利用变温促进罗非鱼生长的研究

在实验室内不同温度条件(恒温28℃、30℃和周期性变温28±4℃、30±4℃)下,分四组饲养罗非鱼,测定其增重、耗氧率、并推算能量同化率和组织生长效率(K_2)。结果表明,变温组均比相应恒温组生长迅速。其中以变温28±4℃组日增重最快,增重百分率最高,其次为变温30±4℃组,恒温28℃组日增重最慢,增重百分率最低。能量同化率和组织生长效率也以变温28±4℃组最高;30±4℃组能量同化率虽较高,但组织生长效率却最低。本文对变温促进罗非鱼生长的机理和其在生产实践中的意义进行了分析与探讨。     

Reproductive characteristics in female Swedish moose (Alces alces), with emphasis on puberty,timing of oestrus,and mating

Background

The moose (Alces alces) is an intensively managed keystone species in Fennoscandia. Several aspects of reproduction in moose have not been fully elucidated, including puberty, timing of mating and oestrus, and the length of the oestrus period. These aspects are relevant for an adaptive management of moose with respect to harvest, population size, demography and environmental conditions. Therefore, an investigation of female moose reproduction was conducted during the moose-hunting period in southern Sweden from 2008 to 2011.

Results

A total of 250 reproductive organs and information on carcass weight and age was collected from four different hunting areas (provinces of Öland, Småland, Södermanland, and Västergötland) in southern Sweden. The results showed that puberty in female moose varied with carcass weight, age, and time of season. The period for oestrous/mating lasted from about mid September to the beginning of November.

Conclusions

The oestrus period (predominantly for heifers) is longer than previously reported and was not finished when the hunting period started. Sampling the uterine cervix to detect spermatozoa was a useful method to determine if mating had occurred. To avoid hunting of moose during oestrus, we suggest that the hunting period should be postponed by at least 14 days in southern Sweden.     

Horizontal transmission dynamics of White spot syndrome virus by cohabitation trials in juvenile Penaeus monodon and P. vannamei

White spot syndrome virus (WSSV), a rod-shaped double-stranded DNA virus, is an infectious agent causing fatal disease in shrimp farming around the globe. Within shrimp populations WSSV is transmitted very fast, however, the modes and dynamics of transmission of this virus are not well understood. In the current study the dynamics of disease transmission of WSSV were investigated in small, closed populations of Penaeus monodon and Penaeus vannamei. Pair cohabitation experiments using PCR as a readout for virus infection were used to estimate transmission parameters for WSSV in these two species. The mortality rate of contact-infected shrimp in P. monodon was higher than the rate in P. vannamei. The transmission rate parameters for WSSV were not different between the two species. The relative contribution of direct and indirect transmission rates of WSSV differed between the two species. For P. vannamei the direct contact transmission rate of WSSV was significantly lower than the indirect environmental transmission rate, but for P. monodon, the opposite was found. The reproduction ratio R₀ for WSSV for these two species of shrimp was estimated to be above one: 2.07 (95%CI 1.53, 2.79) for P. monodon and 1.51 (95%CI 1.12, 2.03) for P. vannamei. The difference in R₀ between the two species is due to a lower host mortality and hence a longer infectious period of WSSV in P. monodon.     

Genetic variation in the ovine uncoupling protein 1 gene: association with carcass traits in New Zealand (NZ) Romney sheep,but no association with growth traits in either NZ Romney or NZ Suffolk sheep

The uncoupling protein 1 (UCP1) plays an important role in the regulation of lipolysis and thermogenesis in adipose tissues. Genetic variation within three regions (the promoter, intron 2 and exon 5) of the ovine UCP1 gene (UCP1) was investigated using polymerase chain reaction‐single‐strand conformational polymorphism (PCR‐SSCP) analyses. These revealed three promoter variants (designated A, B and C) and two intron 2 variants (a and b). The association of this genetic variation with variation in lamb carcass traits and postweaning growth was investigated in New Zealand (NZ) Romney and Suffolk sheep. The presence of B in a lamb's genotype was associated with decreased subcutaneous carcass fat depth (V‐GR) (p = 0.004) and proportion of total lean meat yield of loin meat (p = 0.005), and an increased proportion of total lean meat yield of hind‐leg meat (p = 0.018). In contrast, having two copies of C was associated with increased V‐GR (p < 0.001) and proportion of total lean meat yield of shoulder meat (p = 0.009), and a decreased hind‐leg yield (p = 0.032). No associations were found with postweaning growth. These results suggest that ovine UCP1 is a potential gene marker for carcass traits.     

某猪场猪瘟免疫程序的调整及免疫效果评价

为了更好地预防和控制猪瘟,找出适合四川某猪场的猪瘟免疫程序,笔者根据实际情况对免疫程序进行了调整。然后用ELISA和IHA法对免疫程序调整前后的不同日龄猪血清进行了抗体检测,结果显示:调整前用ELISA法检测到3日龄、25日龄、50日龄、90日龄和120日龄猪只的猪瘟抗体阳性率分别为80%、54.54%、77.78%、80%和95%,用IHA法测得的阳性率分别为100%、63.64%、77.78%、90%和95%;调整后用ELISA法测得的猪瘟抗体阳性率分别为100%、80%、77.27%、77.78%和95%,用正向IHA法测得的抗体阳性率分别为97.73%、94.44%、96.15%、100%和100%。调整前用ELISA和IHA测得的平均阳性率为77.46%、85.28%,调整后则变为86.01%、97.66%,虽然均符合农业部颁布的猪群猪瘟抗体阳性率应不低于70%的标准,但免疫程序调整后的抗体阳性率明显高于调整前,可见调整后的免疫程序更适合于该猪场。     

日本对虾仔虾的温度适宜性实验研究

日本对虾 (Penaeusjaponicus)仔虾体全长 (11 7± 1 0 )mm ,分别置于 2 4,2 0 ,18,16 ,14 5 ,13℃水槽中培养 ,经 10d观察的结果 :仔虾成活率与水温呈负相关 ,依次为 0 12 ,0 2 8,0 39,0 5 3,0 5 3,0 6 0 ;长度增长率与水温呈正相关 ,依次为 0 2 7,0 19,0 12 ,0 0 9,0 0 4,0 0 1。认为仔虾放流海区水温应 >16℃。     

不同保活方法对菲律宾蛤仔保活效果的研究

采用低温、真空、麻醉３种方法对菲律宾蛤仔（下称蛤仔）的保活效果进行了探讨。结果表明，温度是蛤仔保活的重要条件；低温法优于真空和麻醉法；乙醇、盐酸氯丙嗪均对蛤仔有促死作用。     

6种杀菌剂对桑树轮纹病菌的室内毒力测定

在室内培养条件下,采用菌丝生长速率法测定了6种杀菌剂对桑膝节霉的抑制效果。结果显示,6种杀菌剂对桑树轮纹病病原菌桑膝节霉的菌丝生长均有不同程度的抑制作用,其中50％多菌灵、75％百菌清、10％苯醚甲环唑、250 g／L丙环唑、450 g／L咪酰胺和70％甲基硫菌灵的EC50分别为2.45 mg／L、2.51 mg／L、1.68 mg／L、1.31 mg／L、0.46 mg／L和7.99 mg／L。测试药剂中,供试桑树轮纹病菌对450 g／L咪酰胺最为敏感,250 g／L丙环唑次之。450 g／L咪酰胺和250 g／L丙环唑皆可作为防治桑树轮纹病的最佳药剂,用于田间试验。