浇施沼液对狼尾草植株硝酸盐累积及其氮素利用效率研究

 采用土柱栽培法,通过不同氮素水平的沼液浇灌（设Ｎ０～Ｎ６共７个氮素水平,即每次浇灌折纯氮０,５,１０,２０,４０,８０,１６０ｋｇ／ｈｍ^２,每４５ｄ刈割周期浇灌９次）,研究浇施沼液对狼尾草植株硝酸盐累积及其氮素利用效率的影响。结果表明,狼尾草植株的硝酸盐含量受沼液中氮素水平的影响较大,二者之间呈正相关。但在高氮肥水平下,牧草各个刈割期的硝酸盐含量均低于硝酸盐有毒限量指标０．２５％。另外,随着沼液中氮素水平的提高,牧草蛋 白质含量和蛋白质产量逐渐上升,蛋白质含量和蛋白质产量最高值分别达到２１．３５％和４４．０９ｇ／盆。对全年牧草生产的氮肥利用率、蛋白质生产效率、氮素生理利用率、氮素农学生产效率和氮肥偏生产力等５个氮素利用效率指标分别表明,随着沼液中氮素水平的提高,氮素利用效率也越低,损失率也越大。从土柱淋溶的氮量分析也表明,氮素淋溶的量随着氮素水平呈明显的加大趋势,其中Ｎ５和Ｎ６处理全年淋溶的氮量分别达到８０．６９和３１２．３ｍｇ。此外,Ｎ５和Ｎ６处理土柱４０ｃｍ 以下土层全氮含量也显著高于Ｎ０～Ｎ３处理（P＜０．０５）。综合考虑认为,在１个刈割周期,狼尾草草地消纳的沼液中氮量应低于纯氮３６０ｋｇ／ｈｍ^２ 较为合理。     

施氮水平与方式对黑麦草生物学特性和硝酸盐含量的影响

禾本科牧草的产量、品质和硝酸盐含量等性状与施氮量密切相关。本试验在大田种植情况下,研究6个施氮水平和4种施肥方式对黑麦草的农艺性状、产量、品质和氮素生产效率的影响,以及相关性状与施氮量的相关性。结果表明,随着施氮量的增加,黑麦草的分蘖数、株高、产量、粗蛋白和氨基酸含量能显著提高,黑麦草的硝态氮含量也随之提高,但随着施氮量的继续增加,氮肥对黑麦草农艺性状、产量和品质的作用增幅变小,氮素生产效率降低。当每次刈割后施纯氮肥量超过100 kg/hm2时,施氮肥能较好促进黑麦草粗蛋白含量提高,而不能有效促进氨基酸含量的提高;当每次刈割后施纯氮肥量达250 kg/hm2时,黑麦草的株高和产量还表现出降低的趋势;当每次刈割后施纯氮肥量超过150 kg/hm2时,黑麦草的硝态氮含量明显提高,部分刈割期黑麦草的硝酸盐含量还超过0.25%的致毒标准。黑麦草的分蘖数、株高、产量、粗蛋白含量、氨基酸含量和硝态氮含量6个测定指标相互间均呈正相关,产量与施氮量只有在撒施情况下呈显著相关,粗蛋白和氨基酸含量与施氮量多数呈显著或极显著相关,硝酸盐含量与施氮量呈极显著相关。深施对黑麦草的分蘖数和株高产生影响,但促进黑麦草产量、粗蛋白含量和氨基酸含量的提高。     

施氮水平对甜高粱硝酸盐含量和氮素利用特性的影响

试验采用完全随机区组设计,分别于2009和2010年在华东农区生态条件下进行田间试验,研究不同施氮水平(0,100,200,300,400,500kg N/hm2)对大力士甜高粱硝酸盐积累,粗蛋白含量和氮素利用特性的影响。结果表明,随着生育期的推进,植株地上部硝酸盐含量不断降低,相比于叶片,茎秆更有利于硝酸盐的积累。随着施氮水平的提高,粗蛋白生产效率(CPPE),氮素干物质生产效率(NDMPE),干物质生产效率(DMPE)和表观回收率(NARR)逐渐下降,说明施氮量越高,氮素利用越低,损失越大。粗蛋白(crude protein,CP)和游离氨基酸(free amino acid,FAA)含量均随施氮量的增加而增加,但FAA的增幅低于CP,施氮量为500kg N/hm2时,CP的平均增幅为6.11%,FAA的平均增幅为2.99%,说明施氮虽然增加了植株CP含量,但优质蛋白质比例下降。施氮提高了甜高粱硝酸盐含量,施氮量大于400kg N/hm2时,甜高粱硝酸盐含量大于0.2%,青饲时易导致家畜硝酸盐中毒。综合考虑,大力士甜高粱在华东农区较为适宜的施氮量为200~300kg N/hm2,既可满足对甜高粱高产优质的需求,提高氮素的利用效率,又可减少氮素流失和对土壤及地下水的污染。     

