Partial Substitution Of Fish Meal Research Articles

Alternative Dietary Sources in Feeding of Blackspot Sea Bream Pagellus bogaraveo (Brunnich, 1768)

The present review reports the results of two studies carried out at the Institute for the Coastal Marine Environment of Messina (Italy) on the suitability of plant-derived raw materials as dietary components for an innovative fish species for aquaculture, black spot sea bream Pagellus bogaraveo. The research focused on the effects of the use of plant (protein/lipid) dietary sources on growth performance, body composition and gastro-intestinal enzyme patterns in nutrient digestion of wild juveniles of P. bogaraveo. In particular, the effect of a total replacement of Fish oil by Echium and linseed oils and a partial substitution of fish meal with a graded level of Rice Protein Concentrate, will be discussed.

Effects of the partial substitution of fish meal by soy bean meal with or without mannanoligosaccharide and fructooligosaccharide on the growth and feed utilization of sharpsnout seabream, Diplodus puntazzo (Cetti, 1777): preliminary results

The present study was carried out in order to investigate the effects of the mannanoligosaccharide (MOS) and fructooligosaccharide (FOS) on sharpsnout seabream, Diplodus puntazzo in the context of partial fish meal substitution by soybean meal. One-hundred-forty-four sharpsnout seabream of about 100 g initial body weight were randomly divided in 12 experimental tanks (180 litre each). Testing conditions included 12 fish per tank, with triplicate tanks for treatment. The experimental period lasted 114 days. Average water temperature was 21.9±1.6°C, salinity was 30.0%0 and pH ranged from 7 to 8. Four isonitrogenousisolipidic diets were tested: a control diet (FM) with fish meal as the sole protein source; a second diet (SBM) with approximately 40% of the protein supplied by soybean meal. The remaining two diets were formulated adding 8g of MOS and FOS per kg of the SBM diet respectively. Average final weight, specific growth rate, feed conversion ratio and protein efficiency ratio remained unaffected by partial fish meal substitution and by MOS or FOS supplementation. Also apparent digestibility coefficients values for organic matter, protein, lipid and energy were not significantly affected by dietary treatment.

Survey of qualitative traits of European sea bass cultivated in different rearing systems

AbstractThe purpose of this study was to evaluate the main qualitative traits of European sea bass fattened in farms adopting different rearing techniques (offshore cages, inshore cages, land‐based basins) but fed the same diets in each production cycle, in a three year survey (2006, 2007, 2008). Three farms were chosen for each rearing technique and two sampling sessions of ten fish each were carried out for each rearing cycle. Proximate composition, fatty acid profile, and cholesterol content were evaluated in the fillet of marketable size fish as well as morpho‐biometric parameters and indices. Diets administered in 2008 had higher amounts of lipids, lower proportions of n–3 polyunsaturated fatty acids (PUFA) and higher proportions of n–6 PUFA compared to 2006 and 2007 diets. The chemical and fatty acid composition of the fish fillet was affected by the diet composition: fish fattened in 2008 exhibited statistically higher amounts of fat and cholesterol, lower proportions of n–3 PUFA and higher proportions of n–6 PUFA in comparison with fish cultivated in 2006 and 2007. Fish cultivated in cages, both offshore and inshore cages, exhibited leaner fillets, lower amounts of cholesterol and higher proportions of n–3 PUFA than fish cultivated in basins.Practical applications: In this study we have analyzed the combined effects of feeding and rearing systems of sea bass in a 3‐year survey for the first time. The results showed that feeding is the main factor affecting fish quality as regards both the chemical composition and the fatty acid profile. The partial substitution of fish meal and fish oil with vegetable sources, with the aim of saving the wild fish biomass as well as formulating less expensive diets, strongly alters the fillet composition. We also showed that the rearing system of fish in offshore cages makes it is possible to obtain better quality products.

