The significance of African vegetables in ensuring food security for South Africa’s rural poor     

Tim G. B. Hart 《Agriculture and Human Values》2011,28(3):321-333

Technologies and services provided to resource-poor farmers need to be relevant and compatible with the context in which they operate. This paper examines the contribution of extension services to the food security of resource-poor farmers in a rural village in South Africa. It considers these in terms of the local context and the production of African vegetables in household food plots. A mixture of participatory, qualitative and quantitative research tools, including a household survey, is used to argue that local production practices contribute more to food security requirements than the extension services. This is because of the ability of African vegetables to grow relatively well in semi-arid areas where other exotic plants do not, their ability to provide at least two foodstuffs during their life cycle, and the ability of either the fruit or the leaves, or both, to be dried and stored for consumption in the winter months. These crops can make a significant contribution in terms of household food security, but a number of social and agroecological factors are constraining their production and placing their availability under threat. Despite this, the extension services remain focused on certain activities within vegetable garden projects, even when these are not meeting their proposed purpose—food security by means of cash-crop production. The paper concludes that social and agroecological constraints could be improved if the extension services were changed. This could include the use of context specific and low-cost technologies to ensure that these crops are able to increase their contribution to household food security for resource-poor farmers in semi-arid areas.  相似文献   

Efficacy of a glycoprotein DNA vaccine against viral haemorrhagic septicaemia (VHS) in Pacific herring, Clupea pallasii Valenciennes     

LM Hart  N Lorenzen  SE Lapatra  CA Grady  SE Roon  J O'Reilly  JL Gregg  PK Hershberger 《Journal of fish diseases》2012,35(10):775-779

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氨基酸分析仪法快速测定玉米籽粒中赖氨酸含量   总被引：2，自引：0，他引：2  

齐建双 《中国农学通报》2014,30(30):199-202

以9 个高赖氨酸玉米和2 个普通玉米杂交种籽粒样品为材料,用日立L-8900 型全自动氨基酸分析仪对高赖氨酸玉米和普通玉米籽粒中赖氨酸含量进行定量测定。了解全自动氨基酸分析仪的检测效果是否可以很好的比较普通玉米与高赖氨酸玉米籽粒中的赖氨酸含量。结果表明高赖氨酸玉米籽粒赖氨酸含量介于0.34%~0.42%之间,普通玉米赖氨酸含量介于0.24%~0.25%,存在显著差异。日立L-8900型全自动氨基酸分析仪法测定玉米籽粒中赖氨酸含量与其它传统方法相比较,该方法快速、简便、灵敏度高、重现性好、样品需求量少,可以较好的在玉米育种中应用。  相似文献   

Effect of whole-crop pea (Pisum sativum L.) silages differing in condensed tannin content as a substitute for grass silage and soybean meal on the performance, metabolism, and carcass characteristics of lambs     

Hart KJ  Sinclair LA  Wilkinson RG  Huntington JA 《Journal of animal science》2011,89(11):3663-3676

Two experiments were conducted to investigate the effect of inclusion of whole-crop pea (WCP) silages, differing in condensed tannin content, as a substitute for grass silage (GS) and soybean meal on lamb metabolism, performance, plasma metabolites, digestibility, and carcass characteristics. In both experiments lambs were offered either solely GS or a 50:50 mix on a DM basis of GS with either low-tannin (LTPS) or high-tannin (HTPS) pea silage ad libitum. Each forage mix was fed with either 400 g/d of low-protein (LP) concentrate or 400 g/d of LP with an additional 200 g/d of pelletized soybean meal (HP), resulting in 6 dietary treatments. Experiment 1 examined the effects of the diets on metabolism, digestibility, and N balance using 6 lambs in 4 periods of 21 d in an incomplete crossover design. Experiment 2 used 48 lambs and examined the effects of the diets on ADG, plasma metabolites, and carcass characteristics over 56 d. Both experiments were analyzed using a 3 × 2 factorial arrangement of treatments. In Exp. 1, lambs offered the LTPS diets had a greater (P < 0.05) digestibility of DM and OM than those offered the GS diets. Lambs offered the WCP silages had an increased (P < 0.05) N intake, N output, and digestibility of GE compared with those offered GS. Mean N digestibility was greatest (P < 0.05) in lambs offered LTPS. Lambs offered HP diets had increased (P < 0.001) digestibility of DM, OM, GE and N, and N- intake, output, retention, and digestibility compared with those offered the LP diets. In Exp. 2, there was no effect (P > 0.05) of forage type on intake, slaughter BW, or feed conversion efficiency (FCE). However, lambs offered the LTPS had a greater (P < 0.05) ADG than those offered the GS diets. Feeding diets containing HP increased (P < 0.001) total DMI, slaughter BW, ADG, and FCE. Lambs offered the WCP had a greater (P < 0.05) plasma β-hydroxybutyrate and urea concentration compared with those offered the GS diets. Feeding lambs HP diets increased (P < 0.05) plasma urea and total protein. Forage mix had no effect (P > 0.05) on carcass composition except for fat depth, which was greater (P < 0.05) in lambs offered WCP silage. Diets containing the HP increased (P < 0.05) carcass weight, hind leg circumference, chop dimensions, and kidney weight. It was concluded that lambs offered LTPS performed better than those offered GS and that LTPS has a concentrate sparing effect. Additionally, the increased tannin concentration in HTPS did not increase performance over lambs offered either GS or LTPS.  相似文献   

