Advances in pasture management for animal productivity and health     

Lambert MG  Clark DA  Litherland AJ 《New Zealand veterinary journal》2004,52(6):311-319

A wide range of management techniques is available to enhance quantity and quality of forage supply to grazing animals throughout the annual production cycle. Within broad limits, dry matter (DM) production is relatively insensitive to management of defoliation frequency, severity and duration. However defoliation management has effects on feed quality which can be enhanced, in particular, by control of pasture growth in the spring through maintenance of relatively low average pasture masses. Treading damage can have significant immediate and ongoing effects on pasture production and farmers can use a range of management techniques to minimise these. Fertiliser application practices have a potent influence on pasture production and seasonality of that production. Available soil nitrogen is the primary nutrient deficiency limiting production in New Zealand's characteristically grass-dominant pastures. Nitrogen fertiliser usage has increased markedly in recent years, particularly to grow substantially greater amounts of forage during the cool season, and this trend looks set to continue. However, the use of nitrogen fertiliser has important environmental implications. Pasture renewal and forage crop use has also increased in recent years. Care needs to be taken in conducting cost-benefit analyses, selecting the options that best meet the needs, and in establishment and subsequent management practices. Ryegrass (perennial and hybrids) and white clover remain the primary choice for permanent pasture renewal, the availability of safe endophytes having largely alleviated effects of endophyte toxicosis. Special-purpose mixtures are used, especially in dry environments. Italian ryegrasses, brassicas and chicory are common choices for forage crops. A range of management techniques can be used to alleviate deleterious effects of some forages, including ryegrass endophyte toxicosis, facial eczema, and toxins associated with Fusarium fungi. Generally these techniques are not totally effective. More research is required to increase our understanding of these disorders, and in order to develop more effective and reliable management practices.  相似文献   

Effect of molecular weight and concentration of legume condensed tannins on in vitro larval migration inhibition of Haemonchus contortus     

H.D. Naumann  S.A. Armstrong  B.D. Lambert  J.P. Muir  L.O. Tedeschi  M.M. Kothmann 《Veterinary parasitology》2014,199(1-2):93-98

The effect of molecular weight of condensed tannins (CT) from a variety of warm-season perennial legumes commonly consumed by sheep and goats on anthelmintic activity has not been previously explored. The objectives of this study were to determine if molecular weight of CT from warm-season perennial legumes could predict the biological activity of CT relative to anthelmintic activity against ivermectin resistant L3 stage Haemonchus contortus (HC) using a larval migration inhibition (LMI) assay. A second objective was to determine if CT from warm-season perennial legumes possess anthelmintic properties against L3 stage (HC). Lespedeza stuevei had the greatest concentration of total condensed tannin (TCT; 11.7%), whereas, with the exception of Arachis glabrata, a CT-free negative control, Leucaena retusa had the least TCT (3.3%). Weight-average molecular weight of CT ranged from 552 Da for L. stuevei to 1483 Da for Lespedeza cuneata. The treatments demonstrating the greatest percent LMI were L. retusa, L. stuevei and Acacia angustissima var. hirta (65.4%, 63.1% and 42.2%, respectively). The ivermectin treatment had the smallest percent LMI (12.5%) against ivermectin resistant L3 HC. There was a weak correlation (R² = 0.34; P = 0.05) between CT M_W and percent LMI, suggesting that molecular weight of CT is a weak contributing factor to CT biological activity as it relates to LMI of L3 stage HC. L. stuevei, L. retusa and A. angustissima var. hirta STP5 warrant further evaluation of anthelmintic properties in vivo.  相似文献   

First Description of Scrotal Testicles in a Dog Affected by 78, XX Testicular Disorder of Sex Development     

AP Del Carro  E Rosset  A Josson‐Schramme  V Lambert  S Buff 《Reproduction in domestic animals》2014,49(5):E48-E52

An eight‐month‐old female dog presented with ambiguous external genitalia. A thorough clinical examination together with various imaging techniques and a histology examination showed the presence of two testicles linked to both the Mullerian and Wolffian ducts. The discovery of the 78,XX SRY‐negative karyotype led to the diagnosis of incoherence between the chromosomal and gonadal sex, which is typical for a 78,XX testicular disorder of sex development. Our case was unique because the testicles were still located in their normal scrotal position, whereas the literature contains reports of the presence of cryptorchid testicles in this karyotype setting. To our knowledge, this is the first case that describes an SRY‐negative 78,XX testicular disorder of sex development with bilateral scrotal testicles.  相似文献   

