Recent progress on analytical techniques for mycotoxins in feedstuffs.

Analysis of mycotoxins in feedstuffs is a difficult task because only trace amounts of the toxins are present in the sample. However, rapid progress in the area of mycotoxin analysis has been made during the last few years. Simplified sample cleanup protocols and new chromatographic methods, especially HPLC, have been developed. New, more sensitive and versatile instruments such as high-resolution mass spectrometry (MS) and gas chromatography/tandem MS/MS are coming to the market. After 15 yr of laboratory research, immunoassay techniques have gained more acceptance as analytical tools for mycotoxins. Several immunoassay kits for mycotoxins are currently available. The development of these new techniques and their application for monitoring various mycotoxins in foods and feeds are described in this review.     

Conditions for the formation of mycotoxins in animal feed

The development of moulds and the production of mycotoxins are closely related, but the optima of environmental factors for both do not necessarily coincide. Depending on the species, the percentage of toxinogenic strains differs considerably. Complex substrates, with a high content of carbohydrates, are favoured. Over a wide range of temperature toxin-production is possible, also at a very low partial pressure of oxygen. Too few is known about the factors, which promote toxin-production in the field. There seems to be a dependence on the area, where the grain is grown, and on the weather during the year of cropping, but the influence of methods of plant production, fertilization, plant protection and choice of cultivars have to be investigated.     

Evaluation of dehydrated restaurant food waste products as feedstuffs for finishing pigs

Two dehydrated restaurant food waste (DFW) products were evaluated as potential feedstuffs for finishing pigs. For each product, fresh food wastes were obtained from food service operations at a resort complex in central Florida. The wastes were mostly leftover food and plate scrapings. The wastes were minced, blended with a feed stock (soy hulls and wheat flour [DFW1] or soy hulls and ground corn [DFW2]), pelleted, and dried. The dried product was then blended with additional minced fresh food wastes and dried; this process was then repeated. The final DFW products contained approximately 60% dried food wastes. The DFW1 and DFW2 products contained 11.4 and 8.4% moisture, 15.0 and 14.4% CP, 13.8 and 16.0% crude fat, 10.4 and 14.5% crude fiber, 5.8 and 4.7% ash, .63 and .64% lysine, .54 and .63% Ca, .34 and .38% P, .69 and .86% Cl, and .35 and .47% Na, respectively. Two feeding trials with 48 and 72 finishing pigs (56 to 112 kg), respectively, were conducted comparing diets without (control) or with the DFW product included at 40% of the diet (DFW1) for Trial 1 and 40 or 80% of the diet (DFW2) for Trial 2. Pigs fed the DFW diets in both trials had ADG that were similar (P > . 10) to and average gain:feed ratios that were superior (P = .06, Trial 1; P < .01; linear, Trial 2) to those for control pigs. Carcass lean content and lean quality scores were not reduced (P > . 10) by feeding pigs the DFW diets in either trial. Carcass fat became softer (P < .01; linear) with increasing amount of DFW2 in the diet in Trial 2. Thus, dehydrated restaurant food wastes have the potential to produce a nutritious feedstuff for pigs while offering a viable solid waste disposal option.     

Live and frozen Artemia nauplii for catfish Lophiosilurus alexandri (Steindachner, 1876) larvae in different salinities

Tropical Animal Health and Production - The objective of the study was to verify the combination of live and frozen Artemia nauplii, in different salinized water, and its influence in growth and...     

水果蔬菜和鱼类的副产物作为猪饲料的可行性分析

我们对水果蔬菜和鱼类的副产物作为育肥猪的饲料进行了可行性分析。这些副产物主要是指水果蔬菜的皮、核以及鱼内脏等，主要来自于西班牙的Salamanca的商店，并且对它们的营养成分、矿物质含量以及可消化性进行了评估。在本次实验中，这些副产品的干物质含量偏低（在果菜和鱼类副产物分别为12％和26％），但这些干物质却包含了所有猪饮食中所需的营养成分。鱼类的副产物含有58％的粗蛋白、22％的灰份、19％的醚提取物和1％的粗纤维，而果菜副产物中含有65％自由氦提取物、13％粗纤维、12％粗蛋白、8％的灰份以及2％醚提取物。这些副产物随着温度的升高，它们的可消化性会逐渐降低，所以温度高于65℃的果菜副产物和高于105℃的鱼类副产物，我们都予以废弃，这也是出于控制微生物含量的考虑。     

