Inclusion Level Of Soybean Meal Research Articles

243 The Effect of Totally or Partially Replacing Soybean Meal by Alternative Protein Sources on Performance and Carcass Characteristics of Growing Finishing Pigs

Abstract In many countries, soybean meal (SBM) is the premier protein source in pig diets because of the optimal amino acid (AA) content. However, due to developments in sustainability and local availability of SBM, it is of great interest for the feed industry to explore the effect on the growth performance and carcass characteristics of replacing SBM inclusion in pig diets by alternative protein sources. The objective of the current study was to explore the effect of partially and/or totally replacement of SBM in the starter, grower and finisher diets formulating based on the same NE, dig AA/NE, and similar AA profile on the growth performance and carcass characteristics of growing-finishing pigs (25 kg to slaughter at ±120 kg). In total, 120 boars and 120 gilts (Top Pi x T20) entered the experiment with an average body weight of 23.4 ± 1.87 kg and age of 61.4 ± 1.43 days. Pigs were blocked and randomly allocated to four dietary treatments depending on the inclusion level of SBM in the starter, grower and finisher phases. In treatment 1, the starter, grower and finisher feeds contained 16.0, 12.0 and 8.0% of SBM, respectively. In treatment 2, the starter, grower and finisher feeds contained 10.8, 8.1 and 0% of SBM, respectively. In treatment 3, the starter, grower and finisher feeds contained 5.3, 0 and 0% of SBM, respectively. In treatment 4, none of the feeds contained SBM. Pigs were housed in pens with 10 pigs per pen. The pens were equipped with individual feeding stations (IVO-G stations), which allowed for the measurement of individual feed intake. Pigs were individually weighed at the start of the experiment and at the diet changes at approximately 50 and 80 kg body weight and slaughter (±120 kg). During the grower phase, pigs fed according to treatment 1 showed reduced ADFI than the other treatment groups (1.91 vs. 2.0, 2.02 and 2.02 kg/d, P = 0.021) and subsequently decreased ADG (882 g/d vs. 927, 924 and 948 g/d, P = 0.005). Similar results were found during the starter + grower phases, where the pigs fed according to treatment 1 showed less ADFI than the other treatment groups pigs (1.63 vs. 1.71, 1.73 and 1.71 kg/d, P = 0.013) and subsequently less ADG (842 vs. 878, 878 and 874 g/d, P = 0.039). No major differences were found regarding the carcass characteristics. In conclusion, feed intake and growth performance were improved and carcass quality was not penalized by totally or partially replacing the SBM by other protein rich feedstuffs including rape seed meal (RSM), sunflower seed meal (SFM) and peas in diets for growing-fishing pigs.

PSIV-20 Impact of High Protein Dried Distiller Grains and Soybean Meal Inclusion Level on Grow-finish Pig Performance and Carcass Traits

Abstract High protein dried distiller grains are a novel protein source for commercial swine diets. Questions related to how concentrations of branched chain amino acids (BCAA) in corn protein sources affect pig performance remain. A randomized complete block design (RCBD) grow-finish experiment was conducted at the South Dakota State University Commercial Research Facility using NexPro® protein ingredient (HPDDG) to determine the performance response of grow-finish pigs fed corrected levels of BCAA through soybean meal (SBM) or synthetic amino acids (SAA). Pigs (n = 1,170; 59.5 ± 0.48 kg) were used in a 79-d study (9 replicates per treatment). Pens of pigs were allotted to one of five dietary treatments which consisted of 1) corn-SBM diet, 2) HPDDG not corrected for BCAA levels or HPDDG corrected for BCAA levels through additions of 3) SBM, 4) 50% SBM and 50% SAA blend or 5) SAA only. The HPDDG were included in diets at 15% in phase 1 and 10% in phases 2 and 3. Additions of SAA were included to maintain a SID Ile:Lys of 65% and SID Val:Lys of 75% for BCAA corrected diets. Data was analyzed as a RCBD, pair-wise comparisons and single degree of freedom orthogonal polynomials (BCAA corrected only) were used to evaluate treatment responses, and pen served as the experimental unit for all analyses. Reducing SBM in BCAA corrected diets decreased cumulative ADG and G:F (linear; P < 0.05). Decreasing SBM in BCAA corrected diets tended to decrease (linear; P = 0.09) standardized fat-free lean but increase (linear; P = 0.07) dressing percent and back fat depth (quadratic; P = 0.08) while not impacting hot carcass weight (P > 0.14). This data indicates HPDDG is a suitable feedstuff for grow-finish swine diets at low inclusion levels due to minimal impact on performance and carcass characteristics. Correction of BCAA levels through SBM inclusion provided an improved performance response compared to SAA only.

