The effect of ivermectin treatment of late pregnant dairy cows in south-west Victoria on subsequent milk production and reproductive performance

SUMMARY A total of 498 dairy cows in 5 predominantly pasture-fed herds were allocated to pairs. One cow in each pair was treated with a single dose of ivermectin during the dry period. Treated and untreated cows were managed as a single group throughout the trial. Most cows calved between 45 and 115 days after treatment. When data from all herds were pooled, treated cows produced an extra 74 L of milk over the first 100 days of the subsequent lactation (95% confidence interval 20 to 128). Means were greater among treated groups relative to untreated groups in all 5 herds. However, when analysed individually, differences were statistically significant (P < 0.05) in 1 herd only. Over the complete lactation, mean milk volume for treated cows was 86 L greater than for untreated cows (95% confidence interval of difference -57 to 229; P = 0.24). Untreated cows produced 2473 L and 5883 L for the first 100 days of lactation and for the complete lactation, respectively. Milk production responses to treatment did not vary significantly with parity, body condition score, previous production index, calving date category or with plasma pepsinogen concentration or faecal egg count at the time of treatment. Faecal egg counts and plasma pepsinogen concentrations were low at the start of the study. The interval from calving to conception was 4.8 days less in treated cows (95% confidence interval 1.2 to 8.2) relative to untreated cows when data from all 5 herds were pooled. Differences within individual herds were not statistically significant.     

Herd and within-herd BoHV-1 prevalence among Irish beef herds submitting bulls for entry to a performance testing station

Infectious bovine rhinotracheitis (IBR), caused by bovine herpes virus 1 (BoHV-1), may result in various clinical consequences, including severe respiratory disease and conjunctivitis, venereal disease and reduced reproductive performance and abortion. This paper presents the serosurveillance findings from an intake of bulls into a performance testing station in Ireland during November 2007. The herd and within-herd BoHV-1 prevalence in 53 Irish beef herds and the risk factors for infection in these herds were determined, among bulls entering a beef performance testing station in Ireland. BoHV-1 status was determined for 41 herds, of which 30 (73.2%) herds were infected and the mean within-herd BoHV-1 prevalence was 28 (± 20)%. Multivariate exact logistic modelling revealed increasing numbers of contiguous herds and decreasing percentage of males within the herd as significant risk factors associated with infected herds. These findings highlight the high prevalence of BoHV-1 infection in those Irish beef herds that submitted bulls to this performance testing station, and raise concerns regarding IBR control nationally.     

蝗虫微孢子虫病在优势蝗虫种类中的持续传播

对施用蝗虫微孢子虫后1-10年的草场中5种主要蝗虫种群中微孢子虫病的流行状况进行了研究,结果表明,蝗虫微孢子虫病能在蝗群中长期传播,蝗虫种群的感病率和感染指数呈波动趋势,随着施用后年限的增加,波幅变动范围趋于稳定。感染率波幅范围为20％-80％,感染指数为10％-41％;鼓翅皱膝蝗、白边痂蝗和毛足棒角蝗种群对微孢子虫病的感染指数,不同年份波动较大,短期内难以形成一个稳定的流行群体;而在小车蝗和宽须蚁蝗种群中引入微孢子虫4年后,感染指数下降,但能够形成比较稳定的感染群体。     

Hollows on Mercury: MESSENGER evidence for geologically recent volatile-related activity

High-resolution images of Mercury's surface from orbit reveal that many bright deposits within impact craters exhibit fresh-appearing, irregular, shallow, rimless depressions. The depressions, or hollows, range from tens of meters to a few kilometers across, and many have high-reflectance interiors and halos. The host rocks, which are associated with crater central peaks, peak rings, floors, and walls, are interpreted to have been excavated from depth by the crater-forming process. The most likely formation mechanisms for the hollows involve recent loss of volatiles through some combination of sublimation, space weathering, outgassing, or pyroclastic volcanism. These features support the inference that Mercury's interior contains higher abundances of volatile materials than predicted by most scenarios for the formation of the solar system's innermost planet.     

