The Effect of Initial Stocking Density on Growth and Survival of Pike-perch Fingerlings Reared under Intensive Conditions

Pond-nursed pike-perch (Sander lucioperca) fry were trained to artificial diet and reared under controlled conditions maintained in aquaria using three stocking densities (1.25, 1.66 and 2.08 g/l). Two replicates per treatment were applied. The survival during the 4-week period of the experiment ranged from 44.2 to 49.6%. The majority of the losses were caused by cannibalism; only 8–14% could be attributed to natural mortality. Both cannibalism and natural mortality occurred in the first 2–3 weeks of rearing. The differences in the rate of cannibalism were independent of the stocking density. Natural mortality decreased with increasing density, consequently the highest survival was observed under the highest stocking density. Stocking density did not significantly influence growth, feed consumption and feed conversion ratio of the pike-perch fingerlings (p < 0.05).     

冰雹对美国玉米带作物产量影响模拟

为了尝试计算机模拟方法能否成为制定作物保险保费的辅助性工具,该研究运用计算机模拟模型预测冰雹对作物产量的影响。通过对现有EPIC(综合气候因素的环境政策)模型增加冰雹天气模块,即冰雹事件发生概率的数学模型,模拟冰雹对作物产量的影响。除此之外,该研究还模拟了干旱和霜冻等天气因素对美国Iowa,Illinoi和Indiana等3个玉米带州作物产量的影响。首先介绍数据来源及处理方法,讨论建立冰雹模拟模型过程以及对模型进行有效性检验;然后运用统计分析方法对模型模拟结果与实际观察结果进行比较,检验模型模拟结果的准确性。结果表明EPIC模型可以达到95%甚至更高的产量预测的准确性;同时,冰雹灾害模拟结果也可以达到一个较为合理的准确性(R2>0.7)。这些结果表明本研究所建立的增加冰雹模块的EPIC模型可以作为一个较为可靠的冰雹引起的作物产量损失的预测方法.该模型可以用来模拟冰雹事件发生的概率以及其对各种作物产量造成的损失。     

Comparison between pre‐ and postnatal acid‐base status of calves and their perinatal mortality

Summary

The acid‐base status of 58 calves (all in normal anterior presentation) was determined from venous blood samples before the onset of traction and immediately after vaginal delivery.

Calves were assigned to one of three groups according to their blood pH value: group 1 ‐ normal, pH >7.2; group 2 ‐ acidotic, pH 7.2 to 7.0; group 3 ‐ severely acidotic, pH < 7.0. Before the onset of traction (i.e. during the 30 minutes following the appearance and rupture of the membranes), 43 calves (74.1%) had normal acid‐base values, 14 (24.1%) had slight acidosis, and only 1 (1.7%) had severe acidosis. At birth the three groups of calves showed the following distribution: 23 (39.7%) were normal, 29 (50%) had slight acidosis, and 6 (10.3%) had severe acidosis.

Seven calves (12. 1%) died during birth or within 48 hours after birth; 2 were normal shortly before birth, 4 were acidotic shortly before birth, and 1 was severely acidotic even before the onset of traction. Traction was significantly longer for cows that delivered severely acidotic calves compared to cows in the other two groups.     

Urethral infection of male monkeys by Mycoplasma hominis and Ureaplasma urealyticum

Seven male Macaca nemestrina, eight male Macaca mulatta and three male Papio hamadrias were infected with M. hominis or U. urealyticum separately or simultaneously into the urethra. Animals of the first two species exhibited moderate infection and mild clinical urethritis characterized by increased number of PMNL in the urethral discharge and colonization and lymphocytic infiltration of the mucous membrane of the urethra and urinary bladder. Animals of the third species proved to be less sensitive.     

Simultaneous fluorometric determination of vitamins A and E in serum

A simple fluorometric method suitable for serial determinations is reported for simultaneous determination of vitamins A and E in serum. The solvents are pretreated chemically and by distillation. After shaking with ascorbic acid in ethanol, the vitamins are extracted from the serum samples with petroleum ether. The extract is used for the determination. The sensitivity of the method is 20 micrograms/100 ml for vitamin A and 0.04 micrograms/ml for vitamin E. Recovery rates are between 87 and 106%. The method was tested on a total of 160 serum samples of healthy animals belonging to 8 different species. The results showed good agreement with the so-called reference values published in the literature.     

Occurrence and pathology of Sinergasilus lieni (Copepoda: Ergasilidae), a parasite of the silver carp and bighead, in Hungarian ponds

Sinergasilus lieni Yin, 1949, a well-known and pathogenic parasitic copepod in China and Russia, has been detected in Hungarian carp farms for the first time. The parasite infected the third-year generation of silver carp (Hypophthalmichthys molitrix) and bighead (Aristichthys nobilis). The gills of the infected fish specimens showed severe pathological changes. At the attachment sites of female copepods clubbing and fusing of the gill filaments were observed and in some parts of the pale or whitish hemibranchia deep indentations were recorded in places where the tips of the damaged filaments had broken off. Silver carp and bighead were infected at a similar rate, having 8 to 27 copepods attached to the end of the clubbed filaments or the proliferated epithelium of 2 to 10 fused filaments. In histological sections the head part of the parasite was found in a deep cavity of the proliferated epithelium, piercing its antennae deep into the tissues. Only the end of the filaments showed changes. In this part the proliferated epithelium was infiltrated by eosinophilic granular cells. In the central and basal parts of the hemibranchia the original structure of the filaments was preserved with intact secondary lamellae.     

