Short communication: Variability of response to feed restriction in lactating Charolais cows

Involuntary temporary feed restriction on commercial cattle is likely to become more frequent with forage shortages in the context of climate change. If general consequences of feed restriction have been the subject of an abundant scientific literature, focus on the inter-individual variability of response is scarce. Here, we explore the response profile in terms of BW, body condition score, milk production, calf weight and cyclicity resumption of 293 lactations from 169 Charolais cows during a winter feed restriction in early lactation and its subsequent recovery at grazing using a principal component analysis followed by a hierarchical clustering on principal component. Results show a very continuous range of response profiles that was divided into three clusters: one with light animals having an intermediate response in terms of milk production and body maintenance, one with animals prioritising body maintenance and cyclicity resumption over milk production and calf weight, and the last one with animals prioritising milk production and calf weight over the rest. Among the animals performing more than one lactation, 57% remain in the same cluster on two successive lactations. This work highlights that an average group response to feed restriction may hide various resilience individual profiles. Further studies are required to determine the existence of a genetic component as well as the consequences of not taking this phenomenon into consideration with the regular use of feed restriction in commercial farms.     

Pomphorhynchus laevis (Müller) in the flounder, Platichthys flesus L., in the tidal River Thames: population structure, microhabitat utilization and reproductive status in the field and under conditions of controlled salinity

The infection of R. Thames flounders, Platichthys flesus L., at Fulham by the acanthocephalan parasite Pomphorhynchus laevix (Müller) is described in terms of parasite population structure, life-cycle organization, reproductive biology and host microhabitat utilization. The parasites demonstrated 100% prevalence in this tidal but essentially freshwater locality (intestinal intensity 34.47) and were overdispersed in the flounder population (variance/mean ratio = 10.39, k= 1.04). Overall about 11% of the worms occurred in peritoneal cavity sites, the remainder being firmly attached to the gut wall in the posterior region of the intestine and rectum. The P. laevis populations were reproductively active, demonstrating that the flounder acts as a significant final host in this locality. Viable larval stages were identified in Gammarus zaddachi Sexton, a predominantly estuarine amphipod, indicating that P. laevis is likely to be able to complete its life cycle at Fulham. Over half the female parasites examined were gravid and many of the non-gravid worms were inseminated but had not yet started egg production. The proportion of females gravid, the number of ovarian balls and the number of eggs in gravid females was seen to increase with worm size. Both the identity of the intermediate host and the reproductive status of P. laevis in the Thames flounders differ from the Pomphorhynchus/flounder system studied by Kennedy (1984) in the R. Avon, suggesting that the two P. laevis populations may belong at least to discrete subspecies or strains. Parasites in flounders maintained under laboratory conditions in fresh water, 50% sea water and 100% sea water showed similar population, microhabitat and reproductive characteristics to those observed in the field. This suggests that increased salinity has a negligible effect on established parasites in the short term, and therefore that salinity may not form a barrier to the survival and dispersal of the R. Thames parasite when the flounders return to sea.     

桂平市竹笋资源及其开发利用

桂平市食用竹笋资源丰富,有大头竹笋、吊丝竹笋、浦竹笋、毛竹笋等十余种,年产鲜笋８５００ｔ以上。原有的加工方法比较落后,现已注意引进新技术,今后还需进一步开发利用。     

庐山野生观赏植物资源多样性及持续利用对策

庐山是我国著名的风景旅游和避暑胜地,也是我国中亚热带北缘植物多样性的宝库．本文在广泛调查、收集、整理的基础上,研究了庐山野生观赏植物资源多样性特征、分布、类型及其配置．本区分布有野生观赏植物５２８种,隶属于１１５科２９０属,其中乔木类１３８种,灌木类１４０种,藤木类５２种,草本类１９８种．并根据开发与保护现状对庐山野生观赏植物资源多样性的持续利用提出了切实可行的对策．     

白浆土－植物系统营养物质转化机制及其有效性研究——Ⅰ．32P同位素示踪法对白浆土中P肥利用率

利用³²P同位素示踪法对白浆土中P肥利用率进行了研究.结果表明,在岗地白浆土上,表层土壤表现出一定程度的供P不足现象,白浆层土壤有效P含量严重缺乏.表层土壤中当季P肥利用率的变幅范围为6.09～12.35%,白浆层土壤P肥利用率为13%左右.施用有机肥能明显提高白浆土Olsen P的含量,加速土壤本身P的活化,各种有机物中,以猪粪对土壤潜在P的活化效果最好.将Olsen P与X值、A值比较,认为Olsen P是评价白浆上P肥力简便易行的可靠指标.     

