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71.
Rocío González Jesús Domingo Celada José Manuel Carral Vanesa García María Sáez‐Royuela Álvaro González 《Aquaculture Research》2011,42(9):1385-1392
Recent advances in crayfish feeding have enabled the development of size grading studies from the start of first‐feeding. A 180‐day experiment aimed at intensive rearing of Pacifastacus leniusculus was carried out under controlled conditions, evaluating the effects of size grading at two different periods from the onset of exogenous feeding. Stage 2 juveniles were stocked in fibreglass tanks at a density of 100 m2, and fed a dry diet for salmonids combined with restricted amounts of Artemia cysts. Five groups were tested: no grading, grading at 60 days (large and small size) and grading at 100 days (large and small size). After 6 months, no significant differences were found in the survival among groups (mean: 73.06%). The highest final growth (pooled results from upper and lower classes: 17.39 mm carapace length, 1.43 g weight) was achieved by the crayfish sorted at 60 days, showing significant differences from the ungraded group. Smaller crayfish graded at 60 days grew significantly faster than smaller crayfish graded at 100 days. The food conversion ratio was lower in the graded groups (mean: 2.64), showing significant differences from the ungraded group (3.23). This study shows that size grading allows a better performance and an improved feeding efficiency. 相似文献
72.
ObjectivesCaudal vena cava (CVC) diameter and collapsibility index (CVCD and CVCCI) have been used to assess intravascular volume status (IVS). Maladaptations with progressive degenerative mitral valve disease (DMVD) lead to hypervolemia. We hypothesised that stages of DMVD will affect ultrasonographic CVC variables in dogs without clinically important right heart disease.Animals, materials and methodsThis retrospective study included 79 dogs with DMVD presented to the cardiology department between January 2017 and 2019. Subxiphoid views were used to obtain CVC cineloops. By visual inspection, CVC was subjectively scored as flat, normal or fat. Maximal and minimal CVCD were measured and indexed to aortic diameter (CVCD-max/Ao and CVCD-min/Ao); CVCCI was calculated as (CVCD-max-CVCD-min)/CVCD-max. Fisher's exact and Kruskal–Wallis tests were used to compare CVC variables.ResultsSubjective assessment was associated with American College of Veterinary Internal Medicine (ACVIM) stages (P < 0.001). The proportion of fat CVC was greater in stages C and D. In stage D, CVCD-max/Ao was larger compared with stages B1, B2 and C (P = 0.002, P = 0.002 and P = 0.035, respectively). In stages C and D, CVCD-min/Ao was larger compared with B1 (P = 0.016 and P = 0.001) and B2 (P = 0.002 and P < 0.001. In stages C and D, CVCCI was less than stage B1 (P = 0.016 and P = 0.044) and B2 (P = 0.001 and P = 0.010).ConclusionsIn dogs with DMVD without clinically important right heart disease, CVC variables differ across ACVIM stage. Subjective and objective CVC variables may be used to predict hypervolemia. 相似文献
73.
穗长、穗粒重两性对小区产量直接影响较大;每穗实粒数和每穗不实粒两性状数对小区产量直接影响很小,但通过其他性状对小区产量的间接负影响很大;每穗总粒数对小区产量直接负影响很大,株高通过其他性状对小区产量间接正影响很大。 相似文献
74.
为了从材料细观非均质角度揭示混凝土强度尺寸效应机理,建立了混凝土细观单元等效非均质力学模型,开展了立方体抗拉、抗压强度尺寸效应细观数值模拟研究。研究结果表明:混凝土强度尺寸效应根源于材料细观非均质性,随着模型尺寸的增加,混凝土材料细观单元弹性模量变异系数增大,材料细观非均质性增强,大尺寸模型内部存在更多的低强度单元或缺陷,导致混凝土立方体抗拉、抗压强度降低,极限应变减小,脆性增大;混凝土损伤破坏由少量集中区域,发散扩展形成多条非贯通的裂纹带;数值模拟结果与尺寸效应实验数据相吻合。 相似文献
75.