Proposal to reclassify Paenibacillus larvae subsp. pulvifaciens DSM 3615 (ATCC 49843) as Paenibacillus larvae subsp. larvae. Results of a comparative biochemical and genetic study

The bacterial pathogen Paenibacillus larvae subsp. larvae (P. l. larvae), is the etiological agent of American foulbrood, an extremely contagious and disastrous disease of honeybee brood. In case of American foulbrood the destruction of infected colonies is often considered the only workable control measure. Therefore, the ability to diagnose this disease properly is important to prevent unnecessary economic loss to beekeepers. The development of suitable methods for the early and reliable detection of P. l. larvae is hampered by the fact that the two subspecies of Paenibacillus larvae, P. l. larvae and Paenibacillus larvae subsp. pulvifaciens (P. l. pulvifaciens), seem to be indistinguishable by cultural characteristics as well as by PCR protocols. Here we present an extensive analysis of several P. larvae reference strains. We employed conventional culture techniques, morphological and biochemical identification, PCR-based methods and sequencing of the 16S rDNA. We found indeed that P. l. pulvifaciens strain DSM 3615 is indistinguishable from P. l. larvae (DSM 7030). We did not face any problems to discriminate between P. l. larvae and P. l. pulvifaciens strains DSM 8442 and DSM 8443. Therefore, classification of DSM 3615 as type strain of P. l. pulvifaciens seems not to be justified. We propose to reclassify this strain as P. l. larvae. Former problems in differentiating the two subspecies might have arisen from this misclassification. PCR-based methods as well as appropriate biochemical identification systems provide a reliable means for the discrimination between the two subspecies P. l. larvae and P. l. pulvifaciens.     

Animal-derived feeds as possible vectors for bovine spongiform encephalopathy (BSE) in Germany. 1. Comparative risk assessment for a single animal food of animal origin

The occurrence of BSE cases in Germany after the ban of meat and bone meal for ruminant feed in 1994 requires a detailed investigation of animal derived feedstuffs regarding their specific risks as vectors for the disease. Accepting the theory that BSE is a prion transmitted disease, the theoretical infectious potential was calculated for animal derived feedstuffs. This calculation was based on the assumption, that risk material (brain, spinal cord) of one clinically diseased cattle was rendered in the process as established in Germany (133 degrees C, 3 bar, 20 min) or, alternatively, that one diseased animal was slaughtered resulting in normal processing of the by-products for human food production. From this risk assessment it became obvious that meat and bone meal was one, but probably not the most important source for the spreading of BSE. Taking into account the high sensitivity of calves it can be speculated that certain products, e.g. from bone processing (bone meal) and fat melting (mixed animal fats), commonly used for the formulation of milk replacers, might have been more important as pathways. As it can't be excluded retrospectively that infected meat and bone meal was imported from the UK, this non-calculable influence may have been related to the significance of the other products. The calculation model underlines that efficient removal of specified risk material (brain, spinal cord) and adequate processing (133 degrees C, 3 bar, 20 min) or alternatively other equivalent treatments of fats are prerequisites for minimising the risk of feed borne transmission of BSE by animal derived feedstuffs. The epidemiological consequences are part of a subsequent paper.     

A sensitive bioassay for detection of dietary estrogens in animal feeds

Estrogen-responsive proliferation in the MCF-7 cell line was used as a bioassay for detection of dietary estrogens. The bioassay procedure was adapted to screen for estrogenic activity in feedstuffs that have been associated with hyperestrogenism in livestock. Methanolic feed extracts were added to the cell culture medium at microliter/ml concentrations for 4 days, after which the cell proliferation response was measured as DNA content. The half-maximal response for estradiol occurred at 2 pM, or 0.54 pg/ml. For zearalenone, a weaker estrogen, the half-maximal response occurred at approximately 200 pM, or 64 pg/ml. The bioassay was calibrated against a number of known estrogens (estradiol, diethylstilbestrol, zearalenone, zearalanol [cattle implant], beta-zearalenol, zearalane), including the naturally occurring phytoestrogens (formononetin, genistein, daidzein, biochanin A, and coumestrol). The estrogenic activity of feed samples was expressed as equivalents of zearalenone (ppm zearalenone) that would have to be present to equally stimulate proliferation of the MCF-7 cells. The sensitivity of the bioassay was 0.05-0.1 ppm equivalents of zearalenone in feed, well below the threshold level associated with reproductive problems. The feed additive melengestrol acetate (MGA) showed no estrogenic activity in this assay. Estrogenic activity of feed extracts was confirmed by competitive inhibition with the antiestrogens tamoxifen or LY156758 (keoxifene) to show that stimulation of growth by feed extracts was through an estrogenic mechanism. Confirmation of known estrogens was by tandem mass spectroscopy. The assay is a sensitive and reliable screening procedure for detecting estrogenic activity in feedstuffs.     

