Cold storage of wheat. 1. Ergosterol, ochratoxin A and citrinin after inoculation with Penicillium verrucosum]

Seed wheat was inoculated without having been sterilized with an ochratoxin A and citrinin forming strain of Penicillium verrucosum and stored at moisture contents of 18, 20, 22, 24, and 26% at 10 and 4 degrees C. The production of ergosterol, a chemical indicator of fungal biomass, started within the storage time investigated (240 days). Only at 18% H2O/4 degrees C an increase of the ergosterol content was not observed. Ochratoxin A and Citrinin were not detected at 18% H2O/4 degrees C and 20% H2O/4 degrees C within 240 days (detection limit: 10 and 25 micrograms/kg, respectively). At the other combinations of moisture content and temperature the first detection of the two toxins approximately coincided with the onset of ergosterol production. With increasing moisture content and temperature the time up to the start of ergosterol production decreased, whereas the production rates of ergosterol, ochratoxin A and citrinin increased. Both toxins were produced with about the same rate during a first phase of accumulation. At 20-26% H2O there was no influence of moisture content and temperature on the relation between toxin content and the simultaneously reached ergosterol content. It is recommended that wheat highly contaminated with Penicillium verrucosum should not be stored beyond the start of ergosterol production.     

长白山原始森林土壤源耐低温乳酸菌的筛选

试验旨在筛选长白山原始森林土壤中耐胁迫生长能力强、产酸能力强、体外抑菌特性好的耐低温乳酸菌,并对其相关生物学特性进行分析,为东北地区寒冬季节低温青贮提供优良乳酸菌菌种资源。采用低温（10℃）进行耐低温乳酸菌初筛,经不同pH、温度及盐度等条件下进行乳酸菌生长特性测定后,进行候选菌株的种属鉴定,并对候选菌株进行生长曲线、产酸曲线、耐酸和耐胆盐性能、抑菌性能测定及小鼠饲喂试验。结果显示,通过10℃低温条件培养,初筛获得11株能够良好生长的耐低温乳酸菌,其中C37、C34和C4212经16S rRNA测序分析后鉴定为植物乳杆菌,在培养7 d时,pH均可下降至4.25以下,均能够在4℃、45℃、pH 3.0、6.5% NaCl等条件下良好生长。生长曲线分析发现,3株乳酸菌均在4 h达到对数生长期,10~12 h后进入生长稳定期。在培养24 h时,C37、C34和C4212可将pH分别降至4.04以下,在pH 3.0条件下,C37和C4212具有较高的存活率,且对0.5%胆盐具有一定的耐受性,其存活率均在80%以上。对常见病原菌体外抑菌表明,3株乳酸菌对产肠毒素大肠杆菌、鼠伤寒沙门氏菌、金黄色葡萄球菌及肠炎沙门氏菌均有抑制作用,小鼠饲喂试验表明生物安全性好。本试验结果表明,从长白山原始森林土壤中筛选和鉴定出的乳杆菌C37、C34、C4212可作为东北地区寒冬季节低温青贮优良乳酸菌菌种资源。     

