Effects of three methionine sources in diets on temporal B0AT1 and ASCT2 mRNA expression in different intestinal segments of cobia,Rachycentron canadum     

Yuanfa He  Shuyan Chi  Beiping Tan  Xiaohui Dong  Qihui Yang  Hongyu Liu  Shuang Zhang 《Journal of the World Aquaculture Society》2021,52(1):171-183

A 4‐week feeding trial was conducted using five groups of hybrid grouper (61.15 ± 0.15 g) to explore the potential effects of three methionine (Met) sources. Five isonitrogenous and isolipidic diets were formulated that included a fishmeal (FM) diet; nonsupplemented (NS) diet; or NS diets with the addition of the L‐methionine (L‐Met), DL‐methionine (DL‐Met), or coated Met (Co‐Met) to obtain the same Met level as the FM diet. Fish were randomly distributed into sea cages (30 fish per cage). Weight gain and specific growth rate in the DL‐Met group and FM group were significantly higher than those in all other groups (p < .05). In the proximal and distal intestines, of the 20 gene and time combinations (10 per gene), there were 14 combinations (70%) in which there were no significant differences in gene expression levels between the FM and DL‐Met groups (p > .05). The main reason for the same growth effect between the DL‐Met and FM groups may be attributed to the synchronized absorption at most time points after feeding, which had similar expression patterns of B⁰AT1 and ASCT2 of the proximal and distal intestines between two groups.  相似文献   

基于"量-质-域-流"四维指标体系的水资源荷载状况评价——以黑河流域三地市为例     

周云哲  粟晓玲  周正弘 《干旱地区农业研究》2019,37(3):215-223

随着社会经济用水不断增加，水资源供需矛盾加剧，水资源系统出现荷载不均衡现象，制约了区域发展，危及生态环境良性循环。本文从水资源系统的负荷需求和承载能力出发，基于“量、质、域、流”四个维度构建水资源荷载均衡评价指标体系，采用指标规范化的正态云模型，评价2015年黑河流域张掖市、酒泉市、阿拉善盟水资源配置方案的荷载均衡状况，并依据负荷与承载能力评分二维坐标，分出低负荷-高承载能力、低负荷-低承载能力、高负荷-高承载能力和高负荷-低承载能力四个分区。评价结果表明：2015年三地水资源荷载状况均为Ⅳ级，张掖市综合评分为3.697，酒泉市为3.657，阿拉善盟为3.901，三地均处于高负荷-低承载能力区域；三地在水质维度上处于低负荷-高承载能力区间，水质维度评分均处于Ⅱ级，酒泉市水质评分优于张掖市，张掖市水质评分优于阿拉善盟；在水量、水域、水流维度上均处于高负荷-低承载能力区间，水量方面三地处于Ⅳ级，张掖市优于酒泉市，酒泉市优于阿拉善盟；水域方面张掖和阿拉善盟评分均处于Ⅴ级，酒泉评分处于Ⅳ级；水流方面三地均处于Ⅴ级。需要采取调控手段在水量、水域、水流方面上进行“增强承载”和“卸荷”。  相似文献   

内蒙古高原紫花苜蓿土壤氮素丰缺指标和推荐施氮量     

米春娇  孙洪仁  王显国  高凯  张玉霞  刘庭玉 《草地学报》2021,29(12):2785-2791

为了给内蒙古高原紫花苜蓿（Medicago sativa L.）测土施氮奠定科学基础，本研究采用“零散实验数据整合法”和“养分平衡-地力差减法”新应用公式，开展了该自然区域紫花苜蓿土壤氮素丰缺指标和推荐施氮量研究。结果表明：内蒙古高原生长第1年紫花苜蓿土壤碱解氮第1~6级丰缺指标为≥48，20~48，8~20，4~8，2~4和<2 mg·kg^-1，土壤全氮第1~5级丰缺指标为≥1.4，0.8~1.4，0.4~0.8，0.2~0.4和<0.2 g·kg^-1，土壤有机质第1~6级丰缺指标为≥17，10~17，6~10，3~6，2~3和<2 g·kg^-1。当紫花苜蓿目标产量9~18 t·hm^-2、氮肥利用率40%时，内蒙古高原紫花苜蓿第1~6级土壤推荐施氮量分别为0，68~135，135~270，203~405，270~540和338~675 kg·hm^-2。  相似文献   