Validation of a cell culture bioassay for detection of petroleum exposure in mink (Mustela vison) as a model for detection in sea otters (Enhydra lutris)

OBJECTIVE: To validate a luciferase bioassay, which is based on a recombinant mouse hepatoma cell line, for the detection of exposure to petroleum in mustelid species. ANIMALS: 122 American mink (Mustela vison) and 15 sea otters (Enhydra lutris). PROCEDURES: Mink were exposed to Bunker C fuel oil or Alaska North Slope crude oil externally as a single exposure or internally via low dose concentrations in their ration for 6 months. Serum samples were analyzed for cytochrome P450 1A1 induction by quantification of luciferase activity in the bioassay. Mink liver specimens were also evaluated for cytochrome P450 1A1 induction by quantification of ethoxyresorufin-o-deethylase activity. Serum collected from exposed and unexposed sea otters was also analyzed using the luciferase bioassay. RESULTS: Serum samples from mink externally exposed to petroleum had significantly increased luciferase activities at 1 week after exposure. Serum samples taken at later time points or from mink exposed to either product in the ration did not cause significant luciferase induction. Samples from otters exposed to petroleum had significantly higher luciferase induction as compared with samples from otters not exposed to petroleum at 2 and 8 years after the spill. Cytochrome P450 1A1 activity in liver specimens collected from mink that were internally exposed through diet was significantly increased at the conclusion of our study. CONCLUSION AND CLINICAL RELEVANCE: The luciferase bioassay is a sensitive and specific method for determining recent exposure to petroleum in mink. The lack of luciferase activity in serum samples collected from mink greater than 1 week after experimental exposure was likely attributable to lower overall petroleum exposure in our trial, compared with natural exposures.     

Animal-derived feedstuffs as possible vectors for bovine encephalopathy (BSE) in Germany. Part 2: Assessment of vector risk for compounded feed

Specific conditions and practices of cattle feeding in Germany have to be taken into account for assessing the risk of feed born transmission of bovine spongiform encephalopathy, especially regarding the situation before the year 2000 when specific directives were introduced for feed production. The present retrospective epidemiological study includes data on feed production and the estimated amount of animal derived feedstuffs for the production of compounded feed for cattle. Risk assessment was performed based on the 'reproduction rate' (R0), that is defined as the estimated number of infections resulting from the processing of brain and spinal cord of BSE affected cattle that is recycled to bovines via feed. Under the conditions as given in Germany until the year 2000 the reproduction rate of BSE via the inclusion of animal derived feedstuffs in compounded feed production for cattle was estimated to be 1.1. Thus, it can be expected that BSE could be reproduced in the system, but with comparatively low efficiency. The expected incidence of BSE should be considerably lower compared to the situation during the 90th in the UK, due to the markedly lower recycling rate of animal protein in cattle feeding. Animal fat could have been a significant factor for BSE transmission due to contamination by proteinaceous brain and spinal cord material during the production process. The relative significance of fat containing feedstuffs for BSE transmission could have been higher in Germany compared to the situation in the UK where meat and bone meal was produced under different conditions and frequently used in higher proportions as an ingredient for compounded feed for ruminants.     

