Immune Response and Resistance of Channel Catfish to Edwardsiella ictaluri Challenge when Fed Various Dietary Levels of Zinc Methionine and Zinc Sulfate

Abstract

The effects of dietary levels of zinc from zinc methionine (ZnM) and zinc sulfate ZnSO₄ on nonspecific immune responses and disease resistance of juvenile channel catfish Ictalurus punctatus (mean initial weight of 3.3 g) were determined. Fish in triplicate aquaria were fed to satiation twice daily for 16 weeks with an egg white basal diet without zinc supplementation or supplemented with 5, 20, and 60 mg zinc/kg as ZnM or 20 and 60 mg zinc/kg as ZnSO₄. Relative percentages of peripheral blood lymphocytes, thrombocytes, and macrophages were not affected by dietary zinc. The relative percentages of neutrophils significantly increased in fish fed 20 and 60 mg Zn/kg as ZnM. Chemotactic responses of macrophages were significantly higher for fish fed the three ZnM-supplemented diets and the 60-mg ZnSO₄. Dietary zinc, however, had no influence on the phagocytic activity of macrophages for Edwardsiella ictaluri. Likewise, neither the source nor the level of dietary zinc provided protection to channel catfish against E. ictaluri. The severity of E. ictaluri infection (number of colony-forming units/g trunk kidney) and the percentage offish that were culture negative for E. ictaluri (15 d postchallenge) were also unaffected by dietary zinc.     

Effect of Dietary Lipid Sources on Production of Leukotriene B by Head Kidney of Channel Catfish Held at Different Water Temperatures

Abstract

Separate and combined effects of dietary fatty acids and water temperature on the production of leukotriene B (LTB) by the head kidney of channel catfish Ictalurus punctatus were investigated. Fish were fed semipurified diets containing 7% lipid as beef tallow, corn oil, linseed oil, menhaden oil, or a mixture (1:1:1) of menhaden oil, beef tallow, and corn oil. At 28°C, fish fed corn oil produced the greatest amount of LTB, and fish fed beef tallow produced the least. At 17°C, production of LTB by fish fed the beef tallow diet was again lowest; production of LTB by fish fed the corn oil diet was highest but was not significantly different from that obtained with the mixed-oil or menhaden oil diet. Production of LTB for the other diets was intermediate. This is the first report that the head kidney of channel catfish produces LTB; this production was affected by dietary lipid sources but not by the two water temperatures tested. Production of LTB was not related to weight gain. Moreover, the pattern of LTB production does not explain survival rates of channel catfish observed in a previous experiment in response to pathogen challenge. However, LTB concentration does appear to be roughly proportional to the amount of eicosanoid precursors (arachidonic acid and eicosapentaenoic acid) previously reported for liver phospholipids of channel catfish fed diets containing different amounts of essential fatty acids.     

Effect of Low Dietary Magnesium on Immune Response and Osmoregulation of Atlantic Salmon

Abstract

The influences of dietary magnesium on immune response and on osmoregulation in parr of Atlantic salmon Salmo salar were determined. Groups of fish were fed a casein–gelatin diet unsupplemented (containing about 200 mg Mg/kg) or supplemented with either 300 or 500 mg Mg/kg dry diet (as MgSO₄) for 12 weeks before vaccination to produce fish with different Mg levels, and the feeding regime was continued throughout the study. No differences were observed between the treatment groups in serum-specific antibody levels every second week for 8 weeks after vaccination against Vibrio anguillarum serotypes O1 and O2. Both lysozyme levels and spontaneous hemolytic activities in serum were elevated in vaccinated fish compared with unvaccinated fish. Neither lysozyme activity, complement hemolytic activity, total protein in serum nor blood hemoglobin were affected by dietary Mg. The spontaneous hemolytic activity in serum was lower in fish fed the unsupplemented diet and highest in fish fed the diet supplemented with 500 mg Mg/kg. After 28 weeks on the diets supplemented with graded levels of Mg, a salinity tolerance test (32.5 g/L, 24 h) was performed. High mortality and elevated serum chloride concentrations in all groups after 24 h reflected a general salinity intolerance, but the highest serum chloride level was observed in fish fed the unsupplemented diet. This indicates that low dietary Mg affects the osmoregulation of Atlantic salmon.     