Screening of Pychrotrophic Lactic Acid Bacteria from Changbai Mountain Soil

The purpose of the experiment was to screen psychrotrophic lactic acid bacteria with strong stress-resistant growth ability,acid production ability and good bacteriostatic characteristics in vitro,and analyze its related biological characteristics,so as to provide excellent psychrotrophic lactic acid bacteria resources for low temperature silage in Northeast China.The culture condition of 10 ℃ was used to screen the psychrotrophic lactic acid bacteria.After the determination of the growth characteristics of Lactobacillus under different pH,temperature and salinity conditions,the species identification of the candidate strains was carried out,and the growth curve,acid production curve,acid and bile salt resistance,bacteriostatic performance and feeding test of mice were conducted for the candidate strains.The results showed that 11 strains of psychrotrophic lactic acid bacteria could grow well at 10 ℃.The strains C37,C34 and C4212 were identified as Lactobacillus plantarum by 16S rRNA sequencing analysis.The pH of C37,C34 and C4212 decreased to below 4.25 after 7 days of culture.In addition,C37,C34 and C4212 could grow well at 4 ℃,45 ℃,pH 3.0 and 6.5% NaCl.The analysis of growth curve showed that the three strains of Lactobacillus all had a fast growth rate,entered the logarithmic growth period at 4 h,and entered the stable growth period in 10-12 h after inoculation.In the aspect of acid production rate,C37,C34 and C4212 could reduce pH below 4.04 at 24 h of culture.At pH 3.0,C37 and C4212 had a high survival rate,they all had a certain tolerance to 0.5% bile salt,and the survival rate was more than 80%.C37,C34 and C4212 had inhibitory effect on enterotoxin producing Escherichia coli,Salmonella Typhimurium,Staphylococcus aureus and Salmonella Enteritis,and the animal test of three Lactobacillus plantarum were safe.Based on the results of this experiment,Lactobacillus C37,C34 and C4212 were screened and identified from the forest soil of Changbai Mountain,which could provide excellent lactic acid bacteria resources for low temperature silage in winter in Northeast China.     

粗饲料及食品加工副产品的瘤胃有机物降解率的研究

本实验用瘤胃尼龙袋法测定了酱油渣（长营）、酱油渣（豆各庄）、白酒糟（大厂）、白酒糟（围场）、玉米淀粉渣、麦芽根、啤酒糟、麸皮、羊草、稻草、氢化稻草、高梁青贮（豆各庄）、大麦青贮（长营）、高粱青贮（长营）、苜蓿、王米秸、麦秸、氨化麦秸的瘤胃有机物动态降解率（％）分别为４６．５０、４６．０２、２５．４１、１８．５４、３８．５８、５９．０３、３２·８４、６９·１４、４１．１４、３２．０９、３７．７７、３９．８６、３６．３６、３６．７８、４５．１３、３２．８７、２９．５０、３７．１５。前８种饲料营养成份的粗脂肪（ＥＥ）、粗蛋白（ＣＰ）、粗纤维（ＣＰ）、无氮浸出物（ＮＰＥ）与瘤胃有机物动态降解率（ＦＯＭ）的回归方程为：ＦＯＭ＝１９１．４５＋０．８０ＥＥ－２．２０ＣＰ－４．３９ＣＦ－０．９１ＮＦＥ（Ｒ＝０．９１．ｎ＝８）相应后１０种饲料的回归方程为：ＦＯＭ＝－１０．５３－０．４１ＥＥ＋１．８３ＣＰ＋０．４４ＣＦ＋０．５６ＮＦＥ（Ｒ＝０．９０，ｎ＝１０）     

Measures for lessening the mycotoxin formation and concentration in feed

Procedures for lowering the production of mycotoxins in cereals before harvest are not available. Breeding of cereal varieties which are resistant to fusaria is a promising approach. Development of storage fungi and fusaria after harvest can be inhibited by drying with warm or ambient air, refrigerated storage, chemical preservation (e.g. by propionic acid, urea), and airtight storage. For the quantitative determination of fungal growth in feedstuffs a chemical indicator such as ergosterol must be determined. A preservation procedure can be regarded as effective only if it is able to inhibit mold growth completely. This is concluded from the observation that an initial toxin-free phase of growth which has been found in mold cultures with liquid medium could not be detected during refrigerated storage of wheat. Under these conditions the production of ochratoxin A and other mycotoxins by Penicillium strains started simultaneously with the production of ergosterol. For an effective ambient air drying of cereals the depth of the whole bulk and the velocity of air must afford complete drying within 8-10 days. During refrigerated storage of cereals maximal storage periods which depend on moisture content and temperature should not be exceeded. Maximal storage periods based on ergosterol determinations are described for wheat with an initial moisture content between 18 and 26% and storage temperatures of 4 and 10 degrees C. The effect of propionic acid concentration on the development of molds is described, recommendations for selecting optimal acid dosages are given.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and characterization of potentially human pathogenic, cytotoxin-producing aeromonas strains from retailed seafood in Berlin, Germany

