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71.
72.
Abstract

A study was carried out in sandy clay loam textured soil of Mymensingh, Bangladesh to evaluate weed control efficiency of pre-emergence herbicide pyrazosulfuron-ethyl either alone or in sequential application with post-emergence herbicide in transplanted rainy season rice under non-puddled strip-tilled (NPST) field condition and also to examine the residual effect of those herbicides on germination and growth of the subsequently grown wheat crop. Five treatment combinations of pyrazosulfuron-ethyl were tested against one weedy check and one weed-free check. The study revealed that NPST rice field was mostly infested by grass and sedge weeds and herbicide treatments offered a wide range of control (above 50% to 95%) on all types of weeds. Application of pyrazosulfuron-ethyl followed by (fb) orthosulfamuron fb butachlor plus propanil provided the most effective and economic weed control over two years of the study. Moreover, micro-plot bioassay study claimed germination and growth of subsequently grown wheat were not adversely affected by herbicides that were applied in rice. Therefore, application of pyrazosulfuron-ethyl followed by post-emergence herbicide could be effective and economic to control weeds in NPST rice under rice-wheat system, but proper rate and time of application should strictly be followed.  相似文献   
73.
ABSTRACT

1. The aim of this study was to explore genetic diversity and possible origin of Bangladeshi (BD) native chickens. The complete mtDNA D-loop region was sequenced in 60 chickens representing five populations; naked neck, full feathered, Aseel, Hilly and autosomal dwarf. The 61 reference sequences representing different domestic chicken clades in China, India, Laos, Indonesia, Myanmar, and other Eurasian regions were included. The mtDNA D-loop sequence polymorphism and maternal origin of five BD populations were analysed.

2. A total of 35 polymorphic sites, and 21 haplotypes were detected in 60 mtDNA D-loop sequences. The haplotype and nucleotide diversity of the five populations were 0.921 ± 0.018 and 0.0061 ± 0.0019, respectively. Both mtDNA network and phylogenetic analysis indicated four clades (four haplogroups) in BD populations (21 haplotypes) along with 61 reference haplotypes. Clade E contained the most individuals (20) and haplotypes (11) of BD chickens, followed by clade D (17, 6), clade C (12, 2) and clade F (11, 2), respectively.

3. The higher number of unique haplotypes found in Yunnan, China, suggested that the origin of BD chickens was in this region. The haplotypes from different haplogroups were introduced in Bangladeshi chickens from India, China and Myanmar. The phylogenetic tree showed a close relationship of BD chickens with the clusters from India, China, Myanmar and Laos, and indicated the dispersion of BD chickens from these sources. The phylogenetic information revealed high genetic diversity of BD chickens because of their origin from different lineages with high genetic variation and distance, which was determined from four cluster and neighbour-joining trees.

