Investigations into the toxicity of Echium plantagineum in sheep: 2. Pen feeding experiments

In a pen feeding trial fresh Echium plantagineum was fed as the sole diet to crossbred sheep with or without a history of previous access to the plant. Control groups received a diet of lucerne chaff and oats. During the trial, sheep on the Echium diet lost weight and deaths occurred with histological evidence of excessive copper accumulation, usually accompanied by pyrrolizidine alkaloid damage, in the liver and biochemical evidence of liver toxicity. It is concluded that E. plantagineum alone is not a suitable fodder for sheep and can be toxic due to its pyrrolizidine alkaloid content and high copper to molybdenum ratio.     

Pyrrolizidine alkaloid poisoning of sheep in New South Wales

Pyrrolizidine alkaloid poisoning of sheep in New South Wales was reviewed, based on the records of the New South Wales Department of Agriculture's Regional Veterinary Laboratories. The plant species causing significant mortalities were Echium plantagineum and Heliotropium europaeum. The syndrome of hepatogenous chronic copper poisoning was more frequently diagnosed than primary pyrrolizidine alkaloid poisoning, particularly when grazing E. plantagineum. The data indicated that adult crossbred ewes were the most commonly affected class of sheep.     

The epidemiology of fasciolosis in Papua New Guinea

Fasciola hepatica metacercariae were present on pasture throughout the year at the trial site. The highest infection rate in trial sheep occurred in the first year after the beginning of the wet season, in December/January, when contamination of the pasture was maintained by other sheep. Variation in rates of infection in consecutive years was linked to differences in grazing pressure and to a change from sheep to cattle as accompanying grazing stock. A minimum precipitation of 125 mm over 4 consecutive weeks appears to be necessary for infected snails to move from their normal habitats and to contaminate wet pasture with cercariae. Infection of sheep can occur during a dry season if pasture has permanent seepage sites or swampy areas where infected snails can remain active and continue to liberate cercariae.     

牧压和肥力对亚热带山地牧草净生产的影响

在亚热带山地湿润环境条件下, 研究牧压和土壤肥力对人工草地净生产的影响。三年试验结果表明, 绵羊在轮牧下, 产草量和磷肥对全年及各月牧草净生产具有显著影响。禁牧时, 夏季地上生物量积累到一定程度后, 只有很少量的净生产。放牧时, 产草量在1000kgDM/hm²左右时, 净生产最大, 当产草量低于300kgDM/hm²以下时, 净生产量则降低。每年施一次 P2O536～ 60kg/hm², 可以显著增加牧草净生产, 尤以春末夏初时施肥更为显著。最低产草量出现在不施肥处理     

人工草地绵羊放牧系统研究—产羔期试验

试验监测了在划区轮牧条件下的放牧系统中两种产盖期中的牧草生长速度、绵羊采食量以及绵羊生产性能等有关指标的动态变化，探讨了两种产羔期对放牧系统中草地和绵羊产生的影响。     

不同类型藏羊消化率与采食量的比较研究

采食量是放牧家畜生产性能的重要影响因素,在草地生态系统中起重要作用。夏季在甘南夏河分别选取不同生理类群(羔羊、1岁母羊、2岁母羊、3岁母羊、4岁母羊、羯羊和种公羊)的欧拉型、甘加型和乔科型藏羊各4只进行试验。采用二氧化钛指示剂法与粪氮指数法分别测定藏羊排粪量和牧草有机物质消化率,从而计算放牧采食量,并对特征间的相关性进行研究。结果表明:欧拉型、乔科型和甘加型藏羊的平均放牧采食量分别为1031.93、834.59和956.15 g·d^-1,乔科型藏羊放牧采食量显著(P<0.05)小于欧拉型和甘加型藏羊。3个类型藏羊的每kg代谢体重采食量和干物质采食量占体重比差异均不显著(P>0.05)。欧拉型、乔科型和甘加型藏羊对夏河天然草地牧草的平均有机物质消化率分别为50.79%、47.22%和55.58%。欧拉型、乔科型和甘加型藏羊的平均排粪量分别为561.26、484.06和466.74 g·d^-1,其中欧拉型藏羊的排粪量显著高于其他两个类型。试验在高寒地区天然草地研究不同类型藏羊的排粪量、有机物质消化率和放牧采食量,旨在为该地区放牧藏羊的科学饲养与管理提供理论依据。     

