Influence of Commercial Diets on Quality Aspects of Cultured Gulf of Mexico Surgeon (Ancipenser oxyrinchus desotoi)

ABSTRACT: Cultured sturgeons were fed commercially available diets formulated for hybrid bass, catfish, and trout. The impact of these diets in the quality of the edible muscle was investigated through determination of processing yields, proximate compositions, fatty acid profiles, muscle color, and sensory characteristics. Sturgeon fed the catfish diet were significantly smaller but dressed fillets (percent live weight) were similar for all feeds. Consumer visual acceptability scores were highest for fillets from fish fed the catfish diet, and color differences were determined. Sturgeon fillets from fish fed the trout diet presented a yellowish orange coloration instead of a pale pink coloration. Results show that the diets tested had no detrimental impact in the composition of sturgeon fillets.     

Chronic effects of dietary selenium on juvenile Sacramento splittail (Pogonichthys macrolepidotus)

The chronic effects of dietary selenium (Se) exposure in juvenile Sacramento splittail (Pogonichthys macrolepidotus) were investigated in the laboratory. A total of 960 (40 fish per tank, 3 tanks per diet) 7-month-old juvenile splittail were fed one of eight Purified-Casein diets supplemented with selenized yeast for 9 months in a flow-through system. These diets contained the following: 0.4 (control), 0.7, 1.4, 2.7, 6.6, 12.6, 26.0, and 57.6 mg of Se kg(-1) dry weight. Survival, Se tissue concentration, growth, gross morphology, and liver histopathology were assessed at 5- and 9-month of exposure. Mortalities occurred only in the two highest Se treatments and were accounted for 8.3 and 18.3% at 5-month and 10.0 and 34.3% at 9-month, respectively. Liver and muscle Se concentration were significantly correlated with dietary Se concentration. Fish exposed to 0.4-12.6 mg of Se kg(-1) diets had reached equilibrium in liver Se concentration by 5 month. Splittail fed diets at concentrations > or =26.0 mg of Se kg(-1) had not reached equilibrium in liver, and muscle Se concentrations and grew significantly slower (p < 0.05) at 5- and 9-month exposure. Se-induced deformities were observed in fish fed > or =2.7 mg of Se kg(-1) diets at 5-month and in fish fed > or =0.7 mg of Se kg(-1) diets at 9-month. Fish fed 26.0 and 57.6 mg of Se kg(-1) diets had higher liver lesion scores at 5-month while fish fed 6.6 and 57.6 mg of Se kg(-1) diet had higher liver lesion scores at 9-month. Results indicate that survivals, growth, changes of tissue Se concentrations, and histopathology of juvenile splittail were dose-dependent, but their response thresholds to dietary Se concentrations differed and depended on treatment concentrations and duration of exposure. Chronic exposure to 6.6 mg of Se kg(-1) diet induced deleterious health effects that can potentially impact survival of juvenile splittail.     

Effect of Soybean Meal-based Diets on the Product Quality of Rainbow Trout Fillets

ABSTRACT:  This study investigated the long-term effects of soybean meal (SBM)-based diets on rainbow trout quality. Two levels of SBM inclusion diets, 20% and 40%, were employed and compared with a fish meal control diet. Rainbow trout were fed one of the three diets for 6 mo, then harvested and filleted. Proximate composition, color, lipid oxidation and sensory quality of the fillets were evaluated. Thiobarbituric acid reactive substances (TBARS) and headspace propanal in ground fillets stored at 4 °C were measured over a 9-d period. Tristimulus color was measured on day 2 and day 13 of refrigerated storage. Sensory evaluation included discriminatory (difference) and affective (acceptance) testing. TBARS and propanal in the trout fed the highest (40%) SBM level were significantly lower than in the control and trout fed the 20% SBM diet. Significant differences in color were also recorded during refrigerated storage. Sensory difference testing revealed a significant difference between the trout fed the 40% SBM and the control. No significant differences were observed in the acceptability ratings of trout fillets from the three different dietary treatments.     

