Effect of varying density and water level on the spawning response of African catfish Clarias gariepinus: Implications for seed production     

Gamal O. El Naggar  George John  Mahmoud A. Rezk  Waheed Elwan  Mohammed Yehia 《Aquaculture (Amsterdam, Netherlands)》2006,261(3):904-907

The development of a reliable methodology for spawning of African catfish, Clarias gariepinus without the use of hormone injections would greatly improve the prospects of aquaculture in Africa. Earlier work has shown that it is possible to produce C. gariepinus fingerlings by subjecting the broodfish to a physical stress of reduced water depth and/or increased temperature. The hypothesis that C. gariepinus could be induced to spawn through a combined physical stress of lowered water level and increased stocking density was tested in concrete tanks. Three water levels (25, 50 and 75 cm) and three stocking densities (2, 4 and 6 pairs of broodfish at a 1:1 sex ratio in each hapa) were tested. Water depth in the tanks and brood fish density in the hapas affected spawning success. The percentage of spawning females was significantly higher when broodfish were stocked at 2 and 4 pairs in each hapa at water levels of 25 cm or 50 cm. There was no significant difference in spawning response between the 25 and 50 cm depths while a significant difference was seen between the 75 cm and both 25 and 50 cm depths. The results indicate optimum levels and densities for enhancing spawning success in C. gariepinus.  相似文献   

Emerging Biomedical Applications of Nano-Chitins and Nano-Chitosans Obtained via Advanced Eco-Friendly Technologies from Marine Resources     

Riccardo A. A. Muzzarelli  Mohamad El Mehtedi  Monica Mattioli-Belmonte 《Marine drugs》2014,12(11):5468-5502

The present review article is intended to direct attention to the technological advances made in the 2010–2014 quinquennium for the isolation and manufacture of nanofibrillar chitin and chitosan. Otherwise called nanocrystals or whiskers, n-chitin and n-chitosan are obtained either by mechanical chitin disassembly and fibrillation optionally assisted by sonication, or by e-spinning of solutions of polysaccharides often accompanied by poly(ethylene oxide) or poly(caprolactone). The biomedical areas where n-chitin may find applications include hemostasis and wound healing, regeneration of tissues such as joints and bones, cell culture, antimicrobial agents, and dermal protection. The biomedical applications of n-chitosan include epithelial tissue regeneration, bone and dental tissue regeneration, as well as protection against bacteria, fungi and viruses. It has been found that the nano size enhances the performances of chitins and chitosans in all cases considered, with no exceptions. Biotechnological approaches will boost the applications of the said safe, eco-friendly and benign nanomaterials not only in these fields, but also for biosensors and in targeted drug delivery areas.  相似文献   

Influence of overplanting paddy rice on irrigation water delivery performance: a case study in the Dakalt branch canal,Nile Delta of Egypt     

Farig  Mohamed  Shimizu  Katsuyuki  El-Kassar  Gamal  Abou El Hassan  Waleed H.  Fujimaki  Haruyuki  Kita  Ichiro  Watanabe  Tsugihiro 《Paddy and Water Environment》2022,20(1):51-60

In the North Nile Delta of Egypt, the impacts of overplanting paddy rice on water delivery performance have not been discussed quantitatively. Further, the amount of water that could have been saved if farmers would follow the planned area is unknown. In this study, water delivery performance was assessed by comparison of actual paddy rice planting and the government’s planned conditions. For both conditions, performance indicators relating to adequacy, equity, and dependability were analyzed across six locations in conjunction with the branch canal water level in 2013 and 2014. Based on the difference between the actual water supply and planned water demand, the amount of water that could have been saved for downstream uses was calculated. The average adequacy for the investigation period was good at one location, fair at 2 locations, and poor at 3 locations in both years. Further, adequacy under both actual and planned conditions was poor in late July at all locations. The planned adequacy and dependability downstream and equity among locations improved compared to the actual condition in both years. Under the condition that paddy rice area is the upper limit planned by the government, about 12.3% and 9.6% of water could be potentially saved in each year. The difference between actual and planned water delivery performance is caused by the branch canal’s low water level. Control of overplanting paddy rice and coordination of water distribution among water user associations would improve stable water level in the canal and, eventually, water delivery performance.

