Glyphosate tolerant canola meal is equivalent to the parental line in diets fed to rainbow trout

Two separate studies were conducted to evaluate the utility of glyphosate tolerant canola (GTC) as a feed ingredient in diets fed to rainbow trout. In the first study, two forms of GTC were compared to a parental line, Westar. In the second study, one line of GTC was reevaluated to Westar. In each study, processed canola meals were incorporated at 5, 10, 15, or 20% of the dry diet and a diet containing no canola was fed for comparison. All diets were fed to triplicate groups of fish in each study. In the first study, weight gain, feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) were not significantly different in fish fed either Westar or GT200 at any level of substitution. Fish fed GT73 exhibited a gradual reduction in weight gain, FE, and PER as the level of GTC increased. However, the only significant reduction was in weight gain of fish fed 20% GT73 as compared to fish fed 5% GT73. Because of an error in preparing samples prior to the experiment, samples GT200 and GT73 were essentially equivalent in composition. The differences were explained by differences in processing temperatures that occurred after the sample mixing error occurred. In the second study, mean weight gain, PR, and survival were not significantly different among forms of canola. FE and PER values were significantly lower in fish fed 15% Westar as compared to fish fed 10% Westar; other FE and PER values were not significantly different. On the basis of these results, GTC processed into a toasted meal and incorporated into diets for rainbow trout is equivalent to a parental line of canola.     

Effects of dietary vitamin B6 supplementation on fillet fatty acid composition and fatty acid metabolism of rainbow trout fed vegetable oil based diets

Fish oil replacement in aquaculture feeds results in major modifications to the fatty acid makeup of cultured fish. Therefore, in vivo fatty acid biosynthesis has been a topic of considerable research interest. Evidence suggests that pyridoxine (vitamin B(6)) plays a role in fatty acid metabolism, and in particular, the biosynthesis of LC-PUFA has been demonstrated in mammals. However, there is little information on the effects of dietary pyridoxine availability in fish fed diets lacking LC-PUFA. This study demonstrates a relationship between dietary pyridoxine supplementation and fatty acid metabolism in rainbow trout. In particular, the dietary pyridoxine level was shown to modulate and positively stimulate the activity of the fatty acid elongase and Δ-6 and Δ-5 desaturase enzymes, deduced by the whole-body fatty acid balance method. This activity was insufficient to compensate for a diet lacking in LC-PUFA but does highlight potential strategies to maximize this activity in cultured fish, especially when fish oil is replaced with vegetable oils.     

Influence of dietary genistein levels on tissue genistein deposition and on the physical, chemical, and sensory quality of rainbow trout, Oncorhynchus mykiss

Genistein, the primary isoflavone in soybean, is one of the chemical components responsible for some of the off-flavors associated with soy-based foods. The potential effects of genistein on the sensory and chemical quality of fish muscle may affect the full utilization of soybean meal as an alternative protein in aquaculture diets. Fingerling trout fed commercial diets containing 0, 500, 1000, or 3000 ppm pure genistein were analyzed after 6 and 12 months of feeding. Genistein was extracted by enzymatic digestions in Tris buffer and quantified by high-performance liquid chromatography. Moisture, fat, protein, ash, and tristimulus color of the fillets were determined. The extent of lipid oxidation occurring in fillets harvested after 12 months of feeding was studied by measurements of thiobarbituric acid reactive substances (TBARS) after 4 and 8 days of refrigerated storage at 4 degrees C. Triangle tests were performed to determine if there were any detectable sensory differences. A dietary genistein content of 3000 ppm led to the deposition of approximately 5.4 pmol of genistein/mg of fillet. Triangle test panelists were unable to detect any significant (p < or = 0.05) differences between the fillets from trout fed the 0 and 3000 ppm genistein concentrations. Moisture, ash, and protein content were influenced by time of harvest, while color was unaffected. TBARS levels on days 4 and 8 were significantly (p < 0.05) higher in the fillets from the 0 ppm genistein level than in fillets from fish fed dietary genistein.     

