Substitution of fish meal by sesame oil cake (<i>Sesamum indicum</i> L.) in the diet of rainbow trout (<i>Oncorhynchus mykiss</i> W.)

The present study evaluated the nutritional value of sesame oil cake (SOC) in rainbow trout fry (initial body weight of 1.42 g) in a growth trial performed for 45 feeding days at 15 ± 1 °C. A series of five isonitrogenous (380 g digestible protein kg-1 dry matter (DM)) and isoenergetic (18.1 MJ digestible energy kg-1 DM) diets were formulated in which the digestible SOC protein progressively replaced 0%, 13%, 26%, 39% and 52% of the digestible protein of a high quality fish meal (D0-D52). Growth rate of fry significantly improved in fish fed SOC diets compared to the fishmeal control diet (D0) whatever the SOC inclusion level. This positive effect on growth was mainly related to a marked improvement of voluntary feed intake. The decrease of feed efficiency observed with increasing SOC was entirely explained by the reduction of DM and energy digestibilities with SOC incorporation. Nitrogen retention efficiency (nitrogen gain/nitrogen intake) was high (40–41%) and significantly reduced only in fish fed D52 (37%). Our results suggest that SOC can be a suitable protein source for a carnivorous fish and replace at least half of the fishmeal protein (without amino acid supplementation) without growth reduction in rainbow trout fry

Effects of fish size and diet adaptation on growth performances and nitrogen utilization of rainbow trout (<i>Oncorhynchus mykiss</i> W.) juveniles given diets based on free and/or protein-bound amino acids

The quality of dietary protein is an important factor influencing fish growth. It is usually assessed by amino acid (AA) composition, protein digestibility and protein utilization efficiency. Here it was investigated with rainbow trout (Oncorhynchus mykiss W.) juveniles 1) if the molecular form of the ingested nitrogen (free (F) AA, peptides or proteins) may also affect the dietary protein quality; 2) if this possible influence may be affected by juvenile size and adaptation to the diet; and 3) what is the optimum synthetic FAA to protein ratio. Two experiments were carried out at 15 °C (3 tanks/treatment) in which 1050 small juveniles (0.70 g) and 450 large juveniles (2.85 g) were randomly assigned to fifteen 15 l-tanks (70 fish/tank) and to fifteen 45 l-tanks (30 fish/tank), respectively. In both experiments, fish were fed twice a day to satiation for 9, 17 and 25 feeding days (3 periods) five isoenergetic and isonitrogenous (412 g crude protein/kg dry matter (DM)) diets containing graded levels of coated FAA, replacing 0, 25, 50, 75 or 100% (D0–D100) of the cod muscle meal, an intact protein. Compared to D0, growth rate (DGC, % per day) and feed intake (g DM/kg0.75 per day) were significantly reduced only for small juveniles and large juveniles fed diets containing at least 50 and 75% of FAA, respectively. Protein deposition (g/kg0.75 per day) was not significantly reduced for juveniles fed diets D25–D50, but well for juveniles fed diets D75–D100. The decrease of growth rate and protein deposition at FAA inclusion rate below 75% was largely explained by a reduction of voluntary feed intake while nitrogen retention efficiency was significantly reduced only for diet D100. The maximum FAA level that still ensured reasonable growth (85% of maximum) was 65%, at both juvenile sizes, after an adaptation period of 17 days. Larger juveniles tolerated higher FAA dietary levels than smaller juveniles, indicating ontogeny-related changes in FAA utilization efficiencies. Finally fish accustomed to FAA-rich diets were able to tolerate higher FAA dietary levels but the maximum FAA inclusion level was modulated by fish size. In conclusion, here we show that the dietary protein quality is dependent of the molecular form of the ingested nitrogen in rainbow trout juveniles and that this quality is modulated by the ratio of synthetic FAA to protein (or FAA inclusion rate), the adaptation of the fish to the diet and the fish size

Enzyme-linked immunoassay for dengue virus IgM and IgG antibodies in serum and filter paper blood

Background: The reproducibilty of dengue IgM and IgG ELISA was studied in serum and filter paper blood spots from Vietnamese febrile patients. Methods: 781 pairs of acute (t0) and convalescent sera, obtained after three weeks (t3) and 161 corresponding pairs of filter paper blood spots were tested with ELISA for dengue IgG and IgM. 74 serum pairs were tested again in another laboratory with similar methods, after a mean of 252 days. Results: Cases were classified as no dengue (10%), past dengue (55%) acute primary (7%) or secondary (28%) dengue. Significant differences between the two laboratories' results were found leading to different diagnostic classification (kappa 0.46, p < 0.001). Filter paper results correlated poorly to serum values, being more variable and lower with a mean (95% CI) difference of 0.82 (0.36 to 1.28) for IgMt3, 0.94 (0.51 to 1.37) for IgGt0 and 0.26 (-0.20 to 0.71) for IgGt3. This also led to differences in diagnostic classification (kappa value 0.44, p < 0.001) The duration of storage of frozen serum and dried filter papers, sealed in nylon bags in an air-conditioned room, had no significant effect on the ELISA results. Conclusion: Dengue virus IgG antibodies in serum and filter papers was not affected by duration of storage, but was subject to inter-laboratory variability. Dengue virus IgM antibodies measured in serum reconstituted from blood spots on filter papers were lower than in serum, in particular in the acute phase of disease. Therefore this method limits its value for diagnostic confirmation of individual patients with dengue virus infections. However the detection of dengue virus IgG antibodies eluted from filter paper can be used for sero-prevalence cross sectional studie