利用苇状羊茅改良黑麦草越夏性的初步研究

本试验通过黑麦草和苇状羊茅的杂交、杂种和黑麦草的回交以及杂种细胞遗传学的研究表明:四倍体多花黑麦草和苇状羊茅杂交所获种子发芽率极低,只有通过幼胚培养才能获得较多的杂种苗。苇状羊茅和黑麦草间种质的转移是有细胞学基础的;[L.multiflorum(4x)×F.arundinacea(6x)]F_1杂种植株与四倍体多花黑麦草回交以及与二倍体多年生黑麦草杂交时,可育雌配子染色体数分别约是n=28-35和n=13-24;从黑麦草育种的角度出发,四倍体多花黑麦草和苇状羊茅F_1杂种用四倍体多花黑麦草回交的效果比F_1杂种自交、F-1杂种和二倍体多年生黑麦草杂交的效果好;二倍体黑麦草和苇状羊茅F_1杂种回交结实率与回交后代的自交结实率极低不可能获得较大的群体,就这点而论,通过这种F_1(2n=28)和黑麦草回交进行黑麦草育种的途径效率较低。二倍体多花黑麦草×苇状羊茅和二倍体多年生黑麦草×苇状羊茅F_1杂种经秋水仙素处理后均获得了双二倍体(2n=56)。多花黑麦草(2n=28,14)和苇状羊茅F_1杂种植株田间越夏情况介于双亲之间。     

多花黑麦草×苇状羊茅杂种后代的细胞学可育性和越夏性

二倍体和四倍体多花黑麦草×苇状羊茅杂种 F_1 花粉母细胞减数分裂染色体具有较高的配对水平,单价体少,二价体多。存在低频率的三价体、四价体和较低频率的五价体,表明多花黑麦草和苇状羊茅染色体之间存在同源或部分同源和异源苏会配对,F_1 正常花粉频率平均为0～18.2%,不同杂交组合甚至同一组合不同植株均有很大的差异。F_1 的回交结实率很低,平均为0.05粒种子/小穗,且易与多花黑麦草回交。杂种后代自交结实率与其亲本一样均很低。开放授粉结实率则随着世代的增加显著提高,F_1 代平均仪为0.4%,至第五代高达65.5%。杂种后代越夏性以 F_1为最强,平均达79.9%,介于双亲之间或与苇状羊茅相近,随着世代的增加越夏性则逐渐丧失。推测越夏性丧失与杂种后代群体过早或过多地丢失苇状羊茅染色体,减少了优良基因重组的机会有关。育性正常、越夏性较强的黑麦草型第四代选系“891”的获得,表明把苇状羊茅的越夏性部分地转移到多花黑麦草中是可行的。     

细胞悬浮法培养苇状羊茅、多年生黑麦草和多花黑麦草再生植株

本文就细胞悬浮法培养牧草再生植株的方法进行了研究,并成功地用此法从苇状羊茅、多年生黑麦草和多花黑麦草原生质体细胞克隆中获得了再生植株,而且进一步使苇状羊茅和多年生黑麦草在土壤中建植。     

海盐胁迫对苇状羊茅和多花黑麦草种子发芽的影响

用不同浓度的海盐溶液处理,研究了苇状羊茅Festuca arundinacea和多花黑麦草Lolium multiflorum种子在发芽阶段对海盐胁迫的反应.结果表明,海盐浓度低于6.4 g/L时,2种牧草种子的发芽不受影响;随海盐处理浓度增高,种子发芽率和种子活力指数逐渐下降.2种牧草相比,多花黑麦草种子发芽阶段对海盐的耐受性高于苇状羊茅.苇状羊茅和多花黑麦草种子发芽率降至50%的农业盐渍临界值的海盐浓度分别为19.98和22.78g/L.     

