根腐病原镰刀菌-品种-土壤水分互作对苜蓿保护酶活性的影响

为了探明不同水分、镰刀菌对苜蓿品种保护酶活性的影响,本研究选择紫花苜蓿品种‘阿尔冈金’、‘丰宝’与‘苜蓿王’在不同水分条件下接种半裸镰孢和腐皮镰孢后,对其幼苗分别进行PPO,POD,SOD及PAL的活性的测定,评价接种真菌对保护酶活性的影响及菌种、水分、品种三者之间对其保护酶活性的相互关系。结果表明:接菌显著抑制了苜蓿品种PPO的活性(P<0.05),而且菌种和品种、菌种和水分之间有显著的互作(P<0.05)。同一水分条件下,无论是30%,50%还是70%的水分处理,均以‘丰宝’的酶活最低,‘苜蓿王’的酶活最高。在接菌条件下,‘阿尔冈金’、‘丰宝’均提高了其PAL活性但差异不显著。菌种和水分均显著影响各苜蓿品种的POD,SOD,PAL活性(P<0.05),且多因素之间存在显著的互作效应(P<0.05)。     

紫花苜蓿镰刀菌根腐病抗病种质资源筛选

紫花苜蓿根腐病是我国苜蓿产区普遍发生的病害之一,其主要致病病原为尖孢镰刀菌.采用水培接菌法接种尖孢镰刀菌,测定58份供试苜蓿材料的病情指数、株高、根长、地下生物量并进行相关分析和聚类分析,评价紫花苜蓿种质材料苗期根腐病抗性.结果表明,株高、根长、地下生物量与病情指数均呈负相关.病情指数变化范围为12.50～70.83,...     

立枯丝核菌病原致病性及苜蓿品种抗病性研究

为了探明立枯丝核菌对苜蓿种苗的致病性,本研究采用菌饼上放置种子的方法,将分离自3个地点6个苜蓿品种上的6个菌株接种于14个紫花苜蓿品种的种子上,14 d测定相对发芽率、根长、苗长和病情指数。结果表明,参试菌株的菌降低了种子的发芽,从金皇后分离到的菌株对苗长的抑制作用最强;致病性差异显著(P<0.05),其中从金皇后分离出菌株的致病性最强,从丰宝中分离出菌株的致病性最弱;从金皇后、8920MF和爱菲尼特中分离出的立枯丝核菌对苜蓿种子与幼苗的致病力较强;参试的苜蓿品种对同一菌株的抗病性不同,佛拿尔、阿尔冈金和苜蓿王的抗病力最强,丰宝、丰叶721抵抗力最弱。     

黑龙江省哈尔滨市苜蓿镰孢根腐病病原菌分离鉴定

【目的】明确黑龙江省哈尔滨市苜蓿根腐病病原菌种类。【方法】采集 38 株黑龙江省哈尔滨市农业科学院示范区的苜蓿根腐病病株，经组织分离法分离致病菌，通过科赫氏法则验证其致病性并结合形态学和 rDNA-ITS 序列分析鉴定病原菌。【结果】从患有苜蓿根腐病的病根分离并选取具有代表性的 5 株真菌 KY1、J1、S1、SA1、C1，分别被鉴定为腐皮镰孢(Fusarium solani)、尖镰孢(F. oxyspo- rum)、水稻恶苗病菌(F. fujikuroi)、三线镰孢(F. tricinctum)和层出镰孢(Fusariumproliferatum)。致病性测定表明 5 株真菌均为苜蓿根腐病致病菌。【结论】腐皮镰孢不仅分离率最高，为 57. 45%，且致病性也较强，病情指数为 61. 00，是优势病原菌。     

不同紫花苜蓿品种根部入侵真菌研究

为探讨紫花苜蓿(Medicago sativa L.)品种不同季节常见根部入侵真菌及其表现规律,并为苜蓿品种选择及其病害防治提供科学依据,以30个紫花苜蓿品种为材料,分别于2006年的春、夏、秋季取样,分离和鉴定根部入侵真菌.结果表明:不同生长季节苜蓿根部入侵真菌区系中优势菌种类明显不同,春、夏、秋3季均有的建群种为细交链孢(Alternaria alternata)和腐皮镰孢(Fusarium solani),其中春、夏季还有半裸镰孢(F.semitectum)和尖孢镰孢(F. oxysporum),秋季有锐顶镰孢(F. acuminatum)和柱孢(Cylindrocarpon destructuns);不同苜蓿品种在3个季节的入侵真菌种类和其分离率均有显著差异(P<0.05),且根部带菌率与生长季节苜蓿品种密切相关,春季以赛特(Sitel)的带菌率最高,夏、秋季以农宝(Farmers)和佛纳尔(Vernel)为最高,平均带菌率较高的5个苜蓿品种依次是:赛特、农宝、皇冠(Phabulous)、航海4号(Flight No.4)和猎人河(Hunfer river),平均带菌率较低的5个苜蓿品种依次是:苜蓿王(Alfaking)、爱菲尼特(Affinity)、WL-525HQ、顶点(Apex)和丰叶 721(Amerileaf 721).     

