Apparent Digestibility Coefficients Of Dry Matter Research Articles

Effects of dietary microbial protease on growth performance, nutrient apparent digestibility, hepatic antioxidant capacity, protease activities and intestinal microflora in juvenile genetically improved farmed tilapia, Oreochromis niloticus

The study was to evaluate the effects of four types of microbial protease on growth performance, nutritional composition, apparent digestibility coefficients (ADC), physiological parameters and microbiota of genetically improved farmed tilapia (GIFT, Oreochromis niloticus). Six diets were prepared, including a positive control diet (protein 300 g/kg, high protein group, HP) and one negative control diet (protein 280 g/kg, low protein group, LP) and four proteases were added to the low protein diets, included HuPro protease (LPH), acid protease (LPAC), neutral protease (LPN) and alkaline protease (LPAK). Compared with the fish fed LP diet, the weight gain rate (WGR), specific growth rate (SGR), feed conversion rate (FCR), protein efficiency ratio (PER) and feed intake ratio (FIR) were improved in fish fed LPH diet. The ADC of dry matter in LPH diet was improved. The serum total protein (TP) in LPH diet was higher than the LP diets. The activities of total antioxidant capacity (T-AOC) and catalase (CAT) in LPH group was higher than the LP and HP group, respectively. The protease activities of stomach and gut in fish fed LPH diet was higher than LP group. Shannon and Simpson indices in LPH group were higher than the LP group. The abundance of Fusobacteria in the six groups reached more than 70 % at the phylum level, and the largest difference in the relative abundance at the genus level was Cetobacterium. In conclusion, this study demonstrates the positive effects of HuPro protease on tilapias and selection of HuPro protease to the low protein diet is suitable.

Effects of supplementing a plant protein-rich diet with insect, crayfish or microalgae meals on gilthead sea bream (Sparus aurata) and European seabass (Dicentrarchus labrax) growth, physiological status and gut health

This study was aimed at evaluating growth response, gut health and physiological status of seabream (GSB) and European seabass (ES) juveniles fed diets totally deprived of fish meal and supplemented with alternative ingredients. Fish were fed four isoproteic (45%) and isolipidic (20%) diets in which meals from black soldier fly (Hermetia illucens, H) prepupae, whole red swamp crayfish (Procambarus clarkii, RC) or a microalgae blend (Tisochrysis lutea and Tetraselmis suecica, MA) were used as supplements to replace 10% protein of a fish meal-free, plant protein-based diet high in soybean meal (CV). Each diet was fed to triplicate fish groups kept in a RAS (Temperature 23.5 °C, Salinity 29 ppt) over 12 (GSB) and 18 (ES) weeks. In both fish species, MA diet resulted in the worst specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) compared to CV. Diet H significantly improved the SGR only in GSB without affecting FCR. The dry matter apparent digestibility coefficient (ADC) was highest in the H diet (approximately 76%) and lowest in MA (around 73%), while an intermediate value was recorded for the RC diet, in both fish species. Slightly inflamed intestine and altered mucosa morphology were observed in both fish species fed on CV diet, highlighting a higher susceptibility of GSB to this diet. On the contrary, diets H, RC and MA led to a modulation of inflammatory gene expression in the distal intestine from the two fish species. However, while H and RC diets lead to a more evident intestine status improvement in GSB, in ES this result was evident even in response to MA diet administration. The MA diet induced a lowering of nutritional status compared to CV in both GSB and ES. Overall the results have shown that 10% protein from H and RC in a plant protein-based diet, tends to improve fish growth and gut health in both fish species. In ES also the diet including microalgae turned in a beneficial effect on fish gut health, compared to CV one, although it needs further refinement to reduce the adverse impact on growth and physiological status. Our findings suggest the potential use of insect and crayfish meals as functional ingredients in fish meal-free diets for GSB and ES, while further studies are needed to refine the use of microalgae as functional feed supplements in diets for sub-adult gilthead seabream and European seabass.

Comparative estimation of the lysine requirements in two generations of improved strain of Nile tilapia (Oreochromis niloticus) at the grow-out stage