The presence of potentially human pathogenic strains of Aeromonas was investigated in 84 samples of seafood which were purchased from retail traders in Berlin, Germany in spring 2000. A total of 134 Aeromonas strains were isolated on selective [GSP agar and Aeromonas (Ryan) agar] and unselective (standard count agar and enterohaemolysin agar) media from 27 (32.1%) of the samples and were classified as Aeromonas hydrophila (67.9%), A. caviae (26.1%) and A. sobria (6.0%) by biotyping. Thirteen (48.1%) of the 27 positive samples contained more than one species of Aeromonas. Production of haemolysins on enterohaemolysin agar was found with 132 (98.5%) of the strains at 28 degrees C and with 130 strains (97.0%) at 37 degrees C growth temperature. Vero cytotoxins were produced by 99 (73.9%) of the strains when grown at 28 degrees C but only by 24 of the strains (17.9%) at 37 degrees C. The latter strains were identified as A. hydrophila (n = 22) and A. sobria (n = 2) which came from 17 (20.2%) samples of raw seafood and from ready-to-eat salted herring 'Matjes' products. Cytotoxin-encoding genes for aerolysin (aer) and haemolysin A (hlyA) were investigated by PCR. Aer and hlyA genes were detected in both, strains which produced toxins only at 28 degrees C and strains which produced toxins at 37 degrees C. Our data indicate that raw seafood and ready-to-eat fish products can harbour potential human pathogenic, cytotoxin producing Aeromonas strains.     

Propionic acid preservation of corn following inoculation with molds and yeasts

In laboratory tests spores of 7 Fusarium species, 6 yeast species, and of the molds Paecilomyces varioti and Trichoderma viride were inoculated into propionic acid treated corn. The initial moisture content of the corn was adjusted to 19, 25, 32, and 40%, the propionic acid dosages being 0.3, 0.5, 0.7, and 1.0% respectively. By these treatments the growth of the inoculated fungi was inhibited for a storage of a least 6 months at 20 degrees C. The inhibition of growth was indicated by the decrease of viable mold count, the percentage of surface-sterilized kernels infected with fungi being 0% after 6 months. In addition, by the propionic acid treatment the production of zearalenone by two strains of Fus. culmorum and three strains of Fus. graminearum, and the production of T-2 toxin by two strains of Fus. tricinctum and one strain of Fus. sporotrichioides was inhibited. These results were obtained during an incubation period of 1-4 months using a temperature shift (20 and 10 degrees C). The propionic-acid dosage sufficient for the inhibition of the inoculated fungi was lower than that recommended in the literature for large-scale treatment of corn.     

Simultaneous measures of rates of ruminal digestion and passage of feeds for prediction of ruminal nitrogen and dry matter digestion in lactating dairy cows

Three ruminal-cannulated Holstein cows in early lactation were fed three diets, each containing different energy and protein supplements in two consecutive 3 X 3 Latin squares. Each supplement contained a combination of three different feedstuffs (ground corn, soybean meal and wheat mids; corn gluten feed, rolled oats and distiller's dried grains; ground barley, brewer's grains and cottonseed meal). Diets consisted of 30% corn silage, 10% alfalfa hay, 10% alfalfa haylage, 17.7% ground corn plus minerals and vitamins, with the remainder as supplemental feedstuffs individually marked for measurement of ruminal turnover and in situ digestion rates. An extra period at the end of each Latin square was used to measure ruminal turnover and in situ digestion of individual forages. Diet had no effect on dry matter intake or milk yield. Mean fractional turnover (per hour) rate, measured by labeling feedstuffs with cerium, samarium or lanthanum was .044, .048, .049, .043, .047, .046, .050, .047, .049, .037, .046 and .045 for corn, soybean meal, wheat mids, corn gluten feed, oats, distiller's dried grains with solubles, barley, brewer's dried grains, cottonseed meal, alfalfa hay, corn silage and alfalfa haylage (P greater than .1), respectively. In situ-predicted ruminal degradation of N weighted for rate of passage was 61.4, 67.0, 81.5, 74.8, 86.3, 71.0, 75.7, 52.1, 54.2, 60.8, 71.7 and 70.9% for respective feedstuffs (P less than .05). In comparison with mean literature values for in vivo-measured N degradability, mean literature value = 1.172 (in situ predicted) -9.73 (P less than .05, R2 = .51). Results are interpreted to indicate a tendency for overestimating ruminal N degradability by in situ methods in feedstuffs of low degradability, while underestimating degradability in more highly degraded feedstuffs. Estimates were 11 to 17 percentage units lower than literature values for alfalfa hay and haylage and 17 units lower than literature values for distiller's dried grains.     

