豆科牧草种子萌发特性与其抗旱性差异的研究

试验采用PEG模拟干旱测定了3种豆科牧草(5个品种)种子的相对发芽率和胚根／胚芽比值，并在温室条件下采用盆栽控水研究了这3种牧草在水分胁迫下叶片相对含水量和质膜透性的变化规律。结果显示：种子萌发期抗旱性强的牧草其分枝期抗旱性亦强，抗旱能力依次为游客＞德福＞百脉根＞胡亚＞瑞文德。试验证明，利用生理生化方法和种子萌发实验进行牧草品种间抗旱性鉴定是可行的。     

4种牧草种子在不同逆境下的萌发特性

为了探究牧草种子萌发期的抗逆性,本研究使用NaCl和聚乙二醇(PEG-6000)分别模拟盐胁迫(0、0.2%、0.4%、 0.6%和0.8%)和干旱胁迫(0、 5%、 10%、 15%和20%),测定沙打旺(Astragalus adsurgens)、沙蒿(Artemisia desertorum)、黄花草木樨(Melilotus officinalis)和黄花苜蓿(Medicago falcata) 4种供试物种萌发期抗逆性指标(相对发芽率、相对发芽势、相对发芽指数和相对活力指数)。结果表明:1)随着NaCl浓度的增加,种子各指标均呈下降趋势,隶属函数法综合评价结果显示,供试牧草萌发期耐盐性强弱依次表现为黄花苜蓿>沙蒿>黄花草木樨>沙打旺。2)低浓度PEG (5%)胁迫处理,对沙蒿、沙打旺和黄花草木樨3种牧草种子萌发指数具有明显的促进作用;与对照组相比,10%～20%PEG下各指标显著低于对照组(P <0.05);采用隶属函数法分析4种牧草的萌发期抗旱性,强弱依次表现为黄花苜蓿>黄花草木樨>沙蒿>沙打旺。说明黄花苜蓿种子萌发期抗旱性、耐盐性均...     

6种高寒牧区禾本科牧草抗旱性研究与评价

本研究选择在高寒地区种植多年的6种禾本科牧草,对其进行种子萌发期和苗期抗旱性试验。用PEG模拟水分胁迫及连续干旱法来研究干旱胁迫对种子发芽率及种子幼苗期生理指标的影响,以此来综合评价六种禾本科牧草的抗旱性强弱。种子萌发期研究结果表明,5%的PEG浓度有效促进种子萌发,高PEG浓度显著抑制种子发芽率。经连续干旱胁迫法处理的苗期牧草,测定其相对含水量、丙二醛含量、可溶性糖含量和叶绿素含量四项生理指标。对两个时期隶属值综合分析可知,六种牧草的抗旱性强弱为：草原看麦娘（Alopecurus pratensis） > 无芒雀麦（Bromus inermis） > 同德短芒披碱草（Elymus breviaristatus） > 同德贫花鹅观草（Roegneria pauciflora） > 大颖草（Roegneria grandiglumis） > 扁穗冰草（Agropyron cristatum）。     

不同燕麦品种萌发期的抗旱性比较研究

燕麦(Avena L.)是禾本科燕麦属的一年生的草本植物,属于粮饲兼用作物,具适应性广、抗逆性强等特点。为比较不同燕麦品种种子萌发期的抗旱性,以7个饲用燕麦品种为供试材料,采用15%的聚乙二醇(PEG-6000)模拟干旱胁迫,测定相对发芽率、相对发芽势等8个生长指标,并对其进行了主成分分析和加权隶属函数法综合比较。结果表明,与燕麦种子萌发期抗旱性关系最密切的评价指标有种子萌发指数、发芽指数、活力指数、鲜重、胚芽长、胚根长和发芽势;在15%PEG-6000干旱胁迫下,燕麦品种贝勒抗旱性综合评价值最高,D值为0.710;品种Haywire的抗旱性最差,D值为0.103;饲用燕麦萌发期抗旱性强弱依次为:贝勒>坝莜6号>定燕2号>蒙饲草2号>蒙燕1号>冀张燕4号>Haywire。     

川西北高寒草地3种禾草种子萌发期抗旱性

摘要:为研究川西北高寒草地牧草种子萌发期的抗旱性,选用川西北高寒草地当地的3种牧草--‘阿坝’硬秆仲彬草（Kengyilia rigidula ‘Aba’）、川草2号老芒麦（Elymus sibiricus cv.‘chuancao No.2’)和垂穗披碱草(Elymus nutans)为研究对象,用0、50、100、150和200 g/L的聚乙二醇（PEG 6000）溶液模拟干旱胁迫。采用隶属函数法对各材料的相对发芽率、相对发芽势、相对发芽指数、相对活力、抗旱指数进行抗旱性综合评价。结果显示,50 g/L的PEG 6000有利于种子的萌发;相对发芽指数、抗旱指数为鉴定川西北高寒草地3种牧草种子萌发期抗旱性的较好指标;抗旱性强弱依次为硬秆仲彬草＞垂穗披碱草＞川草2号老芒麦。     

