurus puntatus to determine apparent digestibility/availability coefficients of protein, amino acids, lipid and energy for alternative plant‐protein feedstuffs: corn gluten feed, corn germ meal, distillers dried grains with solubles, and canola meal, compared with those for soybean meal. A 32%‐protein, chemically defined diet containing 8% fish meal was used as the reference diet. Test diets consisted of 70:30 ratio of reference diet to test ingredient with chromic oxide (0.75% of the diet) as an inert indicator. Apparent digestibility/availability coefficients of protein, essential amino acids and energy in alternative protein feedstuffs tested were generally lower than those in soybean meal by channel catfish. Apparent digestibility coefficients of protein ranged from 75 to 87% and those of energy ranged from 52 to 59% for alternative feedstuffs. Lysine in alternative feedstuffs was 67–79%, methionine was 69–85% and cystine was 73–82% available to channel catfish. There were no significant differences in lipid ADCs among test feedstuffs (91.9–96.8%). Results from the present study can be useful in formulating cost‐effective catfish feeds using these alternative feedstuffs.     

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.     

Effects of a dietary organic acids blend and oxytetracycline on the growth,nutrient utilization and total cultivable gut microbiota of the red hybrid tilapia,Oreochromis sp., and resistance to Streptococcus agalactiae

A 20‐week feeding trial was conducted to measure growth, nutrient utilization and faecal/gut bacterial counts in triplicate groups of red hybrid tilapia, Oreochromis sp., when fed diets supplemented with 0.5% organic acids blend (OAB), 1.0% OAB, 0.5% oxytetracycline (OTC) or a control diet (no additives). At the end of the feeding trial, tilapia were challenged with Streptococcus agalactiae for 22 days. Fish fed the OTC diet had significantly higher (P < 0.05) growth than the control treatment, while growth between fish fed the OTC or OAB diets was not significantly different (P > 0.05). Phosphorus, dry matter and ash digestibility were significantly higher in the 1.0% OAB diet than the control diet. Fish fed the OAB diets had significantly lower colony‐forming units of adherent gut bacteria compared to the control or OTC treatments while those fed the 1.0% OAB diet had the lowest total faecal bacterial counts. Tilapia fed the 0.5% OTC or OAB diet had significantly higher resistance to S. agalactiae than those fed the control diet. This study indicates that dietary organic acids can potentially replace OTC as a growth promoter and antimicrobial in tilapia feeds.     

Digestibility and feeding value of some feed ingredients fed to tilapia Oreochromis niloticus (L.)

The apparent digestibility of protein, organic matter and energy of high‐fibre and fibre‐reduced sunflower cakes, Kenya's ‘omena’ fishmeal, anchovy fishmeal and wheat bran were investigated in tilapia Oreochromis niloticus (L.) fingerlings. The feeding values and protein qualities of the above ingredients were also determined at two dietary protein levels. Fourteen diets were formulated, and each was provided to three tanks containing 12 fish in Expt 1 (digestibility study) and 25 fish in Expt 2 (feeding trial). Water temperatures and dissolved oxygen concentrations were maintained above 26 °C and 5.5 mg L^?1 respectively. Anchovy and ‘omena’ fishmeals each had an apparent digestibility coefficient for protein (ADC‐P) of 90%, whereas the fibre‐reduced and high‐fibre sunflower cakes had ADC‐P values of 89% and 86%. Wheat bran had an ADC‐P value of 75%, which was significantly lower than those found for the other test ingredients. Apparent digestibility coefficients for energy (ADC‐E) and digestible energy values (DE) were 86% and 78% and 4003 kcal kg^?1 and 3624 kcal kg^?1 for anchovy and omena fishmeals respectively. The corresponding values for the plant protein sources were 42% and 30% and 2200 kcal kg^?1 and 1400 kcal kg^?1 for the fibre‐reduced and high‐fibre sunflower cakes respectively. Diets based on the fibre‐reduced cake had higher levels of all amino acids than those based on the high‐fibre cake. Fish fed diets with 30% protein gained 40 g and had a feed conversion ratio (FCR) of 1.87, whereas those fed diets with 20% protein gained 35 g and had a FCR of 2.2. The source of protein had a significant effect on weight gain.     

Nutritional Quality and Safety of the Important Commercial Cuttlefish Sepia lycidas

Proximate composition, amino acid, fatty acid composition, and contaminants (As, Cd, Hg, and Pb) of the kisslip cuttlefish Sepia lycidas were determined and compared with the recommendations and maximum allowed levels. The ratio of essential amino acids (EAA) to nonessential amino acids (NEAA) was 0.82. All of the amino acid scores were > 100, except for valine (93), and the highest essential amino acid score was obtained for tryptophan (327). The fatty acids profile was dominated by polyunsaturated fatty acids (PUFA; 45.01% of total fatty acids), and docosahexaenoic acid (DHA; 24.54% of total fatty acids) was the dominant fatty acid. S. lycidas was rich in n-3 PUFA, and the ratio of n-3/n-6 PUFA was 2.48. Regarding contaminants, As, Cd, and Pb concentrations in S. lycidas were 2.2, 0.28, and 0.02 mg kg^?1, respectively. Moreover, Hg values were below the detection limit (0.01 mg kg^?1).     

Nutrient Digestibility of Cereal Grain Products and By‐products in Extruded Diets for Nile Tilapia

Apparent digestibility coefficients (ADCs) provide estimates of nutrient availability in feedstuffs and can be used as a tool for selecting ingredients to compound cost‐effective diets for fish. Extrusion process is one factor that could influence ADC values. Thus, a digestibility trial was undertaken to evaluate ADC of protein, energy, and dry matter, and apparent amino acid availability (AAAA) in five cereal grain products/by‐products (corn, wheat middlings, broken rice, rice bran, and sorghum) in compounded diets for Nile tilapia. Chromic oxide was used as an external inert marker. The digestibility values of energy and dry matter in ingredients, in decreasing order, were highest for broken rice (95.34 and 96.45%), sorghum (82.37 and 87.29%), corn (67.34 and 82.21%), rice bran (57.58 and 55.59%), and wheat middlings (48.94 and 45.88%). Protein digestibility value was higher for corn (72.86%) and the lowest value was observed for sorghum (56.77%), while broken rice, wheat middlings, and rice bran presented values ranging from 63.01 to 66.88%. AAAA values were higher for corn (70.05%) and the lowest methionine and cystine availability values were recorded for wheat middlings and broken rice, respectively. Broken rice appears as one of the most indicated ingredient for using in Nile tilapia diets because of its highest values of nutrient digestibility when compared to the other energetic sources. The use of this information should aid more precise and economic diet formulation for Nile tilapia.