  相似文献   

Efficacy of furunculosis vaccines in turbot, Scophthalmus maximus (L.): evaluation of immersion, oral and injection delivery     

Santos Y  García-Marquez S  Pereira PG  Pazos F  Riaza A  Silva R  El Morabit A  Ubeira FM 《Journal of fish diseases》2005,28(3):165-172

The commercial furunculosis vaccine Aquavac Furovac 5 and an autogenous vaccine, based on the challenge strain, induced immune protection in turbot, Scophthalmus maximus (L.), as shown in challenge tests 120 days post-immunization by injection (relative percentage of survival, RPS = 72-99%). This protective effect lasted for at least 6 months post-immunization at appreciable levels (RPS = 50-52%). Neither the autogenous vaccine nor the commercial vaccine was able to induce significant levels of protection against Aeromonas salmonicida in turbot when administered by immersion. Antibody levels were high or moderate in fish vaccinated by injection with the different vaccines and very low in fish vaccinated by immersion. The field results show that delivering an oral boost after the primary vaccination by injection did not enhance protection of turbot against furunculosis and that water-based (autogenous vaccine) and oil adjuvanted (Alpha Ject 1200) vaccines administered by injection conferred similar levels of protection (RPS > 80%) in turbot.  相似文献   

Frost Hardiness Expression and Characterisation in Wheat at Ear Emergence     

M. Al‐Issawi  H. Z. Rihan  N. El‐Sarkassy  M. P. Fuller 《Journal of Agronomy and Crop Science》2013,199(1):66-74

  相似文献   

Aspartic Proteinase Members Secreted by the Ruminant Placenta: Specificity of Three Radioimmunoassay Systems for the Measurement of Pregnancy-associated Glycoproteins   总被引：1，自引：0，他引：1  

ZS Perényi  O Szenci  PV Drion  H Banga-Mboko  NM Sousa  B El Amiri  JF Beckers 《Reproduction in domestic animals》2002,37(6):324-329

Pregnancy‐associated glycoproteins (PAGs) isolated from the placenta of various ruminant species are enzymatically inactive members of the aspartic proteinase family. The measurement of these proteins in the maternal blood can be a good indicator of the presence of a live embryo. As certain aspartic proteinases are present in biological fluids in physiological and pathological conditions at various concentrations, it was necessary to determine the specificity of three radioimmunoassay (RIA) systems currently used for the detection of PAG molecules. Commercially available members of the aspartic proteinase family like pepsinogen, pepsin, chymosin, rennet, cathepsin D and renin were tested in a wide concentration range (10 ng/ml – 1 mg/ml). Pepsinogen cross‐reacted in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 50 μg/ml and 500 μg/ml concentrations, respectively. In the presence of pepsin, cross‐reaction was observed in RIA 1, RIA 2 and RIA 3 over 1 mg/ml, 500 μg/ml and 1 mg/ml concentrations, respectively. Chymosin and rennet could cross‐react in RIA 2 and RIA 3, while renin and cathepsin D did not decrease the binding of the tracer to antisera more, than that of the minimal detection limit. As the plasma/serum concentrations of the examined aspartic proteinases reported in the literature were outside the concentration range where cross‐reaction was observed, it can be concluded that these RIA systems were specific for the detection of PAGs in biological fluids.  相似文献   

Effect of Genotypes and Plant Maturity on Forage Quality of Certain Forage Legume Species Under Rainfed Conditions     

