Effect of extrusion on trypsin inhibitor activity and nutrient digestibility of diets based on fish meal, soybean meal and white flakes

The effects of moist extrusion processing of diets containing fish meal (FM) and conventional defatted soybean meal (SBM) or untoasted defatted soybean meal (white flakes [WF]) on amino acid composition, trypsin inhibitor activity (TIA), and apparent total tract digestibility of nutrients were studied. Three diets with the nutritional characteristics of feeds for salmonid fish were formulated: one control based on FM as protein source and two others where 40% of total amino acids from FM were substituted by either SBM or WF. Each diet was fed to mink either as an unextruded mixture of the ingredients or as extruded pellets in order to determine the effect of extrusion processing. Extrusion did not change the amino acid composition of the diets significantly, but reduced the TIA of both diets containing soy products by approximately 76%. Intake of the unextruded WF diet was only one-third compared with the other diets. The dry matter concentration in faeces from mink fed diets containing soy products was significantly lower than in mink fed the FM diet. Digestibility of crude protein, all amino acids and fat was lower, but starch higher, in the unextruded WF diet than in the FM and SBM diets, whereas no significant differences were found among the extruded diets. Extrusion of the WF diet increased digestibility of protein and all amino acids. The greatest increase in digestibility after extrusion of the WF diet was observed for cysteine followed by tryptophan. Extrusion of the FM and SBM diets had no significant effect on amino acid digestibility. Digestibility of starch was, in general, increased by extrusion. It is concluded that the heat treatment involved in typical moist extrusion processing used for fish feed may be sufficient to inactivate most of the TIA in unheated soybean meal, and to increase digestibility of the protein in WF to approximately the same level as found for SBM and FM. Still, extrusion is a lenient process with minor effects on nutrient digestibility of diets containing fish meal or toasted soybean meal as major protein sources.     

Plant products affect growth and digestive efficiency of cultured Florida pompano (Trachinotus carolinus) fed compounded diets

Costs of compounded diets containing fish meal as a primary protein source can be expected to rise as fish meal prices increase in response to static supply and growing demand. Alternatives to fish meal are needed to reduce production costs in many aquaculture enterprises. Some plant proteins are potential replacements for fish meal because of their amino acid composition, lower cost and wide availability. In this study, we measured utilization of soybean meal (SBM) and soy protein concentrate (SPC) by Florida pompano fed compounded diets, to determine the efficacy of these products as fish meal replacements. We also calculated apparent digestibility coefficients (ADCs) for canola meal (CM), corn gluten meal (CGM), and distillers dried grains with solubles (DDGS), following typical methods for digestibility trials. Juvenile Florida pompano were fed fish-meal-free diets containing graded levels of SBM and SPC, and weight gain was compared to a control diet that contained SBM, SPC, and fish meal. Fish fed diets that contained 25-30 percent SBM in combination with 43-39 percent SPC had weight gain equivalent to fish fed the control diet with fish meal, while weight gain of fish fed other soy combinations was significantly less than that of the control group. Apparent crude protein digestibility of CGM was significantly higher than that of DDGS but not significantly different from CM. Apparent energy digestibility of DDGS was significantly lower than CGM but significantly higher than CM. Findings suggested that composition of the reference diet used in a digestibility trial affects the values of calculated ADCs, in addition to the chemical and physical attributes of the test ingredient.     