A 3 × 2 factorial experiment was conducted to investigate the effects of dietary lysine on growth performance, body indices, feed intake, feed efficiency, whole body nutrient composition and amino acid deposition in two successive generations (16th and 17th) of GIFT (Oreochromis niloticus). Three diets containing different levels of lysine at 1.16%, 1.56% and 2.41% were prepared for the feeding trial. Triplicate groups of fish with an initial body weight of 155 g were fed to apparent satiation for 10 weeks in a recirculating aquaculture system. Apparent digestibility coefficients (ADC) of dry matter, crude protein, crude lipids, and total carbohydrates were measured in the experimental diets. At the end of the experiment, no interactions between dietary lysine levels in diet and fish generation were observed on all parameters except for the condition factor (CF) and ADC of crude protein. However, dietary lysine level significantly affected the final weight, weight gain, thermal unit growth coefficient (TGC), protein efficiency ratio (PER) and ADC of dry matter regardless of the fish generation. Final weight, weight gain and TGC of fish were the highest in fish fed 2.41% dietary lysine in diet or 6.52% lysine in the protein. PER was the lowest in fish fed 1.16% dietary lysine. The final weight and the body's accumulation of isoleucine, phenylalanine, and alanine were significantly affected by the fish generation, with the 17th generation having the best performance. Increase growth and higher lysine requirement observed in the improved generation (17th) compared to the (16th) generation at grow out phase indicating that genetic improvement may have changed the dietary lysine requirement.

Anti-Nutritional Factors and Protein Dispersibility Index as Principal Quality Indicators for Soybean Meal in Diet of Nile Tilapia (Oreochromis niloticus GIFT), a Meta-Analysis.

Simple SummarySoybean meal is an effective protein source in aquafeeds and is characterized by high protein content, high digestibility, reasonable price, and stable supply. The quality of soybean meal varies with factors such as seed genotype, soil type, planting area, processing conditions, storage conditions, etc. Differences in soybean meal quality may lead to differences in the production performances of animals. For this reason, we investigated the nutrient composition, anti-nutritional factors and physicochemical properties of different soybean meals produced on the same production line with soybeans from different origins, and compared the effects of different soybean meals on the physiological characteristics of Nile tilapia (Oreochromis niloticus GIFT). This study identified key indicators that could distinguish the quality of soybean meals, and established a correlation model between quality indicators of soybean meal and the growth performance of Nile tilapia. These results are of great significance for evaluating the quality of soybean meals and promoting the efficient application of soybean meal in aquafeeds.Soybean meal (SBM) is the most important plant protein source in animal feed. This study investigated the characteristics of different SBMs, produced by soybeans from America and Brazil (SBM-A and SBM-B) in 2017–2021 under the same controlled conditions. The effects of different SBMs on the growth performance of Nile tilapia (Oreochromis niloticus, GIFT) and apparent digestibility coefficients (ADCs) of nutrients and energy were studied. The results showed that protein dispersibility index (PDI), urease activity (UA), glycinin and fiber were the four primary key indicators for distinguishing the characteristics of the tested SBMs. The meta-analysis results suggested that UA, glycinin, and fiber showed a negative effect on the survival rate (SR) and weight gain rate (WGR) of the Nile tilapia, whereas β-conglycinin, PDI, and nitrogen solubility index (NSI) had a positive effect on the SR and WGR of the fish. The ADCs of dry matter, the gross energy, phosphorus, crude protein, valine (Val), lysine (Lys), histidine (His), serine (Ser), and glutamate (Glu) of the Diet-A group (SBM-A inclusion) were significantly higher than those in the Diet-B group (SBM-B inclusion) (p < 0.05). However, no significant difference was found in ADCs of macro-nutrients between the two SBMs (p > 0.05). Overall, PDI, UA, glycinin, and fiber were the main indicators reflecting the characteristics of the tested SBMs, and UA, glycinin, β-conglycinin, and PDI had the greatest impact on the growth performance of Nile tilapia in this study. PDI was a more sensitive indicator than NSI for representing the protein quality of SBM.

Replacing soybean meal with micronized soybeans in starter piglet diets and their residual effects during growing and finishing phases

Aim of study: To assess the effects of replacing soybean meal (SBM) with micronized soybean (MS) on the digestibility (Experiment I) and performance (Experiment II) of piglets in the starter phase and its residual effects on the growing/finishing phases and carcass and meat quality traits&#x0D; Area of study: São Paulo, Brazil.&#x0D; Materials and methods: The treatments consisted of different levels of dietary replacement of SBM with MS at intervals of 25%, totaling five inclusions (0%, 25%, 50%, 75%, and 100%).&#x0D; Main results: In Exp. I, the administration of the pre-starter I diet resulted in a positive linear effect (p&lt;0.05) on the apparent digestibility coefficient (ADC) of crude protein and a quadratic effect (p&lt;0.01) on the ADCs of dry matter and crude fat. For the pre-starter II diet, there was a quadratic effect on the ADCs of dry matter and crude fat (p&lt;0.05). For the starter diet, a negative linear effect on the ADC of dry matter was observed (p&lt;0.01). In Exp. II, the feed intake and weight gain decreased linearly throughout the starter phase (p&lt;0.01), while no significant difference (p&gt;0.05) in feed conversion was observed with increasing inclusion level of MS.&#x0D; Research highlights: Replacing SBM with MS in the starter diet did not influence performance during the growing and finishing phases. Meat quality was not affected but a lower retail cut weight were observed in animals fed a starter diet with higher levels of MS.