EFFECT OF DIETARY PROTEIN AND FAT LEVELS ON LIVER AND URINARY BLADDER NEOPLASIA IN MICE FED 2-ACETYLAMINOFLUORENE

Weanling female BALB/c mice were continuously fed diets containing combinations of 12 or 24% protein, 4 or 24% fat and 500 ppm of 2 acetylaminofluorene (2-AAF) for 78 weeks. Mice on the high fat diets demonstrated a significant increase in the incidence of hepatocellular neoplasms and urinary bladder carcinomas. The incidence of both liver tumors and bladder tumors was reduced in the mice fed low fat and low protein diet compared to the other three diets. The protein levels alone appeared to have no effect on the incidence of bladder tumors or liver tumors. Mice fed the diet with lower levels of fat and protein showed a significant decrease in the incidence of bladder carcinomas compared to the mice fed the higher levels of fat andlor protein.     

Effects of yeast culture and galacto-oligosaccharides on ruminal fermentation in holstein cows

Four nonlactating, ruminally cannulated Holstein cows were used in a 4 x 4 Latin square design, balanced for residual effects, to evaluate the effects of supplementing dairy cow diets with yeast culture (Trichosporon sericeum; YC), galacto-oligosaccharides (GOS), or the mixture of YC and GOS on ruminal fermentation, microbial N supply, in situ degradation, and energy and nitrogen metabolism. Treatments were arranged in a 2 x 2 factorial as follows: 1) basal diet, 2) basal diet plus 10 g/d YC, 3) basal diet plus 2% GOS, 4) basal diet plus a mixture of 10 g/d YC and 2% GOS. Nitrogen losses in urine were lower, and retained N was higher, for cows supplemented with a mixture of YC and GOS. Ruminal pH was lower in cows supplemented with GOS alone compared with other treatments. Total VFA concentration was higher in cows fed control and GOS-supplemented diets than in those fed YC containing diets. The molar proportion of propionate was higher, and the molar proportion of acetate was lower, in cows fed control diets. Microbial N supply was higher in cows fed control diets. There were no major positive effects of supplements observed in this study. However, supplementation of a mixture of YC and GOS had a tendency for synergistic effects on N metabolism and in situ degradation of a soluble fraction of oat straw DM and CP of concentrates compared with supplementation of YC or GOS alone.     

Effects of diet supplementation with cactus pear seeds and oil on serum and liver lipid parameters in rats

The purpose of this investigation was to evaluate the effects of diets enriched with cactus pear oil (CPO) or seeds (CPS) on serum and liver lipid parameters compared to those of adult rats submitted to a standard diet. Male rats were divided into three groups, the first group represented control group, fed with standard diet, the second group was fed with control diet supplemented with CPO (2.5%, wt/wt) and the third group fed control diet supplemented with CPS (33%, wt/wt), for nine weeks. Feed intake and body weight of rats were measured every two days. Organ weights were determined at the end of treatment; cholesterol, HDL and triglycerides levels were determined by enzymatic methods. Liver and serum lipid extracts were analysed for their fatty acid composition for the three groups of rats. No differences in pancreas, kidney or liver weights were observed in the CPS diet whereas the CPO diet induced a significant increase in liver and pancreas weights. The tested diets significantly decreased the atherogenic index compared to the control diet, whereas serum cholesterol level was only reduced by the supplementation with CPO diet. No variations in serum lipids were observed among the groups, whereas liver lipids showed slight variations. Accordingly, these results indicated that the supplementation with CPO or CPS could be effective in decreasing the atherogenic risk factors in rats.     

Long-term feeding of high zinc sulfate diets to lactating and gestating dairy cows

Thirty dairy cows, fed a control diet consisting of silage and concentrates, were given either 0, 1000, or 2000 ppm of supplemental Zn (DM basis), from zinc sulfate monohydrate (ZnSO4.H2O) for most of a lactation. Feeding 2000 ppm Zn decreased milk yield and feed intake after several weeks. Some cows were affected more severely than others. Generally, primiparous animals were more tolerant of the high Zn diet than multiparous cows. Milk Zn was materially higher for cows fed 1000 ppm added Zn than controls. With 2000 ppm Zn, milk Zn was elevated further but returned to control values when the high Zn diet was discontinued. Plasma Zn was higher in cows fed supplemental Zn with the increase from 1000 to 2000 greater than that for the first addition. Plasma Cu was lower in cows feed 2000 ppm Zn but milk Cu was not reduced. Milk fat content was not affected, but protein and SNF were reduced by the 12th wk with the 2000 ppm Zn diet. There was no apparent effect on long-term health or performance after the cows were removed from the 2000 ppm Zn diet. Except for lower calf weights with 2000 ppm Zn, reproductive performance was not measurably affected by the dietary treatments. The 1000 ppm added Zn diet had no adverse effect on the cows in any parameter measured.     