Influence of partial substitution of dietary fish meal on the activity of digestive enzymes in the intestinal brush border membrane of gilthead sea bream, Sparus aurata and goldfish, Carassius auratus

The sustainable composition of diets of high nutritional value is of the utmost importance for intensive aquaculture. Digestion and absorption of nutrients depend on the activity of the digestive enzymes, in particular those located in the brush border membrane of enterocytes, which are responsible for the final stages of breaking down and absorption of nutrients. In the present study, the substitution of fish meal by lupin or rapeseed meal in the diet was evaluated on gilthead sea bream ( Sparus aurata) and goldfish ( Carassius auratus). The objectives were to compare the activities of intestinal brush border enzymes in both species fed the control and experimental diets. When gilthead sea bream were fed the vegetable diets, significantly lower activities compared with the control group were observed for alkaline phosphatase and γ-glutamyl transpeptidase, but these differences were not significant in goldfish. Maltase activity was found decreased in the group fed lupin meal, both in sea bream and in goldfish. However, in spite of these differences in enzyme activities, growth characteristics of the fishes were similar with the three diets. It seemed that both fish were able to adapt to partial substitution of fish meal, but it remains to investigate the mechanism for compensating the decrease in specific enzymatic activity in the enterocytes of carnivorous gilthead sea bream.

Partial substitution of fish meal with soybean and cottonseed meals in diets for African bonytongue,Heterotis niloticus(Cuvier, 1829) fingerlings: effects on growth, feed efficiency and body composition

A feeding trial was conducted to examine the suitability of soybean meal (SBM) and cottonseed meal (CSM) as a partial substitute for the dietary protein supplied by fish meal for H. niloticus fingerlings. Fish were fed with four isonitrogenous (350 g kg−1 crude protein) and isoenergetic (18.8 kJ g−1 GE) diets in which fish meal protein was gradually replaced by plant protein from a mixture of SBM and CSM (0%, 25%, 50% and 75% in diets 1, 2, 3 and 4 respectively). Triplicate groups of fingerlings H. niloticus (mean weight of 5 g) were handfed twice daily to apparent satiation for 60 days inside net hapas. Growth performances (SGR varied from 3.09% to 3.16% day−1) of fingerlings fed diets containing 0%, 25% and 50% plant protein were not significantly different (P>0.05). At 75% fish meal substitution, growth and feed utilization efficiency indicators were significantly reduced (P<0.05). The carcass composition were also significantly (P<0.05) affected by the replacement level of fish meal, except dry matter and ash. Results suggest that the dietary fish meal protein could efficiently be substituted by a mixture of soybean and cottonseed meals up to 50%, without adverse effects on maximal growth in practical diets for H. niloticus fingerlings.

Partial replacement of fish meal by T-Iso in gilthead sea bream (Sparus aurata) juveniles diets

The aim of this study was the evaluation of microalga Isochrysis sp. T-Iso in partial substitution of fish meal and the study of the effects on gilthead sea bream (Sparus aurata) performances and chemical composition of fillets. The results show that the microalga T-Iso nutrients support growth better than control diets, and the chemical composition of sea bream fillets also meets the needs of consumers for healthy diets. T-Iso resulted highly digestible, and support the best performances of fish fed on 70% alga diet probably due to its high protein efficiency in comparison to other diets. The presence of a high quantity of cyclic isoprenoid could explain this high efficiency of T-Iso. Gilthead sea bream fed on 70% T-Iso showed fillets with a low level of protein and a high level of fat; moreover, their somatic indexes were higher than those of fish fed other diets. Highest percentage T-Iso diet showed the highest amount of the sum of saturated fatty acids, mainly due to myristate and palmitate. On the contrary, the sum of polyunsaturated decreases, mainly because of the reduction of EPA and DHA amounts. If the mass production economical problems are solved, T-Iso will represent a good solution in partial substitution of fish meal.