Apparent Digestibility of Nutrients in Thirteen Animal‐Based Feedstuffs by the Orange‐spotted Grouper Epinephelus coioides

AbstractIn this study, the apparent digestibility coefficients (ADCs) of 13 animal‐based feedstuffs were determined for a common aquaculture fish, the Orange‐spotted Grouper Epinephelus coioides. The feedstuffs included five kinds of fish meal (white fish meal [WFM]; low‐temperature‐steam‐dried brown fish meal [LTSBFM]; domestic flame‐dried fish meal; imported flame‐dried fish meal; miscellaneous fish meal [MFM]), two kinds of blood meal (spray‐dried hemoglobin meal; dried‐blood meal [DBM]), and six kinds of animal by‐product meal (chicken meal; meat and bone meal; pork meat meal; fermented feather meal [FFM]; hydrolyzed feather meal [HFM]; shrimp meal). Experimental diets were composed of reference diet at 699 g/kg, yttrium oxide at 1 g/kg (as a tracer), and each tested feedstuff at 300 g/kg. The ADCs of dry matter, crude protein, lipid, gross energy, phosphorus, and amino acids were determined for each experimental diet by the fecal sedimentation method. Overall, the ADCs of dry matter, crude protein, lipid, energy, phosphorus, and amino acids had ranges of 61.39–76.72, 72.23–91.96, 60.75–91.56, 45.20–88.45, 39.61–76.20, and 70.39–96.71%, respectively. The protein ADCs of the WFM (91.96%) and LTSBFM (91.28%) diets were significantly higher than those of the other feeds. The protein ADCs of the remaining tested diets were over 80%, except for those of the MFM, DBM, and HFM diets. The DBM and HFM diets each had the lowest and second‐lowest ADCs of crude protein, lipid, and energy. In conclusion, Orange‐spotted Grouper demonstrated high nutrient digestibility for the tested animal‐based feedstuffs except MFM, DBM, FFM, and HFM. This digestibility information can aid in the formulation of feed substitutes for least cost diets to be used with cultured Orange‐spotted Grouper.

Use of spineless cactus associated with legume hay in the feedlot-finishing of lambs in semi-arid regions.

The objective of this study were to examine the effects of diets containing spineless cactus associated with hays of different legume species [gliricidia (Gliricidia sepium), “catingueira” (Caesalpinia bracteosa), “sabiá” (Mimosa caesalpiniifolia Benth) and “catanduva” (Piptadenia moniliformis Benth)] on the intake, digestibility, performance and carcass traits of lambs. Twenty-four ½ Santa Inês × ½ Soinga lambs with an average body weight of 21.4 ± 2.53 kg were distributed into four treatments in a completely randomized design. Treatments consisted of diets formulated with the association of spineless cactus (Opuntia ficus-indica Mill) and hay of four legume species, namely, “catanduva”, “sabiá” “catingueira” and gliricidia. The lowest intakes (P<0.05) of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF) and total carbohydrates occurred in the animals that received the diet containing catingueira hay. However, there were no diet effects (P>0.05) on the intakes of crude protein (CP), ether extract and non-fibrous carbohydrates. The diets also did not change (P>0.05) the weight gain (0.197 kg/day) or final weight (33.18 kg) of the lambs or the apparent digestibility coefficients of DM, OM, CP and NDF. Consequently, the parameters of live weight at slaughter (34.10 kg), hot carcass weight (14.81 kg), cold carcass weight (14.66 kg), hot carcass yield (45.60%) and cold carcass yield (45.07%) exhibited the no response to treatment. In addition to these variables, the diets also did not influence subcutaneous fat thickness (2.54 mm), longissimus muscle area (13.34 cm2), morphometric measurements of the carcass, or the proportions of muscle and fat. Therefore, legume hays associated with spineless cactus can be used to feed ½ Santa Inês × ½ Soinga lambs in the feedlot, as this strategy provides heavy animals at the time of slaughter and carcasses with desirable degrees of muscularity and adiposity.