Preliminary Assessment of the Tolerance and Efficacy of Florfenicol against Edwardsiella ictaluri Administered in Feed to Channel Catfish

Abstract

A tolerance study was conducted to determine the palatability of florfenicol to channel catfish Ictalurus punctatus. Four tanks of fish (20 fish/tank) were assigned to each of five treatments distinguished by the amount of florfenicol given in feed per kilogram of body weight, namely, 0, 10, 20, 40, or 100 mg. Fish were fed at a rate of 2.5% of body weight per day for 10 consecutive days. On day 11, all surviving fish were euthanatized, counted, and weighed as a group. Florfenicol- medicated feed was palatable to fish at doses of 10, 20, 40, and 100 mg for 10 consecutive days. All 400 fish were necropsied and examined by histopathology, and no treatment-related changes were observed. In a separate exploratory efficacy study, four tanks (20 fish/tank) were assigned to each of the following treatments: (1) not challenged with Edwardsiella ictaluri and fed unmedicated feed, (2) challenged with E. ictaluri and fed unmedicated feed, (3) challenged with E. ictaluri and fed florfenicol at 10 mg per kilogram of body weight, (4) challenged and fed florfenicol at 20 mg/kg, and (5) challenged and fed florfenicol at 40 mg/kg. Treatment was initiated the day after inoculation, and feed was administered by hand for five consecutive days at 2.5% of body weight. The cumulative mortality observed over a 17-d period in treatment groups 1–5 was 2.5, 57.5, 0, 1.25, and 1.25%, respectively. All 400 fish were necropsied and examined by histopathology. The results indicate that florfenicol was effective in controlling mortality from enteric septicemia of catfish with no adverse treatment-related tissue changes. Florfenicol was palatable, safe, and efficacious in controlling mortality due to infection by E. ictaluri in channel catfish.     

Lipid concentrations of fillets, liver, plasma and lipoproteins of African catfish, Clarias gariepinus (Burchell 1822), fed diets with varying protein concentrations

This study investigated the effect of the dietary protein concentration on lipid concentrations in fillet and liver and concentrations of lipids in plasma and lipoproteins in African catfish. Two experiments were carried out, in which African catfish were fed diets with various protein concentrations. In experiment 1, semisynthetic diets with various concentrations of casein (350, 450 or 550 g protein/kg) were used. In experiment 2, diets were based on a commercial trout diet supplemented with various amounts of casein or carbohydrates, resulting in protein concentrations between 282 and 545 g/kg diet. In both experiments, the dietary protein concentration had a significant effect on growth, feed conversion ratio and carcass composition. Maximum of body weight gains and feed efficiency ratios were reached in both experiments at the highest dietary protein concentrations. Increasing the dietary protein concentration continuously increased masses of fillets and reduced masses of the liver and adipose tissue in the abdominal cavity. Fish fed the diets with the highest protein concentrations had the lowest concentration of total lipids, triglycerides and cholesterol in the fillets, the highest percentage of polyunsaturated fatty acids (PUFA) in total lipids of fillets and the lowest concentrations of saturated fatty acids (SFA). Fish fed the diets with the highest protein concentration also had the lowest concentrations of triglycerides in the liver, the highest percentages of PUFA in liver total lipids and the lowest percentages of SFA. Moreover, fish fed diets with high protein concentrations (501 and 545 g/kg) had significantly lower concentrations of triglycerides, cholesterol and phospholipids in plasma than fish fed diets with lower protein concentrations. In conclusion, this study shows that the dietary protein concentration does not only influence growth, feed efficiency and carcass composition in African catfish, but also influences their lipid metabolism and lipid concentrations of liver and fillet.     

