牦牛放牧率对小嵩草高寒草甸不同植物类群地上生物量生产率的影响

2年的牦牛放牧试验表明:除不同植物本身的生理特性外,降水和地温是影响小嵩草高寒草甸两季草场不同植物类群地上生物量绝对生长率的关键因素。小嵩草高寒草甸两季草场地上总生物量的绝对生长率1999年在7月份最大;1998年,冷季草场各放牧处理的绝对生长率在8月份达到最大,暖季草场的对照组和轻牧组在7月份最大,中牧组和重牧组在8月份最大。不同植物类群地上生物量生长率的变化不尽相同。1998年,冷季草场禾草和莎草地上生物量的绝对生长率8月份达到最大,暖季草场禾草和莎草地上生物量的绝对生长率7月份达到最大,且9月份出现了营养的再次积累;1999年,冷季草场禾草地上生物量的绝对生长率在6月份和8月份出现了两个峰值,暖季草场禾草地生物量的绝对生长率在7月份达到最大。对杂草类而言,1998年冷季草场的绝对生长率6月份最大,暖季草场重牧组的绝对生长率8月份达到最大,其他各处理7月份达到最大;1999年重牧组杂草的绝对生长率在6月份达到最大,其他各处理杂草在8月份达到最大。     

The impact of Theileria parva infections and other factors on calf mean daily weight gains in smallholder dairy farms in Murang'a District, Kenya

The association between mean daily weight gain, Theileria parva infections, clinical East Coast fever and other possible determinants of weight gain were examined in a longitudinal observational study that was conducted in cohorts of female calves from five agro-ecological zone (AEZ)-grazing strata. The strata were upper-midlands (UM) 1 zero-grazing, UM 1 open-grazing, UM 2 zero-grazing, UM 4 zero-grazing and UM 4 open-grazing. In total, 225 calves on 188 smallholder dairy farms were visited within the first 2 weeks of life and thereafter at biweekly intervals up to the age of 6 months between March 1995 and August 1996. During each visit, the calves were weighed and other calf-management practices in the farm during the visit such as housing, feeding and tick control also were recorded. Other events such as morbidity and mortality between or during the visits were also recorded.

The overall mean daily weight gains were 0.24–0.29 kg (S.D.=0.17–0.22 kg) and were lower than the recommended targets for smallholder farms of 0.40–0.50 kg. The major tendency in variability of daily weight gains was due to visit-to-visit variation (especially in calves >3 months old).

Differences in mean daily gains were associated with AEZ-grazing strata and calf-level factors that included breed of calf, calf sickness, incidence of ECF, feeding of milk, concentrate feeds and minerals and interaction between calf age and AEZ-grazing strata (P<0.05). ECF and other calf sicknesses exerted a temporal effect on calf-growth at the height of illness and immediately after; calves later recovered the lost growth except where other factors such as poor calf nutrition prevailed. Improvement in calf-growth in Murang’a District is achievable and extension services should continue to target individual-calf-level management practices.     

中国毡蚧科一新记录种——樱桃隙毡蚧

樱桃隙毡蚧 Kuwanina (Maskell)(图1) Spharerococcus parvus Maskell,1897,The Etomol-ogist's Monthly Magzine,33:244     

太湖麦穗鱼生长、死亡和利用状况评估

为研究太湖麦穗鱼Pseudorasbora parva的种群结构、生长特征、死亡特征和资源利用状况,于2014年1—12月使用虾笼网在太湖水域逐月进行了采样调查,并对采集的1207尾样本进行了分析。结果表明:麦穗鱼样本标准体长为27.03~107.36 mm,平均为(60.03±13.29)mm,体质量为0.4~21.2 g,平均为(4.51±3.16)g;其体长与体质量呈幂函数相关,拟合关系式为W=2.1606×10-5L2.9537(R2=0.9323,n=1207);Von Bertalanffy生长方程各参数为L∞=112.88 mm、K=0.46、t0=-0.51 a,体质量生长拐点为1.84a;应用变换体长渔获曲线法估算总死亡系数(Z)为1.87,利用Pauly经验公式估算自然死亡系数(M)为1.07,捕捞死亡系数(F)为0.80,开发率(E)为0.43。研究表明,太湖水域麦穗鱼面临的捕捞压力较轻,处于适度利用状态,这与太湖水域无针对性捕捞且设有禁渔期有关,同时开捕期内肉食性鱼类面临的捕捞压力也有利于小型鱼类种群增殖。     

