Welfare assessment in rabbits raised for meat and laboratory purposes in enclosures with two floor types: Perforated plastic with holes versus slats.

Due to welfare concerns and legal restrictions in certain countries, alternatives to wire net floors must be developed in rabbit husbandries. Also, there is a difference in regulations in Europe for laboratory rabbits vs. rabbits bred and kept for meat production. While there are regulations concerning floor design of enclosures for rabbits bred for meat production in many European countries, the European Directive 2010/63 lacks regulations for rabbits used for scientific purposes. This study compares two floors, which meet the Austrian legal requirements for growing rabbits intended for consumption as well as the requirements for laboratory rabbits. The dual use of rabbits bred for meat production and applicable for scientific purposes would avoid the problem of surplus animals of specialized producers for laboratory rabbits. A noryl floor with 12 mm circular holes was compared to a 10 mm slatted plastic floor. Parameters were soiling of cages and animals, parasitic burden, clinical health, and losses using objective scoring. Soiling of cages and animals and coccidial oocytes were significantly higher on the floors with circular holes. Obvious signs of disease showed a non-significant trend to be more frequent in the group with circular holes. This was linked with significantly higher losses. In conclusion, our study clearly shows that the floor with circular hole design cannot be endorsed, although it meets legal requirements. The slatted floor type can be cautiously recommended; however, to assure animal welfare in laboratory rabbits, legal authorities in Europe should take on the responsibility of regulating floor design in this sector.

Stability of fear and sociality in two strains of laying hens.

1. This trial studied the effects of strain and age on tonic immobility (TI) duration, emergence time (ET) and social reinstatement time (SRT) in laying hens and investigated the consistency of individual behavioural characteristics over rearing and laying periods and the correlations between these behavioural traits. 2. One hundred chicks from each of ISA Brown (ISA) and Lohmann Tradition (LT) laying hens were reared from one day old in pens. At 3 weeks, birds of each line were divided into 4 groups. Twenty birds in one group of each line were marked individually for repeated testing and the other groups were assigned for single testing to test the habituation effect and possible age effects at a group level. 3. ISA birds had higher overall means for TI duration and latency to leave the start box. ISA also showed longer latency in SRT at week 28 than Lohmanns. TI duration increased from weeks 3 to 10 and then decreased to week 35 in both lines. The latency to explore the test area and to reinstate decreased from weeks 10 to 35. 4. Tonic immobility, exploratory and social reinstatement behaviours were consistent over time in both lines, as revealed by Kendall's W coefficient of concordance. 5. In social test situations, an inter-situational consistency was found, that is, birds emerged quickly from the start box and reinstated quickly with their companion. TI (non-social test) was negatively correlated with ET and SRT. Thus the two lines of laying hens respond differently in social and non-social tests.

[The effect of housing on the development of calluses and subcutaneous mucus cysts on the limbs of swine]. / Zum Einfluss der Haltung auf die Anbildung von Schwielen und subkutanen Schleimbeuteln an den Gliedmassen der Schweine.

Extremities of pigs often show swelling of various size and consistency. The aim of the present investigation was to determine the cause of the swelling with special emphasis on housing conditions. A total of 168 animals kept on slatted and/or partly slatted floors and 55 pigs kept on straw were examined. The swelling was partially caused by connective tissue proliferation only, but more often consisted of non inflamed subcutaneous bursae. Skeletal changes near the periost could never be seen. In pigs kept on straw weals and subcutaneous bursae practically never developed, whereas in animals kept on concrete, these changes did occur more frequently and were more pronounced with time.

[Is there a lasting effect of functional claw-trimming on claw conditions?]. / Hat funktionelle Klauenpflege nachhaltigen Einfluss auf den Klauenzustand?

The influence of regular claw-trimming on the occurrence and prevalence of claw disorders was examined on a total of 164 dairy cows (Simmental, Red Friesian, Holstein Friesian). Ten dairy farms in the Austrian province of Salzburg were used for this study. Three examinations of the claws were carried out with an interval of six months in between to find out claw disorders. The results were recorded according to a claw scoring system. The claw scores were in the range of other studies using the same scoring system. The median of the claw scores at the beginning of the study was 27 in the tied stall group compared with 37 in the loose housing group, remaining at that level in the first group and falling to 25 in the second group. All in all, the positive effect of regular claw trimming was more pronounced in the loose housing group than in the tethered housing group.

