Efficacy for a New Live Attenuated Salmonella Enteritidis Vaccine Candidate to Reduce Internal Egg Contamination

To evaluate the efficacy of a novel attenuated Salmonella Enteritidis (△lon△cpxR) vaccine candidate (JOL919), chickens were immunized through oral and intramuscular routes to reduce egg contamination against S. Enteritidis challenge. Birds were orally immunized with JOL919 on the first day of life and were subsequently boosted in the 6th and 16th weeks through oral (group B) or intramuscular (group C) route, while control birds were unimmunized (group A). The chickens of all groups were challenged intravenously with the virulent S. Enteritidis strain in the 24th week. The immunized groups B and C showed significantly higher plasma IgG and intestinal secretory IgA levels as compared to those of the control group. The lymphocyte proliferation response and CD45⁺CD3⁺ T‐cell number in the peripheral blood of the groups B and C were significantly increased. In addition, the egg contamination rates were significantly lower in the group B (0%, 10.7% and 0%) and the group C (3.6%, 14.3% and 3.6%) as compared to the group A (28.6%, 42.8% and 28.6%) in the 1st, 2nd and 3rd weeks post‐challenge. All animals in the groups B and C showed lower organ lesion scores in the liver and spleen and lower bacterial counts in the liver, spleen and ovary at the 3rd week post‐challenge. These results indicate that this vaccine candidate can be an efficient tool for prevention of Salmonella infections by inducing protective humoral and cellular immune responses. In addition, this vaccine did not prevent egg contamination, but did appear to reduce incidence. Booster immunizations, especially via oral administration route, showed an efficient protection against internal egg contamination with S. Enteritidis.     

Seasonal shift in spawning of Atlantic cod (Gadus morhua L.) by photoperiod manipulation: egg quality in relation to temperature and intensive larval rearing

Commercial intensive fry production of Atlantic cod will be dependent on production of viable eggs independent of season. This can only be done by manipulation of maturation by photoperiod, but little is known about potential effects on egg characteristics and larval viability. In two cod broodstocks, maturation was successfully advanced or delayed 6 months compared with normal spawning season (March–April) by manipulation of photoperiod. The advanced broodstock spawned both in spring and autumn the same year. In two of the spawning tanks during autumn, ambient temperature was reduced after reaching 13.7°C during the first half of the spawning period. Egg quality and viability were monitored, and several egg batches were incubated, hatched and start‐fed for examination of growth and survival. Temperatures above 9.6°C resulted in significant reductions in fertilization and normal egg development. Concurrently, fractions of dead and unfertilized eggs increased with elevated temperature. Actual relative fecundity was not affected by temperature. Egg characteristics improved when temperature was controlled and lowered below 9.6°C. Occurrence of irregular spawners suggests that handling of broodstock fish should be avoided during maturation and spawning. Cod larvae originating from eggs of the advanced or delayed broodstocks were successfully reared beyond metamorphosis. Survival was 9.0–46.6% and 29.3% in green and clear water respectively. Survival correlated with both initial and average feeding conditions, but growth rate did not correlate with either of survival and feeding conditions. Specific growth rates (8.3–13.6% day⁻¹) is comparable with other intensive rearing trials with cod, but were lower than reported from nature‐like systems.     

Possible mechanisms underlying fluctuations in the Far Eastern sardine population inferred from time series of two biological traits

A cycle of fluctuation in the Far Eastern sardine, Sardinops sagax, population is accompanied by an abrupt drop and recovery of fish size and lipid content of parent fish, which may reflect a phase variation from coastal to oceanic and its reverse. The cycle begins with the survival success of a smaller number of eggs produced by high-quality parents, which is triggered by a global climate change (density-independent process), and finally ends in the survival failure resulting from an overexpansion of an enormous number of fish produced by low-quality parents (density-dependent process).     

Effects of temperature and salinity on the reproductive success of Arctic charr, Salvelinus alpinus (L.): egg composition, milt characteristics and fry survival

