[ Objective ] The aim of the study was to explore the resistance development of deltamethrin through selection of dettamethrin resistant strain of wild silkworm （ Bombyx Mandarina）, thus providing the basis for scie...[ Objective ] The aim of the study was to explore the resistance development of deltamethrin through selection of dettamethrin resistant strain of wild silkworm （ Bombyx Mandarina）, thus providing the basis for scientific pesticide application and resistance management. [ Method] The wild silkworms collected from three different regions were reared indoors, and the sensitivity of their parents to deltamethrin was detected by topical application. The larvae in each generation were treated with deltamethdn in median lethal dose or so by.topical application. The mortality of larva was analyzed for the establishment of toxicity regression equations and the calculation of the multiple or increased multiple of deltamethdn resistance.[Result] After the Qidong Bornbyx Mandarina （YQD） fed with mulberry leaves were selected for three generations indoors, the multiple of deltamethdn resistance of F, was 14.26, 1.2 times as great as that of Fo ; after the Bombyx Mandarina from mulberry garden of Soochow University （YSD） fed with mulberry leaves were selected for three generations indoors, the multiple of deltamethrin resistance of F4 was 16.48, 1.9 times as great as that of Fo ; after the Wujiang Bombyx Mandarina （YWJ） fed with artificial diets were selected for three generations indoors during six generations, the multiple of deltamethrin resistance of Fe was 18.67, 1.2 times as great as that of Fo. [ Conclusioa] With the selection in same dose, the resistance multiple of YSD increases more rapidly than that of YQD; under double selection of artificial diets and insecticide, the resistance multiple of YWJ increases more slowly than that of YQD.展开更多
Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was ...Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was verifi ed by monitoring larvae and juveniles of knownage.The results revealed that lapilli and sagittae developed before hatching,and the first otolith increment was identified at 2 days post hatching in both.The shape of lapilli was relatively stable during development compared with that of sagittae;however,growth of four sagittae and lapilli areas was consistent,but the posterior area grew faster than the anterior area and the ventral surface grew faster than the dorsal surface.Similarly,the sum length of the radius of the anterior and posterior areas on sagittae and lapilli were linearly and binomially related to total fish length,respectively.Moreover,daily deposition rates were validated by monitoring knownage larvae and juveniles.The increase in lapilli width was 1.88±0.080 0μm at the ninth increment,which reached a maximum and the decreased gradually toward the otolith edge,whereas that of sagittae increased more slowly.These results illustrate the developmental biology of S.davidi,which will aid in population conservation and fish stock management.展开更多
Starvation has important effects on early development of fish. It determines the survival and growth of fish larvae,and plays an important role in the dynamics of fish population and fisheries recruitment. In this rev...Starvation has important effects on early development of fish. It determines the survival and growth of fish larvae,and plays an important role in the dynamics of fish population and fisheries recruitment. In this review,we discuss the current studies about the effects of starvation on growth and development of fish larval stage. The goals of this review are to understand some adaptive mechanisms and ecological countermeasures of starved fish larvae and to provide the scientific guideline for exploring early life history processes,evaluating the nutrition condition and growth of larval fish,protecting fish resource and breeding fish larvae.展开更多
The effects of sex, housing temperature, feed ingredients and slaughter weight on carcass and meat quality were investigated. A total of three-way crossbred （LWD） 100 pigs were used in a completely randomized design...The effects of sex, housing temperature, feed ingredients and slaughter weight on carcass and meat quality were investigated. A total of three-way crossbred （LWD） 100 pigs were used in a completely randomized design to study the influence of rearing condition, in the growing finishing period, the initial weight, finial weight, live weight, total feeding days, daily weight gain and total feed consumptions affected carcass traits and meat qualities. In conclusion, the rearing condition will give a significant effect on pork and carcass quality so that they can be controlled by changing the raising situation.展开更多
A study was conducted to determine the productive and reproductive performance of dairy cattle reared in major milk production area of Chitwan and Nawalparasi districts of Nepal, as well as determining the existing br...A study was conducted to determine the productive and reproductive performance of dairy cattle reared in major milk production area of Chitwan and Nawalparasi districts of Nepal, as well as determining the existing breeding scenario of cattle farming followed by the farmers. Five years （2008-2012） of data of 728 animals send to data management section of Animal Breeding Division under Dairy Cattle Improvement Program （DCIP） were reviewed and analyzed. Similarly, monthly data recording of 380 animals taken from May 2012 to April 2013 were used to find out information on reproductive performance. Average milk yield, fat percentage and protein percentage of cattle were observed 2,841 ± 84.9 kg, 4.43% ± 0.66% and 3.33% ± 0.17%, respectively, and the effect of genotype on these traits were found significant （P 〈 0.001, P 〈 0.001 and P 〈 0.01, respectively）. Similarly, calving interval, post-partum estrus, post-partum conception, age at maturity and age at first calving were observed 422.8 ± 7.71, 108.9 ± 6.13, 149.93 ± 27.04, 498.5 ±16.32 and 816.0 ±17.41 d, respectively. Age at maturity and age at first calving was significantly affected by genotype （P 〈 0.01 and P 〈 0.05, respectively）. In addition, average number of insemination per conception was observed 1.38 in survey household. Breeding system of cattle followed by the farmers were found satisfactory in the survey household, but needs gradual improvement. It was observed that offspring of cross between Jersey and Holstein performed better in terms of productive and reproductive performance in farmer managed condition of Nepal. Therefore, rotational crossing of Jersey and Holstein for maintaining blood level between 50% and 75% of either breed is the best choice for farmers.展开更多
