Vol. 16 No. 11 (2018)

This experiment was carried out on 90 growing pigs (PiDu25 x F1(Landrace x Yorkshire)) weighted25-50kg to evaluate the growth performance and economic efficiency of using diets self-formulated from available feedstuffs. All the pigs were allotted randomly into the control group and two experimental groups with 10 pigs each and three replications. The control group wasfed ad libitumon a commercial compound feed and the experimental groups were fed diets self -mixed from available feedstuffs. The diet for experimental group 2 had less soybean meal, vitamins - minerals premixes, digestive enzymes, but more L-Lysine and DL-Methionine compared to experimental group 1. Results showed that there were no significant differences in growth performance (P>0.05) between pigs fed the commercial feed and those fed diets formulated from available feedstuffs. The growth rate (ADG) and feed conversion ratio (FCR) were 622.60g/day and 2.23kg, respectively,for the control group, 587.60 g/day and 2.39kg for experimental group 1,600.60 g/day and 2.35kg for experimental group 2. The profit was 596.492VND, 608.904 VND and 608.904 VND/pig for the control group, experimental group 1, and experimental group 2, respectively. Thus, using self-mixed feed can ensure increased growth rate and reduced feed costs.

The objective of thisstudy was to determine the optimal growing density and pellet feed protein level applied during commercial snakeheadculture. The experiment was conducted at the Faculty of Fisheries,Vietnam National University of Agriculture (VNUA). Three replicate composite tanks (1m3/tank) were used for each experiment. The first experiment was carried out fromJuly to 30thAugust, 2017 to test the effect of stocking density at 70, 80 and 90 fish/m3(average weight of fish was 8,90± 0,45g/fish) on fish growthusingthe commercial pellet food of 42% protein. Four weeksaftergrowing at stocking density of 70 fish/m3,the survival rate, growing rate, and food conversion ratio (FCR) were99.05± 0.82%,0.33± 0.02 g/dayand1.18± 0.05, respectively.Thevalues of snakehead stocking at 80fish/m3were 99.17± 1.44%,0.40 ± 0.02 g/dayand1.19± 0.02,respectively and at 90 fish/m3were 99.26± 0.64%,0.36± 0.01 g/dayand1.34± 0.03, respectively. There was no significant difference of survival rate, growth rate and FCR of snakehead at three socking density levels after for 4 weeks of growing. The second experiment carried out from Augustto the end of December, 2017to test the effect of three protein levels (30%, 35% and 42% protein in pellet food) onthegrowth and survival rate of snakehead after 4 months of stocking at the growing density of 80 fish/m2(average weight of fish was 36,6± 1,11g/fish). After 4 months of stocking, fish culturedwith 42% of protein level showed the highest growth rate(1.99± 0.03g/day)and survival rate (86.67± 5.05%).At high protein level (42%) snakeheadhadthe fastest growth rate (total length of 1.34mm/day) and weight gain (1.99 g/day), food conversion ratio(1.19) and fish size distribution rate (10.3± 0.5).Research results show that nursing snakehead fish at density of 80 fish/m3, using food with 42% protein content for best growth and survival compared to the remaining stocking density and protein content.

Swollen siphon disease has been considered to be a serious threat to otter clam farmingin Vietnam; however, the cause of the disease has not been clearly understood. In this study, salinity factor (salinity concentrations of 20‰, 25‰, 30‰, 35‰ and 40‰) was selected for evaluating its impact on the survival and outbreak of the swollen siphon disease in in vivoexperiments. The results showed that the otter clams died at salinity level less than or equal to 25‰and higher or equal to 35‰. However, the dead otter clamsdid not show any clinical signs of the swollen siphon disease. The results of the experiment of otter clam injected with diseased siphon’s filtrates and maintained at different salinity conditions ranking from 20‰to 40‰showedthat the salinity was significantly associated withmortality and outbreak of the swollen siphon diseaseshowing clinical signs. This study indicated that the salinity is not the cause of the swollen siphon disease in otter clam but it may be a risk factor that was significantly associated with the outbreak of the disease, particularly high salinitylevel(higher or equal to 35‰).