4. In conclusion, BD populations had high genetic diversity. The mtDNA network profiles and phylogenetic trees showed multiple maternal origins of BD chickens from India, China, Myanmar and Laos.  相似文献   
74.
Hadi  D. A.  Billah  M.  Biswas  K. F.  Rafiqul  Islam 《Water, air, and soil pollution》1999,111(1-4):377-384
Precipitation was collected on an event basis from July 1994 to August 1995 at towns around the capital Dhaka of Bangladesh. The major chemical components were determined by atomic absorption spectrophotometry, UV-Visible spectrophotometry and ion selective electrode method. The concentrations of nitrate and sulphate were found to be below the minimum detection limit of 1.0 mg L- 1; the concentrations of Cl-, Na+, K+, Ca+2, Mg+2 and NH4+ ranged from <1.0–3.03, 0.14–1.70, 0.04–0.37, 0.04–1.30, <0.02–0.20 and <0.10–2.33 mg L-1, respectively. The values of pH and conductivity ranged from 4.80–6.74 and 3.3–37.5 μS cm-1, respectively.  相似文献   
75.
Volatile organic compounds in the ambient air were measured at four locations in Rousse, Bulgaria for a one year period. A gas chromatograph/mass spectrometer equipped with a cryogenic concentrator was used to analyse the air samples. Forty one compounds (aromatic hydrocarbons and halogen-derivatives of aliphatic and aromatic hydrocarbons) were analysed by EPA method TO-14. Aromatic hydrocarbons, benzene, toluene, styrene, isomers of xylene and isomers of trimethyl benzene were the most frequently occurring pollutants. Styrene, isomers of xylene and isomers of trimethyl benzene frequently exceeded the concentration limits. Among the halogen derivatives, the concentration of chloroform was always very high. A concept called ‘degree of pollution’ was proposed to clarify the contribution of each pollutant to the total air-pollution. Suggestions were made on the need to introduce an integral tolerance parameter to describe the total impact on air-pollution.  相似文献   
76.
A feeding trial was conducted to evaluate the effect of fermented soybean meal and scallop by-product blend (3:2) (FP) on the performance of juvenile red sea bream. Five isocaloric diets were prepared by replacing 0% (FP0), 15% (FP15), 30% (FP30), 45% (FP45), and 60% (FP60) fishmeal (FM) protein with FP, respectively. Triplicate groups of fish (initial mean weight 2.83 g) were fed the test diets for 45 days in a flowthrough seawater system. The results demonstrated that growth rates of fish fed FP0, FP15, and FP30 were similar, and significantly higher (P < 0.05) than those of FP45 and FP60. Nutrient utilization was significantly lower in FP60, with no differences found among the other groups. Dietary heavy-metal contents were affected by inclusion of FP, impacting on whole-body heavy-metal contents. In terms of oxidative stress, fish fed the FP30 diet were in the best condition, since this fish group showed the least oxidative-stressed condition as well as the highest tolerance against oxidation. In conclusion, the approach of utilizing this fermented mixture is promising and it could replace at least 30% FM protein in red sea bream diet without negative effects on performance, body composition or health of fish.  相似文献   
77.
It has been reported that the nucleotide sequences of the mitochondrial and nuclear genes of Takifugu pufferfish torafugu T. rubripes and karasu T. chinensis show 99–100% sequence identity, indicating a very close relationship between the two species. To further investigate this genetic relationship, we compared genetic variation at four microsatellite loci and at the mitochondrial control region (CR) (561 bp) between groups of T. rubripes caught at two locations [TrG, caught in the Genkai Sea off Tsushima Island in 2003 (n = 50); TrS, caught in the Suwo Sea off Kita-Kyushu in 2008 (n = 50)] and T. chinensis caught at one location (TcK, caught off the east coast of Korea in 2004; n = 50). Analyses using microsatellite loci showed that genetic diversity index values of the TrG, TrS and TcK groups were 0.9505, 0.9350 and 0.9335, respectively, while values of genetic distance and genetic differentiation between TrG and TcK (0.0543 and 0.0189, respectively) were smaller than those between TrG and TrS (0.0857 and 0.0194, respectively). Analyses using CR for the same specimens showed that genetic distances were consistent with those obtained using microsatellite loci. These results, together with our previous observations, suggest that T. rubripes and T. chinensis are very closely related and possibly can be regarded as the same species.  相似文献   
78.
Analyses of factors affecting dry matter intake of lactating dairy cows   总被引:1,自引:0,他引:1  