Effects of dietary arginine on hematological parameters and innate immune function of channel catfish

The effects of elevated dietary arginine on the hematology and immune function of juvenile channel catfish Ictalurus punctatus were evaluated by means of in vivo and in vitro experiments. Healthy juvenile channel catfish (average weight, 34.8 g) were fed casein-gelatin-based diets containing 28% crude protein and supplemented with crystalline L-arginine (ARG) at 0.5, 1, 2, or 4% of diet. An intact-protein diet containing 1.3% arginine also was included to investigate the effects of amino acid form (crystalline-free amino acids versus intact protein). Each purified diet was fed to apparent satiation to triplicate groups of fish for 6 weeks. At the end of the experimental feeding period, the fish were injected intraperitoneally with two doses (3 d apart) of 2 mg lipopolysaccharide/kg body weight. Six days after the initial injection, the fish were anesthetized and tissue samples were obtained to evaluate hematological and humoral and cellular immune parameters, including phagocytic activity of peritoneal macrophages, hemoglobin, hematocrit, mean corpuscular volume (MCV), blood cell counts, plasma protein, and hepatic superoxide dismutase activity. High dietary levels (4% ARG) resulted in significantly higher levels of hemoglobin, hematocrit, and circulating erythrocytes. Dietary ARG did not significantly affect MCV and the number of circulating leukocytes, lymphocytes, eosinophils, and monocytes. In vitro, a moderate level (2 mM) of ARG in the culture media was found to be ideal in significantly enhancing phagocytosis. This study demonstrates that some aspects of the immune system of channel catfish are sensitive to changes in dietary ARG.     

Effect of Dietary Vitamin E on Cortisol and Glucose Responses to Handling Stress in Juvenile Beluga Huso huso

Abstract

An 8-week feeding experiment was conducted to investigate the effect of dietary vitamin E on the physiological response to handling stress in juvenile beluga Huso huso. Fish were fed six experimental diets supplemented with 0, 25, 50, 100, 200, or 400 mg Dl-all-rac-α-tocopherol acetate/kg diet. At the end of the experiment, the fish in each tank were subjected to acute handling and air exposure stress. Cortisol and glucose were measured as the primary hormonal and secondary metabolic responses to the stressors, both before and 3 h after application of the stressors. The growth parameters and feed utilization rates were significantly lower in fish fed the diet not supplemented with vitamin E than in fish fed diets supplemented with vitamin E. Cortisol concentration was not affected by dietary treatment but glucose concentration was. Fish fed vitamin E at 0, 25, 100, and 400 mg/kg diet had higher concentrations of glucose than those fed vitamin E at 50 and 200 mg/kg. However, fish fed diets with 50 and 200 mg/kg exhibited higher growth rates. These results indicate that dietary vitamin E has some effect on plasma glucose but no effect on plasma cortisol. In general, when the stressors were applied to belugas, the glucose and cortisol responses were relatively low. This may be due to higher resistance and lower physiological responses to these types of stressors by this species or by chondrosteans in general.

Received January 10, 2011; accepted August 4, 2011     

Effects of replacing a dietary antibacterial agent (zinc bacitracin) with copper salts in Cherry Valley Pekin meat ducks

1. A study was conducted to investigate the effectiveness of high dietary copper concentrations obtained from tribasic copper chloride (TBCC, 58% copper) and copper sulphate pentahydrate (CuSO₄, 25% copper) in replacing antibiotic growth promoters (AGP) in duck diets.

2. A total of 960 one-day-old Cherry Valley meat-strain ducks were divided into 3 treatment groups, with 8 replicates per treatment, in a 6-week feeding trial. The ducks were fed a basal diet supplemented with AGP (40?mg zinc bacitracin/kg and 40?mg garlicin/kg of diet) or 150?mg of Cu/kg of diet, given as either CuSO₄ or TBCC.

3. The body weight, average daily gain, average daily feed intake and mortality of ducks were not affected by the dietary treatments. However, the feed/gain ratio of ducks that were fed TBCC diets was significantly lower than those of ducks that were fed CuSO₄ diets and were similar to those in the AGP group.

4. TBCC increased the Cu content in the liver tissue of ducks compared with the content in those that were fed the diet supplemented with AGP. TBCC also increased the Fe and Zn content in breast muscles compared with that in ducks that were fed the diet supplemented with CuSO₄.

5. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were significantly higher in the serum of ducks that received the diet supplemented with TBCC than AGP or CuSO₄. TBCC treatment decreased the malondialdehyde (MDA) content in serum of ducks compared with groups supplemented with CuSO₄.

