Effect of dietary canola oil level on the growth performance and fatty acid composition of fingerlings of rainbow trout (Oncorhynchus mykiss)

This study evaluated the suitability of canola oil as a source of supplemental dietary lipid for rainbow trout. Triplicate groups of the 30 fingerlings held under identical culture conditions were fed twice daily by iso-nitrogenous, iso-calorific and iso-lipidic diets for eight weeks. Experimental diets consisted of 30.3% protein, 18.7 kJg^-1 energy and 16.7% lipid from fish oil (FO), canola oil (CO) and 1:1 blend of the two oils (FCO). Moisture, ash, protein, lipid, final body weight, condition factor, feed conversion ratio, survival and hepatosomatic indices were not affected by treatments. Specific growth rate and weight gain of fish reared on fish oil diet (FOD) and canola oil diet (COD) were significantly higher than those fed with the fish and canola oils diet (FCOD). Protein efficiency ratio was highest in fish fed with the COD. Whole body fatty acid compositions mirrored those of diet treatments. The highest amounts of HUFAs were detected in fish fed with FOD, which was significantly different from other treatments. In all treatments PUFAs/SFAs and n-6/n-3 ratios were higher than 0.45 and lower than 4, respectively. Our results indicate the fingerlings can be reared on diets in which FO has been replaced with CO, with no significant effects on fish growth performance

The effect of simultaneous application of nitrogen and copper on yield and steroidal sapogenin production in Trigonella foenum graecum L.

Diosgenin (a steroidal saponin of fenugreek) has long been used as a raw substance for the manufacturing of steroid drugs. In order to evaluate the nutritional effect of different nitrogen (0, 50, 100, 150 and 200 kg ha-1) and copper (0, 10, 20 and 30 kg ha-1) doses on the diosgenin content, growth and yield of fenugreek (var. Ardestan), an experiment was carried out in a factorial arrangement based on complete randomized block design. The diosgenin content in the plant was monitored by a high performance liquid chromatography. Lower doses of copper increased yield, yield component and diosgenin content, but its higher level (30 kg ha-1) had negative effects on the plant yield. The simultaneous application of nitrogen and copper ameliorate the diosgenin production, yield and yield component. The result obtained from correlation and stepwise regression analysis showed that traits such as leaf area index, pods number per plant, and dry weight have significantly direct relation to diosgenin production levels in plants, while dry weight has the highest effect on diosgenin production compared to other traits. According the results, we also can conclude that nitrogen application can decrease copper toxicity in fenugreek in the contaminated soils