Uptake by dietary exposure and elimination of aflatoxins in muscle and liver of rainbow trout (Oncorhynchus mykiss)

Uptake and elimination of aflatoxins (AFs) by rainbow trout ( Oncorhynchus mykiss ) during a long-term (21 days) dietary exposure were studied to assess contamination by AFs in aquaculture fish fed AF-containing feed. The uptake factor (UF) of aflatoxin B(1) (AFB(1)) in muscle ranged from 0.40 × 10(-3) to 1.30 × 10(-3). AFB(1) concentrations in liver were 165-342 times higher than in muscle. AFs from feed were more highly accumulated in liver than in muscle. Aflatoxicol (AFL) and aflatoxin M(1) (AFM(1)) were detected in muscle and liver and also in the rearing water. AFL concentrations were higher than AFM(1) by 2 orders of magnitude in muscle, and AFL was a major metabolite of AFB(1). The elimination rate constants (α) of AFB(1) and AFL in muscle (1.83 and 2.02 day(-1), respectively) and liver (1.38 and 2.41 day(-1), respectively) were very large. The elimination half-life (t(1/2)) of AFB(1) was 0.38 days (9.12 h) in muscle and 0.50 days (12.00 h) in liver. The elimination half-life of AFL in muscle and liver was 0.34 day (8.16 h) and 0.29 day (6.96 h), respectively. These data show that AFs are eliminated rapidly and are not biomagnified in fish. Thus, AFB(1) concentration in muscle of fish fed AFB(1)-containing feed (ca. 500 μg/kg) decreased to below the detection limit (20 ng/kg) of the most sensitive analytical method at 1.54 days (36.96 h) after the change to uncontaminated feed.     

棉籽粕固态发酵过程及其动力学模型构建

为了研究枯草芽孢杆菌Bs-1在工业化条件下发酵棉籽粕的过程,该文采用槽式发酵方式,测定了发酵过程中物料堆温、含水率、粗蛋白、酸溶性蛋白和游离棉酚质量分数;并采用Logistic方程建立芽孢杆菌Bs-1生长模型,在其与粗蛋白、酸溶性蛋白和游离棉酚质量分数相关性分析的基础上,构建了固态发酵动力学模型并进行了发酵成本分析。结果表明:棉籽粕槽式发酵过程中的温度和含水率均呈现一定的变化规律;粗蛋白质量分数、酸溶性蛋白质量分数分别较发酵前提高了9.28%和46.51%,游离棉酚质量分数降低了42.31%。Bs-1的生长与粗蛋白质量分数(R2=0.831)和酸溶性蛋白质量分数(R2=0.867)呈正相关,与游离棉酚质量分数(R2=0.976)呈负相关;建立了棉籽粕固态发酵动力学模型。分析表明,该模型计算值与试验值能较好吻合,且发酵成本低。表明该模型可应用于工业化生产,对实现发酵棉籽粕的产业化生产,具有较好的参考价值。     

Detection of transgenic and endogenous plant DNA in digesta and tissues of sheep and pigs fed Roundup Ready canola meal

The persistence of plant-derived recombinant DNA in sheep and pigs fed genetically modified (Roundup Ready) canola was assessed by PCR and Southern hybridization analysis of DNA extracted from digesta, gastrointestinal (GI) tract tissues, and visceral organs. Sheep (n = 11) and pigs (n = 36) were fed to slaughter on diets containing 6.5 or 15% Roundup Ready canola. Native plant DNA (high- and low-copy-number gene fragments) and the cp4 epsps transgene that encodes 5-enolpyruvyl shikimate-3-phosphate synthase were tracked in ruminal, abomasal, and large intestinal digesta and in tissue from the esophagus, rumen, abomasum, small and large intestine, liver, and kidney of sheep and in cecal content and tissue from the duodenum, cecum, liver, spleen, and kidney of pigs. High-copy chloroplast-specific DNA (a 520-bp fragment) was detected in all digesta samples, the majority (89-100%) of intestinal tissues, and at least one of each visceral organ sample (frequencies of 3-27%) from sheep and swine. Low-copy rubisco fragments (186- and 540-bp sequences from the small subunit) were present at slightly lower, variable frequencies in digesta (18-82%) and intestinal tissues (9-27% of ovine and 17-25% of porcine samples) and infrequently in visceral organs (1 of 88 ovine samples; 3 of 216 porcine samples). Each of the five cp4 epsps transgene fragments (179-527 bp) surveyed was present in at least 27% of ovine large intestinal content samples (maximum = 64%) and at least 33% of porcine cecal content samples (maximum = 75%). In sheep, transgene fragments were more common in intestinal digesta than in ruminal or abomasal content. Transgene fragments were detected in 0 (esophagus) to 3 (large intestine) GI tract tissues from the 11 sheep and in 0-10 of the duodenal and cecal tissues collected from 36 pigs. The feed-ingested recombinant DNA was not detected in visceral tissues (liver, kidney) of lambs or in the spleen from pigs. Of note, however, one liver and one kidney sample from the pigs (different animals) were positive for a 278-bp fragment of the transgenic cp4 epsps (denoted F3). Examination of genomic libraries from these tissues yielded no conclusive information regarding integration of the fragment into porcine DNA. This study confirms that feed-ingested DNA fragments (endogenous and transgenic) do survive to the terminal GI tract and that uptake into gut epithelial tissues does occur. A very low frequency of transmittance to visceral tissue was confirmed in pigs, but not in sheep. It is recognized that the low copy number of transgenes in GM feeds is a challenge to their detection in tissues, but there was no evidence to suggest that recombinant DNA would be processed in the gut in any manner different from endogenous feed-ingested genetic material.     