6. No significant difference was observed in liver or muscle fat content among the different dietary treatment groups. The serum low-density lipoprotein cholesterol concentration was lower in ducks fed AGP diets than those fed CuSO₄ diets.

7. It was concluded that the replacement of AGP with 150?mg of Cu/kg of feed from TBCC improved the feed efficiency, trace mineral deposition and antioxidant status more than when the source of copper was CuSO₄.     

Assessment of dietary zinc requirement of weaned piglets fed diets with or without microbial phytase

Fifty-four pigs, weaned at 26 days of age at an average body weight of 7.74 kg were used in a 26-day experiment to assess the zinc requirement of piglets, using diets based on maize and soybean meal, with or without microbial phytase. The nine experimental diets were the basal diet containing 33 mg of zinc/kg supplemented with 10, 25, 40, 60 or 80 mg of zinc as sulphate (ZnSO(4), 7H(2)O)/kg and the basal diet supplemented with 0, 10, 25 or 40 mg of zinc as sulphate/kg and 700 units (U) of microbial phytase (Natuphos)/kg. Pigs were fed the basal diet for a 7-day adjustment period prior to the 19-day experimental period. Microbial phytase enhanced plasma alkaline phosphatase (AP) activity, plasma zinc and bone zinc concentrations. These parameters increased linearly with zinc intake, with a similar slope with and without phytase. The response of bone zinc-to-zinc added did not plateau. Without microbial phytase, plasma AP activity and zinc concentration were maximized when dietary zinc reached 86 and 92 mg/kg respectively. With microbial phytase they were maximized when dietary zinc concentration reached 54 and 49 mg/kg respectively. Accounting for a safety margin, the recommended supply of zinc for weaned piglets up to 16 kg fed maize-soybean meal diets supplemented with zinc as sulphate is thus of 100-110 mg/kg diet. This supply may be reduced by around 35 mg if the diet is supplemented with 700 U of microbial phytase.     

Nano-sized Zinc in Broiler Chickens: Effects on Growth Performance,Zinc Concentration in Organs,and Intestinal Morphology

The effects of dietary supplementation of zinc (Zn) sources and concentrations were investigated on growth performance, absorption into tissues, fecal excretion, nutrient retention, and intestinal morphology in broilers fed a corn-soybean meal basal diet. A total of 525 one-day-old chicks (Ross 308) were assigned based on body weight to seven dietary treatments. There were five replicate pens for each treatment and 15 broilers per replicate pen. The dietary treatments included a basal diet (control, without supplementing Zn), and basal diet supplemented with Zn, as inorganic zinc sulfate (ZnS; 110 mg/kg); organic Zn-methionine (ZnM; 110 mg/kg); hot-melt extruded (HME) 25 zinc sulfate (27.5 mg/kg); HME50 zinc sulfate (55 mg/kg); HME75 zinc sulfate (82.5 mg/kg); or HME100 zinc sulfate (110 mg/kg) for 35 days in two phases (d 1–21, phase I and d 22–35, phase II). Bodyweight and feed efficiency of broiler chicks fed diets supplemented with increasing dietary concentrations of HME-Zn improved linearly during the study period (P<0.05). Compared to the control treatment, the ZnS, ZnM, and HME diets increased Zn concentrations in the serum and liver. Inorganic ZnS supply resulted in the highest Zn concentration in excreta. Increasing supplemented Zn content in diets as HME linearly increased Zn concentration in the excreta, serum, liver, and tibia. Broiler chicks fed diets supplemented with increasing concentrations of HME increased villus height (VH; linear and quadratic) of the jejunum and VH of the ileum (linear). Increasing concentrations of dietary Zn supplied as HME resulted in linearly enhanced dry matter, gross energy, and nitrogen retention of broilers on day 21. These results suggest that dietary HME-Zn at a lower level (55 ppm) shows the same growth performance as common ZnSO₄ at 110 ppm.     

