生物炭及炭基肥影响农田土壤改良效应的研究进展

我国南方农田普遍存在土壤酸化加速、土壤肥力和质量不断下降、土壤微生物群落结构和功能失调等土壤退化现象。近年来,大量研究表明生物炭是一种应用前景广阔的土壤改良剂,而将其与肥料有效结合制成生物炭基肥,将在我国农田酸化土壤改良和作物增产等方面发挥重要作用。本文重点针对生物炭和生物炭基肥在农田生态系统中影响土壤改良的效应进行了综述,旨在为我国南方农田土壤改良和农业生产可持续发展提供参考。     

七种杀菌剂对水稻纹枯病菌的室内毒力及田间防效评价

本研究评价了七种杀菌剂对水稻纹枯病菌的室内毒力及田间防效。室内毒力测定结果表明：30%肟菌.戊唑醇悬浮剂、35%噻呋.氟环唑悬浮剂、32%噻呋.戊唑醇悬浮剂、30%戊唑.嘧菌酯悬浮剂、500g/L苯甲.丙环唑乳油这5种杀菌剂混剂对水稻纹枯病菌均有较强的抑制作用,EC₅₀值在0.0572~0.2265 mg.L^_-1之间。田间防效试验结果表明：在药后7d,对水稻纹枯病防效最好的药剂为30%肟菌.戊唑醇悬浮剂,防效为95.02%,30%戊唑.嘧菌酯悬浮剂、32%噻呋.戊唑醇悬浮剂、35%噻呋.氟环唑悬浮剂和500g/L苯甲.丙环唑乳油的防效分别为93.15%、92.53%、92.26%、91.81%;在药后14d,30%肟菌.戊唑醇悬浮剂这5种杀菌剂混剂对水稻纹枯病的防效均达到93%以上。     

Allozyme diversity in Australian rainbow trout, Oncorhynchus mykiss

Rainbow trout, Oncorhynchus mykiss (Walbaum), were first introduced into Australia over 100 years ago, and forms the basis of important recreational inland fisheries and an aquaculture industry in south‐eastern Australia. This paper investigates the genetic variation within and between samples of Australian rainbow trout using allozyme electrophoresis. The levels of genetic diversity within Australia do not show marked differences from those observed in hatchery and wild populations from throughout North America, New Zealand and South Africa, but there is evidence for the loss of some rare alleles during translocation from California to Australia via New Zealand. No appreciable difference in genetic diversity was apparent between hatchery and self‐sustaining wild populations of rainbow trout from mainland Australia. However, significant differences in allelic frequencies were observed, with consistent genetic differences between Victorian and New South Wales samples most likely reflecting state‐based hatchery and stocking policies.     

3种工业废水对牙鲆胚胎的毒性效应

通过室内实验，研究了印染废水、电镀废水、农药废水3种工业废水及其混合物(等体积混合)对牙鲆胚胎的毒性效应。印染废水的主要有毒物为苯胺(20mg/L)和苯酚(24mg/L)，电镀废水主要有毒物为锌(1970mg/L)、铜(9mg/L)和铅(7．5mg/L)；农药废水及混合物主要有毒物为久效磷和亚磷酸盐。实验表明，这4种类型废水对牙鲆胚胎发育孵化有显著影响的最低体积分数分别为0．5％、0．15％、0．25％和0．25％；对牙Gf胚胎起始半数致死浓度(95％可信限，体积分数)分别为3．38％(2．29％—3．87％)、0．81％(0．71％—0．92％)、1．57％(1．37％—1．82％)和1．48％(1．24％—1，76％)。以牙鲆胚胎起始半数致死浓度(体积分数)为指标，这几种工业废水的毒性顺序为电镀废水＞农药废水＞印染废水。     

考虑应力敏感性影响的三项式产能方程

低渗透气藏存在较强的应力敏感性,大量岩石实验数据回归研究表明,幂函数渗透率应力敏感性经验方程相关性相对较好,而前人利用该关系式来研究低渗透气藏气井产能的报道较少。在这样的背景下,利用幂函数应力敏感性经验公式,综合考虑渗透率应力敏感效应、启动压力梯度、紊流效应和表皮系数,建立了一个新的适用于低渗透异常高压气井的三项式产能方程。不同参数组合情况下的气井流入动态曲线对比研究结果表明,应力敏感性、启动压力梯度和紊流效应对低渗透气藏气井产能的影响较大,在产能评价研究时必须予以考虑。     

2013年隆德县马铃薯脱毒种薯三级繁育体系建设做法及成效

介绍了隆德县马铃薯脱毒种薯三级繁育体系建设主要做法及取得的成效,分析马铃薯脱毒种薯三级繁育体系建设存在的问题,并提出建议,为进一步做大做强马铃薯产业提供依据。     

Effects of Artemisia annua and Foeniculum vulgare on chickens highly infected with Eimeria tenella (Phylum Apicomplexa)

Background

Intensive poultry production systems depend on chemoprophylaxis with anticoccidial drugs to combat infection. A floor-pen study was conducted to evaluate the anticoccidial effect of Artemisia annua and Foeniculum vulgare on Eimeria tenella infection. Five experimental groups were established: negative control (untreated, unchallenged); positive control (untreated, challenged); a group medicated with 125 ppm lasalocid and challenged; a group medicated with A. annua leaf powder at 1.5% in feed and challenged; and a group treated with the mixed oils of A. annua and Foeniculum vulgare in equal parts, 7.5% in water and challenged. The effects of A. annua and oil extract of A. annua + F. vulgare on E. tenella infection were assessed by clinical signs, mortality, fecal oocyst output, faeces, lesion score, weight gain, and feed conversion.

Results

Clinical signs were noticed only in three chickens from the lasalocid group, six from the A. annua group, and nine from the A. annua + F. vulgare group, but were present in 19 infected chickens from the positive control group. Bloody diarrhea was registered in only two chickens from A. annua group, but in 17 chickens from the positive control group. Mortality also occurred in the positive control group (7/20). Chickens treated with A. annua had a significant reduction in faecal oocysts (95.6%; P = 0.027) and in lesion score (56.3%; P = 0.005) when compared to the positive control. At the end of experiment, chickens treated with A. annua leaf powder had the highest body weight gain (68.2 g/day), after the negative control group, and the best feed conversion (1.85) among all experimental groups.

Conclusions

Our results suggest that A. annua leaf powder (Aa-p), at 1.5% of the daily diet post-infection, can be a valuable alternative for synthetic coccidiostats, such as lasalocid.     

Temporal associations between low body condition,lameness and milk yield in a UK dairy herd

Previous work has hypothesised that cows in low body condition become lame. We tested this in a prospective longitudinal study. Body condition score (BCS), causes of lameness and milk yield were collected from a 600-cow herd over 44-months. Mixed effect binomial models and a continuous outcome model were used to investigate the associations between lameness, BCS and milk yield. In total, 14,320 risk periods were obtained from 1137 cows. There were 1510 lameness treatments: the most common causes of lameness were sole ulcer (SU) (39%), sole haemorrhage (SH) (13%), digital dermatitis (DD) (10%) and white line disease (WLD) (8%). These varied by year and year quarter. Body condition was scored at 60-day intervals. BCS ranged from 1 to 5 with a mean of 2.5, scores were higher in very early lactation but varied widely throughout lactation; approximately 45% of scores were <2.5. The key finding was that BCS < 2.5 was associated with an increased risk of treatment for lameness in the following 0–2 months and >2–4 months for all causes of lameness and also specifically for SU/WLD lameness. BCS < 2.5 was associated with an increased risk of treatment for SH in the following 0–2 months but not >2–4 months. There was no such association with DD. All lameness, SU/WLD, SH and DD were significantly more likely to occur in cows that had been lame previously, but the effect of BCS was present even when all repeat cases of lameness were excluded from the analysis. Milk yield was significantly higher and fell in the month before treatment in cows lame with SU/WLD but it was not significantly higher for cows that were treated for DD compared with non-lame cows. These findings support the hypothesis that low BCS contributes to the development of horn related claw lameness but not infectious claw diseases in dairy cows. One link between low BCS and lameness is a thin digital cushion which has been proposed as a trigger for claw horn disease. Cows with BCS 2 produced more milk than cows with BCS 2.5, however, this was only approximately 100 kg difference in yield over a 305-day lactation. Given the increased risk of lameness in cows with BCS 2, the direct costs of lameness and the small variability in milk yield by BCS, preventing cows from falling to BCS < 2.5 would improve cow welfare and be economically beneficial.     

桑1-脱氧野尻霉素降血糖作用的研究进展

1-脱氧野尻霉素是桑树中的一种生物碱,是哺乳动物α-葡萄糖苷酶的有效抑制剂,具有降糖、降脂、抗病毒、抗肿瘤等药理作用。本文针对已报道的1-脱氧野尻霉素功能,综述了近年来1-脱氧野尻霉素降糖作用研究的最新进展,为更好利用和开发桑叶1-脱氧野尻霉素提供参考。     

苦瓜提取物对四种兽医临床常见菌的抑菌活性研究

采用打孔法和二倍稀释法研究不同质量浓度的苦瓜提取物对4种临床常见菌的抑制作用,并测定苦瓜提取物对4种菌株生长曲线的影响。结果显示,10 mg/mL的苦瓜提取物对大肠杆菌和沙门氏菌的抑制作用最强,而对链球菌和金黄色葡萄球菌的抑制作用不显著;苦瓜提取物对4种菌株的最小抑菌浓度（MIC）分别为2.5 mg/mL、2.5 mg/mL、5 mg/mL和10 mg/mL。结果提示,苦瓜提取物具有较强的抑菌活性。