Faecal waste production, characteristics and recovery in European seabass (Dicentrarchus labrax) is affected by dietary ingredient composition

The quantitative and qualitative characteristics of faecal waste was studied in European seabass (Dicentrarchus labrax) fed diets with high inclusion of different feed ingredients (field peas, PEA; feather meal, FeM; sunflower cake meal, SFM; wheat dried distillers grain with soluble, WDG; corn gluten meal, CGM and soya protein concentrate, SPC), in two different experimental trials, in order to evaluate if different ingredients affect waste production. Each of the test ingredients was partially replaced with the basal mixture used in the control diet (CON). The ingredients were chosen for their varying levels of starch, protein, soluble and insoluble non-starch polysaccharide contents. Fish having an initial body weight of 120 g were used (20 fish/tank in triplicate groups) in both trials and were fed at 1.0% in trial I and 1.5% in trial II of their body weight for 40 days. Apparent digestibility coefficients (ADC) of dry matter (DM), nutrients (protein, fat, carbohydrate, and phosphorus) of the test diets were significantly altered between groups in trial I, with SFM showing the least ADC for DM, carbohydrate and phosphorus; starch ADC was the least in PEA but only DM digestibility and phosphorus availability were different in trial II. The quantity, recovery percentage, physical characteristics, appearance and chemical composition of the faeces were affected by the test ingredients. Carbohydrate fraction of the diet was the most influential in affecting the quantity and chemical composition of faeces produced. Increased inclusion of NSP rich ingredients (WDG, soluble or SFM, insoluble) resulted in higher faecal recovery percentage, despite higher faeces load. Overall, high inclusion of alternate ingredients affected quantitative and qualitative characters of the faecal waste in European seabass, which has implications for environmental sustainability of European seabass aquaculture.

Evaluation of sacha inchi meal as a novel alternative plant protein ingredient for red hybrid tilapia (Oreochromis niloticus×O. mossambicus): Growth performance, feed utilization, blood biochemistry, and histological changes

A 10-week feeding trial was conducted to examine the effect of dietary sacha inchi meal (SIM) as a soybean meal (SBM) replacer on growth performance, feed utilization, whole-body fatty acid composition, blood biochemistry, and histological changes in red hybrid tilapia, Oreochromis niloticus × O. mossambicus. Five isonitrogenous and isolipidic diets were formulated with 0 (control diet), 110, 220, 320, and 420 g/kg replacement of SBM with SIM (referred to as SIM0‒420). Each diet was randomly assigned to one of five fish groups in a 100 L indoor tank (n = 15 each, average initial weight 9.36 ± 0.02 g) with four replicates. During the last 2 weeks of the feeding trial, 5 g/kg chromic oxide (Cr2O3) was added to the diet to determine the apparent digestibility coefficient (ADC). The results showed that SIM inclusion significantly increased growth performance, feed utilization, and ADC of dry matter in a quadratic manner with the highest final weight observed in the SIM110 group. Survival rates were not significantly affected by SIM inclusion levels (P > 0.05). The amount of n-3 fatty acids in the whole-body fish, particularly that of C18:3n-3, was linearly and quadratically increased (P < 0.001) with increasing dietary SIM inclusions. Total cholesterol and triglycerides (TGs) were linearly and quadratically decreased in the fish fed the SIM inclusion diets (P < 0.05), but no linear or quadratic effects of dietary treatments were observed on levels of total protein, albumin, globulin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Liver histology showed a significant increase in cytoplasmic vacuolization with increasing SIM inclusion in diets, and fish fed the SIM420 diet showed hepatocyte swelling and displacement of hepatocyte nuclei toward the periphery. Similarly, intestine histology detected a significant linear reduction in villi height and villi thickness with increasing level of dietary SIM (P < 0.001). Overall, the present study indicates that SIM protein can totally replace soybean protein in tilapia diets, while high SIM inclusion results in histological abnormalities. In particular, SIM110 replacement can improve growth without any adverse effects in biochemical parameters, digestibility, and histological changes.

Processed by-Products from Soy Beverage (Okara) as Sustainable Ingredients for Nile Tilapia (O. Niloticus) Juveniles: Effects on Nutrient Utilization and Muscle Quality.

