The study was designed to evaluate the effects of different dietary levels of rice bran (RB) in laying duck diets on performance, egg quality, oxidation status, egg yolk fatty acid composition, and hepatic expression of fatty acid metabolism-related genes. Longyan females (1080) with similar BW at 19 wk of age were randomly assigned to 6 dietary treatments, each consisting of 6 replicates of 30 birds. The basal diet (I) was a typical corn-soybean ration while the experimental diets (II to VI) substituted RB for corn and wheat bran and a small reduction of soybean meal. The level of substitution in diets (II to VI) was 6%, 12%, 18%, 24%, and 30%, respectively. The experiment lasted for 12 wks. Average egg weight and daily egg mass decreased linearly as the level of RB inclusion increased (P<0.001) and feed conversion ratio linearly increased (P<0.001). The proportions of C14:0 and C18:0 and total saturated fatty acids (SFA) in egg yolk linearly decreased with increasing RB, and many of the key polyunsaturated fatty acids (PUFA), like C18:2 n-6 and C18:3 n-3, linearly increased (P<0.001), but not those of C20:5 n-3 and C22:6 n-3. There were linear decreases (P<0.001) in hepatic abundance of FAS and SREBP1 transcripts, with a substantial reduction to about 30% those of ducks fed the control diet; there were no treatment effects on productive performance, eggshell thickness, strength, Haugh unit, antioxidation status, and egg yolk cholesterol or triglyceride content (P>0.05). In conclusion, the current study suggests that ducks from 19 to 31 wk could be fed diets with up to about 18% RB without effect on the number of eggs produced, egg quality, and oxidative status. Increasing amounts of RB linearly increased egg yolk concentrations of key fatty acids like C18:2 n-6 and C18:3 n-3 and decreased the hepatic abundance of FAS and SREBP-1 transcripts.

ABSTRACT:The effect of dietary 18:2n-6/18:3n-3 ratio (by the replacement of corn oil with linseed oil) on n-3 polyunsaturated fatty acids (PUFA) enrichment in breast muscle of broiler chickens and the expression of lipogenic genes were investigated. Broiler chickens were fed ad libitum with diets containing 5% corn oil (CO), 3.75% corn oil + 1.25% linseed oil (CL1), 2.5% corn oil + 2.5% linseed oil (CL2), and 5% linseed oil (LO) based on the basic diets, respectively. Dietary 18:2n-6/18:3n-3 ratio did not affect 42-day body weight and 0-42-day feed conversion efficiency (feed/gain, P > 0.05) of broiler chickens, however, 5% linseed oil significantly increased 0-21-day feed conversion efficiency (feed/gain, P < 0.05) and decreased breast muscle weight (by 16%, P < 0.05) of broiler chickens. With the decrease of dietary 18:2n-6/18:3n-3 ratio, the enrichment of total n-3 PUFA, 18:3n-3, 20:5n-3, and 22:5n-3 increased linearly (P < 0.01), while the enrichment of total n-6 PUFA and 18:2n-6 decreased linearly (P < 0.01) in breast muscle of broiler chickens. Dietary corn oil increased the enrichment proportion of 20:4n-6 in a dosage-independent manner. Replacing 1.5% corn oil with linseed oil increased the enrichment proportion of 22:6n-3 (P < 0.05), but continuing to increase dietary linseed oil could not further elevate its deposition. Real-time quantitative RT-PCR was used to determine the expression of the mRNA levels of related genes. Dietary PUFA had insignificant effect on the expressions of LPIN2, WD, and tetratricopeptide repeats 1 (WDTC1) and △-6 fatty acid desaturase (FADS2) in both breast muscle and abdominal fat. The effect of dietary PUFA on the expression of LPIN1 gene showed clear tissue dependence. Equivalent adding of corn oil and linseed oil could up-regulate the mRNA level of LPIN1 in abdominal fat (P < 0.01). This study demonstrated that decreasing dietary 18:2n-6/18:3n-3 ratio promoted the deposition of desirable n-3 long chain PUFA in the edible tissue and influenced the expression of LPIN1 in a tissue-dependent manner.

Ningxia Tan sheep meat is tender, has no strong smell, a delicious taste, and even fat distribution. Intramuscular fat (IMF) content and the composition of fatty acid (FA) both are important factors associated with meat quality, and are also important for meat tenderness and flavor assessment. We examined the correlation of candidate genes expression with these factors in four muscle tissues, including longissimus dorsi, triceps, biceps and supraspinatus from Tan sheep. The IMF and FA composition in the different muscle tissues were measured and associated with mRNA expression of related genes (PPARγ, C/EBPα, FAS, LPL, FABP4, and ACC). IMF content in longissimus dorsi muscle was 45.4% higher than that in triceps brachii (P < 0.05), 48.4% higher than that in biceps femoris, and 20.1% higher than that in supraspinatus. PPARγ, C/EBPα, FAS and LPL mRNA levels in supraspinatus were significantly different among longissimus dorsi muscle, biceps femoris and triceps brachii. There was significant positive correlation between IMF content and the relative mRNA expression of PPARγ, C/EBPα, FAS, LPL, FABP4 and ACC in longissimus dorsi muscle. The ratio of polyunsaturated fatty acids to saturated fatty acid was positively and significantly correlated with C/EBPα and ACC mRNA levels, and negatively and significantly correlated with FAS and FABP4 mRNA levels. Omega-6 fatty acid (ω6)/omega-3 fatty acid (ω3) ratio was positively and significantly correlated with C/EBPα, FAS and LPL mRNA levels, but negatively and significantly correlated with FAS ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 19 (4): gmr18550 X. Xu et al. 2 and PPARγ mRNA levels. These correlations indicate that PPARγ, C/EBPα, FAS, LPL, FABP4, and ACC are key candidate genes for fatty deposits and the components and contents of FA in sheep, and the evaluation and functional verification of these genes may be useful for improving the meat quality of Tan sheep.