Replacement of Dietary Fish Oil with Vegetable Oils Improves the Growth and Flesh Quality of Large Yellow Croaker(Larmichthys crocea)

We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fish meal and 6.4% menhaden fish oil; whereas the other 3 experimental diets were formulated by replacing the fish oil with 50% soybean oil(SO50), 100% soybean oil(SO100) and 100% palm oil(PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages(3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent satiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100(P<0.05), and crude lipid contents of ventral muscle and viscera were significantly lower in fish fed FO than in those fed the other 3 diets(P<0.05). No significant differences in condition factor, viscerosomatic index, hepatosomatic index, gutted yield and colorimetric values of fish among the dietary treatments were observed(P>0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and water loss from fresh fillets(1 d, 4℃)(P<0.05). Similarly, thiobarbituric acid reactive substance(TBARS) values of fillets under different storage conditions(1 d, 4℃; 7 d, 4℃; 4 weeks,-20℃; 8 weeks,-20℃) decreased significantly after partial or complete replacement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties(liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.

Total Replacement of Fish Oil with Vegetable Oils in the Diet of Juvenile Jade Perch Scortum barcoo Reared in Recirculating Aquaculture Systems

To determine the replacement of fish oil with vegetable oils in the diet of juvenile Jade perch Scortum barcoo, four feeds with each a different oil （fish, sunflower, linseed and a mixture of 75% canola and 25% linseed oil）, were fed to Jade perch reared in recirculating aquaculture systems （RAS）. The trial lasted for 10 weeks and the fatty acid （FA） profile of both feed and fish muscle tissue were examined. There was no difference in growth, feed conversion rate （FCR） and mortality. The fish grew from 10 g to 110 g with a FCR of 1.25 and 0 mortality. The FA profile of the fish muscle tissue reflected the FA profile of the feed. The flesh of the fish that were fed the linseed oil diet, were extremely high in omega-3 （n-3） polyunsaturated FA （n-3 PUFA） with 3.75% of wet weight. This is one of the highest concentrations of n-3 PUFA ever recorded in fish flesh. In a finishing feeding test, the remaining vegetable oil fed fish were fed the fish oil diet for another two weeks immediately after the 10 weeks trial, to check for a possible recovery of n-3 highly unsaturated fatty acids （HUFA）. The wash out rate of FA towards n-3 HUFA in the muscle tissue was about 25% over this two weeks period.

A pressure drop model of post-fracturing shut-in considering the effect of fracturing-fluid imbibition and oil replacement

Since the production regime of shut-in after fracturing is generally adopted for wells in shale oil reservoir,a shut-in pressure drop model coupling wellbore-fracture network-reservoir oil-water two-phase flow has been proposed.The model takes into account the effects of wellbore afterflow,fracture network channeling,and matrix imbibition and oil exchange after stop of pumping.The simulated log-log curve of pressure-drop derivative by the model presents W-shape,reflecting the oil-water displacement law between wellbore,fracture network and matrix,and is divided into eight main control flow stages according to the soaking time.In the initial stage of pressure drop,the afterflow dominates;in the early stage,the pressure drop is controlled by the cross-flow and leakoff of the fracture system,and the fractures close gradually;in the middle stage of pressure drop,matrix imbibition and oil exchange take dominance,and the fracturing fluid loss basically balances with oil replaced from matrix;the late stage of pressure drop is the reservoir boundary control stage,and the leakoff rate of fracturing-fluid and oil exchange rate decrease synchronously till zero.Finally,the fracture network parameters such as half-length of main fracture,main fracture conductivity and secondary fracture density were inversed by fitting the pressure drop data of five wells in Jimsar shale oil reservoir,and the water imbibition volume of matrix and the oil replacement volume in fracture were calculated by this model.The study results provide a theoretical basis for comprehensively evaluating the fracturing effect of shale oil hori-zontal wells and understanding the oil-water exchange law of shale reservoir after fracturing.

Analysis of the Strategies of the 'Replacement of Coal and Oil' with Natural Gas in Sichuan Province

Sichuan Province boasts rich clean energy such as natural gas and hydroelectricity. In order to realize the blueprint of a beautiful China, it is both necessary and feasible for Sichuan Province to ＂replace coal and oil＂ with natural gas. Based on the actual situation of Sichuan Province, through research and investigation, rational thinking and summarization, this paper analyzes the current demand for energy supply in Sichuan, defines the development goals and ideas concerning Sichuan＇s ＇replacement of coal and oil＂ with natural gas, examines the action plan related to such replacement and puts forward relevant policies and suggestions.

Approach and potential of replacing oil and natural gas with coal in China

China’s fossil energy is characterized by an abundance of coal and a relative lack of oil and natural gas.Developing a strategy in which coal can replace oil and natural gas is,therefore,a necessary and practical approach to easing the excessive external dependence on oil and natural gas.Based on the perspective of energy security,this paper proposes a technical framework for defining the substitution of oil and natural gas with coal in China.In this framework,three substitution classifications and 11 industrialized technical routes are reviewed.Then,three scenarios(namely,the cautious scenario,baseline scenario,and positive scenario)are developed to estimate the potential of this strategy for 2020 and 2030.The results indicate that oil and natural gas replaced by coal will reach 67 to 81 Mt and 8.7 to 14.3 Gm^3 in 2020 and reach 93 to 138 Mt and 32.3 to 47.3 Gm^3 in 2030,respectively.By implementing this strategy,China’s external dependence on oil,natural gas,and primary energy is expected to be curbed at approximately 70%,40%,and 20%by 2030,respectively.This paper also demonstrates how coal,as a substitute for oil and natural gas,can contribute to carbon and pollution reduction and economic cost savings.It suggests a new direction for the development of the global coal industry and provides a crucial reference for energy transformation in China and other countries with similar energy situations.