加州鲈对15种饲料原料体外消化率的测定

采用"胃-肠"两步法测定了加州鲈(Micropterus salmoides)对15种饲料原料的体外消化率,并与银鲈(Bidyanus bidyanus)体内消化率数据进行了比较。结果表明:加州鲈对秘鲁鱼粉、喷干血粉、豆粕、花生麸、玉米蛋白粉、酵母膏、破壁酵母7种原料的体外消化率较高(干物质>45%,蛋白质>71%),对玉米、DDGS消化率较低(干物质<17%,蛋白质<61%),且大部分原料的体内、外消化率结果具有极显著的相关性(P<0.01)。体外消化率的结果可为加州鲈饲料原料的选择提供参考依据。     

Evaluation of the suitability of a partially defatted black soldier fly(Hermetia illucens L.) larvae meal as ingredient for rainbow trout(Oncorhynchus mykiss Walbaum) diets

Background: Two trials were performed to evaluate a partially defatted Hermetia illucens(HI) larvae meal as potential feed ingredient in rainbow trout(Oncorhynchus mykiss Walbaum) diets. In the first trial, 360 trout(178.9 ± 9.8 g of mean initial body weight) were randomly divided into three experimental groups(4 tanks/treatment, 30 fish/tank). The fish were fed for 78 days with isonitrogenous, isolipidic and isoenergetic diets containing increasing levels of HI, on as fed basis: 0%(HI0, control diet), 25%(HI25) and 50%(HI50) of fish meal substitution, corresponding to dietary inclusion levels of 0, 20% and 40%. In the second trial, 36 trout(4 tanks/treatment, 3 fish/tank) were used to evaluate the in vivo apparent digestibility coefficients(ADC) of the same diets used in the first trial.Results: Survival, growth performance, condition factor, somatic indexes, and dorsal fillet physical quality parameters were not affected by diet. The highest dietary inclusion of HI larvae meal increased dry matter and ether extract contents of trout dorsal fillet. The use of HI larvae meal induced a decrease of valuable polyunsaturated fatty acids(PUFA) even if differences were only reported at the highest level of HI inclusion. The insect meal worsened the lipids health indexes of the same muscle. Dietary inclusion of insect meal did not alter the villus height of the fish. No differences were found among treatments in relation to ADC of ether extract and gross energy, while ADC of dry matter and crude protein were higher in HI25 if compared to HI50.Conclusions: The obtained results showed that a partially defatted HI larvae meal can be used as feed ingredient in trout diets up to 40% of inclusion level without impacting survival, growth performance, condition factor, somatic indexes, dorsal fillet physical quality parameters, and intestinal morphology of the fish. However, further investigations on specific feeding strategies and diet formulations are needed to limit the observed negative effects of the insect meal on the FA composition of dorsal muscle.     

Evaluation of methods for the euthanasia of cattle in a foreign animal disease outbreak.

In anticipation of the need to euthanize large numbers of cattle in the event of a foreign animal disease outbreak, two models of captive bolt gun and various firearms and ammunition loads were tested in order to assess their suitability. In the first phase of the project, two models of captive bolt stunner were used in an abattoir, and assessed for effectiveness. In the second phase, several firearms and ammunition were used on isolated bovine heads and assessed for effectiveness. Little difference was found between the two captive bolt stunners. Of the firearms and ammunition evaluated, the Ruger Mini-14 and the Core-Shot round, a prefragmented projectile, were determined to be most suitable. In situations where large herds of livestock are to be depopulated, and where the restraint required for the use of captive bolt stunners is not practical, there are commercially available firearms and ammunition that are suitable for this purpose.     

Evaluation of a non-rebreathing circuit for small animal anaesthesia

Several new multi-purpose non-rebreathing anaesthetic systems have been developed for human anaesthesia. This study evaluated a New Zealand designed non-rebreathing circuit, the Palmerston Valve, in anaesthetised spontaneously breathing dogs and compared it to the widely used Lack coaxial circuit. Arterial blood gas measurements 60 minutes after induction demonstrated comparable slight increases in PaCO2 in nearly all dogs maintained on the Palmerston Valve and Lack coaxial circuit with halothane and oxygen mixtures, and a fresh gas flow rate of 70 ml/kg/min. Results suggest the Palmerston Valve is at least as efficient as the Lack coaxial circuit, while offering in the same unit the potential for economical controlled ventilation.     

Evaluation of a non-rebreathing circuit for small animal anaesthesia

Several new multi-purpose non-rebreathing anaesthetic systems have been developed for human anaesthesia. This study evaluated a New Zealand designed non-rebreathing circuit, the Palmerston Valve, in anaesthetised spontaneously breathing dogs and compared it to the widely used Lack coaxial circuit. Arterial blood gas measurements 60 minutes after induction demonstrated comparable slight increases in PaCO₂ in nearly all dogs maintained on the Palmerston Valve and Lack coaxial circuit with halothane and oxygen mixtures, and a fresh gas flow rate of 70 ml/kg/min.