Early precambrian terrains: evolution of the lewisian and comparable precambrian high grade terrains     

Lambert RS 《Science (New York, N.Y.)》1988,240(4850):342-343

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Tumor necrosis factor (cachectin) as an essential mediator in murine cerebral malaria   总被引：113，自引：0，他引：113  

G E Grau  L F Fajardo  P F Piguet  B Allet  P H Lambert  P Vassalli 《Science (New York, N.Y.)》1987,237(4819):1210-1212

Tumor necrosis factor, or cachectin (TNF-alpha), a protein with a wide range of biological activities, is produced mainly by macrophages and may be important in inflammatory processes. The role of TNF-alpha in the pathogenesis of cerebral malaria was investigated in a murine model. Most CBA mice infected with Plasmodium berghei anka die between days 6 and 14 with acute neurological manifestations unrelated to the level of parasitemia, whereas mice of some other strains have malaria of the same severity that ends in death after 3 to 4 weeks without neurological manifestations. The activity of serum TNF-alpha was considerably increased in CBA/Ca mice with cerebral malaria but not in Plasmodium berghei-infected mice that did not develop this complication. One injection of rabbit antibody to TNF-alpha on day 4 or 7 fully protected infected mice from cerebral malaria without modifying the parasitemia, whereas immunoglobulins from normal rabbit had no effect. In mice with cerebral malaria, the cerebral vessels showed focal accumulations of packed macrophages often containing infected erythrocytes; this lesion was not seen in mice treated with antibody to TNF-alpha or in untreated mice without cerebral malaria. These findings indicate that TNF-alpha has an important role in the pathogenesis of cerebral malaria in this murine model and suggest that local accumulation and activation of macrophages may lead to the predominance of lesions in the central nervous system.  相似文献   

Low-Velocity Zone of the Earth's Mantle: Incipient Melting Caused by Water   总被引：1，自引：0，他引：1  

Lambert IB  Wyllie PJ 《Science (New York, N.Y.)》1970,169(3947):764-766

Experimental phase diagrams for the systems gabbro-water and peridotite-water indicate that, if there is any water in the upper mantle, then traces of hydrous interstitial silicate magma will be produced at depths corresponding to the beginning of the low-velocity zone. This explanation for the zone is more satisfactory than others proposed.  相似文献   

Sexuality: attempts at a broad view     

Lambert HH 《Science (New York, N.Y.)》1980,207(4433):877-878

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Hemocyte characteristics in families of oysters, Crassostrea gigas, selected for differential survival during summer and reared in three sites     

Christophe Lambert  Philippe Soudant  Lionel Dgremont  Maryse Delaporte  Jeanne Moal  Pierre Boudry  Frdric Jean  Arnaud Huvet  Jean-Franois Samain 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):276-288

High variability among individuals is often encountered when hemocyte characteristics are measured in bivalves. Such variability is suspected to result partly from genetic factors. In this study, hemocyte characteristics of six families of Crassostrea gigas were compared by flow cytometry at one sampling date in October 2001. These families were obtained from a nested, half-sibling cross design, and reared from July to October 2001 at three sites distributed along the French Atlantic coast from north to south: Baie des Veys (Normandy), Rivière d'Auray (Brittany) and Ronce (Marennes-oléron Basin, Poitou Charentes).

Among the 15 measured hemocyte characteristics, production of reactive oxygen species (ROS) of untreated hemocytes (maintained in filtered sterile seawater) and treated hemocytes (zymosan at 20 particles per hemocyte, and with Vibrio sp. S322 at 50 bacteria per hemocyte) was the most notable differences between families. This supports the existence of a genetic basis, at least partly, for the hemocyte characteristics of oysters, and especially for ROS production.

Among the six families analyzed, three have shown high survival during summer (named as “resistant”, mean mortality 5.2%) and three experienced high mortality during summer (named as “susceptible”, 30.6% mean mortality). Families showing high or low survival to summer mortality had similar hemocyte characteristics, regardless of the environmental conditions or reproductive state. Resistant families were observed to have higher total hemocyte counts and lower production of ROS than susceptible families. Moreover, ROS production of hemocytes from susceptible families was diminished significantly more by pathogenic Vibrio than that of resistant families. However, this study demonstrates also that rearing site strongly affected the hemocyte characteristics of all families of oysters, most notably hemocyte concentration and morphology (size and granularity), production of reactive oxygen species (ROS), and susceptibility to the cytotoxic activity of the pathogenic Vibrio sp. S322 (50 bacteria/hemocyte). Food availability and reproductive state are the most probable explanations for the site differences observed. Finally, it appeared difficult to link oyster survival during summer mortality to hemocyte profiles evaluated at one sampling date; other relevant indicators would probably help explaining oyster survival during summer mortality events.  相似文献   