四种植物蛋白对中华绒螯蟹幼蟹生长性能、氨基酸沉积率和抗氧化酶活性的影响

为了筛选适宜于养殖中华绒螯蟹幼蟹的饲料植物蛋白源,探究不同植物蛋白源饲料对幼蟹生长性能、氨基酸沉积率和抗氧化性能等方面的影响,以50%的鱼粉配制基础饲料（记为FM）,分别采用30.5%发酵豆粕、32.5%豆粕、28%棉粕和39%菜粕替代基础饲料中鱼粉总量的50%,配制成4种等氮等能的饲料（分别记为FSBM、SBM、CSM和RSM）,投喂初始体重为（0.249±0.003）g的中华绒螯蟹幼蟹8周。结果表明:（1）与FM组相比,FSBM、SBM和CSM组的增重率、特定生长率、饲料系数、蛋白质效率和蛋白质沉积率均没有显著性差异;RSM组的增重率与FM组相比差异不显著（P>0.05）,但显著低于SBM组（P < 0.05）,而其饲料系数则显著高于FM、FSBM及SBM组（P < 0.05）,蛋白质效率显著低于其他各组（P < 0.05）,蛋白质沉积率显著低于SBM和CSM组（P < 0.05）。（2）不同植物蛋白组的总必需氨基酸沉积率和FM组相比差异不显著（P>0.05）,而RSM组总必需氨基酸沉积率显著低于FSBM和CSM组（P < 0.05）。（3）与FM组相比,不同植物蛋白组蟹的血清和肝胰腺中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-PX）活性和肝胰腺丙二醛（MDA）含量并没有显著的影响,而RSM组血清丙二醛（MDA）含量显著的高于其他各组（P < 0.05）。结果表明,在幼蟹饲料中,豆粕、发酵豆粕和棉粕替代基础配方中鱼粉的50%后并未对幼蟹的生长性能、氨基酸沉积率及抗氧化能力造成负面的影响,发酵豆粕、豆粕和棉粕可以作为替代鱼粉的适宜蛋白源,且添加水平约在30%左右。菜粕替代后降低了饲料的利用和氨基酸沉积效率,这可能是由于菜粕的蛋白质消化率低、含有相应的抗营养因子和添加水平过高所致,建议使用前应适当进行脱毒处理,并与或和其他植物蛋白配伍使用。     

Estimation of protein digestibility—IV. Digestive proteinases from the pyloric caeca of coho salmon (Oncorhynchus kisutch) fed diets containing soybean meal

The goal of this study was to better understand why dietary soybean products are poorly utilized by salmonids. The influence of dietary intake on coho salmon fingerling weight gain and specific properties of pyloric caeca enzymes was investigated. Fingerlings were fed diets containing heated or unheated soybean meal (SBM) or Promoveal™, as 15–25% herring meal replacer, for 8–12 weeks. Fish fed to apparent satiation with diets containing heated SBM replacer gained more weight than those fed unheated SBM at the same level. Fish increased in body weight at the same rate when fed restricted rations containing either 15% SBM replacer that was variously heated up to 20 min, 15% Promoveal™ replacer or the herring meal basal diet. After the experimental diets were fed, digestive proteinases were isolated from the pyloric caeca. Yield of pyloric caeca enzymes (PCE), recovery of trypsin in PCE, soybean trypsin inhibitor (SBTI) sensitivity of PCE trypsin, specific activity of PCE trypsin and in vitro casein digestibility by PCE were determined for each dietary group. Weight gain vs in vitro casein digestibility by PCE was linear for animals fed unheated SBM to apparent satiation (r² = 0.71, P < 0.1) but not for animals fed either heated SBM to apparent satiation or variously heated SBM as 15% replacer at restricted levels. Trypsin from fish fed diets with heated or unheated SBM, but not Promoveal™ replacer, was less sensitive to SBTI than fish fed no SBM. For fish fed diets with variously heated SBM as 15% replacer, the SBTI activity of the SBM and SBTI inhibition of PCE trypsin were inversely related (r² = 0.88, P < 0.05). The yield of PCE was higher for fish fed 25% of heated SBM replacer than it was for diet groups fed less SBM. The yield of PCE trypsin was higher from animals fed 25% heated SBM replacer than those fed diets with a lower percentage of heated SBM replacer. Feeding coho fingerlings rations with SBM replacer appears to promote physiological compensation of PCE. Heat stable and/or heat-activated factor(s) and SBTI appear to cause the compensation of salmon digestive proteinases from coho salmon fed diets with SBM.     

不同添加方式植酸酶处理豆粕对牙鲆生长和饲料利用率的影响

以初始平均体重(2.02±0.02)g的牙鲆(Paralichthys olivaceus)为实验对象,进行为期70d的摄食生长实验,研究不同添加方式的植酸酶对牙鲆生长和饲料利用的影响。在5000.0g豆粕中添加2.5g植酸酶,然后用产朊假丝酵母(Candidautilis)进行发酵预处理,得到植酸酶预处理豆粕。共制作4种等氮等能(粗蛋白49.7%、总能20.9kJ/g)饲料,对照饲料主要以鱼粉为蛋白源;在对照饲料的基础上,用豆粕蛋白替代45%的鱼粉蛋白配制成豆粕组饲料;在每千克豆粕组饲料中添加1000IU植酸酶,配制成植酸酶组饲料;用植酸酶预处理豆粕蛋白替代45%的鱼粉蛋白配制成植酸酶预处理豆粕组饲料。结果表明,与对照组相比较,用豆粕蛋白替代饲料中45%的鱼粉蛋白,若不添加植酸酶则显著降低牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05);直接添加植酸酶组、植酸酶预处理豆粕组牙鲆的特定生长率、饲料效率、蛋白质效率和氮贮积率与鱼粉对照组相比较没有出现显著差异(P0.05);与不添加植酸酶的豆粕组相比较,在含豆粕饲料中添加1000IU/kg饲料的植酸酶显著提高牙鲆的特定生长率(P0.01)、氮贮积率(P0.05)和磷贮积率(P0.01),显著降低氮排放率(P0.05)和磷排放率(P0.01),但饲料效率和蛋白质效率没有显著变化(P0.05);在豆粕中添加植酸酶进行发酵预处理,降低了豆粕中植酸含量,在饲料中添加植酸酶预处理豆粕显著提高牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05),显著降低氮(P0.05)、磷和钙的排放率(P0.01)。       