Dose Titration of Sarafloxacin (A-56620) against Edwardsiella ictaluri Infection in Channel Catfish

Abstract

Two dose-titration studies were performed with sarafloxacin (A-56620) on channel catfish Ictalurus punctatus infected with Edwardsiella ictaluri. Fish were infected with E. ictaluri by water-bath exposure and subsequently fed rations for 5 d to equal 0, 2, 6, 10, or 14 mg sarafloxacin/kg body weight per day. In trial I, mortality was significantly reduced from 69% for fish receiving no medication to 17% for those receiving 10 or 14 mg sarafloxacin/kg per day (P ≤ 0.01). In trial II, mortality was reduced from 33% of the nonmedicated infected group to 5 and 10% offish receiving 10 and 14 mg sarafloxacin/kg per day, respectively. Fish receiving 2 or 6 mg sarafloxacin/kg per day had intermediate mortality rates.     

Utilization of dipeptide/protein based diets in larval and juvenile Koi carp – post‐prandial free amino acid levels

We have shown previously that diets in which the nitrogen portion is based on synthetic dipeptides (PP) resulted in weight gain by rainbow trout alevins when free amino acid (FAA) based diets did not. However, the protein‐based diet used as a control in the previous study resulted in a significantly better performance of fish than peptide‐ or FAA based diet fed fish. Therefore, the objectives of our study were (i) to test how stomachless fish respond to peptide‐based diets, (ii) to evaluate PP and protein‐PP mixture diets and (iii) to examine if post‐prandial response to FAA concentrations in the fish body can be used as an indicator of the availability of dietary amino acid sources. The first experiment was conducted with a 4‐day old Koi carp (Cyprinus carpio) larvae and included groups fed a casein–gelatin (CG) based diet, a commercial diet and live Artemia nauplii. In the second experiment, fish fed live Artemia for 3 weeks (69 ± 12 mg) were placed in glass aquaria in triplicate per dietary treatment. Four diets provided equivalent amounts of nitrogen in the form of a CG, a PP, a 50% PP and 50% CG (PP50) mix and as FAA. Fish were fed at 1 and 3 h intervals, and the survival and growth were monitored during the second and third weeks of experiments 1 and 2 respectively. Following the completion of feeding, juvenile carp were sampled prior to feeding and 3 h after a meal. Whole body FAA analyses were carried out. We observed marginal suitability of the CG diet for larval Koi carp, as earlier indicated in common carp. Juvenile Koi carp fed the CG diet achieved 236 ± 19 mg, whereas PP50, PP and FAA diet fed fish grew to 140 ± 37, 70 ± 8 and 73 ± 5 mg respectively. Free amino acids in the fish body, and in particular indispensable amino acids (IDAA), were excellent indicators of dietary availability. The present experiment shows that a dietary 1:1 ratio of protein to synthetic PPs results in better growth, survival and whole body IDAA concentrations in relation to FAA‐ and PP‐based diets confirming earlier reports on the use of synthetic PP‐based diets, although this diet does not match the performance of complete protein, CG‐based diet.     

Effect of calcium supplements to a maize-soya diet on the bioavailability of minerals and trace elements and the accumulation of heavy metals in growing rats

Thirty-five (five groups with seven animals each) male albino rats (initial average weight = 44 g) were fed phytate-rich diets (analysed phytic acid concentration = 6.9 g/kg) based on maize and soy bean meal (5 g Ca, 3 g P, 1.2 g Mg, 23 mg Zn, 10 mg Pb, 5 mg Cd/kg diet). Experimental diets were supplemented with 0, 2, 4, 6 and 8 g calcium from CaCO3 per kg. The supplementation of increasing amounts of calcium resulted in a dose-dependent decrease in the apparent absorption of phosphorus. Furthermore, apparent zinc absorption and femur zinc concentration were moderately decreased due to the calcium supplementation. Kidney Cd concentration was significantly lower in rats that were fed the high calcium diets in comparison with the control animals. Femur lead concentration and hepatic delta-aminolevulinic acid dehydratase, which are known to be sensitive parameters of lead accumulation remained unchanged by the different dietary treatments. Magnesium absorption as well as liver and plasma zinc concentration and activity of plasma alkaline phosphatase were also unaffected. Although calcium supplementation may lead to a decrease in the accumulation of certain heavy metals such as cadmium, the carry-over of lead was not affected under the given experimental conditions. Furthermore, calcium-phytate-zinc interactions may adversely affect zinc bioavailability in growing rats.     

