脱防冻剂方法对牛体外受精胚胎冷冻后成活率的影响

为了观察脱防冻剂方法对牛体外受精冷冻胚胎在体内、外发育率的影响,应用常规冷冻法在０．７５ｍｏｌ／Ｌ甘油＋０．５ｍｏｌ／Ｌ丙二醇溶液中冷冻受精后７、８ｄ的囊胚,解冻后在０．２５、０．５ｍｏｌ／Ｌ蔗糖液中二步或在０．２５ｍｏｌ／Ｌ蔗糖液中三步脱防冻剂的胚胎孵化率（分别为６８．６％、６２．２％、６８．７％）与用ＰＢＳ／ＦＣＳ六步脱防冻剂的差异不显著（７０．４％,Ｐ＞０．０５）,但在０．５ｍｏｌ／Ｌ蔗糖液中三步脱防冻剂后,孵化率显著降低（４７．６％,Ｐ＜０．０１）。用０．２５ｍｏｌ／Ｌ或０．５ｍｏｌ／Ｌ蔗糖或海藻糖预先使胚胎脱水后冷冻,解冻后可使胚胎直接在ＰＢＳ中一步脱掉防冻剂,胚胎孵化率（４５．０％～４９．５％）与在０．２５ｍｏｌ／Ｌ蔗糖液中二步脱防冻剂的相似（５１．５％,Ｐ＞０．０５）。移植试验表明,在０．２５ｍｏｌ／Ｌ蔗糖液中二步脱防冻剂获得的妊娠率与六步脱防冻剂相似,与在ＰＢＳ中一步脱防冻剂的亦无明显差异,但妊娠率均偏低（２１．４％～３７．５％）。     

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。     

奶牛胚胎分割与半胚裸露冷冻保存试验

本试验研究了①Ａ、Ｂ、Ｃ三个质量等级胚胎的分割效果；②五种不同冷冻方法冷冻裸露半胚的存活情况；③冻前培养３．０、１．５～２．０、１．０小时的裸露半胚存活率。结果①Ａ、Ｂ、Ｃ级胚胎的分割成功率分别为９５．８％（９２／９６）、７且．４％（７０／９８）、３０％（６／２０），三者间差异极显著（Ｐ＜０．０１）；②半胚冷冻前以２０％ＦＣＳ－ＰＢＳ液培养３．０小时后，以五种不同冷冻方法冷冻，均未获得存活半胚；③半胚冷冻前培养３．０、１．５～２．０、１．０小时后，以添加１０％而聚糖的１０％甘油＋０．１Ｍ蔗糖／ＰＢＳ液冷冻，分别获得了０％（０／４５）、６８．８％（１１／１６）、７５．０％（９／１２）的存活率。结果表明，胚胎质量是影响胚胎分割成功率的关键因素，半胚冷冻前的培养时间是影响裸露半胚存活的重要因素。     

奶牛半胚裸露冷冻保存试验

本试验研究了不同冷冻方法，半胚冷冻前不同培养时间及不同冷冻保护液对奶牛７日龄半胚裸露冷冻效果的影响，结果以１０％（Ｖ／Ｖ）甘油＋１０％（Ｗ＋Ｖ）葡聚糖（Ｔ－５００）＋０．１Ｍ蔗糖＋２０％ＦＣＳ－ＰＢＳ溶液为冷冻保护液，裸露冷冻前培养１．０小时的半胚，获得了８２．４％（１４／１７）的较高存活率。试验结果表明，半胚冷冻前培养时间及不同保护液对奶牛半胚裸露冷冻有显著影响。     

在生产条件下牛冷冻胚胎直接移植的效果

以１８Ｍ乙二醇或１６Ｍ丙二醇作抗冻剂冷冻牛胚胎,解冻后在Ｍ－ＰＢＳ中一步脱除抗冻剂体外培养或不脱除抗冻剂直接移植给受体母牛。结果表明用１８Ｍ乙二醇直接移植法的体外培养存活率和移植妊娠率均显著高于１６Ｍ丙二醇组,分别为８４８％比６５５％和４８５％比４００％（Ｐ＜００５）,但与对照组（１４Ｍ甘油常规法）之间无显著差异,分别为８４８％比８６７％和４８５％比５００％（Ｐ＞００５）。     

硫酸鱼精蛋白和谷氨酰胺对鸡精液冷冻效果的影响

以农大褐父母代种鸡为材料，进行硫酸鱼精蛋白和谷氨酰胺对鸡精液冷冻效果影响表明，Ａ液＋ＤＭＡ和Ｂ液＋甘油，解冻后精子活力分别为０．５３、０．４９，均显著高于其它（Ｐ〈０．０２５），Ａ液＋硫酸鱼精蛋白、Ａ液＋谷氨安、解冻后分别获得了０．４６、０．４１的精子活力、均显著高于对照组（Ｐ〈０．０５）；Ｂ组均不显著（Ｐ〉０．０５）。     