Partial Substitution of Fishmeal by Meat and Bone Meal, Soybean Meal, and Squid Concentrate in Feeds for the Prawn, Artemesia longinaris: Effect on Digestive Proteinases

The effect of alternative protein sources on proteinase activity in the midgut gland of Artemesia longinaris was studied. Three isoproteic feeds were compared: a basal diet containing 48% fishmeal and 17% soybean meal (diet 1), the basal diet containing meat and bone meal as partial replace- ment of the fishmeal (diet 2), the basal diet containing additional soybean meal and a squid protein concentrate as partial replacement of the fishmeal (diet 3). Midgut gland extracts from the three treatments and wild prawns (control) were assayed to quantify proteinase activity. Specific inhibitors were used to identify proteinase classes by SDS-PAGE. Specific proteolytic activity was highest in the wild prawns and in prawns fed diet 2. Trypsin ac-tivity was higher in prawns fed the diets (1.9-2.6 absorbance/min/mg) than in wild prawns (0.6 absorbance/min/mg). Chymotrypsin activity was high- est in prawns fed diet 2. Proteinase activity in samples on azocasein was inhibited by soybean trypsin inhibitor and Nα-p-tosyl-L-lysine chloromethyl ketone. Electrophoresis revealed at least six different bands with zones having caseinolytic activity in prawns fed the diets as compared to wild prawns, including four trypsins (16.6, 18.2, 21.9, and 25.1 kDa) and one chymotrypsin (53.7 kDa). Our findings indicate that proteolytic activity in A. longinaris adapts to the quality of the dietary protein and that fishmeal can partially be replaced by additional soybean meal in combination with squid protein concentrate.

Blood and haemoglobin meal as protein sources in diets for gilthead sea bream (Sparus aurata): effects on growth, nutritive efficiency and fillet sensory differences

Two parallel experiments were conducted to evaluate the effect of partial substitution of fish meal by two different animal protein sources, blood meal (B) and haemoglobin meal (H) at 0, 50 and 100 g kg−1 of level inclusion in diets for gilthead sea bream, considering a long feeding period for juveniles (Trial 1) and a short feeding period (Trial 2) for on‐growing fish. In Trial 1, 33 g juveniles were fed for 242 days and the fish fed with 5% and 10% of haemoglobin dietary inclusion obtained less growth, although feed efficiency, protein efficiency ratio and muscle composition were similar in all diets. In Trial 2, 179 g initial weight fish were fed for 164 days and growth of fish fed H10 showed the lowest growth, although nutrient efficiency and muscle composition were not affected significantly. The results of these experiments demonstrated that blood meal can substitute fish meal (up to 10%) with no effect on performance, but may lead to sensory differences compared with fish fed diet 0, while the inclusion of 5% blood meal had no effect on growth or sensory characteristics. Fish fed 10% haemoglobin inclusion had the poorest growth values.

Effect of dietary taurine supplementation on growth performance and bile salt activated lipase activity of common dentex, Dentex dentex, fed a fish meal/soy protein concentrate-based diet