Use of alternative protein sources for fishmeal replacement in the diet of largemouth bass (Micropterus salmoides). Part I: effects of poultry by-product meal and soybean meal on growth, feed utilization, and health.

Five isonitrogenous and isocaloric diets [containing 54, 30, 15, 10, and 5% fishmeal crude-protein (CP), dry matter (DM) basis] were prepared by replacing fishmeal with poultry by-product meal plus soybean meal to feed juvenile largemouth bass (LMB, with an initial mean body weight of 4.9g) for 8weeks. All diets contained 54% CP and 13% lipids. There were four tanks of fish per treatment group (15 fish/tank). The fish were fed twice daily with the same feed intake (g/fish) in all the dietary groups. Results indicated that the inclusion of 15% fishmeal protein in the diet is sufficient for LMB growth. However, some of the fish that were fed diets containing ≤ 15% fishmeal CP had black skin syndrome (characterized by skin darkening and retinal degeneration, as well as intestinal and liver atrophies and structural abnormalities). The concentrations of taurine, methionine, threonine and histidine in serum were reduced (P < 0.05) in fish fed the diets containing 5, 10 and 15% fishmeal CP, compared with the 30 and 54% fishmeal CP diets. Interestingly, the concentrations of tyrosine and tryptophan in serum were higher in fish fed diets with ≤ 15% fishmeal CP than those in the 54% fishmeal CP group. These results indicated that 15% fishmeal CP in the diet containing poultry by-product meal and soybean meal was sufficient for the maximum growth and feed efficiency in LMB but inadequate for their intestinal, skin, eye, and liver health. A reduction in dietary methionine and taurine content and the possible presence of antinutritional factors in the fishmeal replacements diets containing high inclusion levels of soybean meal may contribute to black skin syndrome in LMB. We recommend that the diets of juvenile LMB contain 30% fishmeal CP (DM basis).

Effects of supplementary amino acids on available energy of soybean meal determined by difference and regression methods fed to growing pigs.

This study was conducted to evaluate effects of inclusion level and supplementary amino acids (AAs) on digestible energy (DE) and metabolizable energy (ME) values of soybean meal (SBM) fed to growing pigs, determined by difference and regression methods. Sixty pigs were fed 10 diets according to a 5×2 factorial arrangement. Two control diets contained 97.34% corn without supplementary AAs or 95.61% corn with supplementary AAs. Eight diets were formulated by replacing corn and AAs in control diets with 8%, 15%, 25% and 31% SBM. There was no difference in DE and ME values of SBM determined by difference method as inclusion level of SBM increased or crystalline AAs were added. No difference was observed in DE and ME values of SBM determined by the two methods in diets without supplementary AAs, but the values determined by the difference method were greater (P<0.05) than those determined by regression method when crystalline AAs were added in diets. In conclusion, inclusion level and supplementary AAs did not affect DE and ME values of SBM calculated by difference or regression methods. There were differences in DE and ME values of SBM determined by the difference method and the regression method when crystalline AAs were added in diets.