施氮对狼尾草在南方贫瘠旱坡地生长、能源品质及氮肥利用率的影响

为探究狼尾草作为生物质能源原材料在南方贫瘠旱坡地生长对氮素的响应,研究4个施氮水平(0、112.5、225.0和337.5 kg N·hm^-2)对能源型狼尾草桂能草1号农艺性状、产量、SPAD值、生物质能源品质及氮肥利用率的影响。结果表明,施用氮肥可促进狼尾草横、纵向生长,随施氮量的增加狼尾草的株高、茎粗和单位面积有效茎数逐步提高,但叶片叶绿素含量和鲜、干草产量的提高程度在施氮量超过225.0 kg N·hm^-2后,有饱和趋势。施用氮肥还可明显提高狼尾草纤维素含量、半纤维素含量、热值和折合标准煤产量,显著降低干物质、木质素和灰分含量,总体改善了狼尾草的能源利用品质;但施氮量达337.5 kg N·hm^-2时,狼尾草热值下降,且对折合标准煤产量的增加作用不明显,降低了狼尾草的能源利用品质。此外,在一定施氮量范围内(112.5~225.0 kg N·hm^-2),狼尾草氮肥利用效率并未随施氮量的增加而显著降低,但施氮量达337.5 kg N·hm^-2时,氮肥利用率显著降低。因此,狼尾草在南方贫瘠旱坡地种植,为获得理想的生物质能源材料需及时补充氮素营养,但施氮量不宜超过225.0 kg N·hm^-2。     

不同栽培方式下C4牧草在沿海滩涂的生产性能评价

本研究利用杂交狼尾草、高丹草和墨西哥玉米3种不同类型的C₄牧草在江苏沿海滩涂进行种植,采取覆膜、起垄、覆膜+起垄等3种栽培方式,从分蘖期到开花期等不同生育期分4次进行取样,分别测定株高、单株叶面积等形态指标,及单株干重和干物质含量等产量性状,并分别测定茎、叶及全株饲用品质(可溶性碳水化合物,粗蛋白,中性洗涤纤维、酸性洗涤纤维、干物质体外消化率)。结果表明,覆膜、起垄、覆膜+起垄3种栽培方式均能有效增加牧草产量、改善牧草饲用品质,其中以覆膜+起垄方式改善效果最显著;杂交狼尾草和高丹草在9月3日收割能获得最优的产量和品质,墨西哥玉米则在9月24日收获饲用品质最好、产量最高。墨西哥玉米和高丹草饲草中可溶性碳水化合物(WSC)含量显著高于杂交狼尾草;高丹草和墨西哥玉米植株体内WSC主要集中于茎秆,且两者茎中WSC含量明显高于叶中的含量,而杂交狼尾草茎中的WSC含量稍高于叶片。本研究的结果明确了不同栽培方式下3种C₄牧草生产性能的差异,为加快滩涂种草开发提供理论依据。     

墨西哥玉米留茬中糖组分含量对氮素的响应

利用高效液相色谱(HPLC)技术测定了墨西哥玉米留茬中糖组分含量,分析了氮素对牧草留茬中糖组分含量及再生草产量的影响。结果表明,墨西哥玉米留茬中含有水溶性多糖(WSP)、蔗糖、葡萄糖、果糖和甘露醇5种可溶性糖组分,施肥后WSP、蔗糖、葡萄糖和果糖含量均低于对照N0,蔗糖和葡萄糖含量随施氮量的增加而降低,果糖含量随施氮量的增加而升高。墨西哥玉米N0处理再生草干物质产量最低,低施氮量(300kg/hm²)一次性施用(N1处理)、高施氮量(600kg/hm²)分次施用(N4处理)可获得较高的生物量。     