Development of Thiamine Deficiencies and Early Mortality Syndrome in Lake Trout by Feeding Experimental and Feral Fish Diets Containing Thiaminase

Abstract

We conducted a laboratory investigation on the consequences of feeding predatory salmonids either experimental diets low in thiamine or diets containing alewife Alosa pseudoharengus. In experiment 1, adult lake trout Salvelinus namaycush were fed experimental diets containing bacterial thiaminase. In experiment 2, adult lake trout were fed natural prey species, alewives, and bloaters Coregonus hoyi. The diets consisted of four combinations of alewives and bloaters from Lake Michigan (100% alewives, 65% alewives–35% bloaters, 35% alewives–65% bloaters, and 100% bloaters), alewives from Cayuga Lake, a casein bacterial thiaminase, and a commercial trout diet. We assessed the effects of each diet on egg thiamine concentration and incidence of an embryonic early mortality syndrome (EMS). In experiment 1, incidence of EMS ranged from 0% to 100%. Significant relationships were found between the incidence of EMS and thiamine. In experiment 2, adult lake trout fed 100% alewives from either Lake Michigan or Cayuga Lake or fish fed the casein bacterial thiaminase diet produced eggs with low thiamine and swim-up fry with EMS. At either 35% or 65% alewives in the diet, egg thiamine was significantly lowered. The number of females that produced offspring that died from EMS were low but demonstrated the negative potential if feral lake trout foraged on either 35% or 65% alewives. Depleted egg thiamine and the onset of EMS required diets containing thiaminase for a minimum of 2 years in lake trout initially fully thiamine replete. We conclude that EMS can be caused by extensive feeding on 100% alewives and dietary levels of 35% or greater may prove detrimental to sustainable reproduction of salmonids in the Great Lakes. The data are consistent with that observed in feral lake trout, and it is concluded that EMS is the result of a thiamine deficiency.     

Effects of supplemental palygorskite instead of zinc oxide on growth performance,apparent nutrient digestibility and fecal zinc excretion in weaned piglets

The aim of this study was to determine the effects of dietary supplementation of palygorskite instead of zinc oxide (ZnO) on growth performance, apparent nutrient digestibility and zinc contents in serum and feces in weaned piglets. One hundred and sixty‐five piglets (28 days of age, 7.10 ± 0.86 kg) were allotted to five treatments on the basis of weight and sex. Each treatment included three replicates of 11 piglets. The piglets were fed the same basal diet supplemented with 0 mg/kg (control group), 1800 mg/kg, 2400 mg/kg, or 3000 mg/kg palygorskite or 2500 mg/kg ZnO for 28 days. There was no significant difference for incidence of diarrhea among the four treatments during the 0–14‐day feeding period. Compared with the control group, piglets offered diets supplemented with 1800 mg/kg palygorskite had higher (P < 0.05) average daily gain (ADG) and crude protein digestibility. Fecal digestibility of energy in 1800 mg/kg palygorskite and ZnO groups were higher (P < 0.05) than that in the control group. Both the zinc concentrations in serum and fecal zinc excretion in palygorskite groups and control group were all lower (P < 0.05) than that in the ZnO group. In conclusion, dietary supplementation with 1800 mg/kg palygorskite can improve growth performance and nutrient digestibility and can also decrease zinc excretion in feces in weaned piglets.     