Restoration of EPA and DHA in rainbow trout (Oncorhynchus mykiss) using a finishing fish oil diet at two different water temperatures

Feeding fish a fish oil finishing diet (FOFD) after grow-out on vegetable oil diet is one strategy to restore eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels. We investigated restoration of EPA and DHA in rainbow trout fed a FOFD preceded by a grow-out period on 50% or 75% palm fatty acid distillate (PFAD) diets at optimal (15 °C) or elevated (20 °C) water temperatures. Using the FOFD restored EPA and DHA in fillet and whole carcass of fish previously fed either 50% PFAD diet from 85% to 98% or 75% PFAD from 66% to 93% of values obtained for fish fed FO diet throughout. Water temperature did not influence EPA and DHA restoration. Growing rainbow trout with diets where FO was replaced by either 50% or 75% PFAD followed by a FOFD reduced FO usage by around 30% and 44% at 15 °C, respectively, and 32% and 48% at 20 °C, respectively.     

Identification of odour‐active compounds in muscle of brown trout (Salmo trutta) as affected by dietary lipid sources

The effect of fatty acid composition on odour‐active compounds in brown trout (Salmo trutta) muscle was evaluated. The fillets were obtained from three groups of fish fed experimental diets containing either fish oil (FO), soybean oil (SO) or linseed oil (LO). Muscle fatty acid composition was shown to be influenced by diet. Thirty‐one odorous compounds were detected by gas chromatography/olfactometry (frequency‐of‐detection method). Most of these compounds were formed by the oxidation of unsaturated fatty acids. Independently of diet, (E)‐2‐pentenal, (E)‐2‐pentenol and (E)‐2‐hexenol contribute strongly to the odour of brown trout. (E,Z)‐2,4‐Heptadienal was detected with high frequency in fish fed diets containing high levels of n‐3 PUFAs (FO and LO groups). Hexanal, (E)‐2‐hexenal and 2‐nonanol seem to contribute most to the odour of fish fed diets containing vegetable oils. Many odorous compounds were derived from the oxidation of mono‐ and di‐unsaturated fatty acids, which could be promoted by high levels of PUFAs. © 2002 Society of Chemical Industry     

Muscle carotenoid content and colour of farmed rainbow trout fed astaxanthin or canthaxanthin as affected by cooking and smoke-curing procedures

Carotenoids and colour characteristics were studied in raw, steamed and smoke-cured muscle of rainbow trout fed synthetic astaxanthin (50 or 100mgkg^-1 diet) or canthaxanthin (100mgkg^-1 diet) for 15 months.
In raw muscle main carotenoid concentration was strongly correlated with hue, chroma, and lightness. Diet and sex effects were significant on most traits, with little or no interaction. Female muscles contained much more carotenoid and were more coloured than male ones. Astaxanthin fed fish were more red than canthaxanthin fed fish.
Significant mean effects of cooking were an apparent increase of carotenoid concentration and an increase of lightness. Hue and chroma were practically unchanged with high correlations between raw and cooked muscle measurements. Lightness increased and differences between sexes and individuals were reduced.
Smoke-curing induced an increase of carotenoid concentration and a decrease of hue and lightness. Hue of canthaxanthin fed fish when smoke-cured was similar to that of raw fish fed astaxanthin. Lightness, still dependant on that of the raw muscle, was reduced and differences among diets, sexes and individuals were reduced.     