新疆放牧绵羊的限制性矿物质元素调查

通过新疆5个羊场矿物质元素营养的研究，以了解新疆全年草场有关矿物元素的变化情况，缺乏程度及缺乏时间。研究表明：5个羊场中牧草含P量在秋草场至冬草场均表现缺乏。含Na量在塔城种羊场一年四季草场均缺乏，在阿勒泰二牧场冬、春、夏草场Na出现明显缺乏，而在秋草场又明显超出需要量；在巩乃斯种羊场春、夏草场明显缺乏，冬、牧草场又明显超量。5个羊场牧草含Se、Zn量的测定值明显低于需要量。而含Fe量在5个羊场中都不同程度地超过最高限量。牧草中元素Fe与Mn之间存在措抗作用；Mo、Cu比例少于1：4，绵羊体内仍表现缺Cu症。通过全面分析对比，初步确定在新疆5个种羊场天然草场上放牧的羊群，存在着P、Na、Zn、Mn、Se和Cu6种限制性矿物元素季节性营养紊乱现象。     

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

AIM: To obtain information on serum and liver vitamin B12 and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B12 in young dairy cattle when grazing pasture of low cobalt content. Methodology. Forty dairy cattle (12 Friesian, 14 Friesian x Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for vitamin B12 concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations. RESULTS: No weight gain response occurred vitamin B12 supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver vitamin B12 concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B12 concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation. CONCLUSION: Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum vitamin B12 concentrations at which growth responses to vitamin B12 or cobalt supplementation are likely under New Zealand pastoral grazing conditions.     

贵州高原人工草地上的绵羊放牧越冬试验

本文研究了绵羊在贵州高原人工草地上的放牧越冬情况,试验结果表明,杂种绵羊冬春季节在足够的优质豆科、禾本科混播人工草地上,进行纯放牧,其体重、羊毛细度均未发生明显变化,证明在这种条件下可以安全越冬;亦说明大力发展人工草地是发展养羊业的重要措施。     

The effect of copper on the response of lambs to selenium supplementation when grazing a selenium deficient pasture

Two trials were undertaken with lambs grazing selenium deficient pasture to determine if copper would enhance liveweight and fleece-weight responses to selenium supplementation. In the first trial, lambs given selenium or selenium plus copper gained significantly more weight and had higher fleece-weights after 260 days than did control lambs or lambs given copper alone. Copper given alone or together with selenium had no significant effect on liveweight or fleece-weight when compared with control lambs and lambs that were given selenium alone respectively. This finding was confirmed in a second trial when growth and fleece-weights of selenium and selenium plus copper treated lambs were compared and no significant differences found. In both trials copper significantly raised liver copper levels. In selenium supplemented but not in selenium deficient sheep, copper significantly increased blood selenium levels.     

Excretion of Eimeria alabamensis oocysts in grazing calves and young stock

The aims of the present study were to investigate the excretion of Eimeria alabamensis oocysts by young cattle during their first grazing season and during the first 16 days of their second grazing period. In trial 1, nine first-season grazing heifers were studied and found to have become infected with E. alabamensis shortly after turnout. The next grazing period they were turned out on to a permanent pasture together with two first-season grazing calves. Faecal samples were collected before turnout and then daily from day 3 to day 16. The second-season grazing heifers excreted insignificant numbers of E. alabamensis oocysts, whereas one of the two first-season grazing calves excreted up to 703,000 oocysts/g of faeces (OPG), indicating that the pasture was contaminated. In trial 2, faecal samples were collected from 12 calves before their first turnout in May, daily from day 2 to day 20 after turnout and then once a week until the end of September. The calves grazed pastures used in previous years by first-season grazing calves. Nine of the calves developed clinical E. alabamensis coccidiosis 4-7 days after turnout and excreted more than 950,000 OPG on days 9-10. By day 17 the oocyst excretion had decreased below 900 OPG and remained low throughout the rest of the grazing season. The results of the two studies indicate that reinfections with E. alabamensis are of little clinical importance in calves grazing contaminated pastures, and that young stock infected with E. alabamensis during their first grazing season may be used to cleanse contaminated pastures without risk of developing clinical coccidiosis.     

