低温对几个苜蓿品种幼苗膜透性的影响

在实验室条件下对６个苜蓿品种，即肇东苜、公农一号苜蓿、爱开夏苜蓿、淮阴苜蓿、和田苜蓿、准格尔苜蓿的子叶期幼苗的电导率进行了测定，并配以Ｌｏｇｉｓｔｉｃ曲线（Ｙ＝Ｋ／１＋ａｅ＾－ｂｘ）求出拐点温度。结果表明：（１）以公农一号苜蓿膜透性最小，淮阴苜蓿膜透性最大，其它４种居中，方差检测表明，品种间差异显著。（２）随着处理时间延长，拐点温度则升高，Ｔ１ｈ≈－２．９６℃。     

混合防冻剂、投液氮温度及解冻温度对牛体外受精胚胎活力的影响

试验一按正交设计比较了三种浓度（０．５Ｍ，０．７５Ｍ和１．０Ｍ）的甘油和丙二醇、三种投液氮温度（－２５℃，－３５℃，－４５℃）、三种解冻温度（１０℃，２０℃，３７℃）对第７、第８天囊胚存活率的影响。结果甘油浓度以１．０Ｍ和０．７５Ｍ的效果较好，胚胎成１６率分别为５４．０％和５３．１％；而丙二醇以０．５Ｍ水平的成活率最高，为６１．６％；投液氮温度以－２５℃的效果最好；（成活率为５６．１％）；解冻温度则以２０℃、３７℃优于１０℃，成活率分别为５７．６％，５８．９％及３７．１％。试验二用０．７５Ｍ甘油十０．５Ｍ雨二醇及１．０Ｍ甘油＋０．５Ｍ丙二醇作为防冻剂，将胚胎降温至－２５℃后投入液氮，在２０℃水浴中解冻。结果两组胚胎的成活率均较高，分别为７９．０％和８０．０％（Ｐ＞０．０５）。     

电导法配合Logistic方程确定燕麦冰冻半致死温度

采用电导法对８个燕麦品种在不同低温下细胞膜透性改变情况进行研究，然后配合Ｌｏｇｉｓｔｉｃ方程求拐点值确定冰冻半致死温度（ＬＴ＿（５０））。试验结果：低温处理下，燕麦组织电解质透出率增加呈Ｓ形曲线增长，在－４℃～－１０℃之间随着温度的下降，燕麦组织电解质透出率有一急剧升高的敏感区域；燕麦品种ＬＴ＿（５０）在－３．３～－８．０之间；品种永久１２抗冻性最强，品种Ｖｉｃｔｏｒｙ其次，品种Ａｔｈａｂａｓｃａ抗冻性最差。     

低温与克伦特罗（CL）对肉仔鸡生产性能的影响

试验采用２×３（温度：１０ｖｓ２２℃，ＣＬ：３ｖｓ０１０＾－６）４重复完全交叉分组试验设计研究低温与克伦特罗对２９￣５６日龄ＡＡ雌性肉仔鸡生产性能的影响。结果表明；低温显著降低肉仔鸡生产性能，全期平均日采食量和耗料增重比分别增加５．９４％和９．０９％（Ｐ〈０．０１），平均日增重降低了２．９４％（Ｐ〈０．０５），且平均日增重还表现出对低温的适应。ＣＬ对试验全期肉仔鸡生产性能没有影响（Ｐ〉０．０５），     

猪胚胎冷冻技术研究现状与分析

本文论述了猪胚胎冷冻技术发展过程，并分析了胚胎冷冻的可能性原理、猪胚胎对低温的敏感性与影响胚胎冷冻成功率的因素等，得出如下结论：（１）猪胚胎对低温较其它畜种敏感的原因是其胚胎内脂肪含量高于其它畜种。（２）目前适于冷冻的胚胎仅限于孵化前后胚胎。（３）慢速冷冻已基本成功，选用１．５Ｍ甘油作冷冻保护剂，－６￣－７℃植冰，植冰前降温速度１℃／ｍｉｎ，植冰后０．３℃／ｍｉｎ，投氮温度－３５￣－３８℃。（４）     

