A feeding trial was conducted to determine the maximum substitution limits of poultry by-product meal (PBM; 66% crude protein) protein for fish meal (FM; 59% crude protein) protein in the diet of juvenile Black Sea Bass Centropristis striata (family Serranidae). Eight isonitrogenous (44% crude protein) and isolipidic (13% crude lipid) diets were formulated to replace FM protein with PBM protein at 0 (control), 40%, 50%, 60%, 70%, 80%, 90%, and 100% in Black Sea Bass diets. Diets were fed twice daily to triplicate groups of juveniles (initial mean weight = 1.2 g) to apparent satiation for 8 weeks in a recirculating aquaculture system. Final survival was excellent (95-100%) in all diet treatments, with no significant differences. No significant differences in body weight gain (BWG) were observed in fish fed the 40-90% PBM protein diets (1,136-1,357%) compared with the control diet (1,307%). However, BWG of fish fed the 100% PBM protein diet (1,045%) was significantly lower than in the control group. Regression analysis with BWG indicated that PBM protein can replace FM protein in Black Sea Bass diets at levels as high as 81.8%, with no reduction in fish growth performance. For fish fed diets with up to 90% PBM protein, feed conversion (1.08-1.17) and protein efficiency ratios (2.01-2.14) were not significantly different from fish fed a control 100% FM-protein-based diet (0.99 and 2.29, respectively). Apparent digestibility coefficients of dietary protein remained high (81.6-87.0%) under all levels of FM replacement with PBM protein. After the feeding trial, whole body and muscle protein content and the concentrations of whole body n-3 polyunsaturated fatty acids showed no significant differences among the treatments at FM protein replacement levels up to 90%. Poultry by-product meal is a promising alternative protein source for sustainable diet development in Black Sea Bass. a Melick Aquafeed, Catawissa, Pennsylvania; 59.5% protein, 12% lipid. b Melick Aquafeed; 67% protein, 15% lipid. g Calculated value based on carbohydrates, proteins, and lipids at 17.2, 23.6, and 39.5 kJ/g, respectively (Blaxter 1989). 76 DAWSON ET AL.
Praziquantel (PZQ) is a drug commonly utilized to treat both human schistosomiasis and some parasitic infections and infestations in animals. In the aquarium industry, PZQ can be administered in a “bath” to treat the presence of ectoparasites on both the gills and skin of fish and elasmobranchs. In order to fully treat an infestation, the bath treatment has to maintain therapeutic levels of PZQ over a period of days or weeks. It has long been assumed that, once administered, PZQ is stable in a marine environment throughout the treatment interval and must be mechanically removed, but no controlled experiments have been conducted to validate that claim. This study aimed to determine if PZQ would break down naturally within a marine aquarium below its 2 ppm therapeutic level during a typical 30-day treatment: and if so, does the presence of fish or the elimination of all living biological material impact the degradation of PZQ? Three 650 L marine aquarium systems, each containing 12 fish (French grunts: Haemulon flavolineatum), and three 650 L marine aquariums each containing no fish were treated with PZQ (2 ppm) and concentrations were measured daily for 30 days. After one round of treatment, the PZQ was no longer detectable in any system after 8 (±1) days. The subsequent two PZQ treatments yielded even faster PZQ breakdown (non-detectable after 2 days and 2 ± 1 day, respectively) with slight variations between systems. Linear mixed effects models of the data indicate that day and trial most impact PZQ degradation, while the presence of fish was not a factor in the best-fit models. In a completely sterilized marine system (0.5 L) PZQ concentration remained unchanged over 15 days, suggesting that PZQ may be stable in a marine system during this time period. The degradation observed in non-sterile marine systems in this study may be microbial in nature. This work should be taken into consideration when providing PZQ bath treatments to marine animals to ensure maximum drug administration.
Sponsoring Agency Code Supplementary Notes AbstractThis research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort included determining the role of freeze-thaw, moisture, and fatigue on structural performance and developing analytical design procedures that account for durability.The results showed that moisture infiltration behind the CFRP, combined with freeze-thaw, was critical in reducing shear panel stiffness and shear capacity. Long-term moisture exposure alone produced only a minor decrease in shear capacity. Freeze-thaw, combined with fatigue, had little effect on shear capacity if water infiltration was minimized. Fatigue caused some debonding, but the debonding was not significant enough to affect capacity.Use of ACI-318 with ACI 440 provided conservative predicted shear strengths after environmental exposure. However, the ACI approach did not provide uniform levels of safety because the observed conservatism was built into the prediction for the unstrengthened base specimens but not for the CFRP contribution. Consequently, a recommendation of the research is to apply the environmental exposure factor at the final design step to limit the effective CFRP stress/strain. For locations with very large numbers of wet freeze-thaw cycles and extended exposure to continuous moisture, the environmental reduction factors should be reduced even further. To better predict the CFRP bond strength demands that can occur due to shear-moment interaction, a further check of the design should be made beyond those required by ACI-440.17.
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