Modeling soil metabolic processes using isotopologue pairs of position-specific C-labeled glucose and pyruvate     

Paul Dijkstra  Jacob J. Dalder  Stephen C. Hart  George W. Koch  Egbert Schwartz 《Soil biology & biochemistry》2011,43(9):1848-1857

Most organic carbon (C) in soils eventually turns into CO₂ after passing through microbial metabolic pathways, while providing cells with energy and biosynthetic precursors. Therefore, detailed insight into these metabolic processes may help elucidate mechanisms of soil C cycling processes. Here, we describe a modeling approach to quantify the C flux through metabolic pathways by adding 1-¹³C and 2,3-¹³C pyruvate and 1-¹³C and U-¹³C glucose as metabolic tracers to intact soil microbial communities. The model calculates, assuming steady-state conditions and glucose as the only substrate, the reaction rates through glycolysis, Krebs cycle, pentose phosphate pathway, anaplerotic activity through pyruvate carboxylase, and various biosynthesis reactions. The model assumes a known and constant microbial proportional precursor demand, estimated from literature data. The model is parameterized with experimentally determined ratios of ¹³CO₂ production from pyruvate and glucose isotopologue pairs. Model sensitivity analysis shows that metabolic flux patterns are especially responsive to changes in experimentally determined ¹³CO₂ ratios from pyruvate and glucose. Calculated fluxes are far less sensitive to assumptions concerning microbial chemical and community composition. The calculated metabolic flux pattern for a young volcanic soil indicates significant pentose phosphate pathway activity in excess of pentose precursor demand and significant anaplerotic activity. These C flux patterns can be used to calculate C use efficiency, energy production and consumption for growth and maintenance purposes, substrate consumption, nitrogen demand, oxygen consumption, and microbial C isotope composition. The metabolic labeling and modeling methods may improve our ability to study the biochemistry and ecophysiology of intact and undisturbed soil microbial communities.  相似文献   

The Impact of Wastewater Treatment Effluent on the Biogeochemistry of the Enoree River,South Carolina,During Drought Conditions     

C. Brannon Andersen  Gregory P. Lewis  Marylea Hart  John Pugh 《Water, air, and soil pollution》2014,225(5):1-21

Drought conditions should magnify the effect of wastewater treatment plant (WWTP) effluent on river biogeochemistry. This study examined the impact of WWTP effluent on the Enoree River in the piedmont region of South Carolina during a period of significant drought. The Enoree River lacks impoundments, upstream agricultural runoff, and significant industrial point sources, so the single most important human influence on river chemistry is WWTP effluent. Water samples were collected from 28 locations on the Enoree River, 13 of its tributaries, and the effluent of four WWTPs. Effluent from the WWTP furthest upstream increased the salinity of the river and temporal variation and concentrations of most ions, especially nitrate, phosphate, sulfate, sodium, and chloride. The upstream WWTP set the downstream chemical composition of the river, with increasing proportions of chloride, sodium, and sulfate and decreasing proportions of dissolved silicon and bicarbonate. Downstream WWTPs had little or no impact on the chemical composition of the river. Mixing model results show that dilution was the dominant process of the downstream decrease in solute concentrations, but in-channel uptake mechanisms also contributed to declines in concentrations of nitrate, phosphate, and carbon dioxide. Despite dilution and uptake, the chemical signature of WWTP effluent was still evident 135 km downstream. These results lead to a better understanding of the effects of WWTP effluent on the biogeochemistry of rivers.  相似文献   

Effects of bovine somatotropin and ruminally undegraded protein on feed intake, live weight gain, and mohair production by yearling Angora wethers.     