Ileal and total tract nutrient digestibility in blue foxes (Alopex lagopus) fed extruded diets containing different protein sources

This study compared apparent ileal and total tract digestibility of macronutrients and amino acids in blue foxes (Alopex lagopus) fed dry extruded diets. The control diet contained fish meal as the main protein source, while in the other diets 50% of the fish meal protein was replaced by not de-hulled solvent-extracted soybean meal, meat meal or bacterial protein meal. Ileal digestibility was obtained with animals modified with ileorectal anastomosis (IRA method). There were no significant differences in the average digestibility of CP, Lys, Trp, Val, Ala or Glu between IRA modified and intact animals. Average ileal digestibilities of His, Thr, Asp, Cys, Gly, Hyp, Pro, Ser, starch and total carbohydrates (CHO) were significantly lower compared with total tract values. Average ileal digestibility of Arg, Ile, Leu, Met, Phe, Tyr and crude fat was significantly higher than total tract digestibility. Digestibility measured in IRA modified animals showed less variability compared with values from intact animals. There were significant differences among diets in ileal as well as total tract digestibility of orude protein, most amino acids, starch and CHO, and in ileal digestibility of crude fat. Ileal crude protein digestibility of the diets ranged from 81.0-86.4% and total tract digestibility from 82.5-86.4%. Ileal amino acid digestibilities ranged from 70.1 (Asp) to 93.3% (Arg) and total tract values ranged from 72.8 (Cys) to 92.2% (Arg). Both ileal and total tract digestibilities of crude protein and most amino acids were significantly lower for diets containing meat meal or bacterial protein meal compared with the control fish meal-based diet and the diet with soybean meal. Although ileal digestibility may be more accurate than total tract digestibility in estimating the protein and amino acid supply in blue foxes, total tract digestibility may be acceptable because of numerically small differences between ileal and total tract digestibilities for protein and most amino acids. It was further concluded that ileal digestibilities of starch and CHO in the blue fox are lower than corresponding total tract digestibilities.     

Effects of feeding low fishmeal diets with increasing soybean meal levels on growth,gut histology and plasma biochemistry of sea bass

The aquaculture industry depends upon the development of sustainable protein sources to replace fishmeal (FM) in aquafeeds and the products derived from soybeans are some of the most studied plant feedstuffs. A key area of investigation for continuing to improve modern aquafeeds includes the evaluation of varying proportions and combinations of plant ingredients to identify mixtures that are more efficiently utilized by the fish. This study investigated the effects of increasing soybean meal (SBM) by replacing a mix of plant ingredients in low FM (20%) diets on growth, blood biochemistry profile and gut histology on European sea bass. Five isonitrogenous and isolipidic experimental diets were formulated: four diets containing increasing SBM levels (0, 10, 20 and 30%; 0SBM, 10SBM, 20SBM and 30SBM, respectively) with a low content of FM (20%) and one control diet (0% SBM; 35% FM). Diets containing SBM brought to comparable performance and protein utilization, while 0SBM had negative impact on feed conversion rate and protein utilization. Blood parameters suggested an optimal nutritional status under all feeding treatments, even though slightly decreased values were reported at increasing dietary SBM. Histology examination did not show any changes indicative of soy-induced enteritis. We can conclude that for European sea bass: (i) different blends of plant protein did not affect feed intake despite the 20% FM dietary level; (ii) the inclusion of SBM maintains optimal growth and feed utilization in low FM diets; (iii) blood biochemistry profile showed a good nutritional status under all feeding regimes; (iv) no evidence of soy-induced enteritis was reported in any group fed low FM diets. For formulation of practical diets in on-growing of European sea bass, SBM up to 30% can be successfully incorporated into feeds containing low FM inclusion.     