Assessment of soybean meal as dietary fishmeal replacement in red sea bream (Pagrus major) juveniles based on energy budget analysis

The effects of soybean meal (SBM) on the energy budget of red sea bream Pagrus major juveniles (3.2 g initial wet weight) were determined by supplementing SBM in the diet at 0% (control diet), 16%, 24%, 32% and 39%, with the fishmeal content correspondingly reduced from 55% to 29%. Diets were made isoenergetic and isonitrogenous by changing the lipid and carbohydrate levels. Fish were fed to apparent satiation for 30 days in duplicates per diet (20 fish per replicate). Ammonia excretion and oxygen consumption were continuously measured during the growth trial, whereas digestibility after the termination of growth trial. Feed intake, body weight gain, and specific growth rate of fish increased to a peak at 24% SBM level, which again decreased as the SBM level was further increased. The apparent digestibility of energy was similar in all dietary treatments, while the digestible of dry matter increased with the SBM level. A lower proportion of energy intake as growth at 39% SBM level was attributed to the higher energy intake channeled to fecal ammonia. This study suggested that the inclusion level of SBM in diets for red sea bream juveniles should be is optimal at the inclusion range 24 – 32%, thus correspondingly replacing the fishmeal content by 24 – 32%.

Results of an international phosphorus digestibility ring test with broiler chickens

The objective of this ring test was to investigate the prececal phosphorus (P) digestibility of soybean meal (SBM) in broiler chickens using the trial protocol proposed by the World's Poultry Science Association. It was hypothesized that prececal P digestibility of SBM determined in the collaborating stations is similar. Three diets with different inclusion levels of SBM were mixed in a feed mill specialized in experimental diets and transported to 17 collaborating stations. Broiler chicks were raised on commercial starter diets according to station-specific management routine. Then they were fed the experimental diets for a minimum of 5 d before content of the posterior half of the ileum was collected. A minimum of 6 experimental replicates per diet was used in each station. All diets and digesta samples were analyzed in the same laboratory. Diet, station, and their interaction significantly affected (P < 0.05) the prececal digestibility values of P and calcium of the diets. The prececal P digestibility of SBM was determined by linear regression and varied among stations from 19 to 51%, with significant differences among stations. In a subset of 4 stations, the prececal disappearance of myo- inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate)-P; InsP6-P) also was studied. The prececal InsP6-P disappearance correlated well with the prececal P digestibility. We hypothesized that factors influencing InsP6 hydrolysis were main contributors to the variation in prececal P digestibility among stations. These factors were probably related to the feeding and housing conditions (floor pens or cages) of the birds in the pre-experimental phase. Therefore, we suggest that the World's Poultry Science Association protocol for the determination of digestible P be should extended to the standardization of the pre-experimental period. We also suggest that comparisons of P digestibility measurements among studies are made only with great caution until the protocol is more refined.

Substitution of fish meal by soybean meal in diets for juvenile marbled spinefoot, Siganus rivulatus

ABSTRACTThe present work was performed to assess whether soybean meal (SBM) could replace fish meal (FM) as a source of dietary protein in diets of the marine herbivore Siganus rivulatus. Five iso-nitrogenous (40% protein) and iso-energetic (14 MJ/Kg) diets were prepared with SBM replacing fish meal at 0%, 25%, 50%, 75%, and 100% dietary protein. A 60-day feeding trial was conducted with 240 juvenile S. rivulatus (initial body mass 1.74 ± 0.03 g). Survival, growth, feed, and protein efficiency and hematological parameters were assessed. Growth correlated negatively with increase in dietary SBM. All production parameters measured were negatively affected at all levels of SBM inclusion. There were no effects on total or differential blood counts, hemoglobin, or plasma protein, but hematocrit values were negatively correlated with SBM addition. Results suggest that total replacement of FM by SBM without adding other supplements is not recommended, even for an herbivorous marine fish such as S. rivulatus.

Soybean meal induces enteritis in turbot Scophthalmus maximus at high supplementation levels

The goal of the present study was to find whether higher soybean meal (SBM) levels might trigger soybean meal-induced enteritis (SBMIE) in turbot. If so, caution must be taken when mixing ingredients containing saponins and other antinutrients to avoid SBMIE like symptoms. In a 8week feeding trial conduced on turbot, three isonitrogenous and isolipidic diets were formulated to include 26%, 40% and 54% SBM to progressively replace 30%, 45% and 60% fish meal (FM) in a FM based diet, respectively. The results showed that SBM caused dose-dependent decreases in growth performance and nutrient utilization. Enteritis developed in the distal intestine in the inclusion range of 26–54%. Dose-dependent increases in severity of the inflammation, with concomitant alterations in brush border membrane enzymes and inflammatory marker genes expression were seen. Our results confirm the hypothesis that high inclusion level of SBM may cause similar inflammatory changes as observed in several other fish species. Thus, caution must be taken when formulating turbot diets based on ingredients that may contain saponins and other antinutrients. Moreover, turbot is also a candidate species for the study of causes and mechanism of diet induced inflammation in the intestine of fish. Statement of relevanceThe present work first describes the soybean meal induced enteritis in turbot and provides the information that caution must be taken when formulating turbot diets based on ingredients that may contain saponins of other antinutrients.

