The effect of feeding diets containing deoxynivalenol contaminated corn on channel catfish (Ictalurus punctatus) challenged with Edwardsiella ictaluri

Channel catfish were fed practical corn‐soybean meal diets for 10 weeks that contained various weighed amounts of ground, dried field corn contaminated with 20 mg deoxynivalenol (DON) kg⁻¹. Weighed amounts of DON corn were blended with weighed amounts of ground, clean corn that contained no DON (0 mg kg⁻¹) to yield five diets that had 0, 2.5, 5.0, 7.5 and 10.0 mg DON kg⁻¹ of diet. Results show that catfish fed diets that contained DON for 7 weeks did not experience lower weight gains or poorer feed conversion ratios that were significantly (P > 0.05) different from control‐fed fish. Mortality of catfish during the 21‐day post‐challenge period indicate that catfish fed diets containing DON‐contaminated corn that provided at least 5.0 mg DON kg⁻¹ of diet had significantly (P < 0.05) lower mortality than catfish fed the control diet or the diet that provided 2.5 mg DON kg⁻¹ of diet. The presence of DON‐contaminated corn in the experimental diets did not significantly (P > 0.05) alter fish body weight gains and appeared to provide a protective effect for channel catfish challenged with the pathogenic bacterium Edwardsiella ictaluri.     

Inheritance of maize resistance to gibberella and fusarium ear rots and kernel contamination with deoxynivalenol and fumonisins

The objective of this study was to investigate the stability, across well‐differentiated environments, of genetic control of maize resistance to Fusarium graminearum and Fusarium verticillioides ear rots and mycotoxin contamination, found in genotypes of diverse origin and adapted to different environments. This knowledge will help to design the most appropriate breeding programme to reduce mycotoxin content across a wide range of environments. Although maize genetics involved in resistance to ear rots and mycotoxin contamination greatly depended on the environment, additive and dominance effects were the predominant genetic effects in most environments. The stability across environments for resistance to ear rots and deoxynivalenol and fumonisin contamination was low, and recommended target areas of breeding programmes for either Fusarium species are different based on the different nature of genetic effect × environment interactions for each species. In general, the classification of inbreds and hybrids according to their resistance levels was similar across environments, suggesting that the same sources of resistance could be suitable for different environments, and breeding for resistance to one species would affect resistance to the other one.     

Effect of two additives on the fermentation,in vitro digestibility and aerobic security of Sorghum–sudangrass hybrid silages

Two additives (Silo Guard (SG) and propionic acid (PA)) were tested for their effects on the quality and aerobic security of sorghum–sudangrass hybrid silages (JC‐1 and WC‐2). Two sorghum–sudangrass hybrid varieties were harvested for ensiling without additives (CK) or after the following treatments: SG at 0·5% of fresh forage or PA at 0·5% of fresh forage, with three replicates per treatment. The addition of SG and PA both affected the fermentation quality and chemical composition of the silages by lowering pH and NH₃‐N/TN and increasing lactic acid, the LA/TA ratio, WSC and CP concentrations compared with the untreated silages. In vitro DM digestibility (IVDMD), in vitro NDF digestibility (IVNDFD) and in vitro CP digestibility (IVCPD) were increased by SG in the JC‐1 silages and WC‐2 silages. Both additives improved the aerobic stability of sorghum–sudangrass hybrid silages. Furthermore, the additives reduced the mould counts and the aflatoxin and zearalenone levels compared with the untreated silages following aerobic exposure. Therefore, ensiling two sorghum–sudangrass hybrid varieties resulted in high‐quality silages. The addition of SG and PA improved silage quality, in vitro digestibility and aerobic security.     

谷物真菌毒素的控制策略

谷物真菌毒素主要是作物在生长阶段或者谷物存放过程中受到真菌感染而由真菌产生的次生代谢产物.被真菌毒素污染的食物和饲料对人和动物具有严重的急慢性毒性,因此研究去除毒素污染的途径,将有效保障谷物类产品的食用安全.本文综述了控制毒素产生的策略,及各种真菌毒素去除方法,主要包括控制真菌生长以减少毒素的产生,利用物理去除、化学吸附方法去除毒素,以及通过化学分解或酶促降解毒素等,并分析了这些方法的应用前景.     