Determination of albendazole and its major metabolites in the muscle tissues of Atlantic salmon,tilapia, and rainbow trout by high performance liquid chromatography with fluorometric detection

A liquid chromatographic procedure for the determination of albendazole ([5-(propylthio)-1H-benzimidazol-2yl]carbamic acid methyl ester) and its major metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole-2- aminosulfone in rainbow trout, tilapia, and salmon muscle with adhering skin tissue is described. The muscle tissue samples are made alkaline with potassium carbonate and extracted with ethyl acetate. The extracts are further subjected to cleanup by utilizing a number of liquid-liquid extraction steps. After solvent evaporation, the residue is reconstituted in mobile phase and chromatographed. The chromatography is carried out on a reversed phase Luna C(18) column, using acetonitrile/methanol/buffer as a mobile phase and a fluorescence detector. The average recoveries from the fortified muscle tissue of the three fish species for albendazole (25-100 ppb), albendazole sulfoxide (15.5-62 ppb), albendazole sulfone (1-10 ppb), and albendazole-2- aminosulfone (10-100 ppb) were 94, 77, 82, and 67%, respectively. The average CV for each compound was < or =10%. The procedure was validated and then applied to the determination of albendazole and its three major metabolites in the muscle tissue of the three fish species obtained after orally dosing with albendazole.     

Bioaccumulation potential of dietary arsenic, cadmium, lead, mercury, and selenium in organs and tissues of rainbow trout (Oncorhyncus mykiss) as a function of fish growth

The distribution and potential bioaccumulation of dietary arsenic, cadmium, lead, mercury, and selenium in organs and tissues of rainbow trout (Oncorhyncus mykiss Walbaum, 1792), a major aquaculture species, was studied in relation to fish growth over a period of >3 years. Fish were reared under normal farming conditions, that is, fed a standard fish food and exposed to negligible levels of waterborne trace elements. The age-related variations in the content of each trace element in gills, kidney, liver, muscle, and skin were studied through nonparametric regression analysis. A buildup of all elements in all tissues and organs was observed, but due to dilution with growth, the concentrations did not increase, except in a few cases such as cadmium and mercury in liver and kidney. In muscle tissue, the concentrations of mercury, lead, and selenium did not alter significantly with growth, whereas cadmium increased but remained at exceedingly low levels. The concentration of arsenic in muscle tissue peaked at 14 months and then decreased in adult specimens. Arsenic speciation by high-performance liquid chromatography--inductively coupled plasma mass spectrometry revealed that arsenic in muscle was almost exclusively present in the form of nontoxic arsenobetaine. Application of a mercury mass balance model gave predicted concentrations in agreement with measured ones and showed that in farmed rainbow trout the ratio of mercury concentrations in feed and in fish is about 1:1. Therefore, rainbow trout does not approach the limits established for human consumption even when reared with feed at the maximum permitted levels. These findings highlight the low bioaccumulation potential of toxic trace elements such as cadmium, lead, and mercury in rainbow trout following dietary exposure. On the other hand, selenium concentrations in muscle (about 0.2 microg g (-1) of fresh weight) show that rainbow trout may be a good source of this essential element.     