Results suggest the Palmerston Valve is at least as efficient as the Lack coaxial circuit, while offering in the same unit the potential for economical controlled ventilation.     

Evaluation of a modified exogenous creatinine clearance as a suitable renal function test for the small animal practice

A suitable method in the routine veterinary practice for the quantitative determination of the glomerular filtration rate (GFR) in dogs and cats has not been available until to date. Therefore, we modified the known plasma clearance model (=P-CL). The resulting P-CLterminal was assessed concerning its diagnostic value. P-CL of exogenous creatinine (P-CLcrea) and of inulin were determined in dogs (n=12, Beagle, 6 months of age) and cats (n=11, Domestic Short Hair, 14 months of age). The marker substances were administered as a bolus injection. In fasted dogs, P-CLcrea was 84.3 +/- 14.85 ml/min/m2 after a creatinine dose of 2.4 g/m2. An electrolyte infusion during the clearance determination did not alter the resulting values (p>0.05). In fasted cats, P-CLcrea was 54.7 +/- 5.8 ml/min/m2 (creatinine dose 2.0 g/m2). The inulin clearance, determined at the same time, was 104.5 +/- 19.81 ml/min/m2. Feeding the cats just before and during the test increased P-CL of both markers significantly (p<0.05). In order to adapt the clearance method for diagnostic assessment of GFR in the small animal practice, we aimed at minimizing the number of required blood samples (3 instead of 7 or more) and introduced the modified exogenous creatinine clearance (P-CLterminal). These values determined were 108.4 +/- 20.81 ml/min/m2 in fasted dogs and 66.3 +/- 11.81 ml/min/m2 in fasted cats. An electrolyte infusion (dogs) and feeding (cats) had the same effect on P-CLterminal values as described above for P-CL. In conclusion,the modified exogenous creatinine clearance is a suitable renal function test for the early diagnosis of renal disease in dogs and cats presented in small animal practices.     

Evaluation of Culicoides insignis (Diptera: Ceratopogonidae) as a vector of bluetongue virus.

Based upon epidemiological evidence, Culicoides insignis Lutz is a probable biological vector of bluetongue viruses (BTV) in South Florida, the Caribbean Region and Central America. The vector potential of this species for BTV was evaluated in the laboratory in a series of experiments using insects caught in the field. Although there was great variation in the percentage of flies that fed from any one catch, it was demonstrated that C. insignis became infected after membrane feeding on a mixture of blood and virus. The infection rates ranged from 20 to 62.5%. Following intrathoracic inoculation, BTV replicated to high titres in C. insignis. Such flies were also shown to be capable of transmitting BTV to susceptible sheep and embryonated chicken eggs. This series of experiments provides the first conclusive evidence that C. insignis is a biological vector of bluetongue virus. This is the first proven vector of BTV in the neotropics.     

A bioassay method for the pheromone(s) of the bont tick Amblyomma hebraeum Koch.

A bioassay was developed which enabled the detection of the pheromones of the bont tick (Amblyomma hebraeum Koch) within 2 hours with a reproducibility of 82 +/- 13%. Dried, solvent-extracted ticks were glued onto the shaved backs of rabbits. Those ticks to which pheromone extract was subsequently applied strongly attracted females of the same species. In a 2-way choice test a cork disc impregnated with pheromone extract was even more attractive to female ticks than a treated dried tick.     

艾叶的化学分析及含艾叶饵料对鱼的饲效观察

艾叶含粗蛋白质13.14％,粗脂肪5.69％,粗灰分10.56％,16种氨基酸和钙、磷等14种矿物质元素;其汞(0.028ppm)、砷(0.183ppm)、铅(1.640ppm)含量均未超过国家的粮食等卫生标准。用添加艾叶的颗粒饲料饲喂鱼,水族箱试验鲤鱼鱼种增长率比对照组提高11.65％。池塘试验组1龄鲤、鲢、鳙的增长率分别比对照组提高22.46％、12.61％和21.96％。网箱试验组2龄鲤的增长率比对照组提高12.55％。试验组鲜鱼肉的概略养分、氨基酸、肥满度及汞、砷、铅含量除池塘鱼肉粗蛋白质和粗灰分高于对照组外,其它与对照组比较无明显差异。