含水率和发酵时间对以全株玉米为基础的发酵全混合日粮养分的影响

本试验研究了含水率和发酵时间对全株玉米发酵全混合日粮(FTMR)发酵品质及养分含量的影响,旨在为FTMR的生产提供参考。试验选用腊熟期全株玉米为主要原料,在保持饲粮精粗比例约为3∶7(干物质基础)的前提下,与干花生秧、混合精料等饲料充分混合配制成含水率为35%的全混合日粮(TMR),然后加水调整TMR含水率分别为40%、45%、50%和55%,将这5种含水率的TMR快速装入塑料密封袋内,压实并抽去空气后密封保存制备FTMR。分别在发酵后的第0、10、20、30、40、50、60、70和80天,测定常规养分含量、发酵指标及霉菌毒素含量。结果表明:5种含水率的TMR在发酵至第80天时感官指标良好,均无发霉现象;发酵初期各组均有涨袋现象,随着发酵时间的增加,涨袋现象逐渐消失;含水率对FTMR常规养分含量影响较小;发酵前20天,pH随含水率的升高而升高,此后随含水率的升高而下降; 45%、50%和55%组具有较高的乳酸含量;乙酸、丙酸含量随发酵时间增加而增加,只在发酵的第10、20、30天检出微量的丁酸;各组均未检出玉米赤霉烯酮、呕吐毒素及黄曲霉毒素B1。综合分析认为,本试验条件下,全株玉米FTMR的含水率以45%和50%为宜,发酵时间不少于40 d。     

小麦赤霉病菌多菌灵抗性群体的扩散路径分析——基于致病菌种类及所产毒素化学型鉴定和抗药性检出的时序性

通过对江苏、安徽、山东、河南、湖北、河北和四川7省小麦赤霉病菌对多菌灵抗性及敏感菌株Fusarium asiaticum和F.graminearum的鉴定、所产生毒素的化学型及多菌灵抗性菌株检出时序性的分析,初步推测了小麦赤霉病菌对多菌灵抗性群体在中国麦区的扩散路径。结果表明:江淮流域的江苏、安徽、湖北3省和四川省小麦赤霉病菌对多菌灵的抗性或敏感菌株优势群体均是F.asiaticum,而黄淮流域的山东、河南2省及河北省小麦赤霉病菌对多菌灵的敏感菌株优势群体为F.graminearum,抗性菌株优势群体则为F.asiaticum。江苏、安徽、山东和河南抗多菌灵菌株F.asiaticum产生毒素的化学型为3-AcDON和NIV,并以3-AcDON为主。江苏省连续使用多菌灵防治小麦赤霉病长达20多年后才检测到田间抗性菌株,而近年来检测到田间抗性菌株的山东、河南2省用多菌灵防治赤霉病的历史较短,且为偶尔使用,药剂的选择压力相对较小,因此推测山东和河南麦区出现的小麦赤霉病菌抗多菌灵菌株可能是通过种子调运及联合收割机跨区作业等方式从抗药性发生较早的江淮麦区流入的。     

Pathological studies in broiler chicks fed aflatoxin or ochratoxin and inoculated with inclusion body hepatitis virus singly and in concurrence

