Abstract
The long-term effects of different dietary oil sources with varying omega-6/omega-3 (omega-6/omega-3) Polyunsaturated Fatty Acids (PUFAs) ratios on the bone marrow fatty acids level, bone growth and ex vivo Prostaglandin E-2 (PGE(2)) release and minerals content in bone were evaluated in rabbits. Weanling male and female New Zealand white rabbits were randomly assigned to five groups and fed ad libitum on diets containing. 70 g kg of added oil for 100 days as follow; Soybean Oil (SBO control), Sesame Oil (SO), Fish Oil (FO), DHA algae oil (DHA) and DHA and ARA algae oils (DHA/ARA). The dietary lipid treatments were formulated to provide the following ratio of omega-6/omega-3 fatty acids: 8.7 (SBO), 21.8 (SO), 0.4 (FO), 0.6 (DHA) and 0.7 (DHA/ARA). The bone marrow fatty acids level of rabbits was significantly influenced by and reflected the dietary level of omega-6 and omega-3 fatty acids fed to rabbits. Rabbits fed the FO diet maintained a lower omega-6/omega-3 ratio and a higher EPA and DHA concentrations in their bone marrow those fed the SO diet maintained a higher to omega-6/omega-3 fatty acids ratio while those fed the SBO diet maintained a higher LA and ALA concentrations and intermediate value of omega-6/omega-3 ratio. Ex vivo PGE(2) level declined progressively as the omega-6/omega-3 dietary ratio declined. There was a significant main effect of dietary treatment on femur Ca, P, Mg and Zn contents in both genders. These results demonstrate that dietary omega-6/omega-3 ratio modulates bone PGE(2) production in growing rabbits, hence may reduce bone resorption and improve bone mass during growth. In addition, the significant elevation in mineral content and the maintenance of optimal Ca/P ratio in bone of DHA/ARA and DHA fed groups demonstrates that marine algae oils may be promising dietary sources for promoting bone mineralization and formation thus improving bone mass during the growth stage.