A study on the effects of lipid levels in formulated feeds for mud crab (Scylla paramamosain) from zoeal 3 stage to instar crablet 1 was conducted in two rearing phases. From zoea 3 to the megalopal stage, the crabs were reared in 120 l composite tanks at salinity of 30‰ and stocking density of 50 Ind./l. From megalopal stage to crablet 1, the crabs were reared in the 50 l plastic tanks at salinity of 26‰ and stocking density of 10 Ind./l. The experiment was set up randomly with five isonitrogenous (53%) diets containing 6%, 8%, 10%, 12% and 14% lipid, and each treatment was done with five replicates. Mud crab larvae were fed experimental feeds combined with Artemianauplii during feeding trial. Results showed that the larval stage index of zoea 3 into zoea 5 stages varied in the range of 4.58-4.96 and the survival of megalopa was 5.45-7.40%, in which the 12% dietary lipid treatment attained highest values and was statistically different (P<0.05) compared to the remaining feeding treatments. Similarly, the highest survival, individual weight and carapace width of crablet 1 were obtained in the dietary lipid level of 12%. These results suggested that formulated diet containing 12% lipid could be considered as the most suitable diet for mud crab from 3 zoeal stage to instar 1 crablet.

Bac Ninh is an industrially developed province and plans to become a city under the central government after 2020, so that the agricultural land has been decreasinggradually. The research objectives were to evaluate the present agricultural land resource and to determine the suitable orientation of agricultural land use for industrialization and urbanization. Results showed that the present agricultural land was classified into 3 subzonesaccording to use: (1) subzone of pure agricultural production, (2) subzone of agricultural production affected by industrialization,and (3) subzone of agricultural production affected by urbanization. Results showed that there were 5 main land use types (LUTs) with 14 main land utilization typesin the province. Commodity oriented land utilization tovegetables, non-rice crops, fruits, rice and flower showedhigh economic efficiency in thesub-zones affected by industrialization and urbanization. The research results serve as basisto select suitableland useand land utilization for agricultural restructuringin order to meet the goalsof the socio-economic development in the process of industrialization and urbanization in BacNinh province.

The study evaluated the current status of land use and the development plan implementation of the Border Gate Economic Zone Dong Dang - Lang Son with the purpose of finding out the disadvantages in land use and in the implementation of planning types that affect the development of the Border Gate Economic Zone. The research methods involvedcollecting secondary data and primary data, processing data by Excel and SPSS, and evaluating the development plan implementation of the Border Gate Economic Zone Dong Dang - Lang Son. Results showed that the current status of non-agricultural land use was extremely low, especially the land use for infrastructural facilities, production - business establishments and industrial zones. By 2017, several land use indicators of functional areas were delayed, so the plan goals were not achieved as initially set. The factors that influenced the plan goal implementation included: policy of attracting investors has been limited and difficulty in fund mobilization and change in land use purpose. According to the evaluation from land users, the plan was not well implemented due to slow process of planning and implementation, and there was no close linkage between the Border Gate Economic Zone development plan and the New Rural Construction plan.

Browning has been a major problem in fresh peach fruitpreservation. The aim of this study wasto identify the optimum concentration and dippingtime inoxalic acidto prevent the browning and prolong theshelf-life of peach fruits.In the first experiment, 3 concentrationsof oxalic acid, viz.1.0,2.0,and 3.0 mM, were testedwith10 minutes dipping. In the second experiment,the dipping time in oxalic acid was 5,10,and 15 minutes in 2.0 mMoxalic acid concentration.Results showed that the peach fruits treated with2.0mM oxalic acid for15 minutes reduced fruit browning and decay and maintained the highest quality after 28days storage in low temperature condition.

The objective of this study was to identìythe most suitable chitosan concentration for postharvest storage of Thach That persimmon (Diospyros kakiThunb.)fruits.Thepersimmonfruitswere firstly exposed toethylene, then treated with different chitosan concentrations of 1%; 1.5%; 2.0% and 2.5%, and finallystored under cold temperature (6-80C). Results showed that chitosan treatment considerably reduced the quality degradation of persimmons during the storage period. Chitosan concentration of 2.0% yieldedlowestweight loss, slowest change infruit color and firmness. Other biochemical parameters such as total acidity, tannin content reduced most slowly while the total sugar content increased most slowly in all samples. Using chitosan concentration of2.0%,Thach Thatpersimmonfruitscan be stored for25 days under cold temperature with good quality.

The designand manufacture fora model of a 3-axis CNC milling machine were made based on theoretical and empirical research. The machine model is usedmainly in the training and scientific research. Using this model, it is possible to fabricate many kinds of details byusingMACH3 software on the computer for control and simulation. The technicalsoftwareis used to produce detailed design drawings and overall model of the machine,followed byfabricatingthe parts and assemblingthem into a complete machine model.

This paper presents initial results of three-dimensional modeling from OpenStreetMap data tof Volunteered Geographic Informationproject. Based on the OpenStreetMapspatial data ofthe centralarea of Vietnam National University of Agriculture, basic data attributeson the height and physical appearance were supplemented to simulate three-dimensional buildingfulfilling the requirements of CityGML LOD2. Three-dimensional model is visually displayedin internet by WebGL F4map.