在散装储藏稻谷的平房仓中比较研究了紫外诱杀灯、瓦楞纸板和取样筛检检测储粮害虫的效果。在夏季近4个月的研究观察中,发现紫外诱杀灯可较取样筛检早近2个月大量检测到锈赤扁谷盗,早约2个月检测到较多的谷蠹,紫外诱杀灯没有诱集到赤拟谷盗。瓦楞纸板诱捕锈赤扁谷盗和赤拟谷盗较取样筛检法所得时间早、数量多,但在检测到谷蠹的时间上要比取样筛检晚4周的时间。随着环境温度的升高,紫外诱杀灯和瓦楞纸板诱集到锈赤扁谷盗和赤拟谷盗的数量都有增加和波动,瓦楞纸板诱集到谷蠹的数量变化很小。 相似文献
76.
Julia Cartelle Anna Pedr Roxana Savin Gustavo A. Slafer 《European Journal of Agronomy》2006,25(4):365-371
Average grain weight is a major yield component contributing to its variation, especially in Mediterranean regions where grain weight is frequently exposed to terminal stresses affecting grain growth. Most of the literature agrees that wheat grain growth is hardly limited by the source. However, no source–sink ratios studies seem to have been conducted in the Mediterranean region to determine to what degree wheat grain growth is actually limited by the source in these particular regions. We conducted two field experiments in Catalonia (north-eastern Spain), where an old cultivar (Anza) and a more recently released one (Soissons) were sown in a range of different nitrogen and water availabilities and sowing dates. This was to analyse the degree of source limitation for grain growth. Sink size was modified by removing half of the spikelets c. 10 days after anthesis, virtually doubling the availability of assimilates per grain effectively growing.
Trimming the spikes did not produce significant changes in grain growth rate or duration of grain filling. Consequently, grain weight did not respond noticeably to the reduction in sink demand and any eventual response has been far from representing a strong competition among grains during grain filling. 相似文献
77.
The measurements of acid detergent fibre in rapeseed by visible and near-infrared spectroscopy 总被引:1,自引:0,他引:1
R. Font B. Wittkop A. G. Badani M. Del Río-Celestino W. Friedt W. Lühs A. De Haro-Bailón 《Plant Breeding》2005,124(4):410-412
Visible and near‐infrared spectroscopy (NIRS) calibrations for acid detergent fibre (ADF) in intact rapeseed (Brassica napus L.) were performed for two different sample volumes (10 ml, 500 seeds approximately; and 1 ml, 50 seeds approximately). The inclusion of brown and yellow‐seeded cultivars in this work has allowed the whole range of ADF currently described in the literature for this character to be covered. Chemometric techniques have been used for developing calibration equations for both procedures when measuring the two different seed sample volumes. On the basis of the coefficient of determination in the cross‐validation (R2cv) obtained for the 10 and 1 ml assays (0.80 and 0.73), and SECV/SEL ratios (2.30 and 2.57), respectively, both equations showed an accuracy sufficient for screening purposes in an ADF range from 6.80 to 13.46% dry wt, which is presented in this work. 相似文献
78.
Identification of QTLs for rice grain size and shape of Iranian cultivars using SSR markers 总被引:6,自引:0,他引:6
Grain size is a main component of rice appearance quality. In this study, we performed the SSR mapping of quantitative trait loci (QTLs) controlling grain size (grain length and breadth) and shape (length/breadth ratio) using an F2 population of a cross between two Iranian cultivars, Domsephid and Gerdeh, comprising of 192 individuals. A linkage map with 88 markers was constructed, which covered 1367.9 cM of the rice genome with an average distance of 18 cM between markers. Interval mapping procedure was used to identify the QTLs controlling three grain traits, and QTLs detected were further confirmed using composite interval mapping. A total of 11 intervals carrying 18 QTLs for three traits were identifed, that included five QTLs for grain length, seven QTLs for grain breadth, and six QTLs for grain shape. A major QTL for grain length was detected on chromosome 3, that explained 19.3% of the phenotypic variation. Two major QTLs for grain breadth were mapped on chromosomes 3 and 8, which explained 34.1% and 20% of the phenotypic variation, respectively. Another two major QTLs were identified for grain shape on chromosomes 3 and 8, which accounted for 27.1% and 20.5% of the phenotypic variance, respectively. The two QTLs that were mapped for grain shape coincided with the major QTLs detected for grain length and grain breadth. Intrestingly, gs2 QTL specific to grain shape was detected on chromosome 2 that explained 15% of the phenotypic variation. 相似文献
79.
80.