青海省祁连圆柏天然林单木生物量模型构建     

陈志林  李国兴  侯晓巍  李智华  郝家田  谭智渊  向安民 《西北林学院学报》2021,36(1):204-207

利用祁连圆柏整株生物量与生长指标数据，为估算祁连圆柏林的生物量估算提供参考。通过野外调查，共获取了63株祁连圆柏天然林样木生物量与生长指标实测数据。用其中50株样木数据进行回归模拟，用其余的13株样木数据对模型可靠性进行检验，构建器官生物量与生长指标间的回归模型。结果表明，祁连圆柏单木水平下，树干生物量模型的R²_adj为0.96，均方根、模型有效性和残差系数分别为0.50、0.85和0.05；枝条生物量模型的R²_adj为0.897，均方根、模型有效性和残差系数分别为0.69、0.80和-0.66；叶生物量模型的R²_adj为0.61，均方根、模型有效性和残差系数分别为0.54、0.86和0.15；根生物量模型的R²_adj为0.93，均方根、模型有效性和残差系数分别为0.12、0.997 和-0.01。在调查数据范围内构建的模型较好地反映了祁连圆柏生物量与生长指标间的关系，形式简单、使用方便；与实测值相比，树干与叶生物量模拟值偏小，枝和根偏大。  相似文献   

饲粮精料水平和蛋氨酸铬添加剂量对舍饲滩羊生长性能、屠宰性能、肉品质和脂肪沉积的影响     

金亚东  贾柔  周玉香  马青 《动物营养学报》2021,33(2)

本试验旨在探究饲粮精料水平和蛋氨酸铬(Cr-Met)添加剂量对舍饲滩羊生长性能、屠宰性能、肉品质和脂肪沉积的影响。采用2×3双因素试验设计,2个因素分别为饲粮精料水平和Cr-Met添加剂量,其中饲粮精料水平分别设为35%(低精料饲粮,饲粮精粗比为35∶65)和55%(高精料饲粮,饲粮精粗比为55∶45),Cr-Met添加剂量分别设为0、0.75和1.50 g/(d·只)。将60只雄性滩羊羔羊[平均体重为(21±1)kg]随机分配到6个试验组,每组10只。试验期为80 d,其中预试期15 d,正试期65 d。结果显示:1)与低精料饲粮组相比,高精料饲粮组滩羊的平均日增重、屠宰率、背膘厚度、肌内脂肪含量和后腿肉比重显著增加(P<0.05),但料重比与肌肉蒸煮损失、剪切力、pH、亮度(L*)值、红度(a*)值和黄度(b*)值则显著降低(P<0.05)。2)低精料饲粮组滩羊背膘厚度、皮下脂肪厚度、肌内脂肪含量和后腿肉比重随Cr-Met添加剂量的增加而线性降低(P<0.05),但肌肉pH则线性升高(P<0.05)。3)高精料饲粮组滩羊肋肉比重、腰肉比重以及肌肉剪切力和pH随Cr-Met添加剂量的增加而线性升高(P<0.05),而肌内脂肪含量和肌肉a*值则线性降低(P<0.05)。综合本试验测定指标,建议在滩羊养殖中选择精粗比为55∶45的高精料饲粮,Cr-Met的适宜添加剂量为1.50 g/(d·只),且不建议在精粗比为35∶65的低精料饲粮中添加Cr-Met。  相似文献   

黑果枸杞茎叶生长及其生态化学计量特征对灌水施肥的响应   总被引：2，自引：0，他引：2  

李发奎  李金霞  孙小妹  陈年来 《干旱区研究》2020,(2):452-461

在石羊河中游田间条件下,通过灌水和施肥调节黑果枸杞生长。测定不同时期黑果枸杞茎、叶生长量及其化学计量学特征变化,分析器官水平生长速率与化学计量学特征的关系,验证生态化学计量学理论"生长速率假说"。灌水施肥显著促进了茎长、基径和叶片长、宽及叶干重的生长(P<0.05),而茎长、基径、叶面积和叶干重的相对生长速率与对照之间无显著差异。各处理下黑果枸杞新梢C含量及C∶N、C∶P随生育期进程呈增加趋势,而N、P及N∶P呈降低趋势;灌水和施肥处理后茎C含量及C∶N、C∶P、N∶P低于对照,茎N、P含量高于对照。各处理叶片C、N、P含量在生育期内呈降低趋势,而C∶N、C∶P及N∶P呈增加趋势;灌水和施肥后叶片C含量及C∶N、C∶P、N∶P低于对照,叶片N、P含量高于对照。茎C含量及C∶N、C∶P显著高于叶片(P<0.05),而N、P含量及N∶P显著低于叶片(P<0.05)。生长速率假说认为,生物个体的生长速率与体内的N∶P、C∶P具有负相关关系,与N、P含量呈显著的正相关关系。各处理黑果枸杞茎、叶的生长速率与其N、P含量及C∶P、N∶P总体相关性不显著。表明施肥灌水调节下黑果枸杞茎叶生长及化学计量学特征不支持生长速率假说。  相似文献   