Influence of pop hole dimensions on the number of laying hens outside on the range.

The aim was to evaluate whether pop hole width is a factor influencing the number of laying hens on the range. Eight groups of 256 birds each were kept in 8 compartments in a deep litter system. Hens could leave each compartment through two equally-sized pop holes arranged evenly along the side of each compartment. Pop hole dimensions were varied every second week in each compartment in a random order from 30, 60, 90, 120 up to 150 x 30 cm (width x height). Range per hen (10 m(2)) were provided. The number of laying hens on range was counted hourly from 07:00 to 20:00 h. Pop hole width did not significantly influence the number of laying hens on the range. Our findings show that, within the limits of the dimensions investigated, other factors are more important than pop hole dimensions.

[Hoof diseases as a result of stall floor defects]. / Klauenerkrankungen als Folge von Stallbodenmängeln.

The pig's hoof is characterized by sudden changes between hard and soft horn and a high growth rate of the horn wall. These facts contribute to the high incidence of hoof alterations, which is seen in various inadequate floors. Hoof alterations are only painful in cases, where the corium is irritated. Some hoof alterations are described, the question of poor footing is discussed. The author provides recommendations regarding the recognition of inadequate barn floors and their improvement. Stable claws develop in animals housed on floors with soft surfaces or under restricted movement. Hoof cracks or soft heel ulcers are frequently seen in animals housed on rough and abrasive floors. Slatted floors with wide gaps and sharp edges cause a high rate of lesions at the coronary border. The construction of slatted floors should be done with respect to the size of the hooves, which is related to the body weight. For prevention of lesions the gaps should not exceed the given values.

Importance of Preferential Flow and Soil Management in Vertical Transport of a Biocontrol Strain of Pseudomonas fluorescens in Structured Field Soil.

The large-scale release of wild-type or genetically modified bacteria into the environment for control of plant diseases or for bioremediation entails the potential risk of groundwater contamination by these microorganisms. For a model study on patterns of vertical transport of bacteria under field conditions, the biocontrol strain Pseudomonas fluorescens CHA0, marked with a spontaneous resistance to rifampin (CHA0-Rif), was applied to a grass-clover ley plot (rotation grassland) and a wheat plot. Immediately after bacterial application, heavy precipitation was simulated by sprinkling, over a period of 8 h, 40 mm of water containing the mobile tracer potassium bromide and the dye Brilliant Blue FCF to identify channels of preferential flow. One day later, a 150-cm-deep soil trench was dug and soil profiles were prepared. Soil samples were extracted at different depths of the profiles and analyzed for the number of CHA0-Rif cells and the concentration of bromide and Brilliant Blue FCF. Dye coverage in the soil profiles was estimated by image analysis. CHA0 was present at 10(sup8) CFU/g in the surface soil, and 10(sup6) to 10(sup7) CFU/g of CHA0 was detected along macropores between 10 and 150 cm deep. Similarly, the concentration of the tracer bromide along the macropores remained at the same level below 20 cm deep. Dye coverage in lower soil layers was higher in the ley than in the wheat plot. In nonstained parts of the profiles, the number of CHA0-Rif cells was substantially smaller and the bromide concentration was below the detection limit in most samples. We conclude that after heavy rainfall, released bacteria are rapidly transported in large numbers through the channels of preferential flow to deeper soil layers. Under these conditions, the transport of CHA0-Rif is similar to that of the conservative tracer bromide and is affected by cultural practice.

Conjugative Transfer of Chromosomal Genes between Fluorescent Pseudomonads in the Rhizosphere of Wheat.