种鸡精液冷冻保护剂的确定

以农大褐父母代鸡为材料，以甘油、乙二醇、ＤＭＡ和ＤＭＳＯ为主要冷冻保护剂的试验表明，乙二醇和ＤＭＡ的毒性较小，以Ａ液为稀释液，加抗冷冻剂ＤＭＡ的解冻精子活力为０．５５，且以１０％的ＤＭＡ浓度最佳，精子活力最高为０．６０，显著高于其它组（Ｐ〈０．０５）。以Ｂ液为稀释液的解冻结果表明，应用混合冷冻保护剂的保护效果较好，可获得０．４１￣０．４５的精子活力，差异显著（Ｐ〈０．０５）。     

硫酸鱼精蛋白和谷氨酰胺对鸡精液冷冻的作用

本文以农大褐父母代种鸡为材料，研究硫酸鱼精蛋白和谷氨酰胺对鸡精液冷冻效果的作用表明，Ａ０液＋ＤＭＡ和Ｂ０液＋甘油，解冻后精子活力分别为０．５３，０．４９，均显著高于其它组（Ｐ＜０．０５）；Ａ０液＋硫酸鱼精蛋白、Ａ０液＋谷氨酰胺，解冻后分别获得了０．４６，０．４１的精子活力，均显著高于对照组（Ｐ＜０．０５）；Ｂ０液各组试验效果差异均不显著（Ｐ＞０．０５）。     

牛体外受精胚冷冻保存的研究

对牛卵泡卵母细胞体外受精（ＩＶＦ）１６８ｈ的致密桑椹胚、囊胚用常规快速冷冻法、预冷和不预冷的超快速冷冻法进行了冷冻保存试验。结果表明：ＩＶＦ囊胚采用含１０％甘油的常规快速冷冻法、含２．１ｍｏｌ／Ｌ甘油和０．２５ｍｏｌ／Ｌ蔗糖预冷５ｍｉｎ的一步冷冻法及含２５％甘油和２５％乙二醇预冷５ｍｉｎ的玻璃化冷冻法等３种方法进行冷冻保存，解冻后的继续发育率（６８．０％，５９．０％，６５．７％）均无显著差异（Ｐ＞０．０５），可用快速、简便、预冷的一步冷冻法或玻璃化冷冻法替代常规快速冷冻法；ＩＶＦ致密桑椹胚可用一步冷冻法（２．１ｍｏｌ／Ｌ甘油＋０．２５ｍｏｌ／Ｌ蔗糖）和玻璃化冷冻法（２５％甘油＋２５％乙二醇或２５％甘油＋２５％１，２－丙二醇）进行预冷的超快速冷冻保存；冻前预冷（５ｍｉｎ）能显著提高ＩＶＦ囊胚的冻后形态正常率和继续发育率（Ｐ＜０．０５）；ＩＶＦ囊胚冷冻—解冻后的继续发育率高于ＩＶＦ致密桑椹胚。     

红三叶组织培养及再生植株

本文采用ＭＳ，Ｂ５和ＰＣ一Ｌ２作为基本培养基，在不同激素组合条件下对红三叶（Ｔｒｉｆｏｌｉｕｍｐｒａｔｅｎｓｅ）子叶及下胚轴进行组织培养。在ＭＳ，Ｂ５和ＰＣ一Ｌ２附加２ｍｇ／Ｌ２，４－Ｄ和０．５ｍｇ／ＬＢＡ的培养基上，子叶及下胚轴愈伤组织诱导率均在８９％以上。愈伤组织继代在Ｂ５无机盐十三倍ＭＳ有机成分＋３％蔗糖＋０．５ｍｇ／Ｌ２，４－Ｄ＋０．５ｍｇ／Ｌ６ＢＡ０．２ｍｇ／ＬＮＡＡ，＋１０ｍｇ／ＬＶｃ的培养基上生长良好。愈伤组织在Ｂ５附加０．１ｍｇ／Ｌ６ＢＡ＋０．２ｍｇ／ＬＩＢＡ的培养基上再生植株。下胚轴在ＭＳ附加２ｍｇ／Ｌ６ＢＡ＋１ｍｇ／ＬＮＡＡ的培养基上直接分化形成丛生苗，转入无激素ＮＳ培养基上再生根。实验表明ＶＥ，Ｖｃ，ＰＶＰ和活性碳对愈伤组织褐化有抑制作用，１０ｍｇ／ＬＶｃ抗褐化作用最好。     

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.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

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

Tropical Animal Health and Production -     

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.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

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