Common dentex were fed three isoprotein and isoenergetic diets to investigate the effect of partial substitution of fish meal by soy protein concentrate (0 [FM], 25 [SM25] and 40% [SM40]) in the presence or absence of taurine (T) supplementation (2 g kg−1 on a dry weight basis) [FM+T], [SM25+T] and [SM40+T], on growth related parameters, muscle composition and bile salt activated lipase activity. The fish were fed twice a day by hand to apparent satiation over the course of a 12-week growth trial.The [SM40] diet resulted in lower feed intake compared to the [FM] and [SM25] diets, lower specific growth rate compared to the [FM] diet, lower condition factor and increased mortality of dentex compared to the [FM] and [SM25] diets. On the other hand, the [SM25] diet had no adverse effect on either feed intake or specific growth rate of dentex compared to the [FM] diet. The hepatosomatic and mesenteric fat indices did not change by increasing soy content. Moreover, no difference was observed in the composition of muscle in dentex fed different proportions of soy protein concentrate. However, the activity of the bile salt-activated lipase in liver was significantly lower in fish fed the [SM25] diet than in fish fed the [FM] diet.Dietary taurine supplementation increased the specific growth rate and daily feed intake while it reduced feed conversion ratio of dentex. Comparison among groups showed that dietary taurine supplementation increased feed intake but not specific growth rate in the [SM40+T] group compared to [SM40] group. The condition factor was higher in fish fed the [FM] diet compared to the [SM25+T] and [SM40+T] diets. However, no difference was observed between the [SM25] and [SM40] groups compared with the [SM25+T] and [SM40+T] groups, respectively. Analysis of the chemical composition of the muscle showed that the [SM25+T] fed fish had higher crude protein compared to the [SM40+T] fed fish. Furthermore, the mesenteric lipid index was higher in [SM25+T] fed fish compared to those fed the [SM25] and [SM40+T] diets. The activity of the bile salt-activated lipase in the liver increased in fish fed the three diets [FM], [SM25] and [SM40] in the presence of taurine, indicating that taurine in diets at 2 g kg−1 may improve lipid metabolism, although no significant differences were observed in the total fat content of the muscle of fish fed either of these experimental diets.In conclusion, it appears that in dentex, partial substitution of fish meal is possible with 25% of soy protein concentrate without affecting growth, which can be improved further by dietary taurine supplementation of 2 g kg−1 diet.

A Preliminary Assessment of Growth and Production of Nile Tilapia, Oreochromis niloticus L., Fed Azolla-Based-Diets in Earthen Ponds

ABSTRACT The effects of the use of Azolla filiculoides Lam., as an alternative source of protein, on growth performances and production of Nile tilapia, Oreochromis niloticus, reared in wetland ponds was evaluated. Three isonitrogenous (27% CP) and isocaloric (4019.14 kcal/g) diets A0, A10, and A20 containing three levels of Azolla 0, 10, and 20, respectively, as a partial substitution of fish meal, were fed to three triplicate ponds of male O. niloticus (initial mean weight = 15.5 g). The Azolla-free diet (0% Azolla) served as a control. The growth performances and production are good in all treatments after 90 days of experiment. No significant differences among dietary treatment (P > 0.05) were noticed for daily growth rate (1.15 g/day–1.26 g/day), specific growth rate (2.27–2.35%/day), survival (74.78–77.43%), annual fish production (31.01–32.75 kg/are/year), and feed conversion ratio (1.06–1.13). Thus, similar growth and production performances were observed with fishes fed with A0 and those fed with A20. Therefore, up to 20% of Azolla in the ration of O. niloticus has no negative effect on either growth or production. The cost-benefit analysis showed a considerable reduction in the production costs of one kilogram of fish with increasing Azolla levels in diet, amounting to US$0.09 between A0 and A10 (P > 0.05) and US$0.14 between A0 and A20 (P < 0.05). These results indicate that, on an isonitrogenous and isocaloric basis, using Azolla at up to 20% in a diet can constitute a viable alternative source of protein for O. niloticus in tropical wetlands.

Partial substitution of fish meal with soybean protein concentrate and extracted rapeseed meal in the diet of sterlet (Acipenser ruthenus)

Partial substitution of fish meal with soybean protein concentrate and extracted rapeseed meal in the diet of sterlet (Acipenser ruthenus)

Partial Substitution of Fish Meal with Vegetable Protein Sources in a Diet for Sea Bass: Effects on Lipogenesis