Simple SummaryThe consumption of soy products increases worldwide and generates large amounts of by-products, which are often discarded. Okara is a soybean by-product with high nutritional value. This work evidenced the great potential of okara meal, after appropriate technological processing, to be used as feed ingredient in Nile tilapia diets. It was clearly demonstrated the effectiveness of the autoclave and the use of proteases from C. cardunculus without fermentation to increase okara nutrient bioavailability. The inclusion of up to 20% okara meal in diets for tilapia did not affect growth performance, nutrient utilization, or whole body composition compared to a reference diet. Flesh quality remained largely unaffected, although fish fed with AOK diets had the highest density of muscle fibers.The apparent digestibility coefficients (ADCs) of differently processed okara meals were assessed in Nile tilapia diets: dried okara not autoclaved (FOK), dried okara autoclaved (AOK), okara hydrolyzed with Alcalase (ALOK) or Cynara cardunculus proteases (CYOK), and hydrolyzed okara fermented with lactic bacteria: Lactobacillus rhamnosus R11 (CYR11OK) or Bifidobacterium animalis ssp. lactis Bb12 (CYB12OK). Okara processing significantly affected nutrient digestibility: dry matter ADC was highest in CYR11OK (80%) and lowest in FOK (40%). The lowest protein digestibility was observed in CYR11OK (72%), and the highest in AOK (97%) and CYOK (91%), evidencing the effectiveness of the autoclave and the use of C. cardunculus proteases to increase okara protein bioavailability. The inclusion of up to 20% of AOK or CYOK did not affect fish growth, nutrient utilization, or whole body composition of Nile tilapia. The flesh quality (color, pH, water activity, cohesiveness, elasticity and resilience) was not affected by the dietary incorporation of AOK or CYOK. Fish fed with AOK diets stand out for their high density of muscle fibers, particularly in AOK20, which can explain their high muscle firmness and may result in further hypertrophic growth. Altogether, results suggest that hydrolyzed or autoclaved okara are valuable ingredients for Nile tilapia diets.

Digestibility of spineless cactus meals in extruded diets for Nile tilapia (Oreochromis niloticus): energy, protein, amino acids, and carbohydrates.

The aim of the present study was to determine the apparent digestibility coefficients (ADCs) of gross energy, dry matter, crude protein, amino acids, and different carbohydrate fractions of spineless cactus meals (SCMs) for Nile tilapia juveniles, fed with extruded diets. Fish were fed a reference diet or one of five test diets, each of which included 70% reference diet and 30% corresponding SCM. Fecal collection was performed in modified Guelph method. The ADCs for dry matter, gross energy, and soluble carbohydrates of the "redonda" spineless cactus meal (RSCM) were higher (P < 0.05) than those of either the "IPA 20" spineless cactus meal (ISCM) or "gigante" spineless cactus meal (GSCM), and the ADCs for crude protein of the RSCM and "Orelha de elefante africana" spineless cactus meal (OEASCM) were higher than those of the other cactus meals (P < 0.05). In addition, the ADCs for dry matter, crude protein, and gross energy of the SCMs were similar to wheat middlings. The digestibility of the less soluble fraction of the evaluated carbohydrates, the non-fibrous carbohydrates, varied between 58.32 and 73.04%, indicating efficiency in the digestion and absorption process. The data obtained in this article can be the basis for growth experiments, with the substitution of traditional ingredients for SCMs. The determination of zootechnical, physiological, metabolic, and health variables can indicate the potential for using SCMs in diets for Nile tilapia.

Dietary inorganic monophosphates in high plant ingredient‐based diets influence nutrient digestibility, postprandial macro‐mineral status and immune functions of juvenile rainbow trout,Oncorhynchus mykiss

Inorganic monophosphates supplementation effects in high plant ingredient‐based diets of juvenile Oncorhynchus mykiss were evaluated by feeding four experimental diets supplemented with 11.4, 10.0, 11.5 and 10.0 g/kg of monocalcium phosphate (MCP), monoammonium phosphate (MAP), monopotassium phosphate (MKP) and monosodium phosphate (MSP), respectively. After 60 days, MAP and MKP supplemented groups showed improved growth and feed intake (p > .05). Apparent digestibility coefficient of dry matter (ADCDM) was significantly higher in MSP diet followed by MKP, MCP; MAP diet showed significantly lower ADCDM. MAP and MSP diets showed significantly higher mineral digestibility. The postprandial plasma P levels were significantly influenced by the dietary treatments and the period after a single meal. MAP, MKP and MSP groups showed significantly higher baseline P concentration than MCP. The other macro‐minerals (Ca, Mg, K and Na) were significantly influenced by the postprandial time. MSP and MKP diets showed significantly higher lysozyme activity. Total immunoglobulin was significantly higher in MSP group. MKP diet showed significantly higher expression of cd4‐2β genes compared with MCP. Significantly higher lysozyme gene expression observed in MSP diet followed by MKP; MAP and MCP groups showed significantly lower value. Finally, MAP, MKP and MSP significantly improved nutrient digestibility, mineral bioavailability and immune functions of rainbow trout compared with MCP in high plant ingredient‐based diets.