J J Davis  T Sahlu  R Puchala  M J Herselman  S P Hart  E N Escobar  S W Coleman  J P McCann  A L Goetsch 《Journal of animal science》1999,77(5):1029-1036

Yearling Angora wethers (n = 24; 24+/-1.0 kg BW) were used in an experiment with a 2 x 2 factorial arrangement of treatments to investigate effects of bovine somatotropin (bST) treatment and dietary level of ruminally undegraded protein on DMI, ADG, and mohair production. Untreated casein (UC) or casein treated with formaldehyde (TC) was included at 7% DM of a diet containing 11% CP and 46% concentrate. A slow-release bST form was administered weekly to deliver 0 (Control) or 100 microg/ (kg BW.d) of bST. Plasma concentrations of bST and IGF-I were increased (P < .05) during the 7-d period following bST injection. Ruminal fluid ammonia N concentration was lower (P < .01) for TC than for UC before feeding (6.6 vs 7.5 mg/dL) and 4 h later (8.2 vs 12.2 mg/dL), and total VFA concentration was lower (P < .01) for TC than for UC. Treatment with bST decreased (P = .08) DMI with UC (1.15 vs .91 kg/d) and increased (P = .08) DMI with TC (.95 vs 1.06 kg/d). Formaldehyde treatment of casein increased ADG (65, 74, 55, and 91 g/d; P = .03) and clean fleece production (P < .01; 14.1, 17.3, 15.0, and 18.4 g/d for UC-Control, TC-Control, UC-bST, and TC-bST, respectively), with no effect of bST during the 8-wk period of treatment or for the 8 wk thereafter (P > .10). In conclusion, with yearling Angora wethers, bST does not seem useful to enhance mohair production and may not alter effects of dietary level of ruminally undegradable protein on mohair production.  相似文献   

A study of feline upper respiratory tract disease with reference to prevalence and risk factors for infection with feline calicivirus and feline herpesvirus.     

S H Binns  S Dawson  A J Speakman  L E Cuevas  C A Hart  C J Gaskell  K L Morgan  R M Gaskell 《Journal of Feline Medicine and Surgery》2000,2(3):123-133

A cross-sectional survey of a convenience sample of cats was carried out to determine the prevalence of and risk factors for respiratory tract disease, feline calicivirus (FCV) infection and feline herpesvirus (FHV) infection. Seven hundred and forty cats were studied; samples for isolation of FCV and FHV were obtained from 622 (84%). Data on individual cat and household variables were obtained by questionnaire for each cat and analysed using univariable and logistic regression analysis. Thirty-eight percent (282/740) of cats surveyed had respiratory tract disease. Eighteen of 24 predictor variables were found to be significantly (P<0.05) associated with the presence of respiratory tract disease in a cat on univariable analysis. Following logistic regression, several factors retained significance including isolation of FCV and FHV, younger cats (4-11 months of age) and multiple cat households. A negative association was found with breeding catteries and other types of household in comparison with rescue catteries. Overall, feline calicivirus was isolated from 162/622 (26%) of cats sampled; 33% of the cats with respiratory tract disease were FCV positive compared to 21% of healthy cats. Variables significantly associated with FCV isolation on logistic regression were the presence of respiratory tract disease and contact with dogs with and without respiratory tract disease. Feline herpesvirus was isolated from 30/622 (5%) of all cats sampled; 11% of cats with respiratory tract disease were FHV positive compared to 1% of healthy cats. Variables significantly associated with FHV isolation on univariable analysis included age, gender, and the presence of respiratory tract disease. Vaccination showed a negative association. Logistic regression analysis of the data for FHV was limited by the sample size and the low prevalence of FHV.  相似文献   

Normal haematological values of axis deer (Axis axis), Père David's deer (Elaphurus davidianus) and barasingha (Cervus duvauceli)     

C M Hawkey  M G Hart 《Research in veterinary science》1985,39(2):247-248

Full blood counts and fibrinogen estimations were carried out on a number of clinically normal adult axis deer (Axis axis), Père David's deer (Elaphus davidianus) and barasingha (Cervus duvauceli). Apart from the finding of higher total red cell counts and a lower mean red cell volume in axis deer than in Père David's deer and barasingha, there was little interspecies variation. Some individual Père David's deer showed eosinophilia, thought to be associated with subclinical intestinal nematode infestation. The findings should provide a useful reference base for monitoring health in these species.  相似文献   

Suspected drug‐induced infiltrative lung disease culminating in acute respiratory failure in a dog treated with cytarabine and prednisone          下载免费PDF全文

Samantha K. Hart BVMS  MS  DACVS  DACVECC  Lori Waddell  DVM DACVECC 《Journal of Veterinary Emergency and Critical Care》2016,26(6):844-850

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