An experiment was conducted to analyze feed, climate and animal factors affecting dry matter intake (DMI) in lactating dairy cows. Sixteen lactating Holstein cows, with parity from 1 to 6, were assigned to a feeding trial for 2 years, comprising 31 lactations. The animals were fed Italian ryegrass silage, oat hay, alfalfa hay, beet pulp and three types of concentrate. The data, pooled and classified by stage of lactation, season of lactation and parity were analyzed by stepwise multiple regression to determine the nature and extent of factors affecting DMI. A total of 45 prediction equations for DMI were derived. Energy‐corrected milk yield or milk yield was selected as the primary factor of DMI in all the equations in which the ratio of contribution (R2) varied from 0.26 to 0.67. The dietary concentration of organic cell wall, crude fiber, crude protein, organic b fraction, forage to concentrate ratio, average ambient temperature and temperature–humidity index were selected as the secondary factors affecting DMI for pooled data, late lactation (251–350 days of lactation), summer (June–August), spring (March–May), ≥4th lactation, autumn (September–November) and 3rd lactation, respectively, and improved R2 up to 0.77. Except for an impact of bodyweight in several equations, feed and climatic factors significantly improved prediction equations effectively for data classified in different ways. To estimate DMI accurately in lactating dairy cows, feed and climatic factors should be considered for specific conditions.  相似文献   
79.
Tilapia lake virus (TiLV) is an emerging pathogen in aquaculture, reportedly affecting farmed tilapia in 16 countries across multiple continents. Following an early warning in 2017 that TiLV might be widespread, we executed a surveillance programme on tilapia grow-out farms and hatcheries from 10 districts of Bangladesh in 2017 and 2019. Among farms experiencing unusual mortality, eight out of 11 farms tested positive for TiLV in 2017, and two out of seven tested positive in 2019. Investigation of asymptomatic broodstock collected from 16 tilapia hatcheries revealed that six hatcheries tested positive for TiLV. Representative samples subjected to histopathology confirmed pathognomonic lesions of syncytial hepatitis. We recovered three complete genomes of TiLV from infected fish, one from 2017 and two from 2019. Phylogenetic analyses based on both the concatenated coding sequences of 10 segments and only segment 1 consistently revealed that Bangladeshi TiLV isolates formed a unique cluster within Thai clade, suggesting a close genetic relation. In summary, this study revealed the circulation of TiLV in 10 farms and six hatcheries located in eight districts of Bangladesh. We recommend continuing TiLV-targeted surveillance efforts to identify contaminated sources to minimize the countrywide spread and severity of TiLV infection.  相似文献   
80.
Soft‐shell crab, a newly moulted crab having non‐calcified and hydrated soft exoskeleton, farming has been increasing tremendously in recent years throughout the world due to its high market price and consumer preferences. However, high aggressiveness and cannibalistic behaviour of mud crab limit its culture to an individual chamber system which ultimately makes the soft‐shell mud crab farming space and labour‐intensive. Therefore, the aim of this study was to improve the efficiency of soft‐shell crab production by autotomy of the claw and/or walking legs to reduce the moulting duration and intensify the culture system through double stocking in the existing individual chamber culture system. To achieve our objectives, a series of experiment were conducted at both indoor and on‐farm levels by removing the claw and/or walking legs of Scylla olivacea for two consecutive moulting cycles. Results showed that both claw ablation significantly (p < .01) shortened the moulting duration and increased the carapace width, weight gain, specific growth rate, feeding efficiency and yield parameter compared to the non‐ablated crabs more prominently at 1st moulting than the 2nd moulting in both indoor and on‐farm trials. Ablation of all walking legs while keeping the claw intact did not significantly influence (p > .05) the moulting duration and carapace width, but significantly (p < .01) improved the specific growth rate, weight gain, feeding efficiency and yield parameters at 1st moulting compared to the non‐ablation and unilateral three walking leg ablation groups. However, ablation of all appendages (both claw and walking legs) showed significant (p < .01) improvements of carapace width, weight gain, specific growth rate, feeding efficiency and yield parameters, and shortened the moulting duration up to 23 days from 34 days during 1st moulting and up to 27 days from 40 days at 2nd moulting. The survivals of different autotomized mud crabs were statistically non‐significant (p > .05) to the non‐autotomized crabs in various indoor and on‐farm trials. Besides improving the production performances, ablation of bilateral claw and all appendages allowed to double the stocking density in the existing individual chamber‐based soft‐shell crab farming that enhanced the production about threefold higher than the existing individual chamber‐based culture system. Finally, our results suggest that autotomy could be a promising technology for the commercial farming of soft‐shell mud crab in near future.  相似文献   
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