多花黑麦草×苇状羊茅属间杂交后代生长特性及品质的研究

试验对黑麦草×苇状羊茅属间杂交后进行比较试验，结果表明，偏羊茅型的杂交后代Ｆ２－４Ｓ－８，偏黑麦草型的杂交后Ｆ２－２－１株高，干物质产量，粗蛋白产量均高于亲本苇状羊茅（Ｋｅｎｔｕｃｋｙ３１，简称Ｋｙ３１）中性洗涤纤维及酸性涤纤维含量均低于苇状羊茅（Ｋｙ３１）。     

江苏地区禾本科冷季牧草生态适应性研究

引进美国冷季型禾本科牧草品种19个，在苏南（南京）和苏北（徐州）进行生态适应性试验。初步结果表明，多花黑麦草和杂交黑麦草产量较高，且集中于春季，尤其是四倍体品种鲜草产量最高。多年生黑麦草虽然产量也较高，但在苏南不能安全越夏。苇状羊茅和鸭茅在江苏能较好地越夏。     

多花黑麦草×苇状羊茅属间杂种及其后代产草性能及品质的研究

１９９２～１９９３年对多花黑麦草和苇状羊茅属间杂种及其后代的产草性能及品质进行了研究，结果表明：杂种Ｆ１植株生长慢，分蘖力差，鲜草及干物质产量极显著低于多花黑麦草（Ｐ＜０．０１），略高于苇状羊茅。饲草品质介于双亲之间。杂种后代选系８９１、８９２植株生长较快，分蘖力强，产草量最高，越夏前干物质产量分别为８３９９．５５ｋｇ／ｈｍ２和９３４６．２０ｋｇ／ｈｍ２。其饲草品质也较好，粗蛋白含量高，分别为１２．８０％和１３．３４％；酸性洗涤纤维及酸性洗涤木质素含量低。这表明杂种Ｆ１结合有双亲优良的产草性状及品质性状，是极好的育种材料，选系可用于替代生产上栽培的黑麦草。     

苇状羊茅及多年生黑麦草内生真菌的研究进展

本文介绍了重要禾本科牧草苇状羊茅及多年生黑麦草内生真菌对家畜的影响，对寄主本身的影响及内生真菌的传播，控制，鉴定和运用。苇状羊茅与多年生黑麦草内生真菌同属枝顶孢霉属，极为相似，苇状羊茅内生真菌导致牛的苇状羊茅中霉症。多年生黑麦草内生真菌造成羊及其它家畜的黑麦草蹒跚病，内生真可促进寄主的生长，延长寄主的寿命，抵抗病虫的侵害。内生真菌通过种子传递给牧草后代，牧草生产中用种子贮藏，种子高温处理，种子或植     

种草养羊实用技术

1品种选择 1．1草种选择人工种草适宜选择的草种有多花黑麦草、高丹草、光叶紫花苕一年生牧草,以及苇状羊茅、多年生黑麦草、鸭茅、紫花苜蓿、白三叶等多年生牧草。对于水源条件较好的良田,可以利用冬闲田种植一季多花黑麦草,或选用肉羊喜食的高丹草与多花黑麦草轮流种植。     

苇状羊茅及多年生黑麦草内生真菌的研究进展

本文介绍了重要禾本科牧草苇状羊茅及多年生黑麦草内生真菌对家畜的影响、对寄主本身的影响及内生真菌的传播、控制、鉴定和运用。苇状羊茅与多年生黑麦草内生真菌同属枝顶孢霉属(Acremonium),极为相似。苇状羊茅内生真菌导致牛的苇状羊茅中霉症。多年生黑麦草内生真菌造成羊及其它家畜的黑麦草蹒跚病。内生真菌可促进寄主的生长、延长寄主的寿命、抵抗病虫的侵害。内生真菌通过种子传递给牧草后代,牧草生产中用种子贮藏、种子高温处理、种子或植株药物处理控制内生真菌,防止牛的苇状羊茅中毒症和羊的黑麦草蹒跚病。草坪生产中通过接种内生真菌增加草坪草的抗虫、抗病能力,并延长其寿命。     

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