PEG-6000模拟干旱胁迫下5份苜蓿材料萌发期抗旱性鉴定与比较

[目的]分析国内外不同品种苜蓿材料萌发期的抗旱性,筛选出抗旱性较强的苜蓿品种。[方法]分别采用浓度为0、5%、10%、15%、20%的聚乙二醇-6000(PEG-6000)溶液对5份苜蓿种质材料（新牧4号、中苜3号、歌纳、A-17、D-23）进行模拟干旱胁迫处理,以蒸馏水处理为对照组（CK）;测定不同品种苜蓿种质材料在不同PEG-6000处理浓度下萌发期的发芽指标及抗旱系数,利用隶属函数法对其抗旱性能进行综合评价。[结果]通过测定种子萌发的相关指标以及利用隶属函数法对不同萌发指标进行多维度综合评价,不同苜蓿材料种子萌发期的抗旱性强弱顺序依次为歌纳>A-17>新牧4号>D-23>中苜3号。[结论]在PEG-6000模拟自然干旱的试验条件下,综合抗旱性最好的苜蓿品种为歌纳,其次是A-17。     

不同糜子品种萌发期对干旱胁迫的响应及抗旱性评价

利用PEG-6000溶液模拟干旱胁迫,对16个糜子(Panicum miliaceum L.)品种萌发期与抗旱性相关的指标进行测定,比较其抗旱性,并采用隶属函数法对其抗旱性进行综合评价.结果表明:不同糜子品种抗旱性有显著性差异.干旱胁迫抑制糜子种子萌发活力,降低了萌发速度和发芽率;干旱胁迫对糜子胚根的抑制要强于胚芽;萌发抗旱指数、相对发芽率、相对发芽势、相对胚芽长、相对胚根长、相对萌发指数和相对活力指数均可作为糜子萌发期抗旱性鉴定的参考指标.河曲红黍子、伊选红糜、粘丰5号这3个品种抗旱性较强.     

干旱胁迫对两种扁穗雀麦种子萌发期抗旱性试验

扁穗雀麦是重要的牧草之一,广泛应用于畜牧业中。用渗透胁迫对野生扁穗雀麦和黔草3号雀麦进行种子萌发期抗旱性进行比较试验,通过对2种种子活力,抗旱指数,发芽势等指标进行测定,结果表明野生扁穗雀麦具有更强的抗旱性.     

野生狼尾草萌发期和幼苗期抗旱性的综合分析

以5个不同生境的野生狼尾草种子为试验材料,萌发期采用10%,15%和20%浓度的PEG6000模拟干旱胁迫,幼苗生长期采用控水处理,通过对相对发芽率、相对发芽势、叶片相对电导率、叶片相对含水量等抗旱相关指标测量,综合评价野生狼尾草种子萌发期和幼苗期的抗旱性。结果表明:萌发期抗旱性较强的是ST、YJ2,抗旱性较弱的是FX、DY;ST和NS苗期的抗旱性较强,YJ2和FX抗旱性弱;萌发期和苗期的抗旱性综合排名为STNSYJ2DYFX。     

盐胁迫对西藏3种野生披碱草属牧草种子发芽影响

为确定披碱草属(Elymus Linn.)3种优良牧草品种的耐盐能力,明确其耐盐浓度范围,试验设0%(对照)、0.4%、0.8%、1.2%、1.6%5个NaCl浓度水平,对3种披碱草属牧草(披碱草、老芒麦、垂穗披碱草)进行单盐胁迫。结果发现:不同的单盐浓度对3种野生牧草种子发芽的影响很大;随着盐浓度的增加,3种野生牧草种子的发芽率、发芽势、相对发芽率、萌发指数和活力指数不断下降;当盐浓度为1.6%时,披碱草、垂穗披碱草的发芽率、发芽势、萌发指数、相对盐害率等均为0,即种子萌发受到了完全抑制。结合指标综合评价,西藏3种牧草种子萌发期的耐盐性排序:老芒麦>垂穗披碱草>披碱草。初步判定,西藏野生老芒麦耐盐性最强,西藏野生披碱草耐盐性最差。     

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.