正确操作挤奶设备 降低牛奶体细胞数

牛奶体细胞数过高——我们应该做些什么？ 现在我们评定牛奶的质量,一般将体细胞数的最大值设定为400000.00／mL。如果体细胞数高于这个数,牛奶生产者收益就会立即受到损失。体细胞的出现一般是对乳腺组织受到感染或损伤的一种回应。这种感染必须得到很好治疗及去除病因后奶牛才能得到适当恢复,否则奶牛将受到长期的感染。保持对体细胞的有效控制,     

Ultrasonographic examination of the omasum, liver, and small and large intestines in cows with right displacement of the abomasum and abomasal volvulus

OBJECTIVE: To describe ultrasonographic appearance of the liver, small and large intestines, and omasum in cows with right displacement of the abomasum (RDA) and with abomasal volvulus (AV) and to determine whether RDA and AV can be differentiated on the basis of ultrasonographic findings. ANIMALS: 17 cows with RDA, 9 cows with AV, and 10 healthy control cows. PROCEDURES: A linear transducer was used to examine the abomasum, liver, omasum, and small and large intestines from the right side. Results-The liver was imaged less frequently in cows with RDA or AV, compared with control cows. In 9 cows with RDA or AV, the liver could not be imaged. The small intestine was imaged less frequently in cows with RDA or AV than in control cows; in cows with AV, the small intestine could not be imaged in the 8th, 9th, or 10th intercostal space. The large intestine was imaged less frequently in the 11th and 12th intercostal spaces and the cranial region of the flank in cows with RDA or AV. The omasum was also imaged less frequently in the 8th and 9th intercostal spaces in cows with RDA or AV. Cows with RDA or AV could not be differentiated on the basis of ultrasonographic findings. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with control cows, cows with RDA and AV had changes in positioning and therefore extent of ultrasonographic imaging of the liver, omasum, and small and large intestines; however, these findings were not useful in differentiating between cows with RDA and AV.     

Effects of aspect and altitude on carbon cycling processes in a temperate mountain forest catchment

Context

Varying altitudes and aspects within small distances are typically found in mountainous areas. Such a complex topography complicates the accurate quantification of forest C dynamics at larger scales.

Objectives

We determined the effects of altitude and aspect on forest C cycling in a typical, mountainous catchment in the Northern Limestone Alps.

Methods

Forest C pools and fluxes were measured along two altitudinal gradients (650–900 m a.s.l.) at south-west (SW) and north-east (NE) facing slopes. Net ecosystem production (NEP) was estimated using a biometric approach combining field measurements of aboveground biomass and soil CO₂ efflux (SR) with allometric functions, root:shoot ratios and empirical SR modeling.

Results

NEP was higher at the SW facing slope (6.60?±?3.01 t C ha^?1  year^?1), when compared to the NE facing slope (4.36?±?2.61 t C ha^?1 year^?1). SR was higher at the SW facing slope too, balancing out any difference in NEP between aspects (NE: 1.30?±?3.23 t C ha^?1 year^?1, SW: 1.65?±?3.34 t C ha^?1 year^?1). Soil organic C stocks significantly decreased with altitude. Forest NPP and NEP did not show clear altitudinal trends within the catchment.

Conclusions

Under current climate conditions, altitude and aspect adversely affect C sequestering and releasing processes, resulting in a relatively uniform forest NEP in the catchment. Hence, including detailed climatic and soil conditions, which are driven by altitude and aspect, will unlikely improve forest NEP estimates at the scale of the studied catchment. In a future climate, however, shifts in temperature and precipitation may disproportionally affect forest C cycling at the southward slopes through increased water limitation.

     

Thermal weed control technologies for conservation agriculture—a review

Research and development activities on non-chemical weed control methods to date have mainly focused on mechanical and thermal applications. Selectivity in mechanical weed control is obtained using dynamically actuated harrows. Selectivity in thermal weed control is obtained through a certain heat tolerance of the crop. In conservation agriculture (CA), weed emergence is partially suppressed by constant soil cover with crops or cover crops. Large amounts of plant residues therefore remain on the soil, which make mechanical methods inefficient or difficult to implement. And thermal methods need to prevent not only crop damage but also fire from situationally dry plant residues. In this review, technologies that can potentially be used for in-crop weed control in CA are discussed. The technologies reviewed include spot-flaming, electric resistance heating, electromagnetic irradiation and steam/hot water application. Their evaluation focuses on efficiency and specificity (spatial precision). This review indicates that existing equipment does not fulfil the spatial precision required in CA and that further research and development is required on this topic. In particular, the authors suggest further research on the use of laser diodes, micro-flames and capacitive coupling of electric fields. It seems that the use of automated imaging systems for weed/crop differentiation is a prerequisite in CA to enable automatisation of weed control.     

Transendoscopic injection of poly-L-lactic acid into the soft palate in horses: A new therapy for dorsal displacement of the soft palate?