188 Effects of low dietary inclusion levels of soybean meal and non-essential amino acid supplementation on the growth performance of late-finishing pigs

188 Effects of low dietary inclusion levels of soybean meal and non-essential amino acid supplementation on the growth performance of late-finishing pigs

Prebiotic Supplementation has Only Minimal Effects on Growth Efficiency, Intestinal Health and Disease Resistance of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi Fed 30% Soybean Meal.

Prebiotics have successfully been used to prevent infectious diseases in aquaculture and there is an increasing amount of literature that suggests that these products can also improve alternative protein utilization and digestion. Therefore, the objective of this study was to examine whether prebiotic supplementation increased the growth efficiency, intestinal health, and disease resistance of cutthroat trout fed a high level of dietary soybean meal. To achieve this objective, juvenile Westslope cutthroat trout (Oncorhynchus clarkii lewisi) were fed a practical type formulation with 0 or 30% dietary soybean meal with or without the commercial prebiotic (Grobiotic-A) prior to experimental exposure to Flavobacterium psychrophilum. Juvenile Westslope cutthroat trout (initial weight 7.8 g/fish ±SD of 0.5 g) were stocked at 30 fish/tank in 75 L tanks with six replicate tanks per diet and fed their respective diets for 20 weeks. Final weights of Westslope cutthroat trout were affected by neither dietary soybean meal inclusion level (P = 0.9582) nor prebiotic inclusion (P = 0.9348) and no interaction was observed (P = 0.1242). Feed conversion ratios were similarly not affected by soybean meal level (P = 0.4895), prebiotic inclusion (P = 0.3258) or their interaction (P = 0.1478). Histological examination of the distal intestine of Westslope cutthroat trout demonstrated increases in inflammation due to both increased soybean meal inclusion level (P = 0.0038) and prebiotic inclusion (P = 0.0327) without significant interaction (P = 0.3370). Feeding dietary soybean meal level at 30% increased mortality of F. psychrophilum cohabitation challenged Westslope cutthroat trout (P = 0.0345) while prebiotic inclusion tended to decrease mortality (P = 0.0671). These results indicate that subclinical alterations in intestinal inflammation levels due to high dietary inclusion levels of soybean meal could predispose Westslope cutthroat trout to F. psychrophilum infection.

Preliminary Investigation of Dietary Soy Sensitivity in Shovelnose Sturgeon

Sturgeon culture has developed greatly since the 1980s. Cultured sturgeon are often fed a commercial salmonid feed high in fish meal (FM). However, economic and sustainability concerns have put pressure on aquafeed manufactures to incorporate alternative proteins such as soybean meal (SBM). This experiment investigates dietary SBM sensitivity in shovelnose sturgeon (Scaphirhynchus platorhynchus). Diets were formulated to contain 0%, 17%, 34%, and 51% SBM and fed for 8 weeks. Weight gain, specific growth rate (SGR), feed efficiency (FE), body and liver composition, and intestinal histology were determined. Although sturgeon growth rates were low for all diets, weight gain in fish fed the diet with 17% SBM averaged 55.6% of sturgeon fed the fish meal-based control diets. Statistically lower negative growth and FE (P < 0.05) were observed when SBM was included at 51% of the diet. However, whole-body proximate composition and hepatic lipid and glycogen content were not altered by dietary SBM inclusion level, and histological evaluation of the distal intestine was inconclusive. These results provide preliminary insight into the effect of diets containing high levels of SBM on growth and health of Scaphirhynchus sturgeon.