Three isoproteic (49.4%) and isolipidic (17.0%) diets were prepared: A control diet FM, in which protein was derived from fish meal and two experimental diets in which 70% of the fish meal protein was substituted with wheat gluten meal (WGM) or wheat gluten meal plus soybean meal (WGMsb), respectively. The essential limiting amino acids were added to satisfy the requirements of the species (Tibaldi et al., 1996). Three hundred and fifteen sea bass (initial weight = 23.9±0. 1g )were randomly divided into nine homogenous groups. The animals were reared in a closed recirculation system at 23.9 ◦ C and were fed ad libitum twice a day for 96 days. The fish were weighed at the beginning and the end of the experiment. The epatosomatic, viscerosomatic and mesenteric fat indices, and the body chemical composition were determined for four fish (AOAC, 1995). Six other fish from each trial were used to determine the fatty levels of the muscles, the liver and the mesenteric fat as described by Folch et al. (1957). The content of total cholesterol, triglycerides, phospholipids (Juaneda and Rocquelin, 1985) and the composition of fatty acid in the muscles (Lepage and Roy, 1984) were determined. The hepatic activity of glucose-6-phosphate deidrogenase (G6PD, EC 1.1.1.49), malic enzyme (ME, EC 1.1.1.40) and ATP citrate lyase (ACL, EC 4.1.3.8) were determined for the same animals (Dias, 1999).

Assessment of soybean meal in diets for discus (Symphysodon aequifasciata HECKEL) farming through a fishmeal replacement study

A 12-week feeding trial was carried out with discus (Symphysodon aequifasciata HECKEL), a valuable ornamental species produced in South East Asia, to determine the suitability of using soybean meal as a partial fishmeal substitution in the diet. Juvenile discus (4.3–4.8 g) was fed eight experimental diets with graded levels of soybean meal replacing fish meal (0%, 10%, 20%, 25%, 30%, 35%, 40%, 50%). Growth performance (relative growth rate, specific growth rate) decreased and feed utilization (feed conversion ratio, protein efficiency ratio) was worsened at 30% replacement and higher. Amino-acid analysis indicated methionine and lysine deficiencies at dietary high soybean replacement levels, although the essential amino-acid requirements for this species are unknown. The level of soybean in diets negatively affected both dry matter and protein digestibility. This present trial showed the need for further studies involving amino-acid supplementation, different soy products and palatability enhancement to improve utilization of diets containing soybean meal to allow higher than the maximum 30% replacement level suggested here.

Dietary protein source affects the susceptibility to lipid peroxidation of rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax) muscle

AbstractThis study was designed to explore the effect of protein source on muscle susceptibility to lipid peroxidation in two representative species of fish farmed for human consumption: the freshwater rainbow trout and the seawater European sea bass. Four isoproteic diets (digestible protein in the range 366 to 392 for rainbow trout and 391 to 415 g/kg for European sea bass) were formulated to contain one of the following as the main protein source: fish meal, warm water alcohol-extracted or toasted soya protein concentrates or maize gluten meal. Highest daily growth indices were always achieved using the diets based on fish meal as the main source of protein (P&lt; 0·05). Fish of both species given diets containing maize gluten and the toasted soya protein concentrate showed slowest growth. The depressant growth effect of the vegetable protein concentrates was greater in sea bass than in rainbow trout. Dietary treatment was not correlated with any significant effect on whole-body composition or intramuscular fat content except for ash concentration in European sea bass. Under conditions of forced peroxidation in vitro for 240 min, muscle specimens of trout and sea bass given diets containing fish protein as the main source of protein showed the highest peroxidation levels (P&lt; 0·05); while the lowest peroxidation values were found in fish given maize gluten-containing diets (P&lt; 0·05). In the present case, the partial substitution of fish meal with vegetable proteins in diets led to a lower susceptibility of fish flesh to peroxidation. This finding may have applications in the production of fish of improved quality and longer shelf life.

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.

Improvement of quality of copra (dried kernel of Cocos nucifera) seed meal protein with supplemental amino acids in feeds for rohu, Labeo rohita (Hamilton) fingerlings

