An experiment was carried out to examine thoroughly the relationships among different n-3 and n-6 polyunsaturated fatty acids (PUFA) in the diet, their deposition into the eggs' fat, and their effect on hens' laying performance. A diet enriched with 4% fish oil (FO) was fed to the birds throughout the 14-wