Chhorn Lim

Evaluation of Soybean Meal as a Replacement for Marine Animal Protein in Diets for Shrimp (Penaeus vannamei)

Six isonitrogenous, isocaloric diets containing 0, 14, 28, 42, 56 and 70% soybean meal as replacement of 0, 20, 40, 60, 80 and 100% of animal protein, which consisted of 53% anchovy fish meal, 32% shrimp head meal and 15% squid meal, were fed to juvenile P. vannamei to satiation six times per day for 56 days. Shrimp fed the three lowest dietary levels of soybean meal (0, 14 and 28%) had similar weight gains of 6.77 ± 0.36, 6.91 ± 0.40 and 6.56 ± 0.23 g, respectively. Weight gains declined significantly (P 0.05) for diets containing 0, 14, 28 and 42% soybean meal (10.94 ± 0.43, 11.02 ± 1.02, 10.22 ± 0.35 and 9.79 ± 0.62 g, respectively). Feed intakes decreased (P 0.05) in whole body composition of lipid, ash, calcium or potassium of shrimp on the various diets. Body phosphorus percentage decreased significantly (P < 0.05) when soybean meal levels exceeded 42%. The 70% soybean meal diet was utilized very poorly by the shrimp.

Effect of soybean meal replacement by cottonseed meal and iron supplementation on growth, immune response and resistance of Channel Catfish (Ictalurus puctatus) to Edwardsiella ictaluri challenge

Abstract Three basal diets containing 0%, 27.5% and 55.0% solvent-extracted cottonseed meal (CSM) as replacements of 0%, 50% and 100% of solvent-extracted soybean meal (SBM) on an equal nitrogen basis were each supplemented with three levels of iron (40, 336 and 671 mg/kg) from ferrous sulfate heptahydrate (3×3 factorial experiment). Each diet was fed to juvenile channel catfish in triplicate aquaria twice daily to apparent satiation for 10 weeks for subsequent determination of growth response, hematology, specific and non-specific immune response, and mortality following Edwardsiella ictaluri challenge. Fish fed diets containing 27.5% CSM as a replacement of 50% of SBM had improved weight gain (WG) and feed efficiency ratio (FER). Total replacement of SBM by 55.0% CSM decreased WG, feed intake (FI) and FER. Total cell count (TCC), red blood cell count (RBC), hematocrit (Ht) and hemoglobin (Hb) were not affected by dietary levels of CSM. Iron supplementation significantly affected TCC and RBC and maximum values of these parameters were obtained at 336 mg of iron/kg diet. However, Ht and Hb were not affected by increasing levels of supplemental iron. Values for TCC, RBC and Hb were significantly affected by the interaction between dietary levels of CSM and iron. For fish fed the diet containing 0% CSM (SBM-based diets), these parameters increased linearly with increasing dietary levels of iron. When CSM levels were increased to 27.5% or higher, 336 mg supplemental iron was sufficient for maximum hematological values. Macrophage chemotaxis in the presence of exoantigen was significantly higher for fish fed diets containing 55.0% CSM as compared to those fed the lower CSM diets. Agglutinating antibody titers were also significantly higher for fish fed diets containing CSM, but the values did not differ for those fed the 27.5% or 55.0% CSM diets. Dietary levels of iron, and interactions between dietary levels of iron and CSM had no effect on macrophage chemotaxis and antibody titers. Cumulative mortality at 15 days post-challenge was significantly higher for fish fed the SBM-based diet (0% CSM) at 54.4% as compared to 35.0% and 21.6% for those fed the 27.5% and 55.0% CSM diets, respectively. No differences were observed among mortality of fish fed the CSM-containing diets. Dietary levels of iron supplementation, and the interactions between dietary levels of iron and CSM had no effect on post-challenged mortality of fish.

Growth response and fatty acid composition of juvenile Penaeus vannamei fed different sources of dietary lipid

Abstract A study was conducted to evaluate the effects of feeding various sources of dietary lipid on weight gain, feed conversion, survival and fatty acid composition of juvenile Penaeus vannamei . Seven semi-purified diets (35% protein and 3400 kcal of metabolizable energy kg −1 ) containing defatted, freeze-dried shrimp meal, 1.0% soybean lecithin and 0.5% cholesterol were supplemented with 6.5% of either stearic acid, coconut, safflower, corn, soybean, linseed or menhaden fish oils. Each diet was fed to shrimp (1.00 ± 0.03 g average weight) in four replicate aquaria four times daily for 10 weeks. Weight gain, feed conversion and survival were best for shrimp fed the diet containing menhaden fish oil. Shrimp fed the linseed oil diet had the second highest weight gain, followed by shrimp on soybean oil, corn oil, stearic acid, coconut oil and safflower oil diets, respectively. Feed conversion values were a reflection of weight gain. Results of this study show that both n -6 and n -3 fatty acids are dietary essential for juvenile Penaeus vannamei , although n -3 fatty acids promoted faster growth than n -6. However, highly unsaturated fatty acids (HUFA) (20:5 n -3 and 22:6 n -3) had better growth-promoting effect than 18:3 n -3, due probably to the limited ability of shrimp to bioconvert fatty acids to polyenoic forms of longer chain length. The fatty acid composition of the shrimp generally reflected that of the dietary lipids, especially for the diets containing unsaturated fatty acids. Shrimp fed stearic acid and coconut oil diets low in polyunsaturated fatty acids accumulated high levels of 16:1 n -7 and 18:1 n -9.

Nutritional value of heat-treated soybean meal for channel catfish (Ictalurus punctatus)

A study was undertaken to evaluate the effect of heat treatment of defatted raw soybean meal (RSBM) on the growth performance, hematology, immune response and resistance of channel catfish to Edwardsiella ictaluri challenge. Six practical-type diets were formulated to be isocaloric (2.8 kcal DE/kg diet) and isonitrogenous (34% crude protein). A diet containing 45% of commercial soybean meal (CSBM) served as the control. RSBM, non-heat treated (RSBM0) and heated in an autoclave using the dry cycle at 130 °C and 22 psi for 5 (RSBM5), 10 (RSBM10), 20 (RSBM20), and 40 min (RSBM40), was used to isonitrogenously replace the CSBM in the control diet. Each diet was fed to juvenile catfish (4.98 g) in triplicate aquaria twice daily to apparent satiation for 10 weeks. Another batch of diets containing 1% of chromic oxide was used for measurement of apparent digestibility coefficients. Heating RSBM for 20 min or longer lowered trypsin inhibitor (TI) content and increased the apparent protein digestibility (APD). The protein dispersibility index (PDI) decreased with an increase in the duration of heat treatment. Fish fed CSBM and RSBM40 diets had similar weight gain, protein efficiency ratio and apparent protein utilization which were significantly higher than those of fish fed the other diets. Feed intake significantly increased when RSBM was heated for 20 min or longer. Fish fed the RSBM40 diet had significantly lower feed intake but higher feed efficiency than those fed the CSBM diet. Whole-body protein was highest for fish fed the RSBM40 diet but did not differ from that of fish fed the CSBM diet. Hepatosomatic and visceral indices (HSI and VI) of the groups fed CSBM and RSBM40 diets were significantly lower than those fed other diets. Total cell count, red blood cell count, hematocrit and hemoglobin were not significantly affected by dietary treatment. Plasma lysozyme activity and protein of fish fed the CSBM and RSBM40 diets were similar and significantly higher than those of fish fed the other diets. Cumulative mortality 14-day post challenge with E. ictaluri was significantly lower for fish fed the RSMB5 and RSBM10 diets but significantly increased when heating time was increased to 40 min. Macrophage chemotaxis in the presence of exoantigen and antibody titer against E. ictaluri was higher for the groups fed the RSBM containing diets than those fed the CSBM diet, although the differences were not always significant. Results of this study indicate that autoclaving the RSBM for 40 min lowered the TI and PDI, improved the nutritional value of RSBM and increased plasma lysozyme and protein. However, this level of heat treatment significantly decreased macrophage chemotaxis, antibody titer and resistance of fish to E. ictaluri challenge.

Growth performance and immune response of channel catfish (Ictalurus puctatus) fed diets containing graded levels of gossypol–acetic acid

Abstract This study was conducted to evaluate the effect of gossypol levels on growth performance, body composition, hematology, immune response and resistance of channel catfish to Edwadsiella ictaluri challenge. A purified basal diet supplemented with 0, 300, 600, 900, 1200 and 1500 mg of gossypol from gossypol–acetic acid was fed to juvenile channel catfish in quadruplicate aquaria to apparent satiation twice daily for 12 weeks. Final weight gain was inversely related to the concentration of dietary gossypol. Fish fed diets without and with 1500-mg gossypol/kg had significantly highest and lowest weight gain, respectively. Feed intake and feed efficiency were a reflection of weight gain. Survival was not affected by dietary levels of gossypol. Whole body moisture increased whereas lipid decreased with increasing dietary gossypol concentrations. Body protein significantly decreased in fish fed with 1500-mg gossypol diet, but did not differ among fish fed with other diets. Body ash did not differ in fish fed diets containing 0–900-mg gossypol/kg but was significantly higher in fish fed higher levels of dietary gossypol. Gossypol concentration in liver was linearly related ( R 2 =0.991) to dietary levels of gossypol. Ratio of (+) to (−) gossypol isomers in liver of fish fed with different diets was relatively constant. Red blood cell (RBC) count of fish fed with the two highest levels of dietary gossypol (1200 and 1500 mg) was significantly lower than those of fish fed with control diet. Hemoglobin significantly decreased in fish fed with 900 mg or higher gossypol diets. Hematocrit was significantly affected at each incremental level of dietary gossypol of 600 mg/kg or higher. Serum protein did not differ for fish fed with the three lowest dietary levels of gossypol but was significantly reduced at 900 mg or higher gossypol. Macrophage chemotaxis ratio was similar for groups fed diets containing gossypol but was significantly higher than that of fish fed with the control diet. Serum lysozyme activity significantly increased at dietary gossypol levels of 900 mg or higher. Superoxide anion production as measured by nitroblue tetrazolium (NBT) reduction assay did not differ among treatments. Mortality at 14-day post-challenge with E. ictaluri significantly decreased at dietary gossypol levels of 900 mg or higher. However, antibody titer against E. ictaluri 15-day post-challenge was not affected by dietary treatments. This study indicates that juvenile channel catfish was more sensitive to gossypol toxicity than previously reported. The toxic concentration ranged from 300 to 1200 mg gossypol/kg diet depending on the parameter evaluated. However, improved macrophage chemotaxis ratio, serum lysozyme activity and resistance of catfish to E. ictaluri challenge were observed at dietary levels of 900 mg gossypol/kg or higher.

Interaction between dietary levels of iron and vitamin C on growth, hematology, immune response and resistance of channel catfish Ictalurus / punctatus to Edwardsiella ictaluri challenge

Abstract Nine egg-white-based diets supplemented with three levels of vitamin C from l -ascorbyl-2-polyphosphate (0, 50 and 3000 mg/kg) for each of the three levels of iron from iron methionine (0, 30 and 300 mg/kg) were each fed to juvenile channel catfish in triplicate aquaria twice daily to apparent satiation for 14 weeks. Fish fed with iron-deficient diets had decreased weight gain, feed conversion and survival. Supplementation of ascorbic acid to the iron-deficient diets further decreased weight gain and survival. Feed conversion was not significantly affected by dietary level of vitamin C or iron and vitamin C interaction. No gross signs of vitamin C deficiency were observed. Total cell count (TCC), red blood cell count (RBC), hematocrit (HCT) and hemoglobin (Hb) were significantly lower for fish fed the iron deficient diet. TCC and RBC significantly increased when 3000 mg of vitamin C/kg was added. However, in the absence of dietary iron, supplementation of ascorbic acid resulted in significant decrease in HCT and Hb values. Hepatic iron concentration increased with increasing dietary level of iron. Supplementation of high level of ascorbic acid to the diet containing 300 mg/kg of supplemental iron significantly increased the liver iron content. Liver ascorbate increased with increasing dietary level of ascorbic acid. Dietary level of iron and the interaction between iron and vitamin C had no effect on liver content of vitamin C. Mean macrophage migration in the absence or presence of Edwardsiella ictaluri exoantigen was significantly higher for fish fed the iron supplemented diets. The significant effect of vitamin C was obtained only when high level (3000 mg/kg) was used. Neither dietary levels of iron nor vitamin C or their interaction influenced survival of juvenile channel catfish against E. ictaluri 14-day post challenge. However, the onset of mortality was earlier for fish fed the iron-deficient diet.

Effects of Probiotic Diet Supplements on Disease Resistance and Immune Response of Young Nile Tilapia, Oreochromis niloticus

Abstract Probiotic microbial feed supplements are gaining wide acceptance in livestock production, and may be applicable to aquaculture production systems. In two experiments, fry of Nile tilapia, Oreochromis niloticuswere fed a basal diet supplemented with commercially-available probiotic microorganisms. Survival, growth, disease resistance, and immunological parameters were monitored for a maximum of 94 days. Bacterial populations were higher in the digestive tracts of tilapia receiving probiotic diets, and colony morphology suggested that viable probiotic bacteria persisted up to 48 hours after feeding. Survival was higher after 39–63 days in fish receiving the Bioplus probiotic, Bacillus spp. There was no difference in growth, lysozyme, total serum immunoglobulin, complement, specific anti-streptococcal antibody levels, or mortality due to Streptococcus iniae infection either before or after disease challenge. The results suggest that these commercially-available probiotic microorganisms do not provide beneficial effects in young Nile tilapia.

