Meta分析法研究亚麻籽对蛋黄中多不饱和脂肪酸的影响

为研究蛋鸡日粮中添加亚麻籽对蛋黄中多不饱和脂肪酸富集的影响,根据相关标准,采用人工和系统的检索方法检索相关文章,并用荟萃分析(Meta-analysis)的方法分析计算合并标准均数差(SMD)及95%置信区间(95%CI)。通过检索与筛选,共有8篇文章21个试验被纳入,共包括1390个研究对象。Meta分析的结果显示:蛋黄中亚麻酸(ALA)、二十二碳六烯酸(DHA)、亚油酸(LA)、总n-3多不饱和脂肪酸(n-3PUFA)、花生四烯酸(AA)、总n-6多不饱和脂肪酸(n-6PUFA)、n-6PUFA/n-3PUFA的SMD和95%CI分别为17.51(13.34,21.69)、5.39(4.22,6.55)、0.42(-0.39,1.23)、8.86(7.59,10.14)、-1.62(-2.54,-0.70)、-0.44(-0.97,0.08)和-5.22(-6.62,-3.82);混合线性模型的结果显示:DHA和n-3PUFA的异质性来源为亚麻籽添加剂量,蛋黄中ALA、AA、LA和n-6PUFA/n-3PUFA的异质性来源为亚麻籽的添加剂量和蛋鸡产蛋周龄。由分析结果可知,蛋鸡日粮中添加亚麻籽能显著提高蛋黄中的ALA、DHA及n-3PUFA的含量并能显著降低AA和n-6PUFA/n-3PUFA的水平,且富集水平受到亚麻籽添加剂量和蛋鸡产蛋周龄的影响。     

The nature of soil erosion and possible conservation strategies in Ntabelanga area,Eastern Cape Province,South Africa

Soil erosion is a major land degradation problem in South Africa (SA) that has economic, social and environmental implications due to both on-site and off-site effects. High rates of soil erosion by water are causing rapid sedimentation of water bodies, ultimately leading to water crisis in SA. Lots of financial and human resources are channelled towards controlling of soil erosion but unfortunately with little success. The level of soil erosion in a particular area is governed by the site properties. Therefore, it is inappropriate to generalize data on soil erosion at a large-scale spatial context. The literature on soil erosion in SA classifies Eastern Cape Province as a high-erosion-potential area using data collected at a large-scale spatial context. Collecting soil erosion data at a large spatial scale ignores site-specific properties that could influence soil erosion and has resulted in failure of many traditional soil erosion control measures applied in the province. Moreover, scientific principles underlying the processes and mechanisms of soil erosion in highly erodible soils are missing in SA. This review was to find effective soil erosion control measures by having an insight on what happens during soil erosion and how soil erosion occurs in Ntabelanga. The literature suggested that erosion in Ntabelanga could be influenced by both the erosivity and erodibility factors though the erodibility factors being more influential. Soil permeability contrast between the horizons could be influencing the rate and nature of soil erosion. To mitigate the impact of soil erosion in Ntabelanga, efforts should aim to improve the vertical flow capacity in the B horizon. Clay spreading, clay delving, addition of gypsum, deep ploughing and mulching could aid the water permeability problems of the subsurface horizons. However for effective soil management and control option, detailed studies of specific site properties are needed. The generated information can assist in formulating soil erosion policies and erosion control strategies in the Ntabelanga area and SA at large.     

Impact of fresh and aged palm shell biochar on N2O emissions,soil properties,nutrient content and yield of Komatsuna (Brassica rapa var. perviridis) under sandy soil conditions

ABSTRACT

Biochar can reduce N₂O emissions and it can be added to the soil once, whereas fertilizers are often applied every cultivation season. The aging of biochar in soil affects its functioning but it is unclear whether palm shell biochar (PSB) could still mitigate N₂O emissions even when additional basal N fertilizers are applied 1 year after the initial biochar application. We studied the impact of fresh and aged PSB (0%, 6%, 12%, and 18% w/w of dry soil) on N₂O emissions, soil properties, nutrient content and yield of Komatsuna (Brassica rapa var. perviridis) under sandy soil conditions. The aged PSB non-significantly reduced N₂O emissions but significantly offset soil acidification, and maintained a high soil nutrient status. Biochar application with fertilizer significantly increased plant tissue K and Ca content but decreased N, P and Mg content compared to the treatments without biochar. At higher application rates, biochar had negative effects on crop yield but as it aged, the negative effects were offset as a result of the similar variation in plant N uptake. Since seasonal N fertilizer application seems to be inevitable in Komatsuna cultivation, addition of biochar could be a possible way of counteracting the effects of excessive fertilizer use. Further research is needed to assess the feasible biochar application rates for Komatsuna fields in various soil types under field conditions.     