栽植密度对不同种源芡实生长的影响     

岳龙  肖凤祥  张永鑫  房文龙  吕迪平  刘明镝  叶雅玲 《防护林科技》2020,(1):18-19,30

对不同栽植密度条件下,不同种源地芡实的生长情况进行了调查研究,结果表明:不同栽植密度间芡实的叶均直径、叶最大直径、果径、果长、果质量、粒数、粒质量均无明显差异,不同栽植密度间产量存在差异;不同种源地间8项物理性状指标均无明显差异;除果长与栽植密度的交互作用对产量无影响外,其余6种性状与栽植密度的交互作用均存在差异,表明交互作用对产量有影响。7种性状与种源地的交互作用下,种源地与产量间的关联不大。  相似文献   

Comparative effect of advanced soy products or corn protein concentrate with porcine meal on growth,body composition,and distal intestine histology of Florida pompano,Trachinotus carolinus     

Romi Novriadi  Elizabeth Spangler  D. Allen Davis 《Journal of the World Aquaculture Society》2019,50(2):433-447

The present study was designed to investigate the effects of diets containing advanced soy products (enzyme‐treated soy and fermented soy) or corn protein concentrate (CPC) in combination with porcine meal (PM) to completely replace poultry byproduct meal (PBM) on growth performance, body composition, and distal intestine histology of Florida pompano, Trachinotus carolinus. Four experimental diets were formulated to be isonitrogenous and isolipidic, to contain 400 g/kg crude protein and 80 g/kg lipid. A reference diet (PBM diet [PBMD]) contained 150 g/kg PBM and 495 g/kg soybean meal (SBM), and three test diets were formulated replacing PBM with 15 g/kg of CPC (CPC diet [CPCD]) or replacing all SBM and PBM with 535 g/kg fermented soy (fermented soybean meal diet [FSBMD]) or 451.3 g/kg enzyme‐treated soy (enzyme‐treated soybean meal diet [ESBMD]). All three test diets were supplemented with 38 g/kg of PM. Diets were fed based on a percentage of bodyweight adjusted after sampling the fish every 2 weeks to triplicate groups of Florida pompano juveniles (mean weight 8.06 ± 0.22 g). After 8 weeks of feeding, fish fed CPCD and ESBMD performed equally well in terms of final body weight, thermal growth coefficient, and percentage weight gain in comparison to fish fed PBMD. In all cases, feeding FSBMD resulted in poor feed conversion and lower feed intake compared to other treatments. Protein retention efficiency, whole‐body proximate composition, phosphorus, sulfur, potassium, magnesium, calcium, sodium, and zinc contents were not significantly influenced by the dietary treatments. The results obtained in the present histological study showed no significant differences in the thickness of serous layer, muscular layer, and submucosal layer of the intestine among treatments. Fish fed CPCD showed a significant widening of the lamina propria with an increase of cellular infiltration and higher presence of goblet cells compared to other dietary treatment. Based on these results, 451 g/kg ESBM or combination of 150 g/kg of CPC and 495 g/kg SBM supplemented with 38 g/kg PM can be utilized to develop a practical diet for juvenile Florida pompano without impacting growth, nutritive parameters, and several distal intestine health parameters.  相似文献   

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China     

Sheng-cai QIANG  Fu-cang ZHANG  Miles Dyck  Yan ZHANG  You-zhen XIANG  Jun-liang FAN 《农业科学学报》2019,18(10):2369-2380

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.  相似文献   

Variability in the performance of juvenile Chinook salmon is explained primarily by when and where they resided in estuarine habitats          下载免费PDF全文

Paul Chittaro  Lyndal Johnson  David Teel  Paul Moran  Sean Sol  Kate Macneale  Richard Zabel 《Ecology of Freshwater Fish》2018,27(3):857-873

Estuarine habitats provide rearing opportunities for the juvenile life stage of anadromous fishes. Because survival is positively correlated with juvenile performance, these estuarine habitats play an important role in population abundance and productivity. To provide information for the recovery of several depressed stocks of Chinook salmon in the Columbia River Basin, we sought to identify the factors that explain variability in performance. Using otolith‐derived estimates of juvenile somatic growth rate as an index of recent performance, we observed a negative nonlinear relationship between growth rate and day of year, and a decreasing and increasing trend of growth rate over the 8 years of this study and distance from the river mouth respectively. Using a generalised linear modelling approach, we found that variability in juvenile somatic growth rate was best explained by where and when individuals were collected, their body size, contaminant loads, stock of origin, and whether a fish was hatchery produced or unmarked. Lastly, we argue that a considerable improvement to the growth rate of juveniles in estuarine habitats is physiologically possible. The results of this 8‐year study provide a baseline of the performance of juvenile Chinook salmon to evaluate habitat restoration programs and to compare against future anthropogenic conditions.  相似文献