除草剂丁草胺对麦穗鱼的毒力及抗氧化酶活性的影响

研究除草剂丁草胺对麦穗鱼的毒力、抗氧化酶系（GST、SOD和CAT）和丙二醛含量的影响。结果表明,丁草胺对麦穗鱼24h半致死浓度（LC50）为0.4512mg/L,随处理浓度的升高,麦穗鱼体内抗氧化酶系（GST、SOD和CAT）活性先升高后降低,其活性表现为低浓度诱导和高浓度抑制;抗氧化酶系活性与丁草胺处理浓度呈抛物线型浓度-效应关系,MDA含量与丁草胺处理浓度呈显著正相关。     

巴夫杜氏藻β-肌动蛋白基因的克隆和分析

[目的]获得巴夫杜氏藻β-肌动蛋白基因cDNA全长序列。[方法]以巴夫杜氏藻cDNA为模板,采用简并引物进行PCR扩增,获得533 bp特异cDNA片段。在此基础上,设计特异引物,采用5′-GenomeWalking和3′-RACE的方法,获得基因的5′-端DNA序列和3′-端cDNA序列,进而获得β-肌动蛋白基因cDNA全长序列。[结果]获得了巴夫杜氏藻β-肌动蛋白基因的特异cDNA片段、5′-端DNA和3′-端cDNA片段。经拼接后,扩增出全长cDNA。β-肌动蛋白基因cDNA全长1 754 bp,包括1 137 bp的开放读码框和617 bp的3′-非翻译区序列。氨基酸序列相似性分析发现,巴夫杜氏藻β-肌动蛋白氨基酸序列与杜氏盐藻、莱茵衣藻等的同源性较高。系统发育分析表明,巴夫杜氏藻β-肌动蛋白与杜氏盐藻的相似性最高。[结论]首次获得了巴夫杜氏藻β-肌动蛋白基因cDNA全长序列并发现巴夫杜氏藻β-肌动蛋白基因非常保守。     

人工养殖麦穗鱼的生长特性

分析麦穗鱼(Pseudorasbora parva)在人工养殖条件下的生长特性,为麦穗鱼养殖提供参考依据。2016年3—11月,于室外水泥池中开展了麦穗鱼养殖试验,分别测量其体重、体长及全长指标,进行生长特性分析。经180天的养殖,麦穗鱼平均全长达到3.96cm,平均体长达到3.23 cm,平均体重达到0.49g。特定生长率、日均增量和肥满度均受水温影响变化明显。体长(LB)与全长(LT)之间存在线性回归关系：LT=1.0589LB 0.767 (R2=0.8628),体长与体重(W)的回归方程为：W=0.0466LB2.1623 (R2=0.8306)。麦穗鱼体长的变异系数范围为6%~14%,体重的变异系数范围为20%~41%,肥满度在1.45~5.31之间变动。麦穗鱼在室外水泥池中生长效果良好,适宜进行规模化人工养殖。     

Determining the strength of exploitative competition from an introduced fish: roles of density,biomass and body size

Britton JR, Cucherousset J, Grey J, Gozlan RE. Determining the strength of exploitative competition from an introduced fish: roles of density, biomass and body size. Ecology of Freshwater Fish 2011: 20: 74–79. © 2010 John Wiley & Sons A/S Abstract – As species introductions can result in increased resource competition for coexisting species in the receiving ecosystems, the effects of increased exploitative competition for limited food resources from an introduced fish (Pseudorasbora parva) on a coexisting fish (Cyprinus carpio) were tested experimentally using a substitutive–additive design. Additive treatments revealed that the growth of C. carpio was significantly suppressed following the introduction of P. parva with the magnitude of growth suppression directly proportional to P. parva density and biomass. A substitutive treatment that tested for the effect of intraspecific competition revealed that when C. carpio were introduced at a similar biomass to P. parva, there was no significant difference in the extent of the suppressed growth. At the same density, however, the effect of C. carpio (higher biomass) on growth was significantly above that of P. parva (lower biomass). This was independent of the initial body sizes of the introduced fishes. Thus, the interspecific competition imposed by P. parva was only as strong as the intraspecific competition of C. carpio when present at a similar biomass.     

白洋淀麦穗鱼的生物学

本文论述了白洋淀麦穗鱼的食性、年龄生长和繁殖.     

玉米花粉作麦穗鱼饵料添加剂的研究

在饵料中添加０．５￣９％８个梯度的玉米花粉，在室内玻璃方缸中进行４０ｄ饲养麦穗鱼幼鱼试验。结果表明：在饵料中添加０．５％以上的玉米花粉，能提高鱼类对饵料的与分解能力，能显著促进鱼类生长。从生产角度，饵料中玉米花粉添加量为０．５％和１％，比较适宜。