Soil properties influencing erodibility of soils in the Ntabelanga area,Eastern Cape Province,South Africa

Soil erosion has serious off-site impacts caused by increased mobilization of sediment and delivery to water bodies causing siltation and pollution. To evaluate factors influencing soil erodibility at a proposed dam site, 21 soil samples collected were characterized. The soils were analyzed for soil organic carbon (SOC), exchangeable bases, exchangeable acidity, pH, electrical conductivities, mean weight diameter and soil particles’ size distribution. Cation exchange capacity, exchangeable sodium percentage, sodium adsorption ratio, dispersion ratio (DR), clay flocculation index (CFI), clay dispersion ratio (CDR) and Ca:Mg ratio were then calculated. Soil erodibility (K-factor) estimates were determined using SOC content and surface soil properties. Soil loss rates by splashing were determined under rainfall simulations at 360?mmh^?1 rainfall intensity. Soil loss was correlated to the measured chemical and physical soil properties. There were variations in soil form properties and erodibility indices showing influence on soil loss. The average soil erodibility and SOC values were 0.0734?t?MJ^?1?mm^?1 and 0.81%, respectively. SOC decreased with depth and soil loss increased with a decrease in SOC content. SOC significantly influenced soil loss, CDR, CFI and DR (P??1. Addition of organic matter stabilize the soils against erosion.     

An innovation systems perspective on strengthening agricultural education and training in sub-Saharan Africa

This paper examines the role of postsecondary agricultural education and training (AET) in sub-Saharan Africa in the context of the region’s agricultural innovation systems. Specifically, the paper looks at how AET in sub-Saharan Africa can contribute to agricultural development by strengthening innovative capacity, or the ability of individuals and organisations to introduce new products and processes that are socially or economically relevant, particularly with respect to smallholder farmers who represent the largest group of agricultural producers in the region. The paper argues that while AET is conventionally viewed in terms of its role in building human and scientific capital, its also has a vital role to play in building the capacity of organisations and individuals to transmit and adapt new applications of existing information, new products and processes, and new organisational cultures and behaviours. The paper emphasizes the importance of improving AET systems by strengthening the innovative capabilities of AET organisations and professionals; changing organisational cultures, behaviours, and incentives; and building innovation networks and linkages. Specific recommendations in support of this include aligning the mandates of AET organisations with national development aspirations by promoting new educational programs that are more strategically attuned to the different needs of society; inducing change in the cultures of AET organisations through the introduction of educational programs and linkages beyond the formal AET system; and strengthening individual and organisational capacity by improving the incentives to forge stronger linkages between AET and diverse user communities, knowledge sources, and private industry.     

Metabolic differentiation of diploid and triploid European sea bass juveniles

International Aquatic Research - The effects of triploidy were studied on indices of growth and metabolism in juvenile European sea bass. Ploidy affected flesh quality of Dicentrachus labrax, as...     

Comparative study of the effects of heavy metals on embryonic development of zebrafish

This study aimed to investigate the effects of heavy metals, such as copper, zinc, iron, cobalt, chromium, aluminium, manganese and molybdenum, on zebrafish egg hatching rate and the subsequent survival rate of the larvae. Each metal was used in the various concentrations of0.05 mg/L, 50 mg/L and 500 mg/L to detect the threshold limit of tolerance. The study's results showed significant differences in the hatching and survival rate of larvae between the control group and most of the experimental groups when adding heavy metals in various concentrations. The highest concentration (500 mg/L) of the induced heavy metals tested in this study resulted in total egg or larval mortality within 96 hr and significantly lower egg or larval life expectancy. Among the tested metals, zinc and molybdenum had the most significant impact on hatching time, in contrast to iron that did not differentiate the results from the control group. Copper, cobalt, chromium, aluminium and manganese did affect zebrafish eggs depending on their exposure concentrations, which differentiated the results from the control group. Also, the study's findings demonstrate a significant dependence of the hatched egg heart rate on the metal concentration, and in particular, higher concentrations of metals correspond to higher heart rate. Zinc, Molybdenum and copper was proved to be the most toxic heavy metals causing increased hazard rate to mortality up to 96 hr and shorter life expectancy. Finally, skeletal deformities that occasionally observed did not significantly affect the total life expectancy of the hatched eggs.     

Bottom shrimp trawling impacts on species distribution and fishery dynamics; Ungwana Bay fishery Kenya before and after the 2006 trawl ban

The Malindi–Ungwana Bay fishery Kenya is one of the most important marine fisheries of the Western Indian Ocean. There are two fishing grounds: Formosa and Malindi, with a designated 5-nM no-trawl zone offshore. However, the fishery was faced with numerous resource use conflicts and a decline in catches, culminating in a trawl ban in 2006. This study analyses catches and fishery dynamics before and after the 2006 trawl ban. Results show that artisanal landings declined before the ban, but rapidly recovered within 2 years after the ban was imposed. However, shrimp landings in the artisanal fishery remain low. Commercial shrimp landings gradually declined before the ban: ~550 t in 2001 to 250 t in 2006, and the shrimp: fish bycatch ratio was 1:1.5 compared to early reports of 1:7 in 1999. SIMPER analyses shows that 6 and 16 families (groups) accounted for 91.0 and 90.2% of the similarity in catch within the Formosa and Malindi fishing grounds, respectively. Formosa was important for Claridae, Cichlidae and Protopteridae, while Malindi recorded Carangidae, Siganidae, Carcharhinidae and Lethrinidae as the main families. Future studies should therefore embark on analyses of the factors driving the spatio-temporal distributions of the species and assess the impacts of bottom trawling on fishery dynamics before the trawl ban can be lifted.