Determination of 17alpha-methyltestosterone in muscle tissues of tilapia, rainbow trout, and salmon using liquid chromatography-tandem mass spectrometry

An analytical method was developed to quantitate and confirm the presence of 17alpha-methyltestosterone in the muscles of tilapia, rainbow trout, and salmon. The method employed two liquid-liquid partitioning steps and two solid-phase extraction columns for sample cleanup. The final extracts were analyzed on an isocratic reverse-phase liquid chromatography-tandem mass spectrometry system with atmospheric-pressure chemical ionization in the positive ion mode. The method was validated at levels from 0.40 to 1.6 ng/g, with MT-d3 used as an internal standard. The accuracy was between 100% and 110%, and coefficients of variation of <10% were obtained for all three fish species. Muscle tissues from dosed fish were also assayed to demonstrate the effectiveness of the method for recovering the parent drug.     

A quantitative method for the determination of cyclopropenoid fatty acids in cottonseed, cottonseed meal, and cottonseed oil (Gossypium hirsutum) by high-performance liquid chromatography

Cyclopropenoid fatty acids (CPFAs), found in cottonseed, have been shown to have detrimental health effects to susceptible livestock. Previous quantitative analytical methods for the determination of CPFAs expressed these acids in terms of their relative abundance with respect to other fatty acids in the oil, necessitating the concurrent analysis of other fatty acids. The proposed analytical method describes the quantitation of three relevant CPFAs for cotton (malvalic acid, sterculic acid, and dihydrosterculic acid) in cottonseed in micrograms per gram fresh weight of sample. The method involves extraction of the oil, saponification, and derivatization of the free fatty acids with 2-bromoacetophenone to give the phenacyl esters. These esters are then separated by dual-column reverse-phase high-performance liquid chromatography and quantitated via external standards. This is the first method to include external calibration standards for CPFAs and, as such, is capable of direct quantification with no further data conversion required. CPFA data generated from the analysis of cottonseed, cottonseed meal, and cottonseed oil produced in the United States in 2002 are presented.     

Effect of pH on the bioaccumulation of low level,dissolved methylmercury by rainbow trout (Oncorhynchus mykiss)

An inverse relationship has been observed between pH and McHg concentration in freshwater fish. Many hypotheses exist regarding the mechanisms which lead to elevated levels of organic Hg in fish from low pH lakes. To determine if pH has a direct effect on the rate of McHg bioaccumulation in fish, rainbow trout fingerlings (Oncorhynchus mykiss) were exposed to a low concentration of aqueous methylmercuric chloride (1.38 ± 0.49 ng·L^?1) at four pH-levels (8.2, 7.0, 6.3, 5.8) for eight weeks. McHg and total Hg were specifically determined on whole fish homogenates and water samples. The pH was found to have a significant: inverse effect on the rate of McHg bioaccumulation in the fish only in the lowest exposure level. Fish held at pH 5.8 had an uptake rate of 1.11 ± 0.07 ng·g^?1·d^?1, while those at pH ≥ 6.3 had a MeHg tissue uptake rate of ≤ 0.64 ± 0.07 ng·g^?1·d^?1. Total body burden of MeHg in the fish held at pH 5.8 also showed an elevated level of MeHg when compared with fish held at higher pH-levels, but the difference was less dramatic. These results suggest that a portion of the Hg burden in fish from low pH systems may be due to the direct effects of low pH on bioaccumulation, but that a threshold may exist above which pH does not play a significant role.     

Relationship between corn leaf composition and high and low yield levels

Abstract

Corn yields and leaf samples were obtained from experimental plots receiving varying rates of N, P, and K. Yields were placed in two groups. One group consisted of yields < 134 bu/A, and a second group consisted of yields ≥ 134 bu/A. Within each group yields were regressed on leaf levels of N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn as independent variables in a second order polynomial. Using stepwise regression procedures the fit of the polynomial was determined for each set of observations, and statistical significance of various effects was determined.

The regression accounted for 71.5 percent of observed variability in yields in the < 134 bu/A category, and 53.2 percent of observed variability in yields in the ≥ 134 bu/A category. With statistical criteria used, twelve interactions were observed in both groupings, but the PFe interaction was the only one common to both analyses. Seven interactions with Mn were observed in the lower yield category, but only one in the upper category. One linear effect and three quadratic effects were observed in the lower yield category, and three linear effects and four quadratic effects were observed in the upper yield category.     