嗜热毛壳菌纤维复合酶对饲料中蛋白质和能量代谢率的影响

本研究选用42日龄的健康AA肉鸡36羽,随机分成12组,采用排空强饲法研究了嗜热毛壳菌纤维复合酶对6种肉鸡常用饲料中粗蛋白质和能量代谢率的影响。试验选择肉鸡常用的3种蛋白质饲料(棉粕、豆粕和花生粕)和3种能量饲料(玉米、小麦和次粉),每种饲料分成2组,即对照组和加酶组。试验结果表明:嗜热毛壳菌纤维复合酶能显著提高棉粕和小麦中粗蛋白质的表观代谢率(P<0.05),对豆粕、花生粕、玉米和次粉中粗蛋白质的表观代谢率的影响差异不显著(P>0.05);能使小麦的表观代谢能提高7.52%(P<0.05),玉米和次粉的表观代谢能分别提高9.06%和10.93%(P<0.01)。使棉粕的表观代谢能提高5.12%,花生粕提高4.06%,豆粕提高1.91%(P>0.05);可以使玉米和次粉中能量的表观代谢率分别提高9.04%和10.95%,均差异极显著(P<0.01);小麦中能量的表观代谢率提高了7.55%(P<0.05)。对棉粕、花生粕、豆粕等蛋白质饲料中的能量表观代谢率无显著影响(P>0.05)。     

The growth of Treponema hyodysenteriae and other porcine intestinal spirochaetes in a liquid medium.

A new simple method for the preparation of a liquid medium containing rabbit serum for the propagation of Treponema hyodysenteriae and other porcine intestinal spirochaetes is described. The medium, when dispensed in shallow layers and sealed under 10 per cent CO2 in nitrogen, had a redox potential not greater than -125mV and an initial pH of about 6.9 when buffered with bicarbonate. Growth of T hyodysenteriae developed more rapidly and viable counts reached higher levels at 42 degrees C than at 37 degrees C. Viable counts increased at least 10,000-fold after two to five days' incubation, depending on the temperature. Growth could be initiated from small inocula that failed to produce colonies on blood agar. Using a 1 per cent inoculum, the medium supported the growth of two strains of T hyodysenteriae through 10 serial passages.     

Long-term cryopreservation of microbial strains relevant to food hygiene

Experiments on long-time cryopreservation at -20 degrees C were conducted, using 42 microbial strains of relevance to food hygiene. Blood slant agar was coated with 10% glycerol solution, so that all strains were in re-culturing conditions, following 12 months of storage. Re-culturing of 18 in 20 of the microbial genera used in the experiment was possible after 24 months of storage, if strains had been kept only in 10% glycerol solution. The method proved suitable particularly for strain keeping of highly sensitive genera (Lactobacillus, Pseudomonas, Aeromonas, Shigella).     

Effect of high temperature and low-protein diets on the performance of growing-finishing pigs