Haemato-immunological and growth response of mirror carp (Cyprinus carpio) fed a tropical earthworm meal in experimental diets

An investigation was conducted to evaluate the effect of feeding a tropical earthworm meal (Perionyx escavatus) on the haemato-immunological response and growth performance of mirror carp (Cyprinus carpio). Fish were fed diets for a total of 88 days, fishmeal served as the main protein source in the control diet. Two remaining diets consisted of fishmeal fixed at 33.65% provision of protein and the remaining 66.35% protein was provided by soybean meal (SBM diet) or P. excavatus meal (EW diet). Compared to control and SBM fed fish (7.69 ± 0.28 and 5.92 ± 0.31 g/dl, respectively), a significant increase in haemoglobin was measured in EW fed fish (9.57 ± 0.24 g/dl). Consequently significant elevations were also observed in mean corpuscular haemoglobin (MCH; 79.13 ± 4.59 pg) and mean corpuscular haemoglobin concentration (MCHC; 22.69 ± 0.54 pg) in EW fed fish. On the contrary, compared to control and SBM fed carp total leukocyte levels (2.72 ± 0.17 and 3.10 ± 0.17 × 10(4)/mm(3), respectively) were significantly decreased in the EW group (2.15 ± 0.14 × 10(4)/mm(3)). Moreover at day 14 and 21 post immunisation with bacterin isolated from Aeromonas hydrophila fish fed the EW diet displayed a significant reduction in respiratory burst activity (RBA) compared to control and SBM fed fish. After 60 days of feeding, fish fed EW diet showed a significant elevation in final body weight compared to fish fed a fishmeal based diet (control treatment) and fish fed a soybean meal based diet. Similar improvements were observed in feed utilisation efficiency. The present study shows that feeding P. excavatus meal to mirror carp decreases some aspects of the innate immune response, but at the same time gives rise to significant enhancement of growth and feed utilisation efficiency.     

Effects of diets containing soybean meal on trypsin mRNA expression and activity in Atlantic salmon (Salmo salar L)

Atlantic salmon develop subacute enteritis in the distal intestine (DI) when fed diets containing soybean meal (SBM) at high levels, a condition accompanied by increased trypsin activity in the DI intestinal content compared to fish fed conventional fishmeal (FM) based diets. To further investigate the responses of Atlantic salmon to dietary SBM, we measured trypsin activity in intestinal contents, quantified pancreatic trypsin mRNA expression, surveyed trypsin mRNA expression in selected tissues and characterized active forms of trypsin in the intestinal wall and brain. Enzyme measurements showed that trypsin activity in the intestinal content of SBM fed fish was lower in the proximal segments of the intestine, but higher in the DI compared to FM fed fish. The difference in enzyme activity was not reflected in a differential expression of pancreatic trypsin mRNA between fish fed the different diets (FM or SBM). Trypsin mRNA was expressed in 18 different tissues (esophagus, stomach, pancreas, pyloric tissue, midintestine, distal intestine, liver, head kidney, kidney, heart, spleen, thymus, brain, eye, gills, gonads, muscle and skin) but was most prominently expressed in tissues of the gastrointestinal (GI) tract and brain. We report for the first time an upregulation of trypsin-like activity in the DI wall using an in-gel trypsin activity assay, as well as modulated activity in the brain of fish fed SBM. The increased activity in the DI wall may contribute to disease severity and higher trypsin activity in the intestinal content.     

Potential use of high levels of vegetal proteins in diets for market-sized gilthead sea bream (Sparus aurata)

The effect of partial or total dietary substitution of fishmeal (FM) by vegetal protein sources on growth and feed efficiency was carried out in on-growing gilthead sea bream (mean initial weight 131 g). The Control diet (FM 100) contained FM as the primary protein source, while in Diets FM 25 and FM 0 the FM protein was replaced at 75% and 100%, respectively, by a vegetable protein mixture consisting of wheat gluten, soybean meal, rapeseed meal and crystalline amino acids. Diets FM 25 and FM 0 also contained krill meal at 47 g/kg in order to improve palatability. At the end of the trial (after 158 d), fish survival was above 90%. Final weight and the specific growth rate were statistically lower in fish fed the Control diet (361 g and 0.64%/d), compared with 390–396 g and 0.69–0.70%/d after feeding vegetal diets. No significant differences were found regarding feed intake and feed conversion ratio. The digestibility of protein and amino acids (determined with chromium oxide as indicator) was similar in all diets. The blood parameters were not significantly affected by treatments. The activity of trypsin and pepsin was significantly reduced after feeding Diet FM 0. In the distal intestine, the villi length in fish fed Diet FM 25 was significantly longer and the intestine of the fish fed the FM 100 diet showed a smaller number of goblet cells. In conclusion, a total FM substitution by a vegetal mix supplemented with synthetic amino acids in on-growing sea bream is feasible.     

