中国-波利维亚经济发展的参照案例

波利维亚是一个具有中等人类发展指数的发展中国家,贫困程度大约为60%.其主要的经济活动包括农业、林业、渔业和矿业.制造品主要有纺织品、服装、冶炼金属以及成品油.     

Functional roles of xylanase enhancing intestinal health and growth performance of nursery pigs by reducing the digesta viscosity and modulating the mucosa-associated microbiota in the jejunum

This study was conducted to investigate the functional roles of an endo-β-1,4-xylanase on the intestinal health and growth performance of nursery pigs. A total of 60 pigs (21 d old, 6.9 ± 0.8 kg body weight [BW]) were allotted based on a randomized complete block design with sex and initial BW as blocks. Dietary treatments had nutrients meeting the requirements with increasing levels of endo-β-1,4-xylanase (0, 220, 440, 880, 1,760 xylanase unit [XU] per kg feed) and fed to pigs in three phases (phases 1, 2, and 3 for 10, 14, and 14 d, respectively). Titanium dioxide (0.4%) was added to the phase 3 diets as an indigestible marker. On day 38, all pigs were euthanized to collect ileal digesta to measure apparent ileal digestibility (AID), jejunal digesta to measure viscosity, and jejunal mucosa to evaluate intestinal health. Data were analyzed using the MIXED procedure for polynomial contrasts and the NLMIXED procedure for broken line analysis of SAS. Increasing xylanase in the nursery diets reduced (linear, P < 0.05) the digesta viscosity in the jejunum. Increasing xylanase tended to reduce the relative abundance of Cupriavidus (P = 0.073) and Megasphaera (P = 0.063); tended to increase the relative abundance of Succinivibrio (P = 0.076) and Pseudomonas (P = 0.060); and had a quadratic effect (P < 0.05) on the relative abundance of Acinetobacter (maximum: 2.01% at 867 XU per kg feed). Xylanase from 0 to 1,087 XU per kg feed reduced (P < 0.05) jejunal malondialdehyde. Xylanase from 0 to 1,475 XU per kg feed increased (P < 0.05) the AID of neutral detergent fiber. Increasing xylanase increased (P < 0.05) the AID of ether extract and tended to increase (P = 0.058) the AID of crude protein. Increasing xylanase did not affect growth performance on overall period, whereas xylanase from 0 to 736 XU per kg feed increased (P < 0.05) average daily gain (ADG) during days 31 to 38. In conclusion, xylanase supplementation showed benefits on intestinal health by reducing digesta viscosity, the relative abundance of potentially harmful bacteria, and the oxidative stress in the jejunal mucosa, collectively enhancing intestinal morphology and the AID of nutrients. Xylanase supplementation at a range of 750 to 1,500 XU per kg feed provided benefits associated with reduced oxidative stress, increased nutrient digestibility, resulting in potential improvement on growth performance of nursery pigs by increasing the average daily feed intake and moderately improving the ADG throughout the last week of feeding.     

Influence of agroforestry practices on the structure and spatiality of shea trees (Vitellaria paradoxa C.F. Gaertn.) in central-west Burkina Faso

This article examines the role of humans in shaping a shea tree (Vitellaria paradoxa C.F. Gaertn.) population in Prata, central-west Burkina Faso. Four management regimes or land uses were considered: fields cultivated by indigenous Gurunsi farmers, fields cultivated by migrant Moose farmers, fallows, and bush lands. The structure of the shea population differed between Gurunsi and Moose fields and between these fields and fallow and bush lands. The size class distribution of V. paradoxa in fallows and bush lands was skewed towards the lower classes and the slope of the distributions was negative and significant, indicating the occurrence of recruitment. In comparison, Gurunsi fields carried young and mature trees with 95 % of individuals in the 15.5–90 cm range, whereas Moose fields carried no specimen with dbh <16.5 cm. The slope of the size class distribution was slightly negative for Gurunsi fields and slightly positive for Moose fields, but non significant in both cases. Vitellaria paradoxa densities did not significantly differ between Gurunsi (35 stems/ha) and Moose (26 stems/ha) fields, but were higher in fallows (172 stems/ha) and in the bush (161 stems/ha) than in cultivated fields. Nearest neighbour distances were progressively greater from uncultivated fields to Gurunsi and finally Moose fields, whereas shea trees were increasingly aggregated from Moose to Gurunsi fields to fallows and bush lands. In Prata, shea tree management is thus associated with ethnicity and/or with a host/migrant status that confers different farm sizes and levels of tenure security to farming households. Gurunsi and Moose farmers cited productivity, spacing and shading effects as the main factors influencing their decision to conserve specific shea trees in their fields. Results signal favorable prospects for V. paradoxa regeneration in Prata’s fallows and bush lands and to a lesser extent in Gurunsi fields.     