Effects of exogenous cortisol on the GH/IGF-I/IGFBP network in channel catfish

Glucocorticoids are known to hinder somatic growth in a number of vertebrate species. In order to better understand the mechanisms through which they may act in channel catfish, we examined the effects of feeding cortisol on the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein (IGFBP) network. Fish (30.6 ± 3.0 g) were fed once daily for 4 weeks and treatments included: (1) High-cortisol (dietary cortisol provided at 400 mg/kg feed), (2) Low-cortisol (dietary cortisol provided at 200 mg/kg feed), and (3) Control (commercial catfish feed). Fish fed diets with cortisol weighed approximately 50% less than Controls. Feed intake was reduced by approximately 30% in both treatments of cortisol fed fish compared to Controls. A 20-kDa IGFBP was observed in plasma from High- and Low-treated fish while it was not detected in Control fish plasma. High-cortisol treatment increased pituitary GH mRNA expression approximately 10-fold while liver IGF-I mRNA expression was not different between cortisol-treated fish and Controls. Cortisol treatments decreased plasma levels of IGF-I. These data indicate that feeding cortisol for 4 weeks reduces weight gain, feed intake, and plasma levels of IGF-I and induces a 20-kDa IGFBP. One mechanism through which cortisol may impede growth of catfish is through an increase in a low molecular weight IGFBP which may lead to inhibitory effects on the action of IGF-I.     

Dietary replacement of fish meal by defatted and fermented soybean meals with taurine supplementation for pompano fish: effects on growth performance,nutrient digestibility,and biological parameters in a long-term feeding period

A 16-wk growth trial was conducted to examine the effects of dietary replacement of fish meal by defatted soybean meal (SBM) and fermented soybean meal (FSBM) with taurine supplementation on growth performance, nutrient apparent digestibility coefficient (ADC) and biological parameters of pompano fish. The FSBM was produced by fermenting SBM with Lactobacillus spp. Seven isonitrogenous and isoenergetic diets were formulated to replace 35% or 50% of fish meal by SBM or FSBM with taurine supplementation. The diets are denoted as follows: FM, SBM35, SBM35T, FSBM35T, SBM50, SBM50T, and FSBM50T. The FM (the basal diet) contained fish meal as a main source of dietary protein. Taurine was supplemented to SBM35T, FSBM35T, SBM50T, and FSBM50T at the level of 15 g/kg diet. Pompano juveniles with an initial body weight (BW) of 80 g reared in floating net cages were fed the experimental diets twice daily for 16 wk. Results showed that the final BW, weight gain, and feed conversion ratio of fish fed SBM35 and SBM50 were significantly lower than those of fish fed FM (P < 0.05), indicating that the replacement of fish meal by SBM at the rate of 35% in the diet is excessive for pompano. Supplementation of taurine to the SBM-included diets significantly increased growth performance and feed utilization (P < 0.05); however, these diets did not restore the performance back to a level equivalent to that of fish offered the basal diet. Meanwhile, fish fed FSBM35T had comparable growth and feed performances to those fed FM. Hematocrit values, total biliary bile acid levels, whole body lipid contents, and tissue taurine concentrations of fish fed SBM35 and SBM50 were the lowest among the treatments, but these parameters were improved by taurine supplementation and FSBM inclusion in the diet. Taurine supplementation increased lipid ADC, and SBM fermentation slightly enhanced both lipid and protein ADCs of the fish. These findings suggest that the combination of FSBM and taurine supplementation is an effective way to improve growth performance, nutrient digestibility, and biological parameters, and that FSBM with taurine supplementation can replace 35% of fish meal in pompano diets without any negative effects on growth and feed performances in a long-term feeding period.     

Organ traits and histopathology of rabbits fed varied levels of dietary fumonisin B1

In a 196‐day feeding trial, 48 male crossbred rabbits (New Zealand × Chinchilla) were randomly assigned and fed varied dietary fumonisin levels of 0.13, 5.0, 7.5 and 10.0 mg fumonisin B₁/kg diet constituting treatments 1 (control), 2, 3 and 4 respectively. Five animals were randomly selected, stunned and killed per treatment. Relative weight of various visceral organs examined except heart and adrenal gland were significantly (p < 0.05) influenced by the dietary treatments. Liver and spleen weights of rabbits fed 10.0 mg fumonisin per kg were significantly (p < 0.05) lower than those fed control diet and diet 2. Kidney and testes weights were significantly (p < 0.05) lower in rabbits fed control diet and increased with increase in the dietary fumonisin levels. Histological examination of the organs revealed that rabbits fed diets 2, 3 and 4 showed increased severe lesion of approximately 20%, 40% and 60%, respectively, of the total slides examined for each treatment. Forty per cent and 80% of the rabbits fed diets containing 7.5 and 10.0 mg/kg fumonisin, respectively, showed severe necrosis whereas 40%, 60% and 20% of the rabbits fed 5.0, 7.5 and 10.0 mg/kg, respectively, showed mild–moderate liver necrosis/lesions as compared with non‐significant lesion observed in the controls. Testicles of rabbits fed diets 3 and 4 showed mild–moderate lesions and sertoli cell degeneration. Tunica mucosa erosion was observed and predominant in the stomach and small intestine of rabbits fed 7.5 and 10.0 mg fumonisin per kg diet. This suggested that fumonisin B₁ above 5.0 mg/kg in rabbit diet is toxic to body organs with potential to induce their hypofunction or total damage.     