Apparent digestibilities and growth experiments with tilapia (Oreochromis niloticus) fed soybean meal, cottonseed meal and sunflower seed meal

Apparent digestibility and growth experiments with three oil seed by-products, soybean meal, cottonseed meal, and sunflower seed meal, were conducted using tilapia ( Oreochromis niloticus ) with an initial average body weight of 93 ± 5 g and 64 ± 1 g, respectively. The diets were formulated on an isonitrogeneous and isoenergetic basis. During the experimental period the fish were fed 1% and 1.5% of their metabolic body weight (kg^0.8) daily in the digestibility experiment and the growth experiment, respectively. Water temperature was maintained at 26.5 ± 1°C. Apparent digestibilities of the components and the diets were determined using an indirect method, i.e. with HCl-insoluble ash as an indicator. Faeces collection was carried out using a sedimentation technique.
Results of the apparent digestibilities showed that the crude protein, crude fat, as well as the gross energy digestibilities of soybean meal (93.0%, 94.6%, and 77.2%, respectively), were better than those of cottonseed meal (79.4%, 83.2%, and 57.9%, respectively) and sunflower seed meal (89.8%, 82.9%, and 49.3%, respectively). With the exception of the crude protein digestibility, nutrient and gross energy digestibilities of the cottonseed meal were found to be better than that of sunflower seed meal.
Growth experiment results indicated that soybean meal diet groups had inferior growth performance and feed conversion in comparison to the fishmeal control diet or the other test diets at an inclusion level of 32% of the digestible protein. Fish fed cottonseed meal diet and sunflower seed meal diet showed a relatively better, but not significantly different performance than did the fishmeal control diet. Supplementation diets with lysine and methionine did not enhance fish performance.     

Amino acid utilization and body composition of growing pigs fed processed soybean meal or rapeseed meal with or without amino acid supplementation

Feed ingredients used in swine diets are often processed to improve nutritional value. However, (over-)processing may result in chemical reactions with amino acids (AAs) that decrease their ileal digestibility. This study aimed to determine effects of (over-)processing of soybean meal (SBM) and rapeseed meal (RSM) on post-absorptive utilization of ileal digestible AAs for retention and on body AA composition of growing pigs. Soybean meal and RSM were processed by secondary toasting in the presence of lignosulfonate to obtain processed soybean meal (pSBM) and processed rapeseed meal (pRSM). Four diets contained SBM, pSBM, RSM or pRSM as sole protein source. Two additional diets contained pSBM or pRSM and were supplemented with crystalline AA to similar standardized ileal digestible (SID) AA level as the SBM or RSM diet. These diets were used to verify that processing affected AA retention by affecting ileal AA digestibility rather than post-absorptive AA utilization. The SID AA levels of the protein sources were determined in a previous study. In total, 59 pigs were used (initial BW of 15.6±0.7 kg) of which five were used to determine initial body composition at the start of the experiment. In total, 54 pigs were fed one of six experimental diets and were slaughtered at a BW of 40 kg. The organ fraction (i.e. empty organs plus blood) and carcass were analyzed separately for N and AA content. Post-absorptive AA utilization was calculated from AA retention and SID AA intake. An interaction between diet type, comprising effects of processing and supplementing crystalline AA, and protein source was observed for CP content in the organ fraction, carcass and empty body and for nutrient retention. Processing reduced CP content and nutrient retention more for SBM than for RSM. Moreover, processing reduced (P<0.001) the lysine content in the organ fraction for both protein sources. Supplementing crystalline AA ameliorated the effect of processing on these variables. Thus, the data indicated that processing affected retention by reducing digestibility. Correcting AA retention for SID AA intake was, therefore, expected to result in similar post-absorptive AA utilization which was observed for the RSM diets. However, post-absorptive AA utilization was lower for the pSBM diet than for the SBM diet which might be related to an imbalanced post-absorptive AA supply. In conclusion, processing negatively affected nutrient retention for both protein sources and post-absorptive utilization of SID AA for retention for SBM. Effects of processing were compensated by supplementing crystalline AA.     

