Keyword Index to Volume 8 (2000)

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Keyword Index to Volume 8 (2000)     

Hatchery Production of Scallop Larvae (Pecten maximus) – Survival in Different Rearing Systems

Scallop farms in Norway rely exclusively on hatchery production of spat. Larval rearing is one of the most difficult parts of the production, and several experiments have been performed during the last years to improve the larval systems. This paper describes results from commercial and experimental trials obtained between 1996 and 2001. Four different rearing systems were compared: untreated batch cultures, chloramphenicol-treated batch cultures, flow-through cultures with filtered water and flow-through cultures with water from a biofilter. The chloramphenicol-treated batch cultures had overall significantly higher survival rates than the untreated and flow-through cultures. There were no significant differences in survival between untreated and flow-through cultures. The average survival rates for the untreated, treated and flow-through cultures were 6.8, 23.0 and 8.6%, respectively. No significant seasonal differences were found for the untreated and treated larval groups, whereas for larvae reared in flow-through systems survival was significantly higher in the winter than the spring. Overall best results were obtained during winter in years with high salinity water in the fjord.     

Effects of Group Size during Pregnancy and Introduction Method on Behaviour of Relevance for Piglet Performance in Multi-suckling Pens

The effects of group size during pregnancy (12 or 24 sows) and introduction methods on behaviour in multi-suckling pens were studied. The introduction methods were: A) (control) all sows and piglets were moved simultaneously to the multi-suckling pen on day 11 after farrowing; B) sows and piglets were moved simultaneously on day 14 after farrowing; C) sows were moved simultaneously and, two hours later, all piglets were moved simultaneously on day 11 after farrowing; D) each sow and her litter were moved separately at three-hours intervals on day 11 after farrowing. The effects of group size during pregnancy interacted with the effects of introduction method. When housed in groups of 12 during pregnancy, treatments B-D resulted in more initiated, but fewer successful nursings compared to A. However, when sows had been housed in groups of 24 during pregnancy, increased age (B) resulted in a decreased number of initiated nursings compared to A, but an increased nursing synchrony. The results indicate that it is possible to affect behaviour in multi-suckling pens through the social environment during pregnancy and by the choice of introduction method.     

Effect of biocontrol agent Bacillus amyloliquefaciens and 1-methyl cyclopropene on the control of postharvest diseases and maintenance of fruit quality

Efficacy of biocontrol agent Bacillus amyloliquefaciens PPCB004 was evaluated on the control of anthracnose and phomopsis rot in ‘Solo’ papaya pre-treated with 1-methyl cyclopropene (100 μl) (1-MCP) during storage. This treatment was compared to the untreated control, commercial treatment (washing in chlorinated water), stand alone 1-MCP and PPCB004 treatment. Although fruit pre-treated with 1-MCP delayed the ripening (100% yellow) after cold storage by 9-10 d, it showed higher incidence and severity of anthracnose and phomopsis rot than the fruit subjected to commercial treatment. Application of PPCB004 after 1-MCP pre-treatment (1-MCP + PPCB004) reduced the anthracnose and phomopsis incidence and severity after cold storage (10 °C, 85% RH for 14 d) and ripening at 25 °C. The 1-MCP + PPCB004 treatment helped to retain the fruit firmness, overall quality and uniform yellow skin (100%) and flesh colour after ripening. The PPCB004 was effectively recovered from stand alone PPCB004 and 1-MCP + PPCB004 treated fruit after cold storage and ripening. The PPCB004 population showed an increase by 1 log units after ripening in 1-MCP + PPCB004 treated fruit. After ripening the recovery of PPCB004 population was higher (0.7 log units) in 1-MCP + PPCB004. The total recovery of fungal population on the fruit surface after ripening was lower in 1-MCP + PPCB004 and stand alone PPCB004 treated fruit. It can be concluded that application of B. amyloliquefaciens PPCB004 with 1-MCP pre-treated papaya (at 25-30% skin yellow stage) can significantly reduce disease incidence associated with 1-MCP treatment. This treatment has the potential for commercial application in the ‘organic’ papaya industry.     

Early detection of sugar beet pathogen Ramularia beticola in leaf and air samples using qPCR

A quantitative PCR method (qPCR) was developed for the detection and quantification of Ramularia beticola causing Ramularia leaf spot in sugar beet. R. beticola specific primers were designed based on the internal transcribed spacer region 2 (ITS2). The assay was applied on DNA extracted from spores trapped on tape from Burkard spore traps placed in an artificially inoculated sugar beet field trial and in two sugar beet fields with natural infections. R. beticola DNA was detected at variable amounts in the air samples 14 to 16 days prior to first visible symptoms. R. beticola DNA was detected in air samples from fields with natural infection at significant and increasing levels from development of the first symptoms, indicating that spore production within the crop plays a major role in the epidemic development of the disease. Sugar beet leaves sampled from the inoculated field trial were also tested with the qPCR assay. It was possible to detect the presence of R. beticola in the leaves pre-symptomatic at least 10 days before the occurrence of the visible symptoms of Ramularia leaf spot. This is the first report of a molecular assay, which allows screening for the presence of R. beticola in plant material and in air samples prior to the appearance of visible symptoms. An early detection has potential as a tool, which can be part of a warning system predicting the onset of the disease in the sugar beet crop and helping to optimise fungicide application.     

Outside enclosure and additional enrichment for dairy goats – a preliminary study

Background

Dairy goats are commonly housed at a space allowance of 0.7 – 0.8 m²/goat in commercial Norwegian goat herds, which is very low compared to regulations and recommendations in other European countries. One easy and cheap way to increase space allowance is to allow the animals’ access to outdoor area. The aim of this study was to investigate the effect of access to an outside enclosure and environmental enrichment for dairy goats kept in slatted floor pens with low space allowance on their activity pattern and social behaviour.

Methods

A group of 82 dairy goats on a commercial Norwegian dairy farm were kept inside during the winter period from October to April. In April the goats were given access to an outside enclosure for 8 hours per day. After having access to the enclosure for another for two days, enrichment (branches) was provided, and after 19 days the enrichment were removed. The goats were observed for 5 hours per day for the two last days before they got access to the outside enclosure, the two days in the enclosure, the two first and the two last days with enrichment and for the following two days without enrichment by two trained observers.

Results

When allowed access to the enclosure, the goats spent nearly 50% of the time outside, and later the time spent outside was reduced to less than 40% (P < 0.0001), but there was no clear effect of enrichment. All the goats appeared to have a regular use of the enclosure. Time spent resting decreased 59.2% to only 25.2% when the goats first got access to the enclosure, but then started to increase again (P < 0.0001). Initially time spent exploring and chewing the branches was 20%, but this was reduced to around 12% in the last part of the ENRICH period (P < 0.0001). Number of aggressive interactions tended to increase when the goats were allowed access to the outdoor enclosure whereas play behaviour was only observed in the outside enclosure (P < 0.05).

Conclusions

In conclusion, the goats preferred to use the outside enclosure when being active, and branches were perceived as an attractive enrichment.