Survival of mouse blastocysts after low-temperature preservation under high pressure

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21 degrees C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0 degrees C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.     

The change of nursing for oestrus induction (biostimulation): Effect of contact between rabbit doe and its young

This study focused on the effects on subsequent reproductive traits of females and development of the current litter as a result of different contact between the rabbit doe and its progeny when a temporary doe–litter separation was used for biostimulation. Immediately after parturition and adjusting to eight young per litter, multiparous Pannon White rabbit does (n = 400) were divided into five groups based on parity, doe condition, and weight of litter and the kits. Rabbits in the control group (C) nursed freely up to weaning at 35 days of age. In the group following local farm practice (F) using a metal-plate for separation, females nursed once a day (8 am to 9 am) for the first 14 days of lactation and freely afterwards. In three biostimulation groups, there was a change from free to once a day nursing before insemination (i.e. controlled nursing at 8, 9 and 10 days) provided with a wire-mesh separation (BW: permits visual, olfactory, and acoustic contact); using a metal-plate for separation (BM: no visual but possible olfactory, acoustic and vibration contact); or with taking the litter with the nest-tray 5 m away from the doe's cage (BN: there is no contact at all) and returning to free nursing just after AI (at 11 days in the morning) up to weaning. The type of separation exerted a significant influence on oestrus and subsequent kindling of does. Comparing C, F, BW, BM and BN groups, sexual receptivity (30.4, 45.4, 24.0, 25.6, 43.0%, respectively; P < 0.05), fertility (74.4, 84.2, 80.8, 80.3, 89.5%; P < 0.05) and kindling rates (71.1, 85.5, 76.9, 77.3, 88.2%, respectively; P < 0.05) improved in F and BN groups. The total number of kits born (10.0, 10.3, 10.5, 10.4, 9.55, respectively; P = 0.392) and kits born alive per litter (9.25, 9.65, 9.59, 9.83, 9.03, respectively; P = 0.607) were not affected, but newborn kit weight was numerically less in the BW group (69.7, 67.5, 65.5, 67.6, 67.3 g, respectively; P = 0.166). Growth rates of current progeny up to weaning were higher and identical in C and BM but less in F and BN groups (27.5, 25.6, 27.1, 27.3, 26.7 g/day, respectively; P = 0.001). However, the total weight of 70-day-old rabbits per doe did not differ significantly (17.51, 17.53, 17.54, 16.81, 15.81 kg, respectively; P = 0.271). On the whole, the production of the F, BM and BN groups was superior to that of the control and BW groups since subsequent kindling results improved without a significant reduction in slaughter rabbits per doe from current litters.     

Small-scale agricultural landscapes promote spider and ground beetle densities by offering suitable overwintering sites

Context

Intensive agricultural management practices and landscape homogenisation are the main drivers of biodiversity loss in agricultural landscapes. Agricultural fields are regularly disturbed and provide unstable habitats due to crop management regimes. This may lead to movement of arthropods into neighbouring non-arable habitats, as natural and semi-natural habitats provide suitable overwintering sites.

Objectives

Here we assessed the effect of landscape composition and configuration on the overwintering spider and carabid fauna of grassy field margins and hedgerows.

Methods

We sampled ground-dwelling arthropods at field edges of different types (grassy field margin and hedgerows), landscape composition (diverse and simple) and configuration (mosaic and large-scale agricultural landscapes).

Results

We detected larger spiders in hedgerows than in grassy field margins and in complex landscapes rather than in simple landscapes. We found a significant effect of interaction between landscape composition and edge type on ballooning propensity of spiders. Agrobiont carabids were more abundant in field edges of compositionally simple and large-scale agricultural landscapes. Furthermore, we showed an effect of interaction between landscape composition and edge type on agrobiont spiders. We collected larger carabids in grassy field margins than in hedgerows and carabids were smaller in simple landscapes than in diverse landscapes. The spider community was affected by edge type, and landscape composition had a significant effect on the carabid community.

Conclusions

Small-scale agricultural landscapes may have higher overall densities of ground-dwelling spiders and carabids than large scale landscapes due to the relatively high edge density and the higher quantity of available overwintering sites.

     

Effect of excess selenium supplementation on the glutathione redox system in broiler chicken

Selenium, as part of selenocysteine, is the active centre of selenoenzymes. Excess amount of selenium generates oxygen free radicals and reacts with thiol compounds such as reduced glutathione, composing seleno-diglutathione. These reactions impair the amount and/or activity of the biological antioxidant defence system. In the present experiment the effects of two inorganic selenium sources (Na2SeO3, Na2SeO4) on lipid peroxidation and on the content and activity of some components of the antioxidant defence mechanism were studied in Ross 308 hybrid cockerels. In the tissues examined, the glutathione redox system was altered in different ways as an effect of excess selenium. The amount of glutathione and, consequently, glutathione peroxidase activity declined in the blood plasma and in the red blood cell haemolysate, while in the liver malondialdehyde concentration increased only at the end of the experimental period as a result of the boosted enzyme activity. The authors suppose that the cause of increased lipid peroxidation was the potential toxic effect of selenium accumulation above the actual demand.