Effects of dietary soybean protein levels on metabolic response of the southern catfish, Silurus meridionalis

A closed respirometer was used to measure oxygen consumption of the southern catfish Silurus meridionalis fed with six isonitrogenous (48% crude protein) diets replacing 0%, 13%, 26%, 39%, 52% and 65% fish meal (FM) protein by soybean meal (SBM) protein, in order to investigate the effects of dietary soybean protein level (SPL) (replacing FM) on metabolic rates of the southern catfish. The results showed that there were no significant differences in routine metabolism among dietary treatments. Either the total metabolic rate or specific dynamic action (SDA) was positively correlated with assimilated food energy at each diet, respectively (P<0.05). The SDA coefficient (means the energy spent in metabolism per unit of assimilated dietary energy) significantly increased with increasing dietary SPL (P<0.05). Fish fed the diet with 13% SPL had a significantly lower SDA coefficient (0.1528) than fish fed the diet with 52% or 65% SPL (0.1826 or 0.1932) (P<0.05). However, there were no significant differences in SDA coefficient among fish fed the diets with 13%, 26% and 39% SPL (P>0.05). Results of the present study suggested that an imbalance of essential amino acids at higher dietary SPL resulted in more energy channeled into metabolism, and subsequently increased the SDA coefficient.     

Use of soybean flour (dehulled, solvent-extracted soybean) as a fish meal substitute in practical diets for African catfish, Clarias gariepinus (Burchell 1822): growth, feed utilization and digestibility

Growth and digestibility trials were conducted using African catfish, Clarias gariepinus (Burchell 1822): (1) to obtain apparent digestibility coefficient (ADC) values for capelin fish meal, soybean flour and corn meal; (2) to formulate diets based on ADC values of the protein feedstuffs; and (3) to evaluate the effects of replacing 25%, 50% and 75% of fish meal in control diets with soybean flour on growth, feed utilization efficiency and carcass composition. Supplemental methionine was added to the diet formulation in which soybean flour replaced 75% of the diet. Diets were formulated (400 g digestible protein kg⁻¹ and 15 kJ digestible energy g⁻¹ dry diet) and fed to catfish fingerlings (13.1 ± 0.5 g) to apparent satiation twice daily for 70 days. The protein and energy digestibilities of fish meal and soybean flour were high (>90% and >80%, respectively; P < 0.05). At 75% fish meal replacement with soybean flour (without methionine supplementation), growth and feed utilization efficiency indicators were depressed compared with other diet treatments which had a similar (P > 0.05) growth and feed utilization efficiency to those fed the control diet. The carcass compositions of catfish in all diets were similar (P > 0.05) and the liver histology of catfish fed any of the diets showed no alterations. The results obtained indicate that 50% of fish meal protein in practical catfish diets can be replaced with soybean flour and that catfish can effectively utilize supplemental methionine, thereby allowing up to 75% of the dietary fish meal protein to be replaced by soybean flour.     

Effects of balancing crystalline amino acids in diets containing heat-damaged soybean meal or distillers dried grains with solubles fed to weanling pigs

Two experiments were conducted to investigate if adjustments in diet formulations either based on total analysed amino acids or standardized ileal digestible (SID) amino acids may be used to eliminate negative effects of including heat-damaged soybean meal (SBM) or heat-damaged corn distillers dried grains with solubles (DDGS) in diets fed to weanling pigs. In Experiment 1, four corn–SBM diets were formulated. Diet 1 contained non-autoclaved SBM (315 g/kg), and this diet was formulated on the basis of analysed amino acid concentrations and using SID values from the AminoDat® 4.0 database. Diet 2 was similar to Diet 1 in terms of ingredient composition, except that the non-autoclaved SBM was replaced by autoclaved SBM at 1 : 1 (weight basis). Diet 3 was formulated using autoclaved SBM and amino acid inclusions in the diet were adjusted on the basis of analysed total amino acid concentrations in the autoclaved SBM and published SID values for non-autoclaved SBM (AminoDat® 4.0). Diet 4 also contained autoclaved SBM, but the formulation of this diet was adjusted on the basis of analysed amino acids in the autoclaved SBM and SID values that were adjusted according to the degree of heat damage in this source of SBM. Pigs (160; initial BW: 10.4 kg) were allotted to the four treatments with eight replicate pens per treatment in a randomized complete block design. Diets were fed to pigs for 21 days. The gain to feed ratio (G : F) was greater (P<0.05) for pigs fed Diet 1 compared with pigs fed the other diets and pigs fed Diet 4 had greater (P<0.05) G : F than pigs fed Diet 2. In Experiment 2, 144 pigs (initial BW: 9.9 kg) were allotted to four diets with eight replicate pens per diet. The four diets contained corn, SBM (85 g/kg) and DDGS (220 g/kg), and were formulated using the concepts described for Experiment 1, except that heat-damaged DDGS, but not heat-damaged SBM, was used in the diets. Pigs fed Diet 1 had greater (P<0.05) G : F than pigs fed Diet 2, but no differences were observed for G : F among pigs fed diets containing autoclaved DDGS. Results demonstrate that the negative effects of heat damage of SBM or DDGS may be ameliorated if the reduced concentration and digestibility of amino acids in heat-damaged SBM or DDGS is taken into account in diet formulation. Further research is needed to improve the prediction of the ileal digestibility of amino acids in heat-processed ingredients used in practical diet formulations.     