Analysis of nutrient depletion in a radiata pine plantation     

John Turner  Marcia J. Lambert 《Forest Ecology and Management》2011,262(8):1327-1336

A trial in an 11-year-old stand of radiata pine (Pinus radiata D. Don) was used to analyse the effects of accelerated loss of nutrients from the site on forest productivity and nutrient status. Raking of litter was undertaken over 14 years prior to thinning, then for 2 years after thinning at which time the trial was destroyed in a wind storm. The experimental design was a factorial of three main treatments: (i) removal (raking) versus nil removal of the forest floor, (ii) replacement or non replacement of nutrients to adjust for imbalances between nutrients in litter and those in the tree stem, and (iii) complete replacement (or not) of all nutrients removed in the litter. Additionally, a small trial was incorporated to address components of physical aspects of litter removal by comparing raking with ‘raking and a cover of woven plastic mesh’. Raking and nutrient additions were carried out approximately every 6 months.Over the study period, the raking treatment removed about 75 Mg ha⁻¹ of organic material with contained nutrients (559 kg ha⁻¹ of N, 68 kg ha⁻¹ of P, 323 kg ha⁻¹ of Ca, 91 kg ha⁻¹ of Mg, 243 kg ha⁻¹ of K, 0.9 kg ha⁻¹ of B) and this related to about four normal sawlog harvests or one total tree harvest. Up to the time of thinning, raking reduced basal area increment by 25% while raking together with replacement of nutrients reduced this by about 12%. Nutrient additions to unraked plots led to increases of up to 14% in basal area increment. The raking treatment reduced foliage nitrogen and this was correlated with reduced growth while other nutrients such as boron and sulphur were reduced but not to a degree to affect growth or health. The results were used to assess the effects on soil nutrient status and growth of different harvesting regimes (wood only, wood plus bark, total tree).  相似文献   

Understory plant diversity and biomass in hybrid poplar riparian buffer strips in pastures     

Julien Fortier  Daniel Gagnon  Benoit Truax  France Lambert 《New Forests》2011,42(2):241-265

Understory plant biomass, species richness and canopy openness were measured in six-year old hybrid poplar riparian buffer strips, in the understory of two unrelated clones (MxB-915311 and DxN-3570), planted along headwater streams at three pasture sites of southern Quebec. Canopy openness was an important factor affecting understory biomass in hybrid poplar buffers, with lower understory biomass observed on sites and under the clone with lower canopy openness. Although tree size was an important factor affecting canopy openness, relationships between total stem volume and canopy openness, for each clone, also support the hypothesis of a clonal effect on canopy openness. Understory biomass and canopy openness as low as 3.6 g m⁻² and 7.6% in 1 m² microplots were measured under clone MxB-915311 at the most productive site. This reduction of understory plant growth could compromise important buffer functions for water quality protection (runoff control, sediment trapping and surface soil stabilisation), particularly were concentrated runoff flow paths enter the buffer. On the other hand, tree buffers that maintain relatively low canopy openness could be interesting to promote native and wetland plant diversity. Significant positive relationships between canopy openness and introduced species richness (R ² = 0.46, p < 0.001) and cover (R ² = 0.51, p < 0.001) were obtained, while no significant relationship was observed between canopy openness and native (wetland) species richness and cover. These results suggest that planting riparian buffer strips of fast-growing trees can rapidly lead to the exclusion of shade-intolerant introduced species, typical colonisers of disturbed habitats such as riparian areas of pastures, while having no significant effect on native (wetland) diversity. Forest canopy created by the poplars was probably an important physical barrier controlling introduced plant richness and abundance in agricultural riparian corridors. A strong linear relationship (R ² = 0.73) between mean total species richness and mean introduced species richness was also observed, supporting the hypothesis that the richest communities are the most invaded by introduced species, possibly because of higher canopy openness, as seen at the least productive site (low poplar growth). Finally, results of this study highlight the need for a better understanding of relationships between tree growth, canopy openness, understory biomass and plant diversity in narrow strips of planted trees. This would be useful in designing multifunctional riparian buffer systems in agricultural landscapes.  相似文献