Effect of selenium sources in plant-based diets on antioxidant status and oxidative stress-related parameters in rainbow trout juveniles under chronic stress exposure

Selenium (Se) is an essential micronutrient required for normal development and antioxidant protection. Oxidative stress induced by stressful conditions has been shown to be reduced by dietary Se supplementation. However, replacing fishmeal, an important source of Se, with ingredients of plant origin usually results in decreased Se content in aquafeeds. The objective of the study was hence to assess the impact of dietary Se supplementation by an inorganic or organic source on the antioxidant defense system of rainbow trout (Oncorhynchus mykiss) juveniles fed practical plant-based feeds under normal or chronic stress conditions. Fish (initial mean weight: 42 ± 2 g) were maintained under normal (25 fish/tank, dissolved oxygen: 7.9 mg/l) or stressful conditions combining decreased water quality with hypoxia and increased stocking density (50 fish/tank, dissolved oxygen: 5.9 mg/l) for 12 weeks at 17 °C. Rainbow trout juveniles were fed three plant-derived protein-based diets containing 0.5 mg Se/kg diet supplemented or not with 0.3 mg Se/kg diet supplied as sodium selenite or Se-enriched yeast, Selsaf®. The apparent digestibility coefficients (ADC) of dry matter, protein, ash and Se were improved by Se-enriched yeast supplementation while the ADC of Se was reduced by sodium selenite supplementation and the ADC of dry matter, starch, energy, ash and phosphorus were reduced by chronic stress exposure. Dietary Se supplementation had no significant impact on growth performance contrary to chronic stress exposure which led to decreased final body weight and feed intake. Total Se content of fish was increased by both dietary Se supplementations but to a larger extent with Se-enriched yeast. Fish fed Se-enriched yeast displayed increased hepatic selenomethionine content and decreased muscle anisidine value. Blood glutathione content was reduced by chronic stress exposure. While hepatic catalase activity and transcript expression were increased by chronic stress exposure, both hepatic and renal glutathione peroxidase (GPX) activity and hepatic transcript expression of gpx1b2 and gpx4a2 were decreased in non-Se supplemented fish. These results suggest the necessity to supplement plant-based diets with Se for rainbow trout juveniles, independently of chronic stress exposure and highlight the superiority of organic form of Se to fulfil the dietary Se requirement and sustain the antioxidant status of fish.

Effects of different dietary carbohydrate‐to‐lipid ratios on growth, plasma biochemical indexes, digestive and immune enzymes activities of juvenile orange‐spotted grouper Epinephelus coioides

An 8-week feeding trial was conducted to investigate the effects of dietary carbohydrate-to-lipid (CHO:L) ratios on growth, liver and muscle glycogen content, haematological indices, and liver and intestinal enzyme activity of juvenile grouper (Epinephelus coioides). Five isonitrogenous (496.0 g/kg protein) and isoenergetic (21.6 KJ/g gross energy) diets with varying CHO:L ratios of 0.65 (D1), 1.31 (D2), 2.33 (D3), 4.24 (D4) and 8.51 (D5), respectively, were fed to triplicate groups of 20 fish (average 10.02 ± 0.1 g) for 8 weeks. Results showed that the weight gain rate, specific growth rate and protein efficiency ratio (PER) of juvenile grouper increased first and then decreased with the increase in CHO:L ratio, reaching a maximum value in the D4 (CHO:L = 4.24) diet. The trend for the feed conversion ratio was opposite to the PER. Along with the diet CHO:L ratios, the apparent digestibility coefficients (ADC) of crude lipid and energy for the juvenile groupers decreased gradually, while the ADC of dry matter, liver and muscle glycogen level increased gradually. Total protein, triglycerides and cholesterol in serum were all maximized in the D4 diet and glucose in the D5 (CHO:L = 8.51) diet. Digestive enzyme activity in the intestine was significantly affected by dietary CHO:L ratio. Liver hexokinase, phosphofructokinase and glucose-6-phosphate dehydrogenase activity increased significantly as CHO:L ratio increased. Liver lysozyme and acid phosphatase activity in the groupers fed the D3 (CHO:L = 2.33) diet was significantly higher than that of other diets. Liver fructose-1,6-bisphosphatase and alkaline phosphatase activity reached a maximum value in the D4 diet and was significantly higher than that in the D1 diet. Taking the above results together, it can be concluded that an optimal dietary CHO:L ratio of 2.33 is suitable for grouper culture concerning growth performance and health.

Broccoli byproduct-wheat straw silage as a feed resource for fattening lambs.

