THE EPIDEMIOLOGY OF EQUINE STRONGYLOSIS IN SOUTHERN QUEENSLAND 2. The Survival and Migration of Infective Larvae on Herbage

The seasonal changes in longevity on herbage of the infective larvae of strongylid nematodes of the horse were studied. During the summer months, 1% of the larvae survived on herbage for 2-3 weeks, with 0.2% still viable for a further 2-3 weeks. Equivalent survival periods in winter were 7-11 weeks and over 11 weeks respectively. During spring and autumn, larvae survived for periods varying from 3-8 weeks. On Rhodes grass (Chloris gayana) growing vigorously in the summer of 1976, the majority of larvae remained in the lowest layers of the pasture, within 10 cm of the soil surface. Very few reached the highest fraction of grass sampled, above 40 cm from the soil. More larvae were recovered higher on the pasture in a period when less torrential rain had occurred. It was concluded that the parasitological benefits to be gained from short-term mixed grazing with horses and cattle may be minimal, in view of the tendency of cattle to eat only the upper layers of the pasture initially, with a consequent increase in the number of infective larvae per unit weight of herbage remaining.     

THE EPIDEMIOLOGY OF EQUINE STRONGYLOSIS IN SOUTHERN QUEENSLAND 3. Seasonal Variation in Arterial Populations of Strongylus vulgaris, and the Prevalence of some Helminths

SUMMARY The anterior mesenteric arteries of 138 horses slaughtered in southern Queensland were examined for the presence of S. vulgaris larvae. Seasonal differences were noted in the size of arterial populations of this parasite, with higher mean monthly numbers of worms per horse occurring in winter. There was an equally high incidence of severe verminous arteritis during the winter months of June, July and August, compared to arteries examined during the warmer months, when there were smaller numbers of larvae. It was concluded that more infective larvae were available on pasture during the warmer months, with subsequently large arterial populations some 3 to 4 months later. The parasite was encountered in 121 arteries (88%). The prevalence of adult helminths in the caeca of the same group of horses was S. vulgaris 88%; S. equinus 70%; S. edentatus 18%; Triodontophorus spp. 23%; A. perfoliata 62%. The overall prevalence of S. vulgaris was 93%, when the results of arterial and caecal observations were combined.     

A STUDY OF THE EPIDEMIOLOGY OF ANAPLASMA MARGINALE INFECTIONS OF CATTLE IN SOUTHERN QUEENSLAND: CLINICAL DISEASE AND THE PREVALENCE OF COMPLEMENT FIXING ANTIBODIES

SUMMARY A total of 386 clinical outbreaks of anaplasmosis were confirmed in Queensland south of the 22nd parallel over the period 1967 to 1976. Seventy-eight per cent of these outbreaks occurred during autumn and winter and only 6.8% involved cattle less than 1 year of age compared with 54.8% for cattle more than 3 years old. Dairy breeds were involved in 48.1% of 258 outbreaks compared with 51.9% for beef breeds. Bos taurus beef breeds were involved in 90.7% of 118 outbreaks compared with 9.3% for Bos indicus crossbreds. Approximately 3 times as much clinical disease per head of population was confirmed in tick (Boophilus microplus) infested southern Queensland south of the 25th parallel (south zone) than in areas between the 25th and 22nd parallel (north zone). A survey was conducted during 1975 in which 3,810 cattle from 241 herds were sampled on the basis of the distribution of the cattle population. The prevalence of CF reactors in tick-infested areas was 42.1% of 3,026 samples compared with 0.4% of 784 samples from tick-free areas. The prevalence in the north zone was 52.3% compared to 30.2% for the south zone and it also varied with the type of animal sampled. The prevalence in Bos taurus cattle was significantly greater than in Bos indicus types and it increased with age of the animal. No significant difference in susceptibility to infection attributable to sex could be demonstrated. Animals exposed to heavy to medium tick infestations had significantly more CF reactors than those exposed to light infestation. Higher stocking densities were associated with higher prevalence levels. Thus anaplasmosis is predominantly a disease of autumn and winter and of cattle greater than 1 year of age. Both clinical and subclinical infection occur only in tick-infested areas and B. microplus is considered to be the main, if not the only vector. Both clinical and inapparent infection are more frequent in Bos taurus than in Bos indicus types.     

