Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time.     

G Breves  R Zitnan  B Schr?der  C Winckler  H Hagemeister  K Failing  J Voigt 《Archives of Animal Nutrition》2002,56(5):371-377

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.  相似文献   

Bursaphelenchus xylophilus– phytosanitäre Einfuhrkontrollen an Holz von Coniferales im Land Brandenburg     

Wolfram Pohl 《Gesunde Pflanzen》2003,55(1):13-20

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Morphological characterization and immunohistochemical detection of the proinflammatory cytokines IL-1β, IL-17A,and TNF-α in lung lesions associated with contagious bovine pleuropneumonia     

Anja Sterner-Kock  Wolfram Haider  Flavio Sacchini  Anne Liljander  Jochen Meens  Jane Poole  Maria Guschlbauer  Martin Heller  Jan Naessens  Joerg Jores 《Tropical animal health and production》2016,48(3):569-576

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Barrier island forest ecosystem: role of meteorologic nutrient inputs     

Art HW  Bormann FH  Voigt GK  Woodwell GM 《Science (New York, N.Y.)》1974,184(4132):60-62

The Sunken Forest, located on Fire Island, a barrier island in the Atlantic Ocean off Long Island, New York, is an ecosystem in which most of the basic cation input is in the form of salt spray. This meteorologic input is sufficient to compensate for the lack of certain nutrients in the highly weathered sandy soils. In other ecosystems these nutrients are generally supplied by weathering of soil particles. The compensatory effect of meteorologic input allows for primary production rates in the Sunken Forest similar to those of inland temperate forests.  相似文献   

Rate of stomatal opening, shoot hydraulic conductance and photosynthetic characteristics in relation to leaf abscisic acid concentration in six temperate deciduous trees     

Aasamaa K  Sõber A  Hartung W  Niinemets U 《Tree physiology》2002,22(4):267-276

Correlations between leaf abscisic acid concentration ([ABA]), stomatal conductance (gs), rate of stomatal opening in response to an increase in leaf water potential (si), shoot hydraulic conductance (L) and photosynthetic characteristics were examined in saplings of six temperate deciduous tree species: Acer platanoides L., Padus avium Mill., Populus tremula L., Quercus robur L., Salix caprea L. and Tilia cordata Mill. Species-specific values of foliar [ABA] were negatively related to the mean values of gs, si, L and light- and CO2- saturated net photosynthesis (P(max)), thus providing strong correlative evidence of a scaling of foliar gas exchange and hydraulic characteristics with leaf endogenous [ABA]. In addition, we suggest that mean gs, si, L and Pmax for mature leaves may partly be determined by the species-specific [ABA] during leaf growth. The most drought-intolerant species had the lowest [ABA] and the highest gs, suggesting that interspecific differences in [ABA] may be linked to differences in species-specific water-use efficiency. Application of high concentrations of exogenous ABA led to large decreases in gs, si and P(max), further underscoring the direct role of ABA in regulating stomatal opening and photosynthetic rate. Exogenous ABA also decreased L, but the decreases were considerably smaller than the decreases in gs, si and Pmax. Thus, exogenous ABA predominantly affected the stomata directly, but modification of L by ABA may also be an important mechanism of ABA action. We conclude that interspecific variability in endogenous [ABA] during foliage growth and in mature leaves provides an important factor explaining observed differences in L, gs, si and Pmax among temperate deciduous tree species.  相似文献   

Eradication of ovine pulmonary adenocarcinoma by motherless rearing of lambs     

Voigt K  Krämer U  Brügmann M  Dewar P  Sharp JM  Ganter M 《The Veterinary record》2007,161(4):129-132

The principles of maedi-visna eradication programmes were applied to a field trial for the eradication of ovine pulmonary adenocarcinoma (OPA). In two maternal flocks the prevalence of gross and histological lesions in slaughtered animals was 18.3 per cent and 29.8 per cent, respectively. The lambing period was supervised for three consecutive years from 1999 to 2001, during which the lambs were taken away from their mothers at birth, deprived of maternal colostrum, and hand-reared away from other sheep. Over the three-year period, 322 hand-reared animals, mainly male lambs between 10 and 14 months old, were slaughtered; their lungs were examined grossly, 52.5 per cent of them were examined histologically, and 105 samples of caudal mediastinal lymph nodes were examined by PCR. No OPA tumours were detected in the slaughter specimens from the derived flock, but one lamb had histological lesions in one lung location; intrauterine transmission was ruled out in this case. No clinical OPA has subsequently been observed in the hand-reared flock. Bronchoalveolar lavage samples from the breeding stock were examined by PCR in order to rule out further subclinical cases of OPA. No Jaagsiekte retrovirus was detected in any of the 488 samples.  相似文献   

Potential effects of acid precipitation on soils in the humid temperate zone     

C. R. Frink  G. K. Voigt 《Water, air, and soil pollution》1977,7(3):371-388

Unmanaged soils in the northeast United States generally tend toward increasing acidity which results from several natural processes in the soil. Possible effects of acid precipitation on these processes may be caused by hydrogen ions associated with excess anions in the precipitation and, in addition, the anions may also have specific effects. This is especially true for N and S both of which have important biological implications. It is likely that direct effects of the H ion will be modest. As an example, the acidity in 114 cm of rainfall per year (Connecticut's average) with a pH of 4.3 would require 28.5 kg ha ^?1 of limestone for neutralization. By contrast agronomic practice in Connecticut frequently dictates limestone additions as high as several thousand kg ha^?1 to neutralize acidity generated by a combination of natural processes and fertilizer amendments. Studies of rainfall composition in Connecticut from 1929 to 1948 showed no clear trends with time and indicated levels of sulfate and nitrate in rainwater similar to those reported today. In a 10 yr lysimeter study in Connecticut in which tobacco was grown using conventional fertilization techniques, soil pH decreased from 5.4 to 5.0 and both gains and losses of soil cations were recorded. Thus it appears that changes in unmanaged soils induced by acid precipitation alone will be modest and subtle and probably cannot be expressed completely by measuring changes in soil pH value.  相似文献   

Dietary conjugated linoleic acid (CLA) intake assessment and possible biomarkers of CLA intake in young women     

Fremann D  Linseisen J  Wolfram G 《Public health nutrition》2002,5(1):73-80

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Harvest maturity specification for mango fruit (Mangifera indica L. ‘Chok Anan’) in regard to long supply chains     

Stefanie Kienzle  Pittaya Sruamsiri  Reinhold Carle  Suparat Sirisakulwat  Wolfram Spreer  Sybille Neidhart   《Postharvest Biology and Technology》2011,61(1):41-55

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Climate trends and global crop production since 1980   总被引：14，自引：0，他引：14  

Lobell DB  Schlenker W  Costa-Roberts J 《Science (New York, N.Y.)》2011,333(6042):616-620

Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. We found that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends from 1980 to 2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8 and 5.5%, respectively, relative to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, carbon dioxide fertilization, and other factors.  相似文献