Biotransformation enzymes and thyroid axis disruption in juvenile rainbow trout (Oncorhynchus mykiss) exposed to hexabromocyclododecane diastereoisomers

Juvenile rainbow trout (Oncorhynchus mykiss) were fed either a reference diet or one of three diets enriched with alpha, beta, or gamma diastereoisomers of hexabromocyclododecane (HBCD, C12H18Br6) for 56 days. This exposure period was followed by 112 days during which all fish were fed the reference diet. Potential effects of HBCD on phase I and II biotransformation enzyme activities and thyroid axis disruption were examined. Disruption of the thyroid axis was most evident in the gamma-HBCD exposed group, as indicated by lower circular FT4 and higher FT3 as well as an increase in thyroid epithelial cell height. However, fish fed the alpha-HBCD enriched diet also exhibited altered glucuronyltransferase activity and thyroid epithelial cell heights and the beta-HBCD group had altered FT4 and FT3 and glucuronyltransferase activity. T4ORD activity was not affected after 14 days, but was significantly lower among all HBCD exposed fish compared to the reference fish after 56 days. Results from these experiments indicate that all isomers have the potential to disrupt thyroid homeostasis.     

Effect of Dietary Partial Hydrolysate of Phospholipids,Rich in Docosahexaenoic Acid‐Bound Lysophospholipids,on Lipid and Fatty Acid Composition in Rat Serum and Liver

Lysophospholipids have been recognized as potent biologically active lipid mediators. However, attention has not been paid to the health benefits of dietary partial hydrolysate of phospholipids (PH‐PL), which is rich in docosahexaenoic acid (DHA)‐bound lysophospholipids. In this study, the effects of PH‐PL on serum and liver lipid profiles of rats upon administration of PH‐PL are demonstrated in comparison to those of fish oil (FO), which comprises eicosapentaenoic acid (EPA) and DHA‐bound triglyceride (TG). PH‐PL containing EPA and DHA was prepared via enzymatic modification of squid (Todarodes pacificus) meal that is rich in phospholipids. Male Wistar rats were fed a basal diet containing soybean oil alone (7%), FO, and PH‐PL. The FO and PH‐PL diets had similar EPA and DHA contents. After the rats had been fed their respective diets for 28 d, their serum and liver lipid contents, fecal lipid excretion, and hepatic gene expression level were measured. The results demonstrated that compared with the soybean oil diet alone, the PH‐PL diet decreased serum and liver TG contents partially because of the enhancement of liver acyl‐CoA oxidase activity and suppression of liver fatty acid synthase activity. In addition, compared with the soybean oil diet, the PH‐PL group exhibited lower serum cholesterol content at least in part because of the reduction of hepatic 3‐hydroxy‐3‐methylglutaryl‐CoA reductase mRNA expression level. We found that dietary administration of EPA and DHA containing PH‐PL has a hypolipidemic effect that may help prevent the development lifestyle‐related diseases.     

EFFECT OF DIETARY FIBER ON THE PREVENTION OF LIVER LIPID ACCUMULATION INDUCED BY HIGH POLYUNSATURATED OIL

This study investigated whether dietary fiber can prevent the accumulation of liver lipids due to the ingestion of polyunsaturated oil. Fifteen percent fish oil (FO) was added to the basal diet as a source of polyunsaturated oil. Ten percent cellulose, pectin, guar gum, konjac mannan or gum Arabic was mixed in the diet as a source of dietary fiber. Commercial Purina rat chow was used as a control and a fiber-free (blank) diets were also employed in the study. Each experimental diet was fed to each group of 6 Wistar rats for 8 weeks. Fish oil feeding lowered the plasma triacylglycerols (TG) and cholesterol (CS) levels. Rats fed a fiber-free diet had higher liver weights indicating hepatomegaly and a marked accumulation of liver lipids. With the exception of cellulose and gum Arabic, the inclusion of dietary fiber in FO diets lowered the plasma total lipids and CS; plasma TG was unchanged. Pectin and guar gum enhanced the CS-lowering effect of the FO diet. All of the test fibers, but especially pectin and guar gum, reduced the accumulation of total lipids, TG and CS in rat liver caused by dietary FO. Hepatic glucose-6-phosphate dehydrogenase activity was reduced in rats fed FO, but dietary fiber had no effect on the activity of this enzyme.     