The effect of feeding broccoli byproduct-wheat straw silage [BBWS; 69:31 ratio, dry matter (DM) basis] on performance, microbial N synthesis (MNS), rumen, and blood parameters in Fashandy lambs were evaluated. Three diets, with equal metabolizable energy and crude protein (CP) with a forage to concentrate ratio of 27:73 (DM basis), were formulated in which forage (lucerne and wheat straw) was replaced by BBWS (0, 100, or 200 g/kg of diet DM). These were assigned to three groups (n = 15/group) in a completely randomized block design for a 70-d period in which diets were offered as a total mixed ration. For each animal, dry matter intake (DMI), average daily gain (ADG), in vivo apparent digestibility, MNS, N retention, rumen, and blood parameters were measured. The BBWS diets had no influence on DMI, ADG, feed conversion efficiency, in vivo apparent digestibility coefficients of DM, organic matter, CP, and ash-free neutral detergent fiber. Neither MNS and N retention nor serum concentrations of glucose, triglycerides, creatinine, cholesterol, urea N, triiodothyronine, thyroxine, total protein, albumin, and globulin were affected. Rumen pH, NH3-N, short-chain fatty acid concentrations, the ratio of acetic to propionic acid, and protozoa numbers were, also, not influenced. In summary, BBWS may be fed to Fashandy lambs up to 200 g/kg of diet DM without any adverse impacts on growth performance.

Nutritional value of different insect larvae meals as protein sources for European sea bass (Dicentrarchus labrax) juveniles

Apparent digestibility coefficients (ADCs) of five commercially available insect larvae meals, H. illucens (HI and HId), T. molitor (TM and TMd) and a locust meal (LM), obtained from different producers, were assessed in European sea bass (Dicentrarchus labrax) juveniles. Each experimental diet was obtained by replacing 20% of a commercial-based diet used as reference (DREF), with 1% of chromic oxide added, by a test ingredient. Each diet was fed to quadruplicate groups of fish (initial weight: 33 ± 1 g) and, after an acclimatization period, daily collection of faeces was performed during 12 days. Dry matter ADC was highest in TM (85%) and lowest in LM (40%). Protein ADC was high in TMd (93%); intermediate in HId and TM (87 and 89%, respectively); and moderate in LM and HI (74 and 76%, respectively). Overall, the ingredient with highest digestible total essential amino acids (EAAs) content was TMd, followed by TM which was higher than HId; HI had a moderate amount of digestible EAAs, and LM had the lowest values. Fat ADC was highest for HId, TMd and TM (93%–95%). Energy and phosphorus ADC were highest in TMd (84% and 91%, respectively) and lowest in LM (53% and 27%, respectively). In conclusion, the high protein level, high protein digestibility and high amount of digestible EAAs of TM and TMd (> 89%) suggests that Tenebrio molitor larvae meals are the most promising protein sources tested for European sea bass, with potential to replace fishmeal without impairing nutrient digestibility.

Cork and guar gum supplementation enhanced the buoyancy of faeces, and protease supplementation alleviated the negative effects of dietary cork on growth and intestinal health of tilapia, Oreochromis niloticus × O. aureus

To evaluate the effects of dietary cork, protease and guar gum on growth, intestinal health and faecal floatability of tilapia, fine or coarse particle cork (0.45–0.60 mm, 0.60–0.83 mm) was included in diets at 0 (control), 20 g/kg, 30 g/kg and 40 g/kg, and then, 0.175 g/kg protease (P) and 3 g/kg guar gum (G) were supplemented to the 40 g/kg coarse particle diet individually or in combination (P + G). Tilapia with an initial body weight of 15.0 ± 0.5 g were fed one of the 10 diets for 60 days. The results showed that weight gain (WG), apparent digestibility coefficient (ADC) of dry matter (DM) and crude protein (CP), intestinal evacuation ratio, intestinal digestive enzyme activity (IDE) and villus height decreased, and floating faeces ratio increased with the increasing cork level in diets. At the same supplementation level, coarse particle groups showed significantly higher floating faecal ratio than fine particle groups (p < .05). Dietary protease increased the WG, ADC of DM, IDE and villus height (p < .05), and guar gum increased floating faecal ratio when compared to 40 g/kg coarse particle group (p < .05). However, the ADC of DM, IDE and villus height of protease group were still inferior to those of control group (p < .05). In conclusion, dietary cork increased the floating faeces ratio, and the coarse particles produced more floating faeces than fine particles. Moreover, the supplementation of guar gum in cork‐supplemented diet further increased the floating faeces ratio. However, dietary cork negatively affected the growth performance of tilapia, which could be partially alleviated by the supplementation of protease.