Gamma-irradiated soybean meal replaced more fish meal in the diets of Japanese seabass (Lateolabrax japonicus)

A feeding trial was conducted to evaluate if gamma-irradiation or fermentation could increase the inclusion level of soybean meal (SBM) in the diet of Japanese seabass Lateolabrax japonicas. A basal diet was formulated to contain 320g/kg fish meal. In the test diets, 25, 50 and 75% of the fish meal in the basal diet was respectively replaced by SBM in three forms (untreated, fermented or gamma-ray irradiated). Juvenile fish (13.0±0.1g) were fed with the test diets for 8 weeks. SBM treatment affected weight gain, feed intake, feed conversion ratio (FCR), phosphorus retention efficiency (PRE), phosphorus wastes output, body contents of crude protein and phosphorus, while the level of fish meal replacement affected weight gain, apparent digestibility coefficient (ADC) of protein, FCR, nitrogen retention efficiency (NRE), PRE, nitrogen wastes output (NW), condition factor, body contents of moisture and phosphorus. Weight gain, ADC of protein and NRE decreased, whereas FCR and NW increased with increasing fish meal replacement by SBM, irrespective of SBM treatments. No significant differences were found in the weight gain and NRE between fish fed the basal diet and the diets with 25% fish meal replacement by untreated or fermented SBM, or between fish fed the basal diet and the diet with 50% fish meal replacement by irradiated SBM. At the end of the feeding trial, no significant differences were found in hepatosomatic index, viscerasomatic index and proximate body composition between fish fed the basal diet and the diets with fish meal replaced by untreated, fermented or irradiated SBM. This study indicates that the use of gamma irradiation provides a novel approach to enhance the level of fish meal replacement by SBM. Fish meal in the diet for Japanese seabass can be reduced to 160g/kg when the gamma-irradiated SBM is used as a fish meal substitute.

The effect of dietary soybean meal on growth, nutrient utilization, body composition and some serum biochemistry variables of two banded seabream , Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817)

This study was performed to determine the optimum level of soybean meal diets for two banded sea bream for growth performance, nutrient utilization, body composition and serum biochemistry. Two banded seabream were fed five experimental diets which were formulated replace fish meal by soybean meal at 0, 20, 30, 40 and 50%. Up to 40% of dietary fish meal was successfully replaced with no growth depression. Whole body composition of two banded seabream was not affected by soybean meal inclusion level. Total protein, triglyceride and total cholesterol of fish fed the SM50 diets were significantly lower compared to fish fed the soybean free diet. On the other hand, serum glucose level significantly increased as dietary soybean meal inclusion increased. Results showed that 40% fish meal can be replaced in diets for the two banded seabream by defatted soybean meal. Further studies to determine the inclusion level of soybean meal more than 40% with amino acid or enzyme supplementation are needed.

Evaluation of soybean meal as protein source for Argyrosomus Regius (Asso, 1801) (Sciaenidae)

The meagre (Argyrosomus regius) is a carnivorous fish which requires diets with higher protein content, causing an increment in diets cost. A way to diminish this cost is to use vegetable meals like soybean meal (SB). So the aim of this trial was to determine the optimum inclusion level of defatted soybean meal in experimental diets for this species. 800 fishes (165 g) were distributed in 8 tanks, two replicates per treatment. Four isoproteic (50% CP) and isolipidic (17% Cl) diets were formulated with four levels of soybean meal inclusion, 0, 15, 30 and 45%. The trial lasted 107 days. Meagre fed diets 15 and 30% obtained the highest final weight. There were no significant differences among treatments in the feed conversion rate (FCR) and the protein efficiency (PER). According to the quadratic regression, the optimum SB inclusion to maximize thermal growth coefficient (TGC) was 26.4% and for FCR was 27.6%. No significant differences were observed in energy, protein and amino acid retention among diets. The inclusion of SB in meagre diets can generate a decrease in the use of fish meal and in turn reduce the cost of producing meagre Mediterranean aquaculture industry. Key words: Argyrosomus regius, fish meal replacement, defatted soybean meal, economic analysis.

Reduction of soybean meal non-starch polysaccharides and α-galactosides by solid-state fermentation using cellulolytic bacteria obtained from different environments.