牛体外受精胚胎一步脱防冻剂冷冻方法的研究

为了研究适合于牛体外受精胚胎的一步除防冻剂的冷冻方法，特进行两个试验。试验１分别用１．５Ｍ甘油＋０．２５Ｍ蔗糖、１．５Ｍ乙二醇和１．５Ｍ丙二醇作防冻剂冷冻体外受精后第７天，已发育至囊胚阶段的牛胚胎。使胚胎降温至－７℃后，植冰，然后以０．３℃／分的速率降温至－３０℃，立即将胚胎投入液氮中冷冻保存。在３７℃水中解冻胚胎后，使其直接在含１５％胎犊血清（ＦＣＳ）的磷酸缓冲液（ＰＢＳ）中脱去防冻剂。经体外培养７２ｈ后，３组胚胎的孵化率分别为７７．２７％（１０２／１３２）、７３．２４％（１０４／１４２）、４７．９０％（５７／１１９），第１、２组的孵化率极显著高于第３组（Ｐ＜０．０１），说明用１．５Ｍ丙二醇溶液冷冻的胚胎，在解冻后不宜直接在ＰＢＳ中脱防冻剂。试验２比较用不同浓度（１．０Ｍ０１．５Ｍ，２．０Ｍ）的乙二醇和不同投液氮温度（－２５℃，－３０℃，－３５℃）冷冻胚胎的效果。结果表明乙二醇浓度和投液氮温度对胚胎孵化率均无显著影响（Ｐ＞０．０５），各组胚胎的孵化率变动于７４．４４％－８５．４８％之间。     

环境温度对肉用仔鸡尿酸排泄及氮代谢影响的研究

４０只周龄“宝星”肉用仔鸡平均分为５组分别在１２．３，１８．１，２２．９，２８．．０和３１．３℃处理４周，研究环境温度对尿酸排泄和氮代谢的影响。结果表明，粗蛋白质食人量，干物质排泄量和氮排泄量均与温度呈显著负相关（ｒ＝－０．７１）。蛋白质的生物学价值与温度呈显著正相关（ｒ＝０．６７）。氮的沉积率（ＮＲＲ）主要受尿氮排出量的影响，在１２．３－２８℃ＮＲＲ随着温度的升高而升高，故低温可造成蛋白质的浪费     

混播草坪锈病植株空间分布型及抽样技术初探

通过对田间１６个混播草坪区的系统调查和用聚集强度指标进行测定分析，１６个混播区的扩散系数Ｃ〉１，负二项Ｋ〉０，Ｃａｓｓｉｅ（１９６２）和Ｋｕｎｏ（１９６８）指标ＣＡ〉０，Ｄａｖｉｄ和Ｍｏｏｒｅ（１９５４）丛生型指标Ｉ〉０，Ｌｌｏｙｄ聚集性指标ｍ＾＊／ｘ↑－〉１。用幂指数法（Ｔａｙｌｏｒ）和Ｉｗａｏ法分析的结果表明，混播草坪上锈病株的空羊分布型在平均发病率８．７％￣４１．２％范围内时为聚焦分布，即田     

冬春低温季节肉鸡饲养管理要点

肉鸡生存的基本条件是温度、空气、饲料和水。在冬春低温季节饲养肉鸡如何创造肉鸡的良好生长环境，是低温季节养好肉鸡的关键所在。冬春低温季节肉鸡的需温要求和新鲜空气通风需求量。１．育雏鸡舍温度要求：１日龄至４日龄２８℃－３０℃５日龄至１０日龄２６℃－２７℃...     

蚕种低温处理对孵化率的影响

－１０℃、－２０℃低温处理蚕种对蚕卵的孵化率有影响，甲胚子短期接触１０℃、－２０℃低温对孵化率影响不大，但丙胚子接触这种低温会严重影响孵化。不同类型蚕品种相同胚子耐低温的能力表现为多丝量品种高于强健性品种。     

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     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

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.