The influence of selected technological processes on the improvement of rapeseed meal and flour feed quality. Part 2. Effect of hydrothermal treatment and ethanol extraction on the nutritional value of rapeseed products

In experiments with rats the effect of feeding flours (dehulled and defatted seeds) and concentrates (flour extracted with ethanol) prepared from non-heated and heated seeds of low-glucosinolate rapeseed var. Jantar was studied. Flours and concentrates were fed either as the main protein supplement in cereal-based diets or as the only protein sources in semi-synthetic diets; ethanolic extracts were either administered by stomach tube or fed with the diets. Heat treatment of seeds reduced ITC + VOT contents about 27 % and did not affect phenol contents; ethanol extraction removed both ITC + VOT and phenols. Feeding the flours from heated and non-heated seeds resulted in the increase of thyroid and liver weights as compared with rats from the control group fed on soybean diet. Heat treatment of seeds improved protein digestibility of flours and concentrates and did not modify negative effect of ethanol extract on protein digestibility. Biological value of protein of flours and concentrates was not affected by heat treatment of seeds. Feeding concentrates influenced positively animal growth performance, elimenated hypertrophic effect of the flour on thyroid and liver, increased biological value of protein as compared with flour. Administration of ethanolic extracts containing ITC + VOT and phenols to rats fed on soya-bean mael diet did not induce hypertrophy of thyroid and liver similar to that observed in rats fed on flours containing these antinutritional substances.     

Effect of low level monensin supplementation on the production of dairy cows fed alfalfa silage

Effectiveness of low level monensin supplementation on N utilization in lactating dairy cows fed alfalfa silage was assessed using 48 multiparous Holsteins. Cows were fed a covariate diet [% of dry matter (DM): 56% alfalfa silage, 39% ground high moisture corn, 3% soybean meal, 1% ground corn, 1% vitamin-mineral supplements] for 2 wk, then grouped by days in milk into blocks of 4. Cows were randomly assigned within blocks to 1 of 4 diets that were fed for 10 wk: 1) control (covariate diet), 2) control plus 3% fish meal (replacing DM from high moisture corn), 3) monensin (10 mg/kg DM), and 4) monensin plus 3% fish meal. Diets 1 and 3 averaged 16.7% crude protein (25% from free AA in alfalfa silage); diets 2 and 4 averaged 18.5% crude protein. Monensin intake averaged 16 mg/d on diets 1 and 2 (due to contamination) and 248 mg/d on diets 3 and 4. There was no effect of fish meal or monensin on DM intake. However, weight gain and yield of milk, protein, and SNF increased with fish meal feeding, indicating metabolizable protein limited production. Feeding monensin increased blood glucose but reduced yield of 3.5% fat-corrected milk, milk fat content and yield, and milk protein content and yield. Apparent N efficiency was greatest on monensin (diet 3) but lowest on monensin plus fish meal (diet 4). Fish meal reduced blood glucose concentration and apparent N efficiency, and increased concentrations of milk and blood urea. Monensin increased ruminal propionate concentration and decreased concentration of acetate and butyrate and acetate:propionate in ruminally cannulated cows fed the experimental diets. However, these changes were small, suggesting that too little monensin was fed. Fish meal reduced ruminal total amino acid (AA) but monensin did not alter ruminal NH(3) or total AA. Both fish meal and monensin increased NH(3) formation from casein AA using ruminal inoculum from the cannulated cows. There was no evidence from this trial that feeding 250 mg of monensin per day to lactating cows improved N utilization by reducing ruminal catabolism of the large amounts of free AA in alfalfa silage.     

Effects of dietary methylmercury on reproduction of fathead minnows

We examined effects of dietary methylmercury (MeHg) on reproduction of fathead minnows (Pimephales promelas). Juvenile fish were fed one of four diets until sexual maturity (phase 1): a control diet (0.06 microg Hg g(-1) dry weight) and three diets contaminated with MeHg at 0.88 (low), 4.11 (medium), and 8.46 microg Hg g(-1) dry weight (high). At sexual maturity, male and female fish were paired, again fed one of the four diets, and allowed to reproduce (phase 2). To assess effects of MeHg during gametogenesis, some fish were fed diets during phase 2 that differed from those during phase 1. Spawning success of pairs fed the same diet during phases 1 and 2 was 75% for controls and 46%, 50%, and 36% for the low-, medium-, and high-MeHg treatments, respectively. Spawning success of pairs fed a contaminated diet during phase 1 and a control diet during phase 2 was 63%, 40%, and 14% for the low-, medium-, and high-MeHg treatments, respectively, whereas exposure to dietary MeHg only during phase 2 did not reduce spawning success. Dietary MeHg delayed spawning, and days to spawning was positively correlated with concentration of total mercury in the carcasses of test fish. MeHg reduced the instantaneous rate of reproduction of fish fed the same diets during phases 1 and 2. Both the gonadosomatic index and reproductive effort of female fish were inversely correlated with mercury in carcasses, whereas developmental and hatching success of embryos, 7-d survival, and 7-d growth of larvae were unrelated to mercury concentrations in parental fish or their diets. MeHg decreased reproduction of adult fathead minnows at dietary concentrations encountered by predatory fishes in aquatic systems with MeHg-contaminated food webs, implying that exposed fish populations could be adversely affected by this widespread contaminant.     