Soybean meal (SBM) is an important protein source in animal feed. However, the levels of SBM inclusion are restricted in some animal species by the presence of antinutritional factors (ANFs), including non-starch polysaccharides (NSPs) and α-galactosides (GOSs). The aim of this study was to reduce the soybean meal NSPs and GOSs by solid-state fermentation (SSF) using a combination of cellulolytic bacteria isolated from different environments (termites, earthworms, corn silage and bovine ruminal content). To analyse the key enzymatic activities, the isolates were grown in minimal media containing NSPs extracted from SBM. The selected bacterial strains belonged to the genera Streptomyces, Cohnella and Cellulosimicrobium. SSF resulted in a reduction of nearly 24% in the total NSPs, 83% of stachyose and 69% of raffinose and an increase in the protein content. These results suggest that cellulolytic bacteria-based SSF processing facilitates SBM nutritional improvement. In addition, the use of fermented SBM in animal diets can be recommended.

Effects of different levels of soybean meal inclusion in replacement for fish meal on growth, digestive enzymes and transaminase activities in practical diets for juvenile tilapia, Oreochromis niloticus × O. aureus

This study evaluated the effects of replacing fish meal (FM) in practical diet for tilapia Oreochromis niloticus × O. aureus with different levels of soybean meal (SBM) on growth, digestive enzymes and liver transaminase activities. Five isonitrogenous (crude protein 300 g/kg) and isoenergetic (gross energy 16 kJ/g) practical diets were formulated by replacing 0 (the control), 25, 50, 75 and 100% of protein from fish meal with SBM. Each diet was randomly assigned to triplicate groups of 30 fish per aquarium (mean initial weight 4.0 g). Fish were fed three times daily to apparent satiation for 8 weeks. The results showed that the growth was affected by dietary SBM level (P<0.05). Fish fed the diet with 100% protein from SBM had lower relative weight gain ratio (RWGR), specific growth rate (SGR) and protein efficiency ratio (PER) than the other groups (P<0.05). Feed conversion ratio (FCR) was higher than other groups (P<0.05) with a 100% substitution level. The activities of protease in both intestine and hepatopancreas decreased (P<0.05) with increasing dietary SBM level. Regression analysis showed a negative effect of soybean meal inclusion on protease activity (P<0.05). Likewise, protease activities were found to be positively correlated (P<0.05) with growth rate of tilapia. However, no significant differences were observed in both intestinal and hepatopancreas amylase activities among dietary treatments. Fish fed the diet with 50% or more protein from SBM had lower glutamyl oxaloacetic transaminase (GOT) and glutamyl pyruvic transaminase (GPT) activities in liver than the control group (P<0.05). A similar trend was observed in the immune response where superoxide dismutase (SOD) and lysozyme activity decreased (P<0.05) compared with the control group when the substitution level was more than 50%. Results of the present study indicated that protein from SBM could substitute less than 75% for fish meal protein without influencing the growth of tilapia. The higher substitution levels of SBM induced negative influences on growth, feed utilization and serum lysozyme of tilapia.

The effect of soybean oil containing stearidonic acid on growth performance, n-3 fatty acid deposition and sensory characteristics of pacific white shrimp (Litopenaeus vannamei)

The ability of shrimp Litopenaeus vannamei to utilize soy oil (SO) modified to contain stearidonic acid (SDA) in replacement of fish oil (FO) by converting SDA to highly unsaturated fatty acids (HUFA) was examined. Six diets with either supplemental modified SO or FO and three levels of fishmeal (FM) replacement (0%, 50% and 100%) by soybean meal (SBM) were fed to shrimp (1.7 g) for 12 weeks. The effect of oil source at the three SBM levels on growth and fatty acid profiles was examined by contrast analysis and sensory attributes by t-tests (5% error rate). At 0% SBM inclusion, there was no effect of dietary oil source, while at the highest SBM inclusion level, shrimp fed the FO diet outperformed those fed the corresponding SO diet. Oil source had no effect on sensory attributes. The fatty acid profiles of the shrimp reflected that of the diets. SDA SO can replace supplemental FO in diets for shrimp with no reduction in growth when there is sufficient oil present from FM. At low FM, however, replacing FO with SDA SO reduces shrimp performance and tissue n-3 HUFA levels. It is concluded that SDA is unable to meet the essential fatty acid needs of shrimp.