Dietary protease, carbohydrase and micro-encapsulated organic acid salts individually or in combination improved growth, feed utilization and intestinal histology of Pacific white shrimp

The present study evaluated the effects of a protease, a carbohydrase complex and a micro-encapsulated organic acid salt blend in low fish meal diet on growth, nutrient utilization, digestive enzyme activity and intestinal histology of Pacific white shrimp (Litopenaeus vannamei). A positive control diet (PC) and a negative control diet (NC) were designed to contain 20% and 10% fish meal respectively. Then a protease complex (P, 175 mg/kg), a multi-carbohydrase (C, 100 mg/kg) and a micro-encapsulated organic acid salt blend (O, 825 mg/kg) were supplemented to the NC diet individually or in combination to formulate another seven diets (P, C, O, P + C, P + O, C + O, P + C + O). The nine isonitrogenous and isoenergetic diets were fed to shrimp (2.1 g) for 49 days. The shrimp fed the PC diet had the highest weight gain (WG) (529.6%) and lowest feed conversion ratio (FCR) (1.20) while those fed the NC diet had the worst growth (382.1% and 1.55, respectively) among the treatments. The supplementation of protease, carbohydrase and micro-encapsulated organic acid salts significantly improved WG and decreased FCR (P < .05) when compared to the NC diet, but did not reach the same level as the PC treatment. The apparent digestibility coefficient (ADC) of crude protein was improved significantly in diets with the additives supplementation, individual or in combination (P < .05). However, the ADC of dry matter was improved only in protease supplemented diets (P < .05). The additives supplementation also significantly improved the hepatopancreatic protease and amylase activity (P < .05). The villus height of shrimp fed the micro-encapsulated organic acid salts supplemented diets (O, P + O, C + O, P + C + O) was significantly higher than those fed the NC diet (P < .05). However, there were no differences in whole body proximate composition, intestinal villi width and hepatopancreatic lipase activity among the treatments (P > .05). The findings showed that the individual or combined supplementation of protease, carbohydrase and micro-encapsulated organic acid salts in low fish meal diet (10% fish meal) could improve the growth performance and nutrient utilization of Pacific white shrimp.

Pectin plays a role in restricting the utilization of rapeseed meal by Chinese mitten crab, Eriocheir sinensis

The present study aims to assess the anti-nutritional effect of pectin and to better understand rapeseed meal (RSM) as a feed ingredient for Chinese mitten crab, Eriocheir sinensis. A semipurified diet containing 280 g/kg fish meal was formulated as a control diet (DF). A second diet (DP) was supplemented with 26.7 g/kg pectin; the amount was estimated to be equal to that in the third diet (DR), which was formulated to include 400 g/kg RSM. Another diet (DRPase) was supplemented with 12 g/kg pectinase based on DR in which pectin was degraded by pectinase. The diets were randomly fed to twelve tanks of the crab for 8 weeks. Compared with the crabs fed DF, the specific growth rate, protein efficiency ratio, apparent digestibility coefficients (ADC) of dry matter and protein, activity of aspartate transaminase (AST) and trypsin (TP), and high-density lipoprotein (HDL) in the serum decreased significantly in the crabs fed DR; the ADC of dry matter, activity of AST and serum HDL decreased significantly in the crabs fed Dp, but they were higher than in the crabs fed DR. Compared with the crabs fed DR, the ADC of dry matter, activity of AST and TP, and serum HDL increased significantly in the crabs fed DRPase. The mRNA expression activity of both Es-pl44 and Es-pp1 was DF < DP < DRPase < DR. These results indicate that pectin contributed to low utilization of RSM in Chinese mitten crab.

Optimum level of dietary lipids for growth, chemical composition and apparent digestibility of lipids for Atractosteus tropicus

Lipids requirement of tropical gar Atractosteus tropicus prejuveniles and juveniles was evaluated on growth, survival, chemical composition and apparent digestibility coefficient (ADC). Four semi-purified experimental diets (5, 10, 15 and 20% of lipids) were obtained with a mix of menhaden oil and soybean lecithin (2:1 ratio). Two trials were carried out, first with 600 prejuveniles of 0.5 g (35 days post-hatching, dph) for 56 days, and the second with 160 juveniles of 15 g (two-months-old) for 42 days. In the first trial, 15 (40.8 g) and 20% (40.2 g) lipid diets showed the best weight. Significant differences were obtained in condition factor (CF), daily lipid intake (DLI), hepatosomatic index (HSI), crude protein, ashes, nitrogen-free extract, moisture and ether extract between treatments. In the second trial, fish fed with the 10% lipid diet obtained the highest weight (89.1 g) compared with the other treatments. Significant differences were recorded for weight gain (WG), feed conversion ratio (FCR), specific growth rate (SGR), condition factor (CF), and lipid efficiency rate (LER). Also, significant differences were obtained in crude protein, ether extract, NFE, gross energy, apparent lipid ADC, protein ADC and dry matter ADC. The polynomial models applied to both trials indicated an optimum lipid requirement of 17% for 0.5 g juveniles and of 9% for 15.2 g juveniles.