A quantitative trait locus on chromosome 5B controls resistance of <Emphasis Type="Italic">Triticum turgidum</Emphasis> (L.) var. <Emphasis Type="Italic">diccocoides</Emphasis> to Stagonospora nodorum blotch

Stagonospora nodorum blotch (SNB) is an important foliar disease of durum wheat (Triticum turgidum var. durum) worldwide. The combined effects of SNB and tan spot, considered as components of the leaf spotting disease complex, result in significant damage to wheat production in the northern Great Plains of North America. The main objective of this study was the genetic analysis of resistance to SNB caused by Phaeosphaeria nodorum in tetraploid wheat, and its association with tan spot caused by Pyrenophora tritici-repentis race 2. The 133 recombinant inbred chromosome lines (RICL) developed from the cross LDN/LDN(Dic-5B) were evaluated for SNB reaction at the seedling stage under greenhouse conditions. Molecular markers were used to map a quantitative trait locus (QTL) on chromosome 5B, explaining 37.6% of the phenotypic variation in SNB reaction. The location of the QTL was 8.8 cM distal to the tsn1 locus coding for resistance to P. tritici-repentis race 2. The presence of genes for resistance to both SNB and tan spot in close proximity in tetraploid wheat and the identification of molecular markers linked to these genes or QTLs will be useful for incorporating resistance to these diseases in wheat breeding programs.     

Timing of Nitrogen Application to Enhance Corn (Zea mays, L.) Yields in a Desert Climate

Experiments were conducted in two consecutive years to investigate the response of two corn (Zea mays, L.) cultivars, Eperon and Challenger, to timing of N fertilizer in a desert climate. Fertilizer was applied three times (at planting, 6 weeks after sowing (6WAS) and at 9WAS) to give a seasonal total of 180 kg N ha^-1 The N treatments were N_ooo (control), N_LOH (60 kg N ha^-1 at planting, none at 6WAS and 120 kg N ha^-1 at 9WAS), N_LLL (60 kg N ha^-1 at sowing, 6WAS and at 9WAS) and N_LOH, (60 kgN ha^-1 at planting, 120 kg N ha^-1 at 6WAS and none at 9WAS). Generally, N ha^-1 was associated with the highest grain and dry matter yields. Plants in N treated plots had significantly larger number of leaves and ear leaf N contents than the control at mid-silk. High ear leaf N was associated with high leaf area index and dry matter yield. Based on these results, it would appear that the application of 60 kg N ha^-1 at planting, followed by 120 kg N ha at 6WAS (N_LHO) is the most suitable for enhancing corn yields in the desert climate.     

Pancreatic Degenerative Atrophy and Chronic Pancreatitis in Dogs a Comparative Study of 60 Cases

During the years 1977–1980 60 cases of non-neoplastic chronic exocrine pancreatic disease in dogs were investigated clinically and pathologically. The disorders were clinically divided into pancreatic degenerative atrophy (PDA) and chronic pancreatitis. Fifty dogs had PDA and 45 of them were German shepherd dogs. The PDA cases formed both clinically and pathologically a homogeneous group except for 1 case. All the dogs had maldigestion and protease activity was absent from the faeces. General inanition and highly atrophic pancreas were the most typical macroscopic findings. Histologically the exocrine pancreas contained atypical acinar tissue and mononuclear cell infiltrations. Five of the dogs died spontaneously, 4 of them had intestinal torsion and 1 had paralytic ileus.There were 10 dogs with chronic pancreatitis. This group was rather heterogeneous both clinically and pathologically. The pancreas was slightly enlarged and the consistency was firm. The histologic picture was one of fibrous tissue proliferation and inflammatory cell infiltrations in the interstitium. The dogs nutritional state as well as faecal protease activity were normal.     

Tissue-culture propagation of banana

The possibility of clonal propagation of banana through tissue culture was explored. Shoot tips isolated from the rhizomes were found to be suitable material for plantlet production in vitro. Excised shoot tips with the youngest leaves produced only one plantlet. However, shoot tips with several older sheathing leaf bases enclosing the axilary buds regenerated multiple plantlets. Individual shootlets, when separated and sub-cultured, produced a new crop of multiple shoots. The plantlets obtained from both types of explants have been successfully transplanted to soil and grown to maturity.     

Intake,performance, and efficiency of nutrient utilization in Saanen goat kids fed diets containing calcium salts of fatty acids

Tropical Animal Health and Production - The objective of this study was to evaluate the effect of feeding Saanen goat kids with calcium salts of fatty acids (CSFA) in diet, on intake, performance,...