Tryptophan and threonine requirements of young pigs and their effects on serum calcium, phosphorus and zinc concentrations

Four 28-d trials were conducted using a total of 432 pigs, with average initial weight across trials ranging from 6.3 to 9.7 kg, to estimate the tryptophan (trials 1 and 2) and threonine (trials 3 and 4) requirements of pigs fed low protein, corn-sunflower meal diets. The effect of tryptophan, threonine and protein level on serum calcium, phosphorus and zinc also was studied. The diets contained either 12 or 13% protein and were calculated to be adequate in all nutrients except crude protein and the amino acid being investigated. A lysine supplemented, 18% protein, corn-sunflower meal diet was included in all trials as a positive control. In trial 1, weight gains of pigs increased linearly (P less than .005) while feed conversion improved cubically (P less than .05) as dietary tryptophan increased from .14 to .22%. Pigs fed the 18% protein diet gained faster (P less than .05) and required less feed/gain than pigs fed low protein diets. In trial 2, weight gains improved quadratically (P less than .005) and feed conversion improved linearly (P less than .05) as dietary tryptophan increased from .104 to .204%. Serum phosphorus and zinc concentrations were lower (P less than .05) in pigs fed the 18% protein diet. In both trials, serum urea N responded quadratically (P less than .05) to increasing dietary tryptophan, and was lower (P less than .05) in pigs that were fed diets supplemented with L-tryptophan than in those fed the low protein basal or 18% protein diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

实用饲料中补充铜对斑点叉尾生长和体色的影响

在实用饲料(含铜11.1 mg/kg)中分别添加0(对照)、5、10、20和40 mg/kg铜[以五水硫酸铜(CuSO_4·5H_2O)形式],制成5种试验饲料,投喂平均体重为(98.1±0.5)g的斑点叉尾42 d,研究实用饲料中补充铜对斑点叉尾生长和体色的影响。每种饲料设3个重复,每个重复放养20尾鱼。结果表明:与对照组相比,饲料中添加10 mg/kg铜显著提高了鱼体的增重率(P0.05),显著降低了饲料系数(P0.05);饲料铜添加量进一步增加到40 mg/kg,鱼体的增重率则较添加量为10 mg/kg时显著降低(P0.05),同时饲料系数显著升高(P0.05)。肝脏和骨骼铜含量随着饲料中铜添加量的增加而上升,其中20、40 mg/kg铜添加组的肝脏铜含量显著高于对照组和5 mg/kg铜添加组(P0.05),40 mg/kg铜添加组的骨骼铜含量也显著高于对照组(P0.05),而肌肉铜含量保持基本不变(P0.05)。饲料中添加0~40 mg/kg铜对斑点叉尾背部皮肤、肌肉色度值、总叶黄素含量及背部皮肤酪氨酸酶活性均未产生显著影响(P0.05)。各组血清天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)活性和总胆红素(T-Bil)含量以及肌肉水分、粗蛋白质、粗脂肪和粗灰分含量无显著差异(P0.05)。10 mg/kg铜添加组具有最高的血清铜锌-超氧化物歧化酶(Cu,Zn-SOD)活性,显著高于其他各组(P0.05),而其他各组间则无显著差异(P0.05)。综上,在本试验条件下,斑点叉尾实用饲料中铜的添加量建议为10 mg/kg(饲料铜含量实测值为20.2 mg/kg)。