Research & Development – Research Briefs


Aquaculture Research, Vol 46, 7 Effects of filleting method, stress, storage and season on the quality of farmed


Atlantic cod (Gadus morhua L.) G JØRPELAND, A IMSLAND, LH STIEN, H BLEIE AND B ROTH The effects of filleting method, pre-slaughter stress, storage and season on drip loss, water content, water-holding capacity, rigour contrac- tion and colour in Atlantic cod, Gadus morhua L., were examined. A total of 182 fish were sampled under commercial conditions. To test the effects of filleting method and stress, stressed (S) and unstressed (C) fish were filleted either pre (Pr) or post rigour (Po) at 1 and 48 h post mortem, receptively. The muscle pH significantly de- creased from 0 to 144 h of storage in all groups. The onset of the rigour contraction was more pronounced in the Pr-S group as compared with the Pr-C group, but after 144 h of storage, no dif- ference in degree of contraction was observed. Filleting method, stress and storage time influ- enced the colour of the fillets. Post-rigour fillet- ing caused a significantly increased in measured Lightness (L*) during storage. Stress caused a significant increase in measured redness (a*). No significant difference was found for water-hold- ing capacity. The water content was influenced by filleting method, where the Pr-S group had a significantly lower water content compared with the Pr-C groups; water content changed also according to season. The findings of this study show that stress, filleting method, time of storage and season had a significant effect on the drip loss, where a combination of all factors will determine the total loss.


Journal of Fish Diseases, Vol 38, 7


Development and application of molecular methods (PCR) for detection of Tasmanian


Atlantic salmon reovirus SC ZAINATHAN, G CARLILE, J CARSON, KA MCCOLL, M ST. J CRANE, LM WILLIAMS, J HOAD, NJG MOODY, HM AIKEN, GF BROWNING AND BF NOWAK Molecular (PCR) diagnostic tests for the


detection and identification of aquareovirus in general, and Tasmanian Atlantic salmon reovirus (TSRV) specifically, were developed, and their diagnostic sensitivity and specificity were de- termined and compared with virus isolation in cell culture. Intralaboratory and interlaboratory comparison of PCR (conventional hemi-nested RT-PCR & RT-qPCR) and virus isolation in cell culture using finfish cell lines, CHSE-214 and EPC, was carried out for the detection and identification of TSRV using field samples of farmed Atlantic salmon Salmo salar, L. from various aquaculture sites around Tasmania. The interlaboratory comparison of diagnostic meth- ods was carried out between two laboratories,


www.fishfarmer-magazine.com Above: Atlantic cod


AAHL-CSIRO and DPIPWE-Tasmania. A total of 144 fish from nine sites (12–33 fish per site) were sampled from two regions of Tasmania (Tamar River estuary in the north and Huon River estuary in the south-east) during late spring to early summer of 2009, and the data were analysed using different statistical approaches. The prevalence of TSRV ranged from 6% to 22% in both regions. All the diagnostic methods (data from both laboratories) had high specificity, while the estimated sensitivity var- ied between tests with RT-qPCR being the most sensitive (95.2%) method followed by virus isolation and then conventional hemi-nested RT-PCR


Fish and Shellfish Immunology, Vol 45, 1 Growth, immune response and intestinal morphology of rainbow trout


(Oncorhynchus mykiss) supplemented with commercial probiotics MA RAMOS, JFM GONÇALVES, S BATISTA, B COSTAS, MA PIRES, P REMA AND ROA OZÓRIO The influence of two commercial probiotics on the growth, innate


immune parameters and intestinal morphology of rainbow trout (Onco- rhynchus mykiss) juveniles (initial weight: 16.4 ± 0.4 g) was evaluated. Two probiotic types: A, multi-species (Bacillus sp., Pedicoccus sp., Enterococcus sp.,Lactobacillus sp.) and B, mono-species (Pediococcus acidilactici) were tested at two levels each (A1: 1.5 g kg−1, 8.6 × 105 CFU g−1; A2: 3 g kg−1, 1.6 × 106 CFU g−1; B1: 0.1 g kg−1, 2.6 × 104 CFU g−1; B2: 0.2 g kg−1, 7.2 × 104 CFU g−1) versus an unsupplemented diet (C). Diets were distributed to sextuplicate tanks, three times a day to visual satiation for 8 weeks. Growth performance and immune responses (plasma lysozyme, ACH50, peroxidase and head kidney respiratory burst) were determined at 4 and 8 weeks of feeding. Body composition and intestine morphology were determined at the end of the feeding trial. At 8 weeks, the lower dose of multi-species probiotic (A1) improved growth rate, while both probiotic types improved feed conversion rate compared to the control animals, at the lower dose of multi-species (A1) and at the higher dose of mono-species (B2) probiotics. Body composition did not vary between treatments. At 4 weeks, ACH50 activity was significantly higher in fish fed higher dose of B probiotic (B2, 123.7 ± 50.6 vs 44.1 ± 7.7 U.ml-1in control). At 8 weeks, lysozyme activity was higher in fish fed A1 (13.1 ± 5.2 μg ml−1) diet compared to fish fed control diet (7.8 ± 1 μg ml−1). Plasma peroxidase and head-kidney res- piratory burst did not differ among the dietary treatments. Villi length and integrity and goblet cell counting of a cross section of the anterior intestine were not significantly different between groups. Results suggest benefits in zootechnical performance and immune humoral responses using both probiotic types, in a dose dependent manner, without apparent alterations in intestinal morphology. FF


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