The purpose of this study was to establish a minimal invasive, transendoscopic technique for injection of poly-L-lactic acid into the free edge of the soft palate that can be performed on the standing sedated horse. Furthermore, whether the implant material induces an increase in fibrous tissue at the injection site, resulting in a greater rigidity of the soft palate, was determined.In 4 horses, the injection was performed bilaterally along the caudal margin of the soft palate, and the influence of the treatment on the soft palate function was determined. Clinical, radiographic and endoscopic examinations at rest were performed before and up to 168 days after injection according to a standardized examination protocol.In 6 horses, the implant material was injected unilaterally into the right half of the caudal margin of the soft palate. After clinical and endoscopic follow-up examinations, 2 horses each were killed 28, 84, and 168 days after the implantation procedure. At necropsy, macroscopic comparison of the treated and the untreated halves of the soft palate showed the influence on the size of the ostium intrapharyngeum and on the soft palate thickness. The localization of the implant material in the soft palate and the tissue response to the poly-L-lactic acid were evaluated histologically.Transendoscopic injection into the soft palate requires neither general anesthesia nor wound management, and it is noted for minimal tissue trauma. After injection, no alteration of the soft palate function was observed in horses with normal upper airway mechanics. One horse with intermittent dorsal displacement of the soft palate showed an improvement of the soft palate function for 112 days after implantation. No significant alteration in the size of the ostium intrapharyngeum was evident in any horse. Histologic assessment indicated the presence of implant material during the entire observation period of 168 days. The implant was accompanied by a granulomatous inflammation, and it was encapsulated by fibrous tissue. This may result in an increase in stiffness, and subsequent a greater rigidity of the soft palate, preventing it from displacement. The injection may therefore be considered an alternative to established therapies in horses showing dorsal displacement of the soft palate because of its unstable free edge.     

Influence of Inoculum Density of Races 0 and 5 of Fusarium oxysporum f. sp. ciceris on Development of Fusarium Wilt in Chickpea Cultivars

Artificial inoculation experiments were carried out at 25°C to determine the effects of inoculum density of Fusarium oxysporum f.sp. ciceris races 0 (Foc-0) and 5 (Foc-5) and susceptibility of chickpea cultivars P-2245 and PV-61 on development of Fusarium wilt. Foc-5 proved much more virulent than Foc-0. Increasing the inoculum density of F. oxysporum f.sp. ciceris caused an exponential reduction in disease incubation period and a monomolecular increase of disease incidence and the area under the disease intensity progress curve. The extent of these effects was highest in the most conducive P-2245/Foc-5 combination and decreased in the less susceptible PV-61 and for the less virulent Foc-0, in that order. For P-2245/Foc-5, the highest disease intensity was attained with 6 chlamydospores g^–1 of soil, the lowest inoculum density in the study. One thousand chlamydospores g^–1 of soil of the same race were needed to attain a comparable disease intensity in PV-61. Twenty thousand chlamydospores g^–1 of soil of Foc-0 were required for maximum disease intensity in P-2245.The disease intensity curves were adequately described by the Gompertz model. Using this model, a response surface for disease intensity was developed, in which the model parameters are expressed as a function of both time from inoculation and inoculum density. This response surface confirmed that the final amount of disease intensity increases in a monomolecular relationship with increasing inoculum density and showed that the relative rate of disease progress increases exponentially with increasing inoculum density of the pathogen.     

Estimating above-ground biomass of trees: comparing Bayesian calibration with regression technique

The commitment to report greenhouse gas emissions requires an estimation of biomass stocks and their changes in forests. When this was first done, representative biomass functions for most common tree species were very often not available. In Germany, an estimation method based on solid volume was developed (expansion procedure). It is easy to apply because the required information is available for nearly all relevant tree species. However, the distributions of neither parameters nor prediction intervals are available. In this study, two different methods to estimate above-ground biomass for Norway spruce (Picea abies), European beech (Fagus sylvatica), and Scots pine (Pinus sylvestris) are compared. First, an approach based on information from the literature was used to predict above-ground biomass. It is basically the same method used in greenhouse gas reporting in Germany and was applied with prior and posterior parameters. Second, equations for direct estimation of biomass with standard regression techniques were developed. A sample of above-ground biomass of trees was measured in campaigns conducted previously to the third National Forest Inventory in Germany (2012). The data permitted the application of Bayesian calibration (BC) to estimate posterior distribution of the parameters for the expansion procedure. Moreover, BC enables the calculation of prediction intervals which are necessary for error estimations required for reporting. The two methods are compared with regard to predictive accuracy via cross-validation, under varying sample sizes. Our findings show that BC of the expansion procedure performs better, especially when sample size is small. We therefore encourage the use of existing knowledge together with small samples of observed biomass (e.g., for rare tree species) to gain predictive accuracy in biomass estimation.     

Electronic liquid crystal state in the high-temperature superconductor YBa2Cu3O6.45

Electronic phases with symmetry properties matching those of conventional liquid crystals have recently been discovered in transport experiments on semiconductor heterostructures and metal oxides at millikelvin temperatures. We report the spontaneous onset of a one-dimensional, incommensurate modulation of the spin system in the high-transition-temperature superconductor YBa2Cu3O6.45 upon cooling below approximately 150 kelvin, whereas static magnetic order is absent above 2 kelvin. The evolution of this modulation with temperature and doping parallels that of the in-plane anisotropy of the resistivity, indicating an electronic nematic phase that is stable over a wide temperature range. The results suggest that soft spin fluctuations are a microscopic route toward electronic liquid crystals and that nematic order can coexist with high-temperature superconductivity in underdoped cuprates.     

High-resolution NMR spectroscopy with a portable single-sided sensor

We report construction of a portable nuclear magnetic resonance sensor with a single-sided open probe design. The resulting magnetic field inhomogeneity is compensated by a pulse sequence that takes advantage of parallel inhomogeneity in the applied radio frequency field. We can thereby acquire fluorine-19 spectra of liquid fluorocarbons with 8 parts per million resolution, surmounting the long-standing obstacle of obtaining chemical shift information with open probe instruments.