The effects of reducing CP level in combination with an increase in ambient temperature (29 vs 22 degrees C) on performance and carcass composition were studied in a factorial arrangement of treatments involving 66 Piétrain x (Landrace x Large White) barrows from 27 to 100 kg BW. Animals were fed at each temperature one of three experimental diets that provided 0.85 or 0.70 g of digestible lysine per megajoule of NE, in the growing (27 to 65 kg) and the finishing (65 to 100 kg) phases, respectively. Diet 1 was a corn, wheat, and soybean meal diet formulated without crystalline AA; CP levels were 20.3 and 17.6% for the growing and the finishing phases, respectively. In Diets 2 and 3, CP level was reduced by substituting part of the soybean meal with corn and wheat (Diet 2), or with corn, wheat, and 4% fat (Diet 3). Diets 2 and 3 were supplemented with AA and balanced according to the ideal protein concept. The CP levels of Diets 2 and 3 were, respectively, 15.8 and 16.3% in the growing phase, and 13.4 and 13.8% in the finishing phase. Pigs were housed individually and had free access to feed and water. The ADFI was measured daily, and animals were weighed weekly. Carcass composition was measured at slaughter (100 kg BW). Increasing ambient temperature from 22 to 29 degrees C resulted in a 15% reduction in ADFI and 13% lower ADG. Leaner carcasses (P < 0.01) were obtained at 29 degrees C (22.8 vs 24.8% carcass fat). At 22 degrees C, ADFI was lower (P < 0.05) for the low-CP diets, but daily NE intake, ADG, and carcass composition were not affected (P > 0.05). At 29 degrees C, ADFI was not different (P > 0.05) between diets and daily NE intake was higher (P < 0.05) with Diet 3 than with Diet 1, and the difference was more important during the finishing period than during the growing period. Using the model ADFI = a BWb, estimates of b were 0.65, 0.53, and 0.53 at 22 degrees C and 0.50, 0.44, and 0.50 at 29 degrees C, for Diets 1, 2, and 3, respectively. The higher NE intake for Diet 3 at 29 degrees C did not improve ADG (P > 0.05) but increased mainly fat deposition. These results indicate that a 4 percentage unit reduction of dietary CP level reduces N excretion (minus 37%) but does not affect growth and carcass composition as long as the ratio between essential AA and NE are kept optimal. In addition, diets with reduced CP limit the effect of high ambient temperature on ADFI. Finally, our results demonstrate the significance of using NE, rather than DE or ME, for formulating diets.     

Pseudomonas aeruginosa in raw and pasteurized milk

Eighteen strains of Pseudomonas aeruginosa, i.e. 8.87%, were isolated during a year from 203 samples of raw milk. Two Pseudomonas aeruginosa strains, i.e. 4%, were isolated from 50 samples of pasteurized milk. The strains were isolated using propagation techniques in meat-peptone broth with malachite green and on selective media--on centrimide agar (CEM) and on Pseudomonas F agar. All the isolated strains produced protease, whereas lipase was produced by only five strains. The strains were devitalized when exposed to pasteurization temperatures (72 degrees C) for 20 seconds. At cold store temperatures (4 degrees C), Pseudomonas aeruginosa strain cells propagated on average by two orders, inhibitory effects of low temperatures were recorded only with one strain. Inhibitory effects of milk cultures (cream, yogurt) on Pseudomonas aeruginosa were observed; their effects were more clear-cut at the temperature of 4 degrees C. The strains were markedly susceptible to gentamycin.     

Effect of culture media and incubation temperature on growth of selected strains of Francisella tularensis.

The rate and amount of growth of 4 field isolates and reference strain ATCC 6223 of Francisella tularensis were evaluated on isolation media with 2 different agar bases and with different supplements and incubated at 25 C, 35 C, and 42 C. Biochemical reactions on conventional differential media with and without cysteine were evaluated. Two of the field isolates and the reference strain were F. tularensis subspecies tularensis (formerly biovar tularensis or Type A), and 2 isolates were subspecies holarctica (formerly subspecies palaearctica or Type B). Bacto cystine heart blood agar supplemented with 1% hemoglobin, glucose cystine heart blood agar, and brain-heart infusion blood agar supported good growth of all 4 field strains, with the most luxuriant growth occurring on Bacto cystine heart blood agar with hemoglobin. Heart infusion blood agar and trypticase soy blood agar supported growth of the field isolates, although growth was diminished and delayed. Strain 6223 was distinctly fastidious and failed to grow on heart infusion or trypticase soy blood agars. Growth of strain 6223 was best on Bacto cystine heart blood agar with hemoglobin. The agar base did not affect growth unless the supplements became limiting, in which case Bacto agar base generally supported growth better than BiTek agar base. Incubation at 35 C was optimum for all 5 strains. Growth at 42 C was slow, with the greatest decrease in the rate and amount of growth occurring with field isolates of F. tularensis subspecies tularensis. Strain 6223 did not grow at 25 C, and the 4 field isolates grew slowly at the lower temperature.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of physicochemical and structural properties of single and double feedstuffs derived from different botanic sources on in vitro starch digestion and glucose release kinetics

