Appearance of Infectious Hematopoietic Necrosis Virus in Rainbow Trout,Oncorhynchus mykiss,During Seawater Adaptation

About 7% mortality occurred in rainbow trout, Oncorhynchus mykiss, during seawater adaptation at a marine farm in the South Sea of Korea during the winter of 2014. Most diseased fish showed petechial hemorrhaging of gills and internal fat with enlarged spleen. Although no parasites or bacteria were isolated from the diseased fish, all tissue filtrates produced cytopathic effects (CPEs) in fathead minnow and Chinook salmon embryo‐214 cells. The cell culture supernatant showing CPE contained specific 1527‐bp fragment for the infectious hematopoietic necrosis virus (IHNV) glycoprotein gene by polymerase chain reaction. Their nucleotide sequences shared 98.1–98.2% identities with IHNV RtUi02 isolated from rainbow trout in Korea. This isolate (RtGoH14) was closely related to Korean IHNV isolates of genogroup JRt rather than to those of North American and European genogroups. These results suggest that this IHNV isolate might have been introduced to rainbow trout farm (land‐based culture system) in Korea. This is the first report of IHNV infection in rainbow trout during seawater adaptation in Korea.     

Growth performance and physiological parameters of conventional and specified pathogen‐free rats fed autoclaved diets with different protein sources

The effects of feeding autoclaved commercial SSNIFF (SN) diet and diets containing soya bean (S) and casein (C) to growing conventional (CON) and specified pathogen‐free (SPF) rats were determined. Diets S, C and SN, autoclaved at 121 °C during 20 min (T1), at 134 °C during 10 min (T2) and non‐autoclaved (T0), were fed during four weeks, each to 8 CON males and 8 females of mean initial body weight 56 g, kept individually. Diets S, C and SN, autoclaved at T1, were fed during two months, each to 20 SPF males and 20 females of mean initial body weight 58 g, kept in group of 5 animals per cage. In CON rats, autoclaving did not affect feed intake and weight gain, decreased thyroid and stomach weight, increased caecal tissue and digesta weight, and concentrations of isobutyric, isovaleric and valeric acid in caecal digesta. Among biochemical blood parameters, autoclaving decreased only total protein concentration and aspartate aminotransferase activity. Feeding C diet resulted in lower feed intake and weight gain in CON and SPF males. Diet affected organ weights and the greatest differences were found in rats on SN diet for weights of stomach, caecum and female reproductive organs. Diet affected concentration of all short‐chain fatty acids, pH and weight of caecal digesta, the most important being the greatest butyric acid concentration on SN diet and isoacids on C diet. It is concluded that autoclaving of both soya‐containing and soya‐free diets does not affect negatively animal performance and physiology.     

A Case of Bronze Turkey Twins Developing from Hatching

A double‐yolked egg that was laid by an 11‐month‐old bronze turkey hen on 2 April, 2013 was reported. The presented case of developing turkey twin embryos is the first ever described case for this species. The egg weighed 125 g and had 74.6 mm in length and 53.0 mm in width. The embryos died between the 23rd and 24th day of incubation. Both twin 1 and twin 2 were fully developed with body weights of: 37.7 g and 40.3 g, respectively. The likely causes of death include inappropriate arrangement of embryos and insufficient gas exchange in the last period of incubation. The embryos were arranged along the long axis of the egg, one underneath the other, and were closely adhering to one another. The twins were different in plumage pigmentation. In twin 1, a spontaneous mutation of plumage pigmentation (B) was observed, whereas twin 2 showed appropriate pigmentation (b+) in respect to parents.     

Social behavior in preweaning lambs and their preferences in social interactions

The aim of this study was to investigate social behavior in preweaning lambs, especially their preferences in social interactions. A total of 30 lambs (16 Polish Milk Sheep 05 and 14 Polish Whiteheaded Mutton Sheep) were observed for 113 h 30 min during the first 2 months of their lives. Interbreed differences were insignificant both in agonistic and affiliative behavior. Males appeared to be more active both in agonistic and affiliative interactions. They also preferred other males in agonistic interactions. On the other hand, females fought more often with males, than with females. Lambs of both breeds preferred individuals of their own breed as partners in affliative behaviors. Twins preferred most their siblings in affliliative interactions and usually did not attack and fight with them. This study shows that sex and breed can influence social preferences in preweaning lambs.     

Factors influencing steel tool wear when milling wood

The wear of high speed steel cutting tools after milling wood of four selected wood species was studied. For the experiments wood specimens were chosen with very different silica contamination, wood density, and high temperature corrosivity (HTC) of wood towards tool material. Analyses performed show that the silica content and wood density display poor linear correlation with the cutting tools wear, while the correlation of the HTC appeared very good. The silica contamination and the HTC effects overshadow each other. Thus, a theoretical multivariable simulation of the cutting edge wearing process, employing all experimental variables, was applied, providing a very good explanation of the analyzed problem.     

Regeneration patterns of the late-successional <Emphasis Type="Italic">Abies alba</Emphasis> Mill.: inhibition in monospecific stands and colonization in mixed stands

Key message

In Abies alba Mill. stands and mixed stands of A. alba and Picea abies L. (H. Karst), microsites neighbouring the trunks of adult trees were more conducive to A. alba regeneration. Although at the stand level, the effect of Fagus sylvatica L. was positive; the local effect of the adult F. sylvatica neighbourhood was insignificant. Hence, forming mixed stands with a fine-grained mosaic of admixed species might better facilitate natural regeneration of A. alba than monospecific stands.

Context

The establishment of natural regeneration in Abies alba Mill. stands is a slow, spatially heterogeneous and stochastic process. Recent studies based on inventory data indicate that A. alba more readily regenerates in mixed stands than in monospecific stands.

Aims

The objective was to examine how this positive association evidenced at the stand level operates on the scale of microsites with contrasting local species composition and stand density.

Methods

In 8 monospecific and 22 mixed stands with Fagus sylvatica L. or Picea abies L. (H. Karst), microsites with a contrasting density of A. alba seedlings were selected and compared in terms of local species composition, stand density, canopy characteristics and topsoil properties.

Results

In A. alba stands, seedling density was positively associated with the proximity of adult trees. In mixed stands of A. alba and P. abies, adult trees of both species exerted a positive effect on A. alba regeneration, but the P. abies neighbourhood influenced regeneration occurrence more strongly than the A. abies neighbourhood. In mixtures with F. sylvatica, however, the effect of local stand density and local species composition was not evidenced at all.

Conclusion

Although at the stand level, P. abies and F. sylvatica exert a positive effect on A. alba regeneration, on the microsite scale, their influences differ. In stands with a dominance of A. alba, the hampered seedling establishment in gaps may be considered an inhibitive effect that facilitates the emergence of other species.

     

Influence of wheat leaf position on leaf rust severity

Summary The relation between flag leaf position and leaf rust severity was investigated in field experiments. Different leaf angles were obtained by attaching ends of flag leaves to strings stretched at different heights along wheat rows. Leaves with angles between lamina and stem of 0° and 45° were significantly less diseased than leaves with horizontal and pendulous positions. In the experiment with seedlings, spore settling and uredia number were significantly lower on erect than on horizontal leaves. The influence of wheat leaf position changes on leaf rust severity was discussed. It has been suggested that breeding of wheat cultivars with erect leaves can improve their resistance to airborne pathogens.