Influence of Dietary Lipid Sources on the Growth Performance, Immune Response and Resistance of Nile Tilapia, Oreochromis niloticus, to Streptococcus iniae Challenge

ABSTRACT This experiment was conducted to determine the effect of dietary lipid sources on growth performance, body proximate composition, hematology, immune response and resistance of Nile tilapia, Oreochromis niloticus, to Streptococcus iniae infection. Six isocaloric (3.2 kcal/g) and isonitrogenous (34% crude protein) semi-purified diets were supplemented with 7% of various sources of lipid, namely, corn oil (CO), beef tallow (BT), menhaden fish oil (FO), linseed oil (LO), and equal combinations of FO+CO+BT or LO+CO+BT. Diets were fed to tilapia in quadruplicate aquaria to apparent satiation, twice daily for 12 weeks. Fish fed the BT-diet exhibited significantly lowest weight gain, diet intake, feed and protein efficiency ratios, apparent protein utilization, and survival. Whole-body protein and ash were significantly (P < 0.05) lowest and highest, respectively, for fish fed the beef tallow-diet, but the values of these parameters did not differ among fish fed other diets. No significant differences (P > 0.05) were found among hematological values, except for fish fed the FO-diet which had abnormally high red and white blood cell counts. Serum protein concentration, lysozyme activity, and natural hemolytic complement activity were significantly (P < 0.05) reduced in fish fed the BT-diet. The values of these parameters did not differ among fish fed other diets. Post-challenge antibody titer was not influenced by dietary lipid sources. Cumulative mortality 15 days post-challenge with S. iniae was significantly lower (P < 0.05) for fish fed the BT diet compared with those fed FO or FO+CO+BT diets. No significant differences were observed in fish fed other dietary lipid sources.

Use of Probiotics in Diets of Tilapia

Aquaculture is one of the fastest growing sectors of agriculture globally. Production in freshwater and marine fisheries has plateaued, and the increasing demand for seafood and need for affordable protein sources in third world countries will ensure growth of aquaculture in the future. Tilapia are the second most cultured fish worldwide behind the carps, and even though they are easily cultured in a wide variety of environments and are relatively resistant to aquaculture stressors compared to other cultured finfish species, significant losses to disease still occur under intensive culture. Traditionally, antibiotics and other chemicals have been used to treat disease outbreaks in cultured fish species. However, the scope of approved application for most antibiotics is very narrow and concern over development of antibiotic resistant pathogens will further limit use in the future. The focus instead has turned to finding safe and effective means of preventing infectious diseases in cultured finfish, including tilapia. In recent years, there has been considerable interest in the use of probiotic bacteria added to diets to increase immunity as well as improve growth performance in fish. Little probiotic research has been conducted in tilapia, but of the research that has been performed, most has taken place within the last five years. Due to its apparent effectiveness in improving health and growth in tilapia, research and interest in probiotics is likely to continue, which will hopefully fill existing research gaps.

Effect of dietary pH on amino acid utilization by shrimp (Penaeus vannamei)

A study was conducted to determine the effect of dietary pH on amino acid utilization by juvenile Penaeus vannamei. A basal diet (diet 1), five diets (diets 2–6) supplemented with crystalline amino acids (AA) to simulate the AA pattern of shrimp protein and in which the dietary pH was adjusted from pH 4.8 to 5.0, 6.0, 7.0 and 8.0±0.2, and a 28% shrimp protein control diet (diet 7) were fed to shrimp to satiation 6 times per day for 10 weeks. Growth and feed consumption of shrimp were improved (P<0.05) by supplementing AA and increasing the levels of dietary pH. Maximum weight gain, which was approximately 85% that of shrimp fed the control diet (diet 7), was obtained when the AA diet was adjusted to pH 8.0 (diet 6). However, this growth improvement was due to increased feed consumption rather than to improvement of nutritional value of diets. Shrimp fed diet 7 also had the best feed conversion (P<0.05), which was about two-fold better than those obtained with other diets. There were no significant differences among the survival rates of shrimp fed the various diets. The pellet water stability at 1 and 3 h was similar for diets 2–6 and diets 1 and 7. However, the dry matter loss of diets 2–6 was approximately twice that of diets 1 and 7. The crude protein losses were negligible for diet 1, 7.0% for diet 7, and 21.2–22.3% for diets 2–6. The total essential amino acids (EAA) including cystine, at 1 h soaking, slightly increased for diets 1 and 7 but decreased by 27.5% for diet 6. Supplementation of AA and increase in dietary pH had no appreciable effect on moisture and crude protein contents of whole shrimp. Body fat increased (P<0.05) and ash decreased with increasing levels of dietary pH. Shrimp fed the control diet had the highest content of crude protein and fat and the lowest levels of moisture and ash. This study indicates that growth and feed conversion of P. vannamei fed the AA-supplemented diets were inferior to that of shrimp fed the control diet. This may be attributed to the lower water stability of the AA supplemental diets and the apparent loss of AA from these diets. However, improved growth and feed consumption were obtained with increasing pH values of the AA-supplemented diets. This growth improvement was due to increased feed consumption rather than to improvement of nutritional value of the diets.