Evaluation of the influence of different species and cultivars of lupin kernel meal on the extrusion process, pellet properties and viscosity parameters of salmonid feeds

This study examined the influence of different lupin species and cultivars and their inclusion levels on the physical properties of an extruded diet. Lupin kernel meals were included into a fish diet formulation at 0%, 10%, 20% and 30%. Soybean meal was also included in a series of diets on a similar basis as a reference. The diet mashes were extruded using a laboratory-scale APV19:45 twin-screw extruder. The pellets were examined for radial expansion, bulk density, vacuum oil uptakes, sink rate, shear and crush strengths. Inclusion of lupin kernel meal significantly increased bulk density, sink rate, shear and crush strength of the pellets. With the increase in lupin kernel meal inclusion level, a concomitant decline in vacuum oil uptake and radial expansion was also observed. An assessment of the diet mashes using a Rapid Visco Analyser showed that the inclusion of lupin kernel meals increased the rate and degree of gelatinization of the mash starch content compared with that with a similar inclusion level of soybean meal. The inclusion of lupin kernel meals in the diet mash also improved the water-holding capacity of the extrudate, which has important implications for the reduction in extruder wear.

Farelo de soja na alimentação de tilápias-do-nilo durante o período de reversão sexual

Foram utilizadas 800 larvas com 2 dias de idade com o objetivo de testar o uso de farelo de soja em rações para tilápias-do-nilo durante o período de reversão sexual (30 dias). O experimento foi conduzido segundo delineamento em blocos casualizados com quatro tratamentos e quatro repetições, no qual um tanque-rede com 50 larvas correspondeu a uma unidade experimental. Os tratamentos consistiram de rações isoprotéicas e isoenergéticas (38,6% de proteína digestível e 3.800 kcal/kg de energia digestível) com 0, 16, 34 ou 42% de farelo de soja. O aumento no nível de farelo de soja teve efeito linear positivo sobre os valores de peso e comprimento finais médios, mas não afetou a condição corporal e os índices de sobrevivência. Recomenda-se incluir o farelo de soja em níveis de até 42% na ração de tilápias-do-nilo na fase de reversão.

Mineral status of African catfish (Clarias gariepinus) fed diets containing graded levels of soybean or cottonseed meals

In order to assess the effect of increasing levels of dietary soybean meal (SBM) or cottonseed meal (CSM) on growth and body mineral composition of juvenile African catfish, five isonitrogenous (39% crude protein) and isocaloric (13 kJ g−1, digestible energy) diets containing various levels of soybean meal (SBM30 and SBM60) or cottonseed meal (CSM30 and CSM60) as partial replacement of fish meal (Control) were fed to triplicate groups of 50 fish (initial mean weight: 10.3 g) in each tank (0.9 m3). Over an 8-week feeding period, significant differences (P<0.05) were observed on growth, body nutrient and mineral composition between fish fed the experimental diets. Fish fed 600 g kg−1 SBM- or CSM-based diets had reduced growth compared to those fed a diet containing 300 g kg−1 CSM or the control diet. Survival, feed utilization and hepatosomatic index were not significantly affected by the inclusion level of SBM or CSM in the diets. Fat content was higher in carcass and fillet of fish fed CSM-based diets than those fed SBM- or fish meal-based diets. Body mineral composition in response to dietary treatment revealed a reduction in carcass Ca and P content with the increasing levels of SBM and CSM in the diets while Mg, K, Fe, Zn and Mn content in carcass did not show any marked change (P>0.05). However, fish fed SBM- or CSM-based diets have reduced Zn in the fillet than those fed the control diet (P<0.05). Moreover, significant correlations were found between body mineral composition and dietary SBM, CSM or phytic acid level, respectively. This study showed that as well as growth is concerned, SBM and CSM can replace fish meal as a source of protein in compound feed for African catfish up to 300 g kg−1. However, in regard to body mineral composition, the inclusion level of these ingredients in the diets should be less than 300 g kg−1 and this may be mainly because of the presence of phytic acid in the feed ingredients used.