Seasonal grazing capacity of an irrigated grass/legume pasture in the Rûens area of the southern Cape

Seasonal changes in grazing capacity of an irrigated grass/legume mixture consisting of lucerne, red clover, white clover, tall fescue, cocksfoot and perennial ryegrass were determined in the Rûens area of the southern Cape. Applying variable stocking rates and three grazing pressures (1,5; 2,25 and 3,0 kg DM/dry sheep‐unit/ day) in a six‐paddock grazing system, it was found that the mean annual stocking rate for maximum wool yield was 54,4 dry sheep‐units/ha over a period of three years. The seasonal grazing capacity of the pasture varied throughout the year and dry matter availability was most limiting during winter and highest during spring. The clover component of the pasture was depressed by the high grazing pressure and declined with age, while the grass content increased proportionally. The proportional lucerne content of the pasture material was more stable and was promoted by the high grazing pressure, but was not influenced by increased pasture age.     

Productivity of cow-calf pairs grazing tall fescue pastures infected with either the wild-type endophyte or a nonergot alkaloid-producing endophyte strain, AR542

The nonergot alkaloid-producing endo-phyte, AR542, has been shown to improve the persistence and yield of tall fescue pastures without causing the animal disorders commonly associated with tall fescue toxicosis. A 3-yr grazing study was conducted to compare effects of AR542-infected tall fescue pastures with wild type endophyte-infected (E+) tall fescue pastures on cow-calf performance. Replicated 7.3-ha pastures of each treatment were grazed by cow-calf pairs (16 pairs per pasture replication) each year from March to weaning in September. The cows were exposed to breeding on their respective pasture treatments from April 1 through June 15. The treatment groups were compared for reproductive performance, ADG, BCS, calf growth rate, and weaning weight. Blood samples were also collected for serum prolactin (PRL) analysis. There were no significant differences in calving rate (P = 0.98) or calving interval (P = 0.62) between pasture treatments. Cows that grazed the AR542 pastures subsequently gave birth to calves that were heavier (P < 0.05) than calves from cows that had grazed the E+ pastures. Cows grazing the AR542 pastures had higher (P < 0.05) BCS at the end of the grazing period, and had higher ADG during the grazing period. Calves raised on the AR542 pasture had higher (P < 0.05) ADG and weaning weights than calves of the same sex raised on the E+ pastures. Serum PRL concentrations were decreased (P < 0.05) in both cows and calves on the E+ pastures compared with serum PRL concentrations in cows and calves grazing the AR542 pastures. The results indicate that grazing tall fescue pastures infected with the AR542 endophyte may give significant advantages in cow-calf growth rates and BCS over grazing E+ pastures. However, there did not seem to be any benefit in reproductive performance in this trial. There was a small, but significant increase in birth weight in cows grazing AR542 pasture.     

免耕改良退化人工草地试验

为改善退化人工草地优质牧草生长条件,对杂草、蛴螬危害引发的退化草地,进行低成本免耕改良试验.结果表明:化学除杂、全日制放牧免耕补播与常规法(耕作重播)均能改善人工种植牧草生长环境,杂草、蛴螬数量明显降低;两种免耕补播比常规法重播成本分别降低54.1%,64.3%;改良草地优质牧草覆盖度、组分、产草量均有显著提高.     

喀斯特山区草地施肥对放牧乌蒙半细毛羊抗氧化系统功能的影响

为选择草地施肥的肥料种类,减少施肥对乌蒙半细毛羊产业的影响,在威宁县凉水沟种羊场多年生人工草地开展施肥和放牧试验。 结果表明:凉水沟种羊场人工草地牧草铜含量相对较低,但仍高于乌蒙半细毛羊营养需要标准;施肥极显著增加牧草氮含量(P<0.01),各施肥处理之间没有明显差异。硫酸铵施肥显著增加牧草硫和锌含量(P<0.01),显著降低了牧草硒的含量(P<0.01)。放牧试验结束时,施硫酸铵草地的乌蒙半细毛羊血液中铜、铁和硒的含量极显著低于施硝酸铵草地和对照组(P<0.01), 动物血液锌和硫含量极显著高于硝酸铵施肥牧场和对照组(P<0.01)。硫酸铵施肥牧场的乌蒙半细毛羊血红蛋白、红细胞压积容量极显著低于硝酸铵施肥牧场和对照牧场(P<0.01),血清铜蓝蛋白含量、血清超氧化物歧化酶活力、血清谷胱甘肽过氧化物酶活力和血清过氧化氢酶等抗氧化酶的活力极显著低于硝酸铵施肥牧场和对照牧场(P<0.01),丙二醛的含量显著高于硝酸铵施肥牧场和对照牧场(P<0.01)。血液其他矿质元素和血液指标及血清生化值在2个施肥处理和对照之间均差异不显著。 因此得出结论,草地施肥的种类需要根据土壤矿物质分布和含量情况确定,铜含量低的牧场不适合硫酸铵施肥,硫酸铵施肥明显影响了乌蒙半细毛羊机体抗氧化系统功能。     