Starch is the largest constituent in animal diets. The aims of this study were as follows: (a) to assess the variability of basic physicochemical properties and in vitro starch digestion of starchy feedstuffs and investigate relationship between physicochemical properties and starch digestion of the feedstuffs, and (b) to explore the effects of different sources of starchy feedstuffs on starch digestion and glucose release. In this study, we determined the inherent molecular structure and granular structure of starch and chemical compositions of seven starchy feedstuffs, as well as starch digestion in single feedstuff and different feedstuffs combined with corn. Scanning electron microscope (SEM) results revealed significant difference between granule shape and size of starch of different feedstuffs. Fourier transforms infrared (FTIR) spectra for barley and wheat had lower (p < 0.05) absorbance band at areas A_860 and A_928 than other feedstuffs, yet rice starch had the lowest value for ratio (R) (1047/1022). Moreover, digestion rate ranged from 0.0157/min for resistant starch (sorghum) to 0.029/min for rapidly starch (broken rice). The principle component analysis (PCA) showed that predicted glycaemic index (pGI) was positively related to A_1022, glucose and rapidly (RDS) content and negatively related to A_995, A_1047, R (1047/1022), resistant starch (RS) and amylose content. Most of the feedstufss with corn combination had no effect on rate of starch digestion. In addition, different starchy feeds and corn combination changed the rate of starch digestion, when barley, however, sorghum combined with corn seemed to affect rate of starch digestion. To sum up, different sources differed in basic physicochemical and structural properties, which would influence the digestion rate of starch and the release of glucose. Combination of different feedstuffs particular sorghum with corn has interactive effect on starch digestion and the release of glucose.     

Influence of high ambient temperatures on performance of multiparous lactating sows.

Multiparous Large White sows (n = 63) were used to investigate the effects of five ambient temperatures (18, 22, 25, 27, and 29 degrees C) and two dietary protein contents on their lactation performance. At each temperature treatment, ambient temperature was maintained constant over the 21-d lactation period. Dietary protein content was either 14 or 17% with essential amino acids levels calculated not to be limiting. The animals had ad libitum access to feed between the seventh and the 19th day of lactation. Diet composition did not influence lactation performance. Over the 21-d lactation, feed intake decreased from 5.67 to 3.08 kg/d between 18 and 29 degrees C. Between d 7 and 19, the corresponding values were 7.16 and 3.48 kg/d, respectively. This decrease was curvilinear; an equation to predict voluntary feed intake (VFI) from temperature (T, degrees C) and body weight (BW, kg) is proposed: VFI = -49,052 + 1,213 T - 31.5 T2 + 330 BW - .61 BW2 (residual standard deviation: 1,018). Skin temperature increased regularly with increased ambient temperature (34.6 to 37.4 degrees C between 18 and 29 degrees C), whereas udder temperature reached a plateau at 25 degrees C (38.3 degrees C). The gradient of temperature between skin and rectum was minimal (2 degrees C ) at 27 degrees C and remained constant at 29 degrees C. This constancy coincides with the marked reduction of feed intake. The respiratory rate increased from 26 to 124 breaths/min between 18 and 29 degrees C, and this indicates that the evaporative critical temperature was below 22 degrees C. The BW loss increased from 23 to 35 kg between 18 and 29 degrees C, but its estimated chemical composition remained constant. Pig growth rate was almost constant between 18 and 25 degrees C (241 g/d) and was reduced above 25 degrees C (212 and 189 g/d at 27 and 29 degrees C, respectively). In conclusion, temperatures above 25 degrees C seem to be critical for lactating sows in order to maintain their performance.     