氮肥水平和刈割间隔对杂交狼尾草根系活力和粗蛋白含量的影响

为探明氮肥和刈割间隔对杂交狼尾草根系活力和粗蛋白含量的影响,在杂交狼尾草第1次刈割后,采用裂区设计(主区为4个N肥水平0,33.75,67.50和101.25 kg/hm2,副区为4个刈割间隔21,28,35和42 d)进行试验,结果表明,1)根系伤流液强度、伤流液中氨基酸总量平均值均以施肥水平33.75 kg/hm2显著高于其他处理,硝态氮总量平均值随施肥水平提高而增加,不同处理间差异均显著.根系伤流液强度、伤流液中氨基酸总量平均值刈割间隔为28 d时显著高于刈割间隔21,35和42 d,硝态氮总量平均值刈割间隔35 d时显著高于刈割间隔21,28和42 d;2)植株粗蛋白含量N肥水平间差异显著,N肥水平101.25 kg/hm2时平均粗蛋白含量达到13.34%,显著高于氮肥水平33.75 kg/hm2和不施N处理,而与N肥水平67.50 kg/hm2的平均粗蛋白含量12.59%无显著差异,刈割间隔28 d时平均粗蛋白含量为13.83%,显著高于刈割间隔21,35和42 d的粗蛋白含量11.86%,11.83%和11.05%;3)植株粗蛋白含量与根系伤流液中的氨基酸总量呈二次曲线关系;4)根系伤流液强度及其氮素形态变化规律为杂交狼尾草适宜施肥技术和刈割间隔的确定提供了依据.     

不同暖季型饲草轮作多花黑麦草模式比较研究

为研究不同暖季型饲草轮作多花黑麦草对牧草产量及品质的影响,以墨西哥玉米、青贮玉米、甜高粱、高丹草、东非狼尾草和多花黑麦草为试验材料,分析测定土壤养分、牧草产量、生长速率及营养品质的变化规律。结果表明,不同暖季型饲草种植影响土壤养分含量,种植高丹草后,土壤全氮、速效磷和速效钾含量最高。轮作能够延长牧草的供草时间、提高牧草总产量,5种轮作模式分别提高了单作暖季型饲草产量,高丹草和东非狼尾草轮作多花黑麦草增产幅度较大,甜高粱轮作多花黑麦草总产量最高。不同前作对多花黑麦草生长速率影响存在明显差异,其中高丹草收割后复种多花黑麦草的生长速率最快,墨西哥玉米收割后复种最慢。墨西哥玉米粗蛋白含量最高,青贮玉米中性洗涤纤维、酸性洗涤纤维和粗脂肪含量均最高。一年生暖季型饲草轮作冷季型牧草多花黑麦草,有利于延长全年供草时间及牧草总产量提高。     

青贮中的硝酸盐(综述)

<正> 在集约化的草地经营中,氮肥的施用量达到500公斤氮/公顷·年。在施氮量高的情况下,由于牧草中可发酵糖类含量降低,蛋白质含量和缓冲能力增大,使牧草的可青贮性降低。牧草中硝酸盐的含量也因施氮肥而增高,一般达到1—8克/公斤干物质,偶尔发现有高达30克/公斤干物质的。玉米也是一种重要的青贮作物,其硝酸盐含量1—4克/公斤干物质之间,间     

氮素运筹对皖草2号和墨西哥玉米吸收Fe、Mn、Cu、Zn的影响

为明确氮素运筹对皖草2号和墨西哥玉米吸收矿质元素的影响,本研究分析了两者茎、叶及整株的Fe、Mn、Cu、Zn元素含量、累积量以及产量的变化情况。结果表明,皖草2号和墨西哥玉米植株中,Fe的含量最高,且叶片中的Fe含量明显高于茎;皖草2号的Mn、Cu、Zn含量高于或显著高于墨西哥玉米,但Fe含量显著低于墨西哥玉米。不同氮素运筹比较,一次性施肥处理中,2种牧草均以300 kg/hm²(N1)处理的Fe含量最高;而分次施肥处理中,Fe含量有随施氮量的增加而增加的趋势;皖草2号的Mn含量以N1处理最高,Cu、Zn含量以低施氮量处理较高;而墨西哥玉米的Mn含量随施氮量的增加而增加,Cu、Zn含量均以底肥一次性施入的含量较高。N1处理的Fe、Mn、Cu、Zn累积量和产量最高,且墨西哥玉米的累积量和产量显著高于皖草2号。不同器官中4种元素的累积量和产量不同,皖草2号叶片中Fe的累积量和产量高于茎,而Mn、Cu、Zn的累积量和产量低于茎;墨西哥玉米叶片中Fe、Mn、Cu、Zn的累积量和产量均显著高于茎。刈割次数对2种牧草吸收4种元素的影响也不同,皖草2号的 Fe、Mn、Zn含量以头茬草最高,而Cu 含量以第3次刈割草的含量最高;墨西哥玉米则以头茬草的Mn、Cu含量和第3次刈割草的Zn含量最高。2种牧草再生草中4种元素的累积速率表现为Fe＞Mn＞Zn＞Cu,且均呈逐渐下降的趋势,墨西哥玉米的降低幅度大于皖草2号。综合分析认为,生产上选择皖草2号牧草类型,采取一次性施入氮肥300 kg/hm²的管理措施,可以获得矿质营养较高的优质牧草,且要重视头茬草的产量。     

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