Survival of Escherichia coli,Enterococci and Campylobacter jejuni in Canada Goose Faeces on Pasture

Freshly excreted Canada goose faeces pose a public health risk as they contain pathogenic microorganisms. Accordingly, a study was carried out on the growth and survival of resident indicator bacteria (enterococci and Escherichia coli) and inoculated Campylobacter jejuni in freshly excreted faeces over summer and winter. Canada goose faeces were collected, mixed thoroughly and inoculated with 10⁸ g^?1C. jejuni. The faeces were mixed again before making the Canada goose dropping. The simulated goose droppings (N = 70) were placed on pasture, and the concentrations of E. coli, enterococci and the pathogen, C. jejuni, were monitored. In summer only, the molecular marker of E. coli LacZ and the avian‐associated bacteria E2 was also monitored. Results of the survival study indicated that significant growth of enterococci and E. coli occurred in summer, before concentrations decreased to less than 15% of the original concentration (day 77) for enterococci and 0.01% for E. coli. LacZ followed a similar pattern to E. coli, while the E2 marker dropped to below 0.1% of the original concentration within 4 days. In winter, enterococci grew slightly, while no growth of E. coli occurred. In both summer and winter, C. jejuni was rapidly inactivated. This research highlights the ability of bacterial indicators to replicate and survive in the environment when harboured by avian faeces, and the limited risk aged Canada goose faeces pose as an environmental source of Campylobacter spp.     

“利用荒漠和盐碱地建立人工草地的研究”总结报告

课题在柴达木盆地实施，４年的研究结果：①碱茅是利用盐渍地建立人工草地的首选牧草，可在中一重度含盐量（０．５％～１．４７％）的土壤上生长，种植第三年产青于草４５００ｋｇ／ｈｍ＾２；②在荒漠地区采用围栏封育２年产量比对照提高３．９１倍，封育＋灌溉提高４．２９倍，灌溉＋补播＋封育提高１．４２～６．２倍；③用沙棘、小红柳、绵柳建立物围栏５ＫＭ，成活率分别为７６％，９６．８％和９４％；④以单位面积粗蛋白产量     

不同利用强度对混播草地牧草产量与组分动态的影响

本试验中,放牧绵羊对草地的实际利用率(采食率)各为40％、60％、70％、80％左右以及适时刈割这五种处理方法,对多年生黑麦草、红三叶、白三叶混播草地不同季节牧草地上生物量、全年产量和植物组分动态等均产生了明显的处理效应。试验期内(1987～1989年),连续刈割条件下,草群中多年生黑麦草和白三叶草比例逐年下降,而红三叶草比例逐年上升;中等偏高的放牧强度(实际利用率为70％左右)下,多年生黑麦草和白三叶在草群中的比例相对稳定,豆、禾比率保持在1:2左右;放牧本身有降低红三叶在草群中的比例的作用,各放牧处理中红三叶比例仅达10％左右。在实际放牧强度为40％～70％的范围内,草地牧草产量较高(各年份情况相似),其中以适度放牧强度(利用率60％左右)下草地产量最高;过度放牧强度(利用率80％左右)明显降低了草地牧草产量,并产生了不可逆转的年度间变化。本试验中,割草处理产生的综合效应与过度放牧强度类似。不同放牧强度对春、夏、秋各季节牧草地上生物量都产生了极显著处理效应,春、秋二季,以适度放牧强度(利用率60％左右)下牧草地上生物量最高;夏季以割草处理下牧草地上生物量最高;过度放牧强度(利用率80％左右)下,春、夏、秋季测得的牧草地上生物量均极显著低于适牧处理。本试验为当地选出的适宜放牧强度是实际利用率为60％左右,相应的牧后地上牧草剩余量约为900公斤干物质/公顷左右。     

青海省草地棘豆属有毒植物危害调查与防治技术研究

豆科棘豆属(Oxytropis)和黄芪属(Astragalus)植物的某些种是目前危害我国草原畜牧业生产最为严重的毒草.在可食牧草缺乏的情况下,动物被迫采食这种毒草后可引起以慢性神经机能障碍为特征的中毒,能使动物发疯,故形象地把这类毒草统称为疯草(locoweed).     