Bacteria released in large numbers for biocontrol or bioremediation purposes might exchange genes with other microorganisms. Two model systems were designed to investigate the likelihood of such an exchange and some factors which govern the conjugative exchange of chromosomal genes between root-colonizing pseudomonads in the rhizosphere of wheat. The first model consisted of the biocontrol strain CHA0 of Pseudomonas fluorescens and transposon-facilitated recombination (Tfr). A conjugative IncP plasmid loaded with transposon Tn5, in a CHA0 derivative carrying a chromosomal Tn5 insertion, promoted chromosome transfer to auxotrophic CHA0 recipients in vitro. A chromosomal marker (pro) was transferred at a frequency of about 10(sup-6) per donor on wheat roots under gnotobiotic conditions, provided that the Tfr donor and recipient populations each contained 10(sup6) to 10(sup7) CFU per g of root. In contrast, no conjugative gene transfer was detected in soil, illustrating that the root surface stimulates conjugation. The second model system was based on the genetically well-characterized strain PAO of Pseudomonas aeruginosa and the chromosome mobilizing IncP plasmid R68.45. Although originally isolated from a human wound, strain PAO1 was found to be an excellent root colonizer, even under natural, nonsterile conditions. Matings between an auxotrophic R68.45 donor and auxotrophic recipients produced prototrophic chromosomal recombinants at 10(sup-4) to 10(sup-5) per donor on wheat roots in artificial soil under gnotobiotic conditions and at about 10(sup-6) per donor on wheat roots in natural, nonsterile soil microcosms after 2 weeks of incubation. The frequencies of chromosomal recombinants were as high as or higher than the frequencies of R68.45 transconjugants, reflecting mainly the selective growth advantage of the prototrophic recombinants over the auxotrophic parental strains in the rhizosphere. Although under field conditions the formation of chromosomal recombinants is expected to be reduced by several factors, we conclude that chromosomal genes, whether present naturally or introduced by genetic modification, may be transmissible between rhizosphere bacteria.

Predominance of Nonculturable Cells of the Biocontrol Strain Pseudomonas fluorescens CHA0 in the Surface Horizon of Large Outdoor Lysimeters.

The persistence of the biocontrol agent Pseudomonas fluorescens CHA0 in the surface horizon of 12 large outdoor lysimeters planted with winter wheat, Phacelia tanacetifolia followed by spring wheat, or maize was monitored for 1 year. Soil was inoculated with a spontaneous rifampin-resistant mutant (CHA0-Rif) of CHA0, and the strain was studied by using colony counts, Kogure's direct viable counts, and total counts (immunofluorescence). The number of culturable cells of the inoculant decreased progressively from 8 to 2 log CFU/g of soil or lower. However, culturable cells of CHA0-Rif accounted for less than 1% of the total cells of the inoculant 8 months after release in autumn. Since viable but nonculturable cells represented less than a quarter of the latter, most cells of CHA0-Rif in soil were thus inactive-dormant or dead at that time. Nonculturable cells of the inoculant were predominant also in the surface horizon of the lysimeters inoculated in the spring, and a significant fraction of them were viable. Results suggest that the occurrence of nonculturable cells of CHA0-Rif was influenced by climatic factors (water availability and soil temperature) and the abundance of roots in soil. The fact that the inoculant persisted as mixed populations of cells of different physiological states, in which nonculturable cells were predominant, needs to be taken into account when assessing the autecology of wild-type or genetically modified pseudomonads released into the soil ecosystem.

Amplification of the housekeeping sigma factor in Pseudomonas fluorescens CHA0 enhances antibiotic production and improves biocontrol abilities.

Pseudomonas fluorescens CHA0 produces a variety of secondary metabolites, in particular the antibiotics pyoluteorin and 2,4-diacetylphloroglucinol, and protects various plants from diseases caused by soilborne pathogenic fungi. The rpoD gene encoding the housekeeping sigma factor sigma 70 of P. fluorescens was sequenced. The deduced RpoD protein showed 83% identity with RpoD of Pseudomonas aeruginosa and 67% identity with RpoD of Escherichia coli. Attempts to inactivate the single chromosomal rpoD gene of strain CHA0 were unsuccessful, indicating an essential role of this gene. When rpoD was carried by an IncP vector in strain CHA0, the production of both antibiotics was increased severalfold and, in parallel, protection of cucumber against disease caused by Pythium ultimum was improved, in comparison with strain CHA0.