浙江海岛盐生植被研究Ⅱ──天然植被类型及开发利用

天然盐生植被是海岛盐生植被的主体,类型丰富,分布广泛,在海岛植被的研究及开发利用中占据重要地位。目前,天然盐生植被的分类尚无统一标准与系统。本文根据作者1990～1993年在浙江海岛用样方法(Ｈ.ＶｏｎＰｏｓｔ,1851;陈彦卓,1965)测定的样地数据,参照《中国植被》的分类方法,根据群落的外貌与结构、生态地理、动态和种类组成等特征进行分类,其中对群系级单位侧重于种类组成,并采用建群植物的重要值(Ｊ.Ｔ.ＣｕｒｔｉｓａｎｄＲ.Ｐ.ＭｃＩｎｔｏｓｈ,1951)作为分类的定量指标。据此,浙江海岛天然盐生植被可划分为3个植被型、8个群系组、18…     

The impact of mycorrhizal colonization upon nitrogen source utilization and metabolism in seedlings of Eucalyptus grandis Hill ex Maiden and Eucalyptus maculata Hook

Analysis of soil solution from forest sites dominated by Eucalyptus grandis and Eucalyptus maculata indicates that soluble forms of organic nitrogen (amino acids and protein) are present in concentrations similar to those of mineral nitrogen (nitrate and ammonium). Experiments were conducted to determine the extent to which mycorrhizal associations might broaden nitrogen source utilization in Eucalyptus seedlings to include organic nitrogen. In isolation, species of ectomycorrhizal fungi from northern Australia show varying abilities to utilize mineral and organic forms of nitrogen as sole sources. Pisolithus sp. displayed strongest growth on NH₄⁺, glutamine and asparagine, but grew poorly on protein, while Amanita sp. grew well both on mineral sources and on a range of organic sources (e.g. arginine, asparagine, glutamine and protein). In sterile culture, non-mycorrhizal seedlings of Eucalyptus grandis and Eucalyptus maculata grew well on mineral sources of nitrogen, but showed no ability to grow on sources of organic nitrogen other than glutamine. In contrast, mycorrhizal seedlings grew well on a range of organic nitrogen sources. These observations indicate that mycorrhizal associations confer on species of Eucalyptus the ability to broaden their resource base substantially with respect to nitrogen. This ability to utilize organic nitrogen was not directly related to that of the fungal symbiont in isolation. Seedlings mycorrhizal with Pisolithus sp. were able to assimilate sources of nitrogen (in particular histidine and protein) on which the fungus in pure culture appeared to grow weakly. Experiments in which plants were fed ¹⁵N-labelled ammonium were undertaken in order to investigate the influence of mycorrhizal colonization on the pathway of nitrogen metabolism. In roots and shoots of all seedlings, ¹⁵N was incorporated into the amide group of glutamine, and label was also found in the amino groups of glutamine, glutamic acid, γ-aminobutyric acid and alanine. Mycorrhizal colonization appeared to have no effect on the assimilation pathway and metabolism of [¹⁵N]H₄⁺; labelling data were consistent with the operation of the glutamate synthase cycle in plants infected with either Pisolithus sp. (which in isolation assimilates via the glutamate synthase cycle) or Elaphomyces sp. (which assimilates via glutamate dehydrogenase). It is likely that the control of carbon supply to the mycorrhizal fungus from the host may have a profound effect on both the assimilatory pathway and the range of nitrogen sources that can be utilized by the association.     