Investigation of the sensory properties of the flesh of rainbow trout (Oncorhynchus mykiss) fed diets with astaxanthin, shrimp waste meal and red pepper meal

Sensory properties (colour, general appearance and taste) were investigated in rainbow trout, Oncorhynchus mykiss, fed standard diets supplemented with either 60 mg/kg astaxanthin, shrimp waste meal or red pepper meal. The fish were divided into three experimental groups (fed diets supplemented with pigments) and one control group, and fed experimental and control diets for 100 days. After the feeding period, the fish were evaluated for sensory properties. Colour was evaluated using a colour card for salmonids. General appearance and taste were evaluated using hedonic scaling. Significant differences between the fish fed diets with and without pigment supplementation were found. Feeding of rainbow trout with diets supplemented with pigments affected their sensory properties.     

The effect of digesta sampling time and dietary protein source on ileal nitrogen digestibility for the growing rat

The effect of time that digesta were collected on the quantity and representativeness of ileal digesta and on the determination of apparent and true ileal nitrogen (N) digestibility for growing rats was investigated. Semi‐synthetic diets containing chromic oxide as an indigestible marker were given to 200 g live weight rats for 8 days as a single daily meal. The experimental treatments comprised six diets (lactalbumin, soy protein isolate, wheat gluten, fish, protein‐free (PF), enzymically hydrolysed casein (EHC)) and four ileal digesta sampling times (3, 4, 5 and 6 h after the start of feeding). On the eighth day the rats were fed and slaughtered according to treatment, and digesta were sampled from the terminal ileum. Endogenous ileal nitrogen excretion was determined using both the protein‐free and peptide alimentation methods. There was a significant (P = 0.027) effect of experimental diet averaged across sampling times for chromium recovery (CrRec). The CrRec was higher for the rats fed the PF diet than for the other diets. Responses to sampling time varied significantly (P < 0.05) among diets for ileal digesta weight (IDW), nitrogen/chromium (N/Cr) ratio, ileal digesta weight relative to dry matter intake (IDW/DMI), CrRec, N flow, apparent N digestibility and true N digestibility (determined using the protein‐free method). The optimal digesta sampling times for each of the diets were 3 h for PF, EHC, lactalbumin and fish and 4 h for soy protein isolate and wheat gluten. Consequently, 3 or 4 h after the start of feeding is recommended as the optimum ileal digesta sampling time for most purified protein sources when fed to the growing rat as a single daily meal. © 2002 Society of Chemical Industry     

FISH OIL WITH ESSENCE OF CHICKEN DECREASES SERUM AND HEPATIC TRIACYLGLYCEROL IN HAMSTERS FED AN ATHEROGENIC DIET

The aim of the present study was to investigate the effect of a mixture of dietary chicken essence and fish oil on possible lowering of blood and hepatic lipids in hamsters. Forty male hamsters were randomly divided into four groups and fed a chow diet, high fat/cholesterol diet (HFC), HFC diets containing 4% (HFC4) or 8% (HFC8) fish oil with essence of chicken for 42 days. The experimental diets contained 10% (w/w) fat. Hamsters fed HFC diets containing either 4 or 8% fish oil with essence of chicken showed significantly decreased serum triacylglycerols (TG) compared to hamsters fed HFC diets. In addition, hamsters fed HFC8 diets exhibited significantly reduced hepatic TG than those fed HFC diet. However, hamsters fed HFC4 or HFC8 diets significantly increased low density lipoprotein cholesterol (LDL-C) and decreased high density lipoprotein cholesterol (HDL-C) when compared with those on HFC diet. These results suggest that 4% (or more) fish oil with essence of chicken might significantly lower serum TG and hepatic TG in hamsters, but seem to increase serum cholesterol levels on HFC diets.