Day-old broiler chicks found negative for maternal antibodies against inclusion body hepatitis (IBH) virus by agar gel precipitation test and viral antigen in cloacal swabs by dot enzyme immunoassay were divided into 6 groups of 20 chicks each. Group A was fed aflatoxin B₁ at 1.25 ppm from 3 to 38 days of age; group O was fed ochratoxin A at 0.5 ppm from 3 to 38 days of age; group V was inoculated with 1 ml of IBH virus of titre log₁₀ 6.5 EID₅₀ per 0.2 ml. Groups AV and OV were given aflatoxin B₁ and ochratoxin A, respectively, and also infected with the virus. Group C served as control. There was mild enlargement and paleness of the liver up to 18 days post inoculation in group V; there were no lesions in group A; and there was gradual enlargement of the kidneys from 10 days post feeding of mycotoxin onwards in group O. In the combined groups AV and OV the gross lesions were slightly more severe. In group V, varying degrees of degenerative histopathological changes, congestion and haemorrhages were seen particularly in the liver, followed by the kidneys, bursa, spleen, myocardium and lungs, along with intranuclear inclusion bodies in the hepatocytes, mostly in the early stages of infection. Similar microscopic changes, but without inclusion bodies, were seen in groups A and O and the changes were pronounced in the later stages. In group O, the kidney lesions were more pronounced than the liver lesions. In the concurrently infected groups, AV and OV, the changes were similar but slightly more marked than in the corresponding individual groups. Inclusion bodies in hepatocytes were more frequent, more prominent and appeared earlier in the concurrent groups.Abbreviations AGPT agar gel precipitation test - DPF days post feeding of the mycotoxin - DPI days post inoculation - EIA enzyme immunoassay - EID₅₀ dose at which 50% of embryos will be infected - IBH inclusion body hepatitis - PAU Punjab Agricultural University     

Measurement of urinary concentrations of the mycotoxins zearalenone and sterigmatocystin as biomarkers of exposure in mares

Mycotoxins may affect animal health, including reproduction. Little is known about the clinical relevance of exposure of horses to contaminated feed. This study aimed at (i) monitoring the levels of the mycotoxins zearalenone (ZEN), with its metabolites α‐ and β‐zearalenol (α‐ and β‐ZOL), and sterigmatocystin (STC) in urine samples from thoroughbred mares in Japan and (ii) relating these findings to the potential effects on reproductive efficacy of breeding mares. Sixty‐three urine samples of breeding mares from 59 breeding farms were used. Urine samples and reproductive records were collected from each mare when it was presented to the stallion station. Urinary concentrations of ZEN, α‐ and β‐ZOL, and STC were measured using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). ZEN, α‐ and β‐ZOL were measurable in the urine of all examined mares, indicating the prevalence of ZEN in equine feeds. In seven of the 63 samples, STC was also detected at levels ranging from 1.3 to 18.0 pg/mg creatinine. No significant correlation between the concentrations of mycotoxins and pregnancy status was observed. In conclusion, measurement of mycotoxins in urine samples is a useful non‐invasive method for monitoring the systemic exposure of mares to multiple mycotoxins.     

东北地区粮库储存3年玉米在仔猪饲粮中应用效果的研究

本试验旨在通过饲养试验研究东北地区粮库储存3年玉米对仔猪生长性能以及血清生化、毒素和抗氧化指标的影响,确定储存玉米在仔猪饲粮中的应用效果,以指导粮库储存玉米的安全有效使用。选取48头平均体重为(14.0±3.8)kg的杜×长×大仔猪,按体重相近、公母各1/2原则随机分为2组(每组6个重复,每个重复4头)进行饲养试验。对照组饲粮选用当年收获的玉米(占饲粮60%)作为主要能量饲料,试验组饲粮则选用东北地区(克东粮库)储存3年的玉米(占饲粮60%)作为主要能量饲料,试验期28d。结果显示:与饲喂当年收获玉米的仔猪(公和母)相比,饲喂东北地区粮库储存3年玉米的仔猪(公和母)的生长性能以及血清生化(尿素氮含量与谷草转氨酶和谷丙转氨酶活性)、抗氧化(超氧化物歧化酶活性、还原性谷胱甘肽含量)和毒素指标(黄曲霉毒素B1、内毒素含量)均无显著差异(P>0.05)。由上述结果得出,将东北地区粮库(克东粮库)储存3年玉米应用于仔猪(12~30kg)饲粮中,可取得与当年收获玉米相同的饲喂效果。