Comparison of carbohydrate utilization and energy charge in the yellow flag iris (Iris pseudacorus) and garden iris (Iris germanica) under anoxia

Carbohydrate and energy metabolism of the flooding- and anoxia-tolerant Iris pseudacorus and the intolerant Iris germanica rhizomes were investigated under experimental anoxic conditions. Rhizomes of I. pseudacorus and I. Germanica were incubated in the absence of oxygen from 0 to 60 and 16 days, respectively. Amounts of glucose, total reducing sugars and non-reducing sugars (starch, fructan and oligosaccharides) in the rhizomes were measured. Ethanol concentration and adenylate energy charge were determined enzymatically. Glucose content of I. pseudacorus rhizomes decreased gradually during the first 30 days under anoxia and then increased at the same time as adenylate energy charge values started to decline. In I. germanica rhizomes the changes were more dramatic and the time scale was much shorter than in I. pseudacorus but the changes were similar. Non-reducing sugar content of I. pseudacorus rhizomes decreased rapidly during the first 15 days under oxygen deprivation and then increased again, to near starting levels at 35 days. In I. germanica the amount of non-reducing sugars decreased gradually during the anoxic incubation. Under aerobic control conditions, adenylate energy charge (AEC) of I. pseudacorus and I. germanica rhizome tissue was 0.87±0.01 and 0.81±0.01, respectively. In I. pseudacorus AEC remained high until 30 days under anoxia. In contrast, the energy charge of I. germanica rhizome tissue remained above 0.6 for 4 days only. Large amounts of ethanol were found in anoxic rhizome tissues of I. pseudacorus (up to 0.21 M ) and I. germanica (0.06 M ) after 45 days and 8 days, respectively. The results are discussed in relation to flooding tolerance of these species.     

Carbon source utilization of soil extracted microorganisms as a tool to detect the effects of soil supplemented with genetically engineered and non-engineered Corynebacterium glutamicum and a recombinant peptide at the community level

Abstract: Substrate utilization of microbial cells extracted from soil with a 0.85% aqueous sodium chloride solution, was determined to estimate effects on soil microorganisms at the community level with microtiter plates (Biolog GN®) containing 95 different sources of organic carbon. A consistent pattern of utilized substrates was obtained after 24 h of microtiter plate incubation at 28°C. The absorbance values (OD₅₉₀) obtained from a microtiter plate reader after background correction were transformed by using the average absorbance values of oxidized substrates as a threshold to distinguish between well utilized and poorly or non-utilized substrates and thereby reduce variances between replicates. Doubling times of the extracted soil microorganisms in the microtiter plates were tested with 12 substrates and ranged from 1.96 h to 3.23 h, depending on the carbon source. The carbon source utilization assay was used to assess the effects of soil inoculation with Corynebacterium glutamicum with and without a genetically engineered plasmid (pUN1; 6.3 kb), which encoded for the synthesis of the mammalian protease inhibiting peptide, aprotinin. Additionally, aprotinin itself was added at two concentrations to soil samples. An identical decrease in the number of carbon sources utilized, especially carbohydrates, occurred upon soil inoculation with both C. glutamicum strains after inoculation with 10⁶ cells g⁻¹ soil. This effect was only detectable during the first three weeks of incubation, as long as cell numbers of C. glutamicum (pUN1) were above 10⁵ cfu g⁻¹. Soil amendment with aprotinin resulted in utilization of additional substrates, most of them carbohydrates. With 0.1 mg aprotinin g⁻¹ soil this stimulation lasted 2 days and with 10 mg g⁻¹ it lasted for 7 days.     

Plain tales from the grasslands: extraction, value and utilization of biomass in Royal BardiaNational Park, Nepal

Royal Bardia National Park in Southern Nepal contains a number of internationally endangered wildlife species, and a mix of habitats, including areas of grassland known as phantas. The conservation and current use of these areas is briefly described, including the extraction of grass from inside the National Park by local people living in adjacent villages. The products collected fulfil a range of human needs, both practical and ceremonial. The study attempts to quantify the annual offtake in both material and monetary terms, and comments on the sustainability of the practice. Alternative sources of roofing materials are apparently outside the scope of poorer households. The use of these materials has particular significance given the initiation of a Parks and People Project to implement a Buffer Zone around the National Park and effectively to link conservation and development needs.