Effects of amino acid supplementation on the nutritive quality of fermented linseed meal protein in the diets for rohu, Labeo rohita, fingerlings

A feeding trial was conducted for 8 weeks to examine the effects of partial substitution of fish meal (FM) protein (crude protein content: 58.5%) with linseed meal protein with and without supplemental amino acids in diets for rohu Labeo rohita (Hamilton), fingerlings (mean weight: 1.50 ± 0.3 g). Prior to incorporation into the diets, linseed meal was fermented with lactic acid bacteria ( Lactobacillus acidophilus ) to reduce/eliminate the antinutritional tannin and phytic acid factors. Twelve experimental diets (diets D1–D12) were formulated to replace the FM protein from a reference diet (RD) with linseed meal protein at different levels (four sets of diets, of which each set of three diets contained 25%, 50% and 75% replacement of FM protein by linseed meal protein, respectively). Diets D1–D3 were not supplemented with any amino acid. Lysine was supplemented in diets D4–D6. Diets D7–D9 were supplemented with methionine + cystine (together), and diets D10–D12 contained lysine and methionine + cystine (together). Lysine and methionine + cystine (together) were added to the diets at 5.7% and 3.1% of dietary protein, respectively. The groups of fish fed diets without amino acid supplementation had significantly lower percentages of weight gain, specific growth rate and high feed : gain ratio than the fish groups fed other experimental diets. The addition of lysine and methionine + cystine to the diet in which 50% of the FM protein was replaced by linseed meal protein (diet D11) significantly improved fish performance. The results of the present study suggest that rohu fingerlings can effectively utilize the supplemented amino acids and that linseed meal protein can replace up to 50% of the FM protein in rohu diets if the linseed meal is properly processed (fermented) and supplemented with the lacking amino acids.     

Evaluation of microbially enhanced soybean meal as an alternative to fishmeal in weaned pig diets

An experimental, microbially enhanced soybean product (MEPRO) was evaluated as a replacement for fishmeal (FM). Assessment of feedstuffs should include estimation of digestibility as well as pig performance and in combination with dietary additives. Digestibility values determined in growing pigs may not apply to nursery pigs; thus, standardized ileal digestibility (SID) of amino acids (AA) in MEPRO and FM were determined using 30±1.6 kg BW ileal-cannulated barrows (n=6) and 9.8±1.2 kg BW barrows (n=37; serial slaughter). Experimental diets included MEPRO, FM and nitrogen free where FM and MEPRO were included as the sole protein source. The SID of AAs was 3% to 5% lower in MEPRO than FM when fed to 30 kg pigs. The SID of arginine and methionine was greater (P<0.05) in MEPRO than FM when fed to 10 kg pigs. The SID of AAs was 12% to 20% lower in FM when fed to 10 v. 30 kg pigs but only 3% to 9% lower in MEPRO. A total of 336 barrows and gilts were weaned at 21 days of age (initial BW=6.1±0.8 kg) and used in a performance trial. Pens of pigs were assigned to one of the six experimental diets (8 pens/diet in two blocks). Treatment diets were fed in Phase I (7 days) and Phase II (14 days) with all pigs fed a common Phase III diet (14 days). Experimental diets included (1) negative control (NEG) containing corn, soybean meal and whey, (2) NEG+acidifier, (3) NEG+FM (POS), (4) POS+acidifier (POS A+), (5) NEG+MEPRO (MEPRO) and (6) MEPRO+acidifier. The FM and MEPRO were included at 7.5% and 5.0% in Phase I and II diets, respectively. Diets were formulated to meet the standard nutrient requirements for weaned pigs. Pig BW and feed disappearance was measured weekly and fecal scores were measured daily for the first 14 days post-weaning as an indicator of post-weaning diarrhea syndrome (PWDS). Performance (BW, daily gain, feed intake and gain : feed) was not significantly different among treatments. Treatment for PWDS occurred on different days in each block. Analysis of fecal score was completed separately by block. Pigs fed the NEG diets had higher (P=0.02) fecal scores than pigs fed the POS diets on days 2 and 3 (block 1) and higher (P<0.05) than pigs fed MEPRO or POS diets and diets with dietary acidifier on days 6 and 3 (block 2). The MEPRO holds promise as an alternative to FM in nursery pig diets.     