Production of cyclopiazonic acid, its effect on the chick embryo and on 1-day-old cockerels

In 1979 to 1983, 148 strains of Penicillium cyclopium were isolated from wheat and from poultry feed mixtures; 11.5% of these strains produced cyclopiazonic acid at the rate of up to 500 mg per kg of wheat. Forty-seven percent of the 96 isolates of Aspergillus flavus and 56% of the nine isolates of Penicillium griseofulvum produced cyclopiazonic acid at the maximum rate of 80 and 10 mg per kg. The ED50 of cyclopiazonic acid for two, three and four days old chicken embryo was found to be 2.40, 4.70 and 2.70 micrograms, respectively. Teratogenic effects were observed only in the two days old embryos in which the caudal end of trunk was shortened at the frequency of 0.36 and microophthalmia occurred at the frequency of 0.33. The LD50 of cyclopiazonic acid in day-old cockerels was found to be 21.71 mg per kg of weight.     

Mycotoxins and reproduction in domestic livestock.

Molds are parasitic plants that are ubiquitous in livestock feedstuffs. Even though molds themselves reduce the quality of grains, their synthesis of chemical substances termed mycotoxins causes the greatest monetary loss to the animal industry. Five major mycotoxins that impair growth and reproductive efficiency in North America are aflatoxins, zearalenone, deoxynivalenol, ochratoxin, and ergot. Aflatoxins are produced by Aspergillus flavus and Aspergillus parasiticus. Consumption of grains containing aflatoxins by swine affects reproduction indirectly by reducing feed intake and growth. In swine, aflatoxins impair liver and kidney function, delay blood clotting, increase susceptibility to bruising, and interfere with cellular humoral immune systems. Ruminants are comparatively resistant to aflatoxicosis, but presence of aflatoxins in milk of dairy cows is closely monitored for human safety. Depending on environmental conditions, Fusarium roseum can produce either zearalenone or deoxynivalenol. Days 7 to 10 postmating seem to be a critical period of gestation for zearalenone to exert its detrimental actions on early embryonic development. Presence of deoxynivalenol in swine feedstuffs decreases feed intake, causes feed refusal, and induces occasional vomiting. Several species of Penicillium and Aspergillus produce ochratoxin, a mycotoxin that causes necrosis of kidney tissue. Ergot alkaloids produced by Claviceps purpurea on wheat can cause reproductive problems and are associated with lactational failure in swine. Various methods have been developed to remove mycotoxins from infected feedstuffs. Chemical analyses in laboratories as well as diagnostic kits suitable for use at the elevator or farm can be used successfully to identify which mycotoxins are present in suspect feedstuffs.     

奶牛常用饲料干物质和淀粉瘤胃降解规律的研究

以3头安装有永久性瘤胃瘘管的泌乳前期荷斯坦奶牛为试验动物，在精粗比为55：45的日粮条件下，采用Insacco法测定了奶牛常用饲料瘤胃内干物质和淀粉的降解规律。试验结果表明。不同饲料干物质和淀粉的降解率不同。能量饲料中，麸皮干物质和淀粉的瘤胃降解率高于玉米：蛋白质饲料中，干物质和淀粉的降解率由高到低顺序依次是豆粕〉胡麻饼〉棉粕：常用粗料中，玉米青贮干物质和淀粉的降解率均高于青干草。     

The pathogenicity of Yersinia enterocolitica strains isolated from various sources in four test systems.

Six tests were applied to 39 strains of Yersinia enterocolitica of various serotypes and from several sources in an attempt to relate the test to pathogenicity of the strains. The tests that were used were the pig gut loop test and the infant mouse test for heat stable enterotoxin, the Sereny and HeLa cell tests for invasiveness, inhibition of growth on magnesium oxalate agar, and the ability to cause diarrhea in infant mice. The pig gut loop test was found to be unsuitable for detection of heat stable enterotoxin but 20 strains produced heat stable enterotoxin that was detected in infant mice. None of the strains was positive in the Sereny test but 21 invaded HeLa cells. The growth of 20 strains was inhibited at 37 degrees C on magnesium oxalate agar and, in the orally-infected mice, 23 strains caused diarrhea or death. These findings indicate a discrepancy between the infant mouse test and the ligated intestine test in pigs for heat stable enterotoxin and a significant difference in Y. enterocolitica heat stable enterotoxin compared with Escherichia coli heat stable enterotoxin because the former failed to elicit a significant response in pig intestine.