12个苜蓿品种种子萌发期耐盐性研究

为了确定不同苜蓿(Medicago sativa L.)品种的耐盐能力,明确其适宜的盐浓度范围,从而为我国盐渍化土地提供适宜种植的牧草品种,试验以12个审定的苜蓿品种为研究对象,测定了不同盐浓度下各品种种子的相对发芽率、相对发芽势、简化活力指数、萌发活力指数。结果表明:在Na Cl浓度为0.8%时苜蓿品种间各指标均差异显著(P0.05)。丰宝的耐盐性最强,阿尔冈金的耐盐性最弱,各苜蓿品种耐盐性顺序为丰宝四季旺爱菲尼特多叶王金皇后WL324West blend皇后2000新疆大叶苜蓿Able宁苜一号阿尔冈金。     

苜蓿根腐病病原菌分离鉴定与抗病种质材料筛选

在黑龙江省大庆市采集具有典型苜蓿根腐病症状的发病植株进行病原分离、纯化,根据形态学和rDNA-ITS序列分析进行鉴定,确定分离获得的苜蓿根腐病病原菌为层出镰刀菌(Fusarium proliferatum)。对来自国内外具有较强抗寒性的16个紫花苜蓿品种芽期接种病原菌菌株,于接种后第14d测定紫花苜蓿幼芽的相对根长、相对苗长和病情指数,利用隶属函数值对不同品种苜蓿进行抗病性综合评价。结果表明,层出镰刀菌接种后,各紫花苜蓿品种幼芽的相对根长、相对苗长及病情指数差异显著(P0.05);根据隶属函数值评价结果,品种WL168HQ、TG4、斯贝德和肇东的综合抗病性表现较强,DS310FY、北极星、皇后、WL319HQ和巨能-CR的综合抗病性较弱。     

紫花苜蓿对尖孢镰刀菌的抗性评价

采用土壤接菌法测定了发病率、病情指数、株高、地上生物量和地下生物量等指标,并对60份紫花苜蓿种质材料进行了苗期抗根腐病评价。结果表明,各品种(系)之间抗病性差异显著,其中牧歌401+2、爱开夏、478572、宝鸡苜蓿等12份苜蓿材料对尖孢镰刀菌表现为耐病,病情指数范围为25.92~29.63,占鉴定材料总数的20.0%;同心、榆次和GT49R等34份苜蓿材料表现为感病,病情指数范围为40.34~57.85,占鉴定材料总数的56.67%;新疆大叶、兴平和普罗旺斯等14份苜蓿材料表现为高感,病情指数范围为60.22~82.78,占鉴定材料总数的23.33%;无表现免疫和抗病的材料。接种尖孢镰刀菌后苜蓿的株高、地上生物量和地下生物量均显著下降(P0.05),感病材料株高、地上生物量和地下生物量的下降幅度明显大于耐病材料。     

几种真菌对3种常见冷季型草坪草的致病性测定

以我国北方常见的冷季型草坪草高羊茅(Festuca arundinacea)、多年生黑麦草(Lolium perenne)和草地早熟禾(Poa pratensis)为材料，将细交链孢(Alternaria alternata)、根腐离蠕孢(Bipolaris sorokiniana)、枝孢(Cladosporium herbarum)、新月弯孢(Curvularia lunata)、德氏霉(Drechslerasp．)、燕麦镰孢(Fusarium avenaceum)、锐顶镰孢(F．acuminatum)、尖镰孢(F．oxysporum)，腐皮镰孢(F．solani)和粉红粘帚霉(Gliocldium roseum)10种分离自草坪草的真菌接种，进行离体叶片的致病性测定。结果表明：细交链孢、根腐离蠕孢、德氏霉、腐皮镰孢、粉红粘帚霉和枝孢对高羊茅具有明显的致病性；根腐离蠕孢、燕麦镰孢和锐顶镰孢对黑麦草有明显的致病性；而仅根腐离蠕孢对早熟未有较明显的致病性。     

醉马草-内生真菌共生体中生物碱的抑菌活性

本研究以Epichloё属内生真菌侵染(E+)和未被侵染(E-)的醉马草(Achnatherum inebrians)生物碱提取液为材料,测定其对麦角菌(Clavieps purpurea)、德氏霉(Drechslera erythrospila)、燕麦镰孢(Fusarium avenaceum)、根腐离蠕孢(Bipolaris sorokiniana)、新月弯孢(Curvularia lunata)、半裸镰孢(Fusarium semitectum)、腐皮镰孢(Fusarium solani)和细交链孢(Alternaria alternata)8种植物病原真菌菌落生长和孢子萌发的抑制率,明确醉马草生物碱提取液的抑菌活性。高效液相色谱(HPLC)检测结果发现,E+醉马草提取液中含有麦角新碱和麦角酰胺两种生物碱,其浓度分别为26.178和369.074 mg·kg-1,而E-醉马草提取液中不含这两种生物碱。不同浓度的E+和E-醉马草提取液对供试植物病原真菌的菌落繁殖和孢子萌发均具有不同程度的抑制作用,E+对真菌菌落生长的抑制率要大于E-,其中对腐皮镰孢菌落生长和孢子萌发的抑制率最大,分别达到63%和57%。生物碱提取液浓度与供试真菌孢子萌发抑制率呈显著正相关(P0.05)。内生真菌的侵染提高了醉马草提取液的抑菌活性,共生体中含有生物碱成分,具体的抑菌机制和机理有待后续研究。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.