Nutritive value of dried lactic acid fermented fish silage and soybean meal in dry diets for juvenile catfish, Clarias gariepinus (Burchell, 1822)

Dry diets containing either fish meal (C-FM) or dried fermented fish silage and soybean meal blend (1:1, ww⁻¹) (C-FS) as the sole protein source, were fed to triplicate groups of juvenile Clarias gariepinus (10.8 ± 0.3 g) at 5% body weight per day for 70 days. Catfish fed the C-FS diet showed reduced (P < 0.05) growth rate, feed conversion, protein efficiency and digestibility. Lower amounts of available amino acids in the C-FS diet resulted in inferior nutritive value for catfish growth than in the C-FM diet. Postprandial changes in plasma amino acids showed similar patterns in both diet treatments, but the maximal mean levels attained for the C-FS diet were correspondingly lower and occurred earlier than with the C-FM diet. There were no effects of feeding C-FS diet on the hepatosomatic index but carcass analysis showed that body protein deposition was lower (P < 0.05). Differences in haematocrit, haemoglobin content and liver histology were demonstrated but were not pathological. Lower digestible energy of C-FS diet also contributed to the poor performance of catfish in this treatment. Results of this study indicate that C. gariepinus cannot metabolize protein from co-dried fish silage as efficiently as fish meal protein when used as the sole dietary protein.     

Bacterial protein meal produced on natural gas replacing soybean meal or fish meal in broiler chicken diets

The effects of replacing soybean meal or fish meal with 2, 4 or 6% bacterial protein meal (BPM) on growth performance, ileal digestibility of amino acids and sensory quality of meat, were examined using 630 broiler chickens. Weight gain from 7-32 days of age did not differ significantly among the treatments. Efficiency of feed conversion was increased when BPM replaced soybean meal, and abdominal fat deposition tended to decline. Feed conversion was not affected when BPM replaced fish meal. Amino acid digestibility was unaffected or improved when BPM replaced soybean meal, whereas replacement of fishmeal with BPM resulted in similar digestibility. Sensory quality of fresh thigh meat was similar among treatments, but for freeze-stored chest meat replacement of fish meal with BPM reduced off-odour and off-flavour and increased juiciness. It was concluded that 6% BPM can replace soybean meal or fish meal protein in broiler chicken diets.     

Effects of dietary soybean meal on growth,nutritive efficiency and body composition of cultured tench (Tinca tinca)

The suitability of defatted soybean meal as a substitute for fishmeal was assessed in juvenile (25 g, average) tench, Tinca tinca, by feeding them diets containing 25 (S25), 37.5 (S37.5) and 50% (S50) soybean meal for 150 days. Soybean meal inclusion increased the relationship between essential and non‐essential amino acids. Fish were hand‐fed to apparent satiation; the feed intake ratio was not dependent upon the dietary soybean level. Survival was over 95% and unaffected by treatment. Growth was reduced at higher soybean meal levels. After 150 days, average weight for the fish fed soybean diets S25, S37.5 and S50 was 65.6, 59.2 and 51 g, respectively. Growth performance was evaluated on the basis of specific growth rate (SGR), final biomass, feed conversion ratio (FCR), and feed intake (FI). Maximum SGR (0.61–0.64) and final biomass (3022–3156 g) were recorded in tench fed diets containing 25 and 37.5% soybean meal. Nutritional parameters such as feed intake and feed conversion ratio were not affected by the soybean meal. Body composition was similar for tench fed the three different diets.