A. M. Abd El  Moneim  M. A. Khair  S. Rihawi 《Journal of Agronomy and Crop Science》1990,164(2):85-92

Evaluation of plant species for animal feed requires the quantitative and qualitative comparison of different genotypes. Promising lines of annual legumes comprising seven genotypes of vetche ( Vicia spp.) and chicklings ( Lathyrus spp.) were compared for herbage quality. The content of crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) in herbage and pods were measured at different stages of plant maturity. The proportion of the leaves to shoots (leafiness) and in vitro dry matter digestibility (IVDMD) were also determined. As plants matured IVDMD, CP and leafiness decreased and NDF and ADF increased. For all the genotypes maximum digestible dry matter (DDM) and CP yields were more or less attained at 50–100 % podding. Narbon vetch had the highest DDM. The possible uses of the different genotypes as animal feed are discussed based on the partitioning of the DDM and CP yield as plants matured.  相似文献   

Pathogenicity of recent bluetongue virus isolates for sudanese cattle     

A. O. Fayza  M. H. Tag El Din  I. Hajer  E. M. E. Abu El Zein 《Tropical animal health and production》1990,22(3):170-170

  相似文献   

Agronomic Potential of Three Vetches (Vicia spp.) Under Rainfed Conditions   总被引：1，自引：0，他引：1  

A. M. Abd El  Moneim 《Journal of Agronomy and Crop Science》1993,170(2):113-120

The major limiting factor to livestock production in West Asia and North Africa is the inadequate feed supply. The introduction of leguminous forage species into fallow lands represents a means of increasing feed supplies for the rapidly growing livestock population.
Twenty five lines each of common vetch ( Vicia sativa L.) wooly-pod vetch ( Vicia villosa ssp. dasycarpa Ten.), and bitter vetch ( Vicia ervilia L.) were tested over three seasons with contrasting rainfalls and winter temperatures. For each species, seedling vigour, winter growth, cold effect, spring growth, leafiness, herbage yield at 100 % flowering, grain yield, harvest index and aspects of herbage quality were recorded. There were considerable variation among entries with the same species, entries of V. ervilia were the earlier in flowering and maturity, and V. villosa ssp. dasycarpa almost the latest by 45 days. V. sativa , was the most affected by frost whilst both V. villosa ssp. dasycarpa and V. ervilia proved to be cold tolerant.
Although V. villosa ssp. dasycarpa produced high herbage yield in springs its grain yield is low resulting in a low harvest index. Both V. ervilia and V. sativa produced high grain yield with high harvest index. Seed yield was negatively correlated (P < 0.01) with days to flowering and maturity indicating the need of earlier types.
Quality of the herbage in term of digestibility was far lower (46 % IVDMD) in V. villosa ssp. dasycarpa than the other two species (69 % and 72 %).
The possible niches and utilization of each species as animal feed in the prevailing farming systems are discussed.  相似文献   

Selection for Non-Shattering Common Vetch, Vicia sativa L.     

A. M. Abd El  -Moneim 《Plant Breeding》1993,110(2):168-171

Loss of seeds from mature pods is common in Vicia sativa L., an important annual, resown forage legume in West Asia and North Africa. Pod shattering restricts its use as a leguminous forage crop. This paper reports the results of germplasm evaluation for non-shattering pods and of breeding and selection to improve seed retention. Wide variation in pod-shattering exists between common vetch ecotypes collected from different regions. Three wild mutants with almost completely non-shattering pods were identified and isolated for use as a genetic resource in cross breeding programmes. Genetic studies revealed that the non-shattering character in the wild types of common vetch is due to a simple recessive gene, whereas shattering in the cultivated types is due to an allelic dominant pair of genes. Incorporation of the non-shattering gene into agronomically-promising lines was achieved by back-crossing. Lines having an average of 95—97 % non-shattering pods were obtained, as compared to 40—50 % in the original cultivated lines which represents a major agronomic advance in common vetch breeding. The importance of seed retention to the economics of seed production is discussed.  相似文献