文摘[ Objective ] The aim of the study was to explore the resistance development of deltamethrin through selection of dettamethrin resistant strain of wild silkworm （ Bombyx Mandarina）, thus providing the basis for scientific pesticide application and resistance management. [ Method] The wild silkworms collected from three different regions were reared indoors, and the sensitivity of their parents to deltamethrin was detected by topical application. The larvae in each generation were treated with deltamethdn in median lethal dose or so by.topical application. The mortality of larva was analyzed for the establishment of toxicity regression equations and the calculation of the multiple or increased multiple of deltamethdn resistance.[Result] After the Qidong Bornbyx Mandarina （YQD） fed with mulberry leaves were selected for three generations indoors, the multiple of deltamethdn resistance of F, was 14.26, 1.2 times as great as that of Fo ; after the Bombyx Mandarina from mulberry garden of Soochow University （YSD） fed with mulberry leaves were selected for three generations indoors, the multiple of deltamethrin resistance of F4 was 16.48, 1.9 times as great as that of Fo ; after the Wujiang Bombyx Mandarina （YWJ） fed with artificial diets were selected for three generations indoors during six generations, the multiple of deltamethrin resistance of Fe was 18.67, 1.2 times as great as that of Fo. [ Conclusioa] With the selection in same dose, the resistance multiple of YSD increases more rapidly than that of YQD; under double selection of artificial diets and insecticide, the resistance multiple of YWJ increases more slowly than that of YQD.
基金Supported by the Double Branch Plan of Sichuan Agricultural University(Nos.03571421,03571779)
文摘Laboratory-reared Schizothorax davidi larvae and juveniles were examined to assess the formation and characteristics of David’s schizothoracin otoliths.Otolith development was observed and their formation period was verifi ed by monitoring larvae and juveniles of knownage.The results revealed that lapilli and sagittae developed before hatching,and the first otolith increment was identified at 2 days post hatching in both.The shape of lapilli was relatively stable during development compared with that of sagittae;however,growth of four sagittae and lapilli areas was consistent,but the posterior area grew faster than the anterior area and the ventral surface grew faster than the dorsal surface.Similarly,the sum length of the radius of the anterior and posterior areas on sagittae and lapilli were linearly and binomially related to total fish length,respectively.Moreover,daily deposition rates were validated by monitoring knownage larvae and juveniles.The increase in lapilli width was 1.88±0.080 0μm at the ninth increment,which reached a maximum and the decreased gradually toward the otolith edge,whereas that of sagittae increased more slowly.These results illustrate the developmental biology of S.davidi,which will aid in population conservation and fish stock management.
文摘Starvation has important effects on early development of fish. It determines the survival and growth of fish larvae,and plays an important role in the dynamics of fish population and fisheries recruitment. In this review,we discuss the current studies about the effects of starvation on growth and development of fish larval stage. The goals of this review are to understand some adaptive mechanisms and ecological countermeasures of starved fish larvae and to provide the scientific guideline for exploring early life history processes,evaluating the nutrition condition and growth of larval fish,protecting fish resource and breeding fish larvae.
文摘The effects of sex, housing temperature, feed ingredients and slaughter weight on carcass and meat quality were investigated. A total of three-way crossbred （LWD） 100 pigs were used in a completely randomized design to study the influence of rearing condition, in the growing finishing period, the initial weight, finial weight, live weight, total feeding days, daily weight gain and total feed consumptions affected carcass traits and meat qualities. In conclusion, the rearing condition will give a significant effect on pork and carcass quality so that they can be controlled by changing the raising situation.
文摘A study was conducted to determine the productive and reproductive performance of dairy cattle reared in major milk production area of Chitwan and Nawalparasi districts of Nepal, as well as determining the existing breeding scenario of cattle farming followed by the farmers. Five years （2008-2012） of data of 728 animals send to data management section of Animal Breeding Division under Dairy Cattle Improvement Program （DCIP） were reviewed and analyzed. Similarly, monthly data recording of 380 animals taken from May 2012 to April 2013 were used to find out information on reproductive performance. Average milk yield, fat percentage and protein percentage of cattle were observed 2,841 ± 84.9 kg, 4.43% ± 0.66% and 3.33% ± 0.17%, respectively, and the effect of genotype on these traits were found significant （P 〈 0.001, P 〈 0.001 and P 〈 0.01, respectively）. Similarly, calving interval, post-partum estrus, post-partum conception, age at maturity and age at first calving were observed 422.8 ± 7.71, 108.9 ± 6.13, 149.93 ± 27.04, 498.5 ±16.32 and 816.0 ±17.41 d, respectively. Age at maturity and age at first calving was significantly affected by genotype （P 〈 0.01 and P 〈 0.05, respectively）. In addition, average number of insemination per conception was observed 1.38 in survey household. Breeding system of cattle followed by the farmers were found satisfactory in the survey household, but needs gradual improvement. It was observed that offspring of cross between Jersey and Holstein performed better in terms of productive and reproductive performance in farmer managed condition of Nepal. Therefore, rotational crossing of Jersey and Holstein for maintaining blood level between 50% and 75% of either breed is the best choice for farmers.