放牧强度对高寒草地产草量及羊体质量增加的影响

以托云牧场高寒草地为研究对象,通过设置3个放牧样地,一个对照样地,研究不同强度放牧对草地地上生物量的影响以及在不同放牧压力下羊体质量增加的效果。结果表明,1）托云牧场是以银穗草（Leucopoa albida）、羊茅（Festuca arioides）、点地梅（Androsace umbellata）和棘豆（Oxytropis falcatae）为优势种的高山草地;2）高寒草地地上生物量较低,禁牧区7月地上生物量（干物质）仅830 kg·hm-2;3）放牧活动对地上生物量有较大影响,重度放牧能显著降低牧场地上生物量;4）以羊体质量增加值为评价指标,该高寒牧场在载畜量为1.05羊单位·hm-2时能获得较好的体质量增加效果。     

Selenised compressed salt blocks for selenium deficient sheep

Salt blocks containing 30 or 120 ppm selenium were tested as the sole supplement for sheep farmed in a selenium-deficient area of New Zealand (Te Anau). Both concentrations were unsatisfactory in preventing selenium deficiency. In five trials using 120 ppm Se salt, the highest percentages of sheep found to be deficient were 31% (lambs) and 32% (ewes). If sheep which were classed as marginally deficient were included these percentages became 63% (lambs) and 56% (ewes). Some instances of selenium-responsive unthriftiness in lambs were encountered, and in one trial there was the possibility of selenium-responsive infertility having contributed to the low lambing performance of the ewes. There was no evidence of white muscle disease. Selenium levels in the liver and kidney were well below the permitted maximum. Because selenised salt failed to eliminate selenium deficiency, its use as a sole supplement for sheep grazing selenium deficient pasture is not recommended.     

人工草地绵羊放牧系统优化生产模式研究：Ⅰ原系统的监测及分析

本项研究对不同水平人工草地绵辜放牧系统的整个生产过程进行了系统监测。内容涉及到草地生产、家畜生产、放牧管理和经营管理中的要求。本文提供了４个农户和一个试验站生产系统的详细监测分析资料，作为下一步进行系统优化和评价的基础。     

Effect of contamination of pasture with military explosives on grazing behaviour in sheep

Abstract

Ungulates grazing in military training areas may be exposed to non-combusted fragments of various explosives, among which 2-methyl-1,3,5-trinitrobenzene (TNT) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) are two of the most common. This study investigated if sheep react to their pastures being contaminated with TNT or HMX. The experiment was conducted in fenced-in study areas on grass-dominated pasture. The eight sheep studied did not differentiate between clean pasture and contaminated pasture when choosing freely between plots containing TNT, HMX or no contamination. The results indicate that sheep grazing military training areas are unlikely to have behavioural responses reducing time spent grazing sites where TNT or HMX are present as fragments in the field layer.     

喀斯特地区三叶草混播草地群落组分20年动态

三叶草（Trifolium）混播草地群落持久性研究对喀斯特草地建设与石漠化治理具有重要意义。在威宁灼圃示范牧场开展的由白三叶（T. repens）、红三叶（T. pratense）、无芒雀麦（Bromus inermis）、紫羊茅（Festuca rubra）,分别加上多年生黑麦草（Lolium perenne）、鸭茅（Dactylis glomerata）、黑穗画眉草（Eragrostis nigra）、鹅冠草（Elymus kamoji）组成4个5组分混播草地,在绵羊适度放牧下测定牧前、牧后草地现存量,连续进行20年持久性研究。结果表明：时间及组合×利用时间的交互作用对所有混播组合影响极显著,而组合间产量差异不显著,其动态变化与年降水量的动态变化之间无显著的对应关系,但同物种在各混播群落中的生产力和稳定性差异明显,说明各组分之间存在显著的生态位互补和竞争共存关系。各物种中生产力与稳定持久性最好的是紫羊茅和白三叶,其次是多年生黑麦草和鸭茅,最差的是无芒雀麦和鹅冠草;而在草地建植初期表现最好的是多年生黑麦草和红三叶。