Effects of different levels of dietary lipids on growth performance, liver histology and cold tolerance of Nile tilapia (Oreochromis niloticus).

This study evaluated the effects of different levels of dietary lipids on the growth performance, feed utilization, body composition and cold tolerance of Nile tilapia (Oreochromis niloticus) fingerlings (7.33 ± 0.12 g fish-1). Four isonitrogenous (275 g kg-1 crude protein), isocaloric (18.5 MJ kg-1) diets containing a mixture of fish oil and corn oil (1:1 ratio) at different levels (70, 85, 110 and 130 g kg-1) were prepared and fed to Nile tilapia reared at a fixed water temperature 25 ± 1 °C for two months. After the feeding trial, the fish were exposed to a cold challenge. The best growth rates and feed utilization were achieved at 70 and 85 g kg-1 dietary lipid, whereas the lowest results were recorded at higher lipid levels (110 and 130 g kg-1). The ability of Nile tilapia to survive the acute cold stress was significantly improved as the lipid level increased from 70 to 110 g kg-1 and decreased with further increase in lipid levels. During the cold stress, saturated fatty acids (SFA) significantly decreased, while unsaturated fatty acids (UFA) tended to increase. Thus, this study demonstrates, to a certain level, that high dietary lipid levels have a positive effect on the cold tolerance of Nile tilapia fingerlings.

Dietary lipid sources affect cold tolerance of Nile tilapia (Oreochromis niloticus).

This study was carried out to evaluate the effects of dietary lipid sources on growth performance, fatty acids composition and cold tolerance of Nile tilapia (Oreochromis niloticus) fingerlings (7.00 ±â€¯0.50 g/fish). The fish were fed four isonitrogenous (28% crude protein), isocaloric (500 kcal/100 g) diets containing four lipid sources; fish oil (FO), corn oil (CO), coconut oil (COCO) or fish oil/ corn oil mixture (1:1 ratio) (oil mix). The diets were offered to the fish at a daily rate of 3% of their body weights (BW), twice a day for two months. After the feeding trial, the fish were exposed to decreasing water temperature from 25 °C until the appearance of death symptoms. The results revealed that FO-based diets (FO and oil mix) produced the best growth rates and feed efficiency, followed by corn oil diet, while COCO resulted in the lowest performance. Fish fed on CO and oil mix showed higher body unsaturated fatty acids (UFA) and lower lethal temperature than those fed on FO- or COCO-based diets. These results indicate that cold shock can modify the lipid metabolism in Nile tilapia by lowering total body saturated fatty acids and raising n-6 and n-3 UFA. This finding suggests that the inclusion of high levels of plant oils in Nile tilapia feeds can enhance their cold tolerance.

Effectiveness of a 20% Miswak extract against a mixture of Candida albicans and Enterococcus faecalis.

OBJECTIVE: To examine the in vitro antimicrobial effect of a 20% Miswak extract against a mixture of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) using the dilution tube susceptibility test, which allows direct contact between the tested material and the microorganisms. METHODS: The study samples were collected and processed between August 2009 and January 2010 in the College of Dentistry, King Saud University, Riyadh, Saudi Arabia. Each microorganism was obtained in a suspension and exposed to a 20% Miswak extract in plastic tissue culture clusters containing 24 wells. Six wells were used per group. The Miswak extract was incubated with the microorganisms for one, 6, and 24 hours. RESULTS: This in vitro study showed that Miswak extract was an effective antifungal and antibacterial agent at all tested experimental time periods, except one hour exposure of a 20% Miswak extract to E. faecalis and a mixture of E. faecalis and C. albicans, which was ineffective in inhibiting their growth. CONCLUSION: Twenty percent Miswak extract is an effective antifungal and antibacterial agent against C. albicans and E. faecalis.