The effects of temperature and salinity on the reproductive success of Arctic charr, Salvelinus alpinus (L.), were examined by holding broodstock under the following conditions from mid‐May until the end of September: fresh water at ambient temperature (NFW; 8–16 °C); salt water (25–30‰) at ambient temperature (NSW; 4–10 °C); fresh water cooled to saltwater temperature (CFW; 4–10 °C); or salt water heated to freshwater temperature (HSW; 8–16 °C). The relative fecundity of females was similar among groups (P > 0.05; 2685 ± 706 eggs), but females reared in NSW produced significantly larger eggs than those raised in NFW. The highest spermatozoa concentrations were found in milt from males reared in SW and the highest milt glucose concentration was from males kept under coldwater conditions (CFW, NSW). Eggs from NSW and HSW females contained more proteins than eggs produced by NFW females. Eggs from NSW females also contained 40% more lipids than was observed in the other groups, and total energy content was 27% higher in eggs from NSW females than in eggs from NFW females. When FW was cooled (CFW), females produced eggs with protein contents similar to those in NSW, but the lipid contents remained 30% lower. Finally, the best survival at the eyed stage and at hatch was observed in families produced by NSW broodstock. Intermediate values were observed in families from NFW or CFW while the highest mortality occurred in families from the HSW group. All these results suggest that, under the experimental conditions used in the present study, coastal seawater conditions offered the most favourable summer rearing conditions with respect to the reproductive success of Arctic charr.     

皮蛋加工辅料的作用及新工艺配方研究

研究了皮蛋加工中使用的红茶末、氯化钠、生石灰3种辅料的作用.结果表明,红茶末能提高料液中金属离子的浓度,控制蛋内碱度的变化,其作用可以被杜仲碎末替代;氯化钠没有实际作用,所以加工中可以用氯化钾代替,从而提高皮蛋的钾钠比;生石灰没有实际作用,可不用.试验得到最佳料液比是每100 mL水加入氢氧化钠5 g、氯化钾1 g、五水硫酸铜0.3 g、杜仲(碎末)9g,浸泡期为30 d,后熟期为30d,所得皮蛋与传统用红茶末加工的皮蛋无感官和味道差异,还使皮蛋产生了一定的保健功效.     

咸鸭蛋蛋清微滤脱盐工艺研究

采用稀释结合匀浆的方法以降低咸鸭蛋蛋清的粘度,再利用微滤法对其进行脱盐淡化处理.以咸鸭蛋蛋清液粘度为指标,通过单因素试验、正交试验确定最优前处理工艺,结果表明：咸鸭蛋蛋清脱盐淡化前处理最优工艺条件为：料液比1∶4,匀浆时间120 s,匀浆转速12000 r/min,在此条件下,咸鸭蛋蛋清混合液粘度为9 mPa·s,粒度为24 μm.以微滤脱盐率为指标,通过单因素试验、正交试验确定最优处理工艺,结果表明：微滤压差0.12 NPa,微滤4次,微滤时间120 min,在此条件下,咸鸭蛋蛋清脱盐率达92.43％,蛋白质截留率78.5％.     

高速打蛋机蛋清蛋黄分离中基于计算机视觉的散黄蛋识别研究

链式打蛋机用于鸡蛋蛋清蛋黄的快速分离,针对鸡蛋散黄无法分离的问题,提出了基于彩色图像处理的对散黄蛋进行自动识别的方法.利用机器视觉装置采集链式打蛋机生产线上的图像,从每一幅原始图像中根据坐标裁剪出目标区域260×240像素的子图像,选定蛋黄的黄色区域作为样本点,在RGB空间利用欧几里得距离对图像进行分割,找出蛋清斗中蛋黄的区域,计算蛋黄区域的面积,通过蛋黄面积大小进行判断鸡蛋是否散黄,达到对散黄蛋进行识别的目的,本方法对散黄蛋识别的正确率达到96.67％;用图像识别的方法可快速判断鸡蛋散黄情况,可以将本方法应用到生产实践中代替人眼进行识别.     

Evaluation of ovum storage techniques for reproductive studies of fishes

Abstract– We compared dry masses of mature oocytes and ripe eggs from Etheostoma lynceum and Etheostoma caeruleum that were stored in varying concentrations of either formalin or isopropyl alcohol. In comparison to 10% formalin, alcohol significantly reduced the weights of both mature oocytes and ripe eggs, with 25% isopropyl alcohol resulting in much smaller reductions than 50% isopropanol. Three percent formalin resulted in smaller decreases in the masses of oocytes and eggs than the alcohol treatments, and not all comparisons with 10% formalin were significantly different. We recommend fixing specimens and storing them and gametic cells removed from them in 10% formalin. In cases where specimens or eggs in alcohol must be used in addition to material in formalin, correction factors (to formalin standard) should be developed, but the correction should not be made uncritically due to the varying effects alcohol may have among samples.     

水文气象因子变化对自然海区对虾早期生命的影响

利用渤海湾对虾卵子、幼体和幼虾调查资料,引用相对成活倍数的概念,并选择与对虾早期生命有因果关系的水文气象因子,通过相关分析方法分析讨论了水文气象因子变化对对虾早期生命的影响。结果表明,６￣７月盐差、５月中旬产卵场现场水温和黄河径流对对虾早期生命影响较明显。