An eight-week feeding trial was conducted in a static indoor rearing system to examine the effects of partial substitution of fish meal (FM) protein with copra meal protein with and without supplemental amino acids in diets for rohu, Labeo rohita fingerlings (average weight 5.50 &plusmn;0.19 g). Prior to incorporation into diets, the meal was fermented with lactic acid bacteria (Lactobacillus acidophilus) in order to reduce / eliminate the anti-nutritional factors, tanin and phytic acid present in it. Twelve experimental diets (D1 to D12) were formulated replacing the FM protein from a reference diet with copra meal protein at different levels (four sets of diets, of which each set of three diets contained 30, 40, and 50% replacement of FM protein by copra meal protein respectively). Diets D1 to D3 were not supplemented with any amino acid. Lysine was added to diets D4 to D6. Diets D7 to D9 were supplemented with methionine-cystine (together) and diets D10 to 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 any supplemental amino-acids had significantly lower percentage weight gain, SGR and high FCR than the groups of fish fed other experimental diets. The addition of lysine and methionine-cystine to the diet in which 50% of FM protein was replaced by copra protein (diet D12) significantly improved fish weight gain and FCR. The percentage live weight gain and SGR values differed significantly (P &lt; 0.01) from each other in the fish fed diets D10 to D12 which were supplemented with all three amino acids. The results of the present study suggest that rohu fingerlings can effectively utilise the supplemented amino acids and that copra meal protein can replace up to 50% of FM protein in the diets for rohu if the meal is properly fermented and supplemented with deficient amino acids.

Improvement of quality of sesame Seasamum indicum seed meal protein with supplemental amino acids in feeds for rohu Labeo rohita (Hamilton) fingerlings

An 8-week feeding trial was conducted in a static indoor rearing system to examine the effects of partial substitution of fish meal (FM) protein with sesame seed meal protein with and without supplemental amino acids in diets for rohu Labeo rohita fingerlings (average weight 3.82 ± 0.05 g). Before incorporation into diets, sesame Seasamum indicum seed meal was fermented with lactic acid bacteria Lactobacillus acidophilus in order to reduce/eliminate the antinutritional factors tannin and phytic acid present in it. Twelve experimental diets (diets D1 to D12) were formulated replacing the FM protein from a reference diet with sesame seed meal protein at different levels (four sets of diets, of which each set of three diets contained 30%, 40% and 50% replacement of FM protein by sesame seed meal protein respectively). Diets D1 to D3 were not supplemented with any amino acid. Lysine was supplemented to diets D4 to D6. Diets D7 to D9 were supplemented with methionine–cystine (together), and diets D10 to D12 contained lysine and methionine–cystine (together). Lysine and methionine–cystine were added to the diets at 5.7% and 3.1% of dietary protein respectively. The groups of fish fed diets without any supplemental amino acids had significantly lower percentage weight gain, specific growth rate (SGR) and higher feed : gain ratio (FGR) than the groups of fish fed on other experimental diets. The addition of lysine and methionine–cystine to the diet in which 50% of FM protein was replaced by sesame meal protein (diet D12) significantly improved fish weight gain and FGR. The percentage live weight gain and SGR values differed significantly (P < 0.01) from each other in the fish fed diets D10 to D12, which were supplemented with all three amino acids. The results of the present study suggest that rohu fingerlings can effectively utilize the supplemented amino acids and that sesame seed meal protein can replace up to 50% of FM protein in the diets for rohu if the sesame seed meal is properly processed (fermented) and supplemented with deficient amino acids.

Improvement of quality of sal (Shorea robusta) seed meal protein with supplemental amino acids in feeds for rohu, Labeo rohita (Hamiltoan), fingerlings

