Feeding steam-pelleted rapeseed affects expression of genes involved in hepatic lipid metabolism and fatty acid composition of chicken meat.

This study investigated the dietary effect of steam-pelleted rapeseed (RS) diets with different inclusion levels on the fatty acid composition of chicken meat and the expression of lipid metabolism-related genes in the liver. Experimental diets included 6 different wheat-soybean meal based diets either in nonpelleted or steam-pelleted form supplemented with 80, 160, and 240 g RS/kg feed and one nonpelleted wheat-soybean meal based diet without RS supplementation as the control. These diets were fed to newly hatched broiler chickens (Ross 308) for 34 days. Compared to the control diet, steam-pelleted diets containing 160 or 240 g/kg RS significantly increased the content of omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) in the breast and drumstick, while their meat yields were not affected. Moreover, the mRNA levels of fatty acid desaturase 1 (FADS1) and acyl-coenzyme A oxidase 1 (ACOX1) in their livers increased. Therefore, steam-pelleted diets with 160 or 240 g/kg RS can be used to increase the n-3 LC-PUFA content in chicken meat without compromising meat yield.

Sesamin modulates gene expression without corresponding effects on fatty acids in Atlantic salmon (Salmo salar L.).

This study examined the effects of sesamin inclusion in vegetable oil-based diets fed to Atlantic salmon (Salmo salar L.). The diets used differed in n-6/n-3 fatty acid (FA) ratio (0.5 and 1) and sesamin content (high 5.8 g/kg, low 1.16 g/kg and no sesamin). The oils used in the feeds were a mixture of rapeseed, linseed and palm oil. Fish were fed for 4 months. Fatty acids and expression of hepatic genes involved in transcription, lipid uptake, desaturation, elongation and ß-oxidation were measured. No major effects on the percentage of DHA in white muscle, liver triacylglycerol and phospholipid fraction were detected. Genes involved in ß-oxidation, elongation and desaturation were affected by sesamin addition. Limited effects were seen on any of the transcription factors tested and no effect was seen on the expression of peroxisome proliferator-activated receptors (PPAR). Expression of both SREBP-1 and SREBP-2 increased with sesamin addition. It was concluded that supplementation of fish feed with a high level of sesamin had a negative effect on the growth rate and live weight and did not alter the proportions of DHA in tissues even though gene expression was affected. Thus, more studies are needed to formulate a diet that would increase the percentage of DHA in fish without negative effects on fish growth.

Influence of dietary sesamin, a bioactive compound on fatty acids and expression of some lipid regulating genes in Baltic Atlantic salmon (Salmo salar L.) juveniles.

The effects of inclusion of sesamin / episesamin in Baltic Atlantic salmon (Salmo salar L.) diets based on vegetable oils were studied. The study was designed as a dose response study with two control diets, one diet based on fish oil (FO) and one diet based on a mixture of linseed and sunflower oil (6:4 by vol.) (MO). As experimental diets three different levels of inclusion of sesamin / episesamin (hereafter named sesamin) to the MO based diet and one diet based on sesame oil and linseed oil (SesO) (1:1 by vol.) were used. The dietary oils were mirrored in the fatty acid profile of the white muscle. Sesamin significantly decreased the levels of 18:3n-3 in the white muscle phospholipid (PL) fraction of all groups fed sesamin, no significant differences were found in the triacylglycerol fraction (TAG). Slightly increased levels of docosahexaenoic acid (22:6n-3, DHA) in PL and TAG were found in some of the sesamin fed groups. Sesamin significantly affected the expression of peroxisome proliferator-activated receptor alpha, scavenger receptor type B and hormone sensitive lipase, in agreement with previous studies on rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar L.) hepatocytes published by our group. No significant effects on toxicological response measured as ethoxyresorufin O-deethylase activity was found. The total cytochrome P450 enzymes were significantly higher in MO 0.29 and SesO group. The amount of alpha- and gamma-tocopherols in liver and the amount of gamma-tocopherol in white muscle were significantly lower in fish fed the FO diet compared to the MO diet, but no difference after inclusion of sesamin was found in this study. Increased inclusion of sesamin increased the levels of sesamin and episesamin in the liver, but did not affect the amounts in white muscle.