Effects of extrusion temperature and dwell time on aflatoxin levels in cottonseed

Cottonseed is an economical source of protein and is commonly used in balancing livestock rations; however, its use is typically limited by protein, fat, gossypol, and aflatoxin contents. Whole cottonseed was extruded to determine if the temperature and dwell time (multiple stages of processing) associated with the process affected aflatoxin levels. The extrusion temperature study showed that aflatoxin levels were reduced by an additional 33% when the cottonseed was extruded at 160 degrees C as compared to 104 degrees C. Furthermore, the multiple-pass extrusion study indicated that aflatoxin levels were reduced by an additional 55% when the cottonseed was extruded four times as compared to one time. To estimate the aflatoxin reductions due to extrusion temperature and dwell time, the least mean fits obtained for the individual studies were combined. Total estimated reductions of 55% (three stages of processing at 104 degrees C), 50% (two stages of processing at 132 degrees C), and 47% (one stage of processing at 160 degrees C) were obtained from the combined equations. If the extreme conditions (four stages of processing at 160 degrees C) of the evaluation studies are applied to the combined temperature and processing equation, the resulting aflatoxin reduction would be 76%.     

Rapid loss of lampricide from catfish and rainbow trout following routine treatment

Rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) were exposed to 3-trifluoromethyl-4-nitrophenol (TFM) and Bayluscide (niclosamide) during a sea lamprey control treatment of the Ford River, located in the upper peninsula of Michigan. Caged fish were exposed to a nominal concentration of 0.02 mg/L of niclosamide for a period of approximately 12 h. Samples of fillet tissue were collected from each fish species before treatment and at 6, 12, 18, 24, 48, 96, and 192 h following the arrival of the block of chemical at the exposure site. The fish were dissected, homogenized, extracted, and analyzed by high-performance liquid chromatography. The major residues found in the fillet tissues were TFM and niclosamide. Niclosamide concentrations were highest 12 h after arrival of the chemical block for rainbow trout (0.0395 +/- 0.0251 microg/g) and 18 h after arrival of the chemical block for channel catfish (0.0465 +/- 0.0212 microg/g). Residues decreased rapidly after the block of lampricide had passed and were below the detection limits in fillets of rainbow trout within 24 h and channel catfish within 96 h after the arrival of the lampricide.     

Two-dimensional gel electrophoresis detection of protein oxidation in fresh and tainted rainbow trout muscle

Protein oxidation is evaluated in rainbow trout muscle by labeling protein carbonyls with 2,4-dinitrophenyl hydrazine (DNPH) followed by immunoblotting of proteins separated by SDS-PAGE or two-dimensional gel electrophoresis (2D-GE). The carbonylation level is accessed on proteins in a whole muscle homogenate or proteins soluble in a high-salt or low-salt buffer. Spoilage-related changes in carbonylation are followed in the high-salt-protein and low-salt-protein fractions by 2D immunoblotting, which reveals increases regarding total number and intensity of carbonylation in both protein fractions for fish kept at room temperature for 48 h. The major amount of carbonylated proteins is found among the high-salt-soluble proteins, and this protein fraction is also responsible for the biggest increase in carbonylation during fish tainting. The results give an estimate of the level of protein carbonylation in rainbow trout and reveal that oxidation increases for a distinct number of proteins during tainting.     

Characterization of aroma-active compounds in rainbow trout (Oncorhynchus mykiss) eliciting an off-odor

The aroma-active and off-flavor compounds of cooked rainbow trout (Oncorhynchus mykiss) were analyzed by sensory and instrumental analyses. Sensory analysis shows that the aromatic extract obtained by vacuum steam distillation was representative of rainbow trout odor. To obtain more information on odorants of volatile compounds, analyses were conducted on two gas chromatography columns of different polarities (DB-5 and DB-Wax). The results of the gas chromatography-olfactometry analysis showed that 38 odorous compounds were perceived when the DB-5 column was used and 36 with the DB-Wax column. Of these, 31 with the DB-5 and 28 with the DB-Wax were identified. (E)-2-Nonenal, 2-ethyl-1-hexanol, 2-methylisoborneol, geosmin, 2-methylnaphthalene, and 8-heptadecene were described as off-flavor compounds by the sniffing assessors. The most powerful off-flavor compounds identified in the extract were 2-methylisoborneol and geosmin, which were described as strong musty and earthy odors, respectively.