微孔草块根的抗逆性研究

采用电导法对微孔草块根的抗逆能力进行了研究。结果表明,微孔草裸体块根在－９℃低温或４９℃的高温环境中可生存０．５ｈ,在－７℃或４４℃条件下生存１．０ｈ,在０℃或４３℃环境中生存１．５ｈ。微孔草块根经逆温处理的半致死最低和最高温度分别为０．５ｈ是－９．３１℃和４９．７４℃和４９．７４℃,１．０ｈ是－７．４６℃和４４．１６℃;１．５ｈ是－０．４７℃和４３．９５℃。     

柑桔冻害的防护管理

１９９９年１２月２０－２５日的强冷空气和低温给我市柑桔带来严重伤害。这次低温为害降温幅度大,低温持续时间长,１２月２１－２４日连续４天最低温低于－５℃,连续３天日平均气温在－０℃以下（据市气象站测报）,加之低温为害前持续２０多天的晴燥天气,加剧了冻害程度。据日前初步调查统计,我市５０％的桔树冻害达３级以上,严重影响２０００年柑桔结果和生长,目前严冬未过,尚需加强柑桔防护工作,以免桔树反复受冻,加重冻害程度。１根外追肥对冻害较轻的桔树（３级以下冻害）,需及时进行根外追肥。可用 ０．５％尿素加 ０．２…     

电导率测定对猪肉新鲜度的判定

通过对电导率的测定，得出猪肉新鲜度与其电导率值呈正相关。结果表明·电导率小于０．５×１０￣３μ－１即为新鲜肉；电导率为０．５×１０￣３μ－０．７×１０￣３μ￣（－１）为次鲜肉；电导率大于０．７×１０￣３μ￣（－１）为腐败肉。     

不同低温强度与次数对南美藜墨引1号苗期霜冻级别的影响

为确定西藏尼洋流域等地区能否秋（冬）播南美黎，对目前被认为抗寒能力最强的品种之一墨引１号幼苗进行不同低温强度，不同低温次数处理，观察其霜段萎蔫级别，找出了该品种苗期出现永久性萎蔫的温度指标（为≤－６．０℃）和死亡温度指标（为≤－７．０℃）结果表明，上述地域不能秋（冬）播南美藜墨引１号。     

假俭草种源抗寒性鉴定及其变异分析

为了进一步鉴定和发掘假俭草抗寒遗传资源,为假俭草抗寒育种和遗传研究提供材料和有价值的信息,本研究采用电解质渗透法对搜集的有代表性的110份假俭草种源进行了抗寒性鉴定。结果表明,我国假俭草不同种源之间的抗寒性存在较大变异,它们的半致死温度的变异范围为-2.55℃～-8.01℃,极差为5.46℃,平均半致死温度为-4.89℃,变异系数为18.01%;进一步对假俭草的半致死温度与地理因子（纬度,经度和海拔）进行了回归分析,结果发现假俭草的半致死温度与纬度,经度和海拔均无线性关系;根据假俭草的半致死温度进行系统聚类分析,可以将110份假俭草种源分为3个类群。     

江永县果树突遇霜冻损失惨重

本刊讯（特约通讯员）湖南省江永县１９９９年１２月２２－２７日连续６天霜冻,其中２３日极端低温达－７．７℃,较历史极端低温还低０．６℃,全县６ ６６６．６７ｈｍ２柑桔严重受冻,直接经济损失 ３ ０００万元,间接经济损失１．５亿元以上。 据统计,这次冻害造成的具体损失为：３ ３３３．３３ｈｍ２江永香柚,冻害达 ３－ ４级,个别达 ５级,预计２０００年将减产五成以上;夏橙、脐橙、大红橙和新会橙等甜橙类受害面积 ２ ６６６．６７ｈｍ２,冻害达 ４级以上,直接经济损失２４００万元;柑、桂晚柑、温州蜜柑等受害面积达 ６…     

不同类型草坪草的抗寒锻炼

采用电导法测定低温处理下不同类型草坪草电解质透出率的变化，并拟合Ｌｏｇｉｓｔｉｃ方程求冰半致死温度，对草地熟禾和沟叶结草抗寒锻炼过程进行数量化分析。     

假俭草体细胞抗寒突变体的获得及其SRAP分子鉴定

假俭草抗寒性差是限制其广泛应用的主要因素之一。本研究目标是以优良假俭草选系E-126为材料,经低温诱导和筛选获得体细胞抗寒突变体。结果表明,假俭草种子诱导的愈伤组织在继代培养的过程中,经0℃的低温条件下培养26 d,获得了2块存活的愈伤组织,该愈伤组织经过继代增殖后,进行分化、生根和移栽,获得株系1和株系2。苗期外部形态观察结果表明,假俭草低温诱导的株系1、株系2和对照在叶色、叶毛、叶长和叶宽上均没有显著性差异。半致死温度分析结果表明,株系1、株系2以及对照叶片半致死温度(LT₅₀)分别为-6.646,-6.546和-5.351℃,处理与对照之间差异显著,且都低于对照,但株系1和株系2之间无显著性差异。SRAP的结果表明,假俭草低温诱导的株系1和株系2在110,230以及240 bp处均存在相同特征带,表明假俭草体细胞突变体植株的变异稳定且在分子水平与对照存在差异,但株系1和株系2无差异。因此,株系1和株系2可作为同一体细胞抗寒突变体株系加以利用。     

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。     

盐类对丝素溶解效应的研究

用０．５％Ｎａ２ＣＯ３溶液对茧层进行不同时间的脱胶试验,结果表明：０．５％Ｎａ２ＣＯ３溶液煮沸１ｈ对茧丝脱胶效果较好,可达２７．２％;将脱胶后的丝素烘干,用ＣａＣＩ２、ＭｇＣＩ２、ＺｎＣＩ２三种不同的氯化物控制在６０℃、８０℃和１００℃不同的恒温下,每种药品均配成３０％、４０％、５０％、６０％四种不同浓度分别处理０．５ｈ、１ｈ、１．５ｈ,经分析比较得知ＺｎＣＩ２对丝素溶解性能最好,其次为ＣａＣＩ２     

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.     

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     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

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

Tropical Animal Health and Production -