不同放牧强度对当年混播草地的影响

研究了云南高降雨地区混播草地播种60 d后,不同放牧强度(0.5,1和1.5黄牛单位/公顷)对草地密度、盖度、高度、频度和生物量的影响.结果表明,放牧能明显抑制一年生禾本科杂草及播种多年生禾本科牧草的生长,但对白三叶和草地有害植物的生长都有促进作用.     

不同放牧强度对当年混播草地的影响

研究了云南高降雨地区混播草地播种60 d后,不同放牧强度(0.5,1和1.5黄牛单位/公顷)对草地密度、盖度、高度、频度和生物量的影响。结果表明,放牧能明显抑制一年生禾本科杂草及播种多年生禾本科牧草的生长,但对白三叶和草地有害植物的生长都有促进作用。     

三眠蚕诱导剂SM-1对家蚕丝蛋白合成调控机理的研究——Ⅱ.SM-1对后部丝腺DNA合成速率和核酸含量的影响

本文探讨三眼蚕诱导剂SM一1对家蚕丝蛋白合成的调控机理.试验结果表明:(1)sM-1处理后,家蚕后部丝腺DNA中~3H-胸腺嘧啶核苷的参入速率明显增快.SM一1诱导三眠蚕在四龄第2天~3H-胸腺嘧啶核苷的参入量最高,比同时的对照高近1倍;五龄第2天SM—1处理区,在五龄第3天~H-胸腺嘧啶核苷的参入速率有所增快.(2)SM-1诱导的三眠蚕,后丝腺DNA和RNA含量的高峰比对照提前4-6天出现,且其末龄(四龄)DNA和RNA含量的增减趋势与对照末龄(五龄)DNV和RNA含量的增减趋势非常相似.(3)五龄前期用SM一1处理家蚕幼虫,对后丝腺DNA和RNA含量增加具有暂时的促进作用.     

青海草地建设投资与草地产出灰色关联分析

用灰色关联分析方法，对青海省草地建设投资与草地产出作相关分析。结果表明：两者相关性较强，关联度系数γｙ０１８＝０．７１６８（畜牧业产值）和γｙ０２８＝０．７２４４（畜产品产量）；在草地建设分项投资中，与草地产出关联度最大的为灭鼠投资，分别为γｙ０１５＝０．９１６２（牧业产值）和γｙ０２５＝０．８８８５（畜产品产量），其次顺序为种草投资（γｙ０１２＝０．８２６６和γｙ０２２＝０．８１３１），草地围栏     

刈割频度、播种比例和施肥量对牛鞭草和白三叶混播草地牧草产量的影响

在不同刈割频度、施肥量和混播比例下,对混播草地牛鞭草和白三叶不同种群年总产草量进行了研究。结果表明,刈割频度对产草量的影响最大,其差异达到极显著水平(P<0.01),其中刈割频度为5次的处理鲜草总产量最高。施肥量和播种比例的互作效应对总产草量的影响差异也达到了极显著水平(P<0.01);其中施肥水平低,牛鞭草混播比例低的处理总产草量高;施肥水平高的处理,牛鞭草混播比例高的则总产草量高,而白三叶则相反。因此,牛鞭草和白三叶的混播在合理的管理措施下是有可能的;同时为了达到高产优质,初步认为刈割间期以45d,较高的施肥量和混播比例以2:1为宜。     

刈割期和留荐高度对新麦草产草量及品质的影响

１９９９年５月～９月在华北农牧交错带研究生育期和留荐高度对新麦草产草量及品质的影响,结果表明,以抽穗期刈割头荐留荐４ｃｍ全年割三次的干草总产量最高,（２０６０．５１ｋｇ／ｈｍ＾２）,其次是初花期刈割头荐留荐１０ｃｍ（１９５１．８４ｋｇＤＭ／ｈｍ＾２）,粗蛋白质总产量最高的处理是抽穗期刈割头荐留荐４ｃｍ（４７０．２９ｋｇＤＭ／ｈｍ＾２０,其次是初花期头荐刈割,留荐４ｃｍ（４２４．２６ｋｇＤＭ／ｈｍ＾