An eight-week feeding trial was conducted in a static indoor rearing system to examine the effects of partial substitution of fish meal (FM) protein with deoiled salseed meal protein with and without supplemental amino acids in diets for rohu, Labeo rohita fingerlings (average weight 5.50 &plusmn;O.19 g). Prior to incorporation into diets, deoiled sal (Shorea robusta) seed meal was fermented with lactic acid bacteria (Lactobacillus acidophilus) in order to reduce/eliminate the antinutritional factors, tannin and phytic acid present in it. Twelve experimental diets (diets D1 to D12) were formulated repalcing the FM protein from a reference diet with salseed meat protein at different levels (four sets of diets, of which each set ofthree diets contained 25%, 50%, and 75% replacement of FM protein by salseed meal protein respectively). Diets D1 to D3 were not supplemented with any amino acid. Lysine was supplemented to diets D4 to D6. Diets D7 to D9 were supplemented with methionine-cystine (together) and diets D10 to 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 any supplemental amino acids bad significantly lower percentage weight gain, SGR and higher FCR than the groups of fish fed other experimental diets. The addition of lysine and methionine-cystine to the diet in which 50% of FM protein was rep1aced by salseed meal protein (diet D11) significant1y improved fish weight gain and FCR. The percentage live weight gain and SGR values differed significantly (P &lt; 0.01) from each other in the fish fed diets D10 to D12 which were supplemented with all three amino acids. The results of the present study suggest that rohu fingerlings can effectively uti1ise the supplemented amino acids and that deoiled salseed meal protein can replace up to 50% of FM protein in the diets for rohu if the salseed meal is properly processed (fermented) and supplemented with deficient amino acids.

Corn gluten and meat and bone meals as protein sources in diets for gilthead seabream ( Sparus aurata): Nutritional and histological implications

Two experiments were conducted to compare the effect of the partial substitution of fish meal by two different protein sources, corn gluten (CGM) and meat and bone meals (MBM) in diets for juveniles gilthead seabream. Growth, feed efficiency, protein efficiency ratio and protein productive values were not significantly affected by the source of dietary protein, although higher values were observed with diets containing increasing levels of meat and bone meal. No differences were found in fish proximate composition at the end of the experiment. Histological studies of liver tissue showed no liver alteration in fish fed diets including increasing levels of corn gluten meal. On the contrary, an increased deposition of lipids, nuclei polarization and isolated necrotic focus were found in hepatocites of fish fed diets exceeding 20% of meat and bone protein. Apparent protein digestibility (ADC) in diets containing CGM showed similar results to those obtained with the control diet. However, a significant reduction in digestibility was observed when MBM was used as partial substitute of fish meal protein. A negative correlation between dietary ash content and protein digestibility was observed. Higher amounts of nitrogen were excreted as levels of CGM and MBM increased in the diets, being significantly higher in the case of 40% substitution either with CGM or MBM protein.

Partial substitution of fish meal and full-fat soya bean meal with wheat gluten and influence of lysine supplementation in diets for rainbow trout, Oncorhynchus mykiss (Walbaum)

A 65-day study was undertaken to evaluate the utilization of lysine-supplemented wheat gluten meal as a protein source for rainbow trout, Oncorhynchus mykiss (Walbaum). The performance of the trout fed wheat gluten was compared to that of trout where protein was principally supplied using fish meal and full-fat soyabean meal. Six isonitrogenous diets (approximately 45% crude protein) were formulated. Thus, the reference diet (FS) was based on fish meal and full-fat soya bean meal while a further five diets were formulated with a mixture of wheat gluten and wheat middlings used to isonitrogenously replace approximately 75% and 57% of the full-fat soya and fish meal respectively. Crystalline l-lysine representing 0.00%, 0.29%, 0.58%, 0.87% and 1.16% of the complete diet was then added to the wheat-gluten-based diets. Optimal performance in terms of weight gain and apparent net protein utilization was achieved by the fish fed a wheat-gluten-based diet supplemented with lysine (0.58%) yielding a digestible lysine level of 1.9% of the complete feed. Within the range of supplements provided, lysine digestibility was high. However, at the highest levels of supplemental lysine the relationship between uptake and supplement level was not linear. Additionally, arginine digestibility was not affected by the level of lysine supplementation. However, amongst the wheat-gluten-based diets, optimal performance was associated with a lysine: arginine ratio of 1.1: 1. Despite a lysine: arginine ratio of approximately 1.1: 1, the overall performance of the fish fed the fish-meal-soya-based reference diet was poorer than expected. The results are discussed with respect to optimal patterns of gross and digestible amino acids, lysine-arginine antagonism and the possible relationship between antinutritional factors and the poor performance of the fish fed the fish-meal-soya-based reference diet.