Manipulating the pathway of ammonia assimilation in transgenic non-legumes and legumes

In this paper we discuss the ways in which our understanding of the nature of the molecular controls of nitrogen assimilation has been increased by the use of non-leguminous and leguminous plants with genetically-altered capacities for ammonia assimilation. Using tobacco or Lotus as model plants, Glutamine synthetase (GS) and glutamate synthase (GOGAT) activities have been altered by stimulating or inhibiting in an organ- or tissue-specific manner the expression of the corresponding genes. In a few selected examples, the physiological impact of these genetic manipulations has been studied on plants grown under different nitrogen regimes. The use of such genetically-modified plants will allow us to better understand the molecular control of this metabolic pathway. It is also potentially of great importance in agriculture if such internal and stable modifications are beneficial in terms of nitrogen use efficiency, thus avoiding an excessive utilization of fertilizers or herbicides (GS inhibitors). Our current knowledge and prospects for future development are explored.     

不同啃食强度对沙拐枣影响的初步研究

在飞播区根据牧畜对沙拐枣啃食程度的不同，采用人工模拟放牧方法对牲畜啃食的绿色部分设置了10％、30％、50％、70％、90％、对照6种不同啃食强度处理，以探讨啃食强度对沙拐枣生长的影响。试验结果表明，30％啃食强度的生物量化90％的高121．37％，比对照高34．85％。沙拐枣的啃食强度在30％－50％时生物量最高，完全不利用或过度利用都会影响其正常生长。     

绵羊放牧方式及强度对围封恢复草场牧草细胞壁成分及营养价值的影响

选取内蒙古自治区典型草原区封育恢复中天然放牧草场,进行毛肉兼用细毛羊的暖季放牧试验.采用2×5完全随机试验设计,设定不同放牧方式（不放牧,连续放牧,四区、五区、六区轮牧）及2种放牧强度（1.0,1.4 hm2/un.sh）,运用酶分析方法分析比较了围封过程中放牧绵羊对封育草场牧草细胞壁成分月动态变化及营养价值的影响.结果表明,整个暖季放牧期内,不同放牧区牧草营养物质含量主要受到放牧方式的显著影响（P＜0.05）.具体表现为,不放牧处理牧草细胞壁有机物（OCW）含量始终显著低于各放牧处理,不同放牧处理间没有明显差异;划区轮牧处理牧草始终保持着较高的消化性部分且显著高于连续放牧处理;不放牧处理牧草始终保持着较高的Oa和较低的Ob,而连续放牧处理与其相反,各轮牧处理间没有显著差异;轮牧处理总可消化养分（TDN）和代谢能（ME）含量较高,尤其在牧草生长旺盛期（八月份）,六区轮牧放牧场牧草可利用营养物质含量最高,营养价值最高.     

Volcanism on Mercury: evidence from the first MESSENGER flyby

The origin of plains on Mercury, whether by volcanic flooding or impact ejecta ponding, has been controversial since the Mariner 10 flybys (1974-75). High-resolution images (down to 150 meters per pixel) obtained during the first MESSENGER flyby show evidence for volcanic vents around the Caloris basin inner margin and demonstrate that plains were emplaced sequentially inside and adjacent to numerous large impact craters, to thicknesses in excess of several kilometers. Radial graben and a floor-fractured crater may indicate intrusive activity. These observations, coupled with additional evidence from color images and impact crater size-frequency distributions, support a volcanic origin for several regions of plains and substantiate the important role of volcanism in the geological history of Mercury.     

三维模式下培养时间对奶牛乳腺上皮细胞酪蛋白基因表达的影响

本试验旨在研究三维模式下培养时间对奶牛乳腺上皮细胞(BMECs)酪蛋白基因表达的影响。采用3头健康的3～5岁泌乳黑白花奶牛的乳腺组织,将BMECs经1代纯化后进行三维培养,在三维模式下分别培养3、5、7、9 d,测定BMECs中αs1-酪蛋白、β-酪蛋白、κ-酪蛋白的基因表达量。结果表明,利用三维模式培养5 d的BMECsαs1-酪蛋白和κ-酪蛋白基因表达量极显著高于培养3、7、9 d(P<0.01);利用三维模式培养5 d的BMECsβ-酪蛋白的基因表达量极显著高于培养3、7 d(P<0.01),高于培养9 d,但差异不显著(P>0.05)。结果显示,三维模式下培养时间影响BMECs中αs1-酪蛋白、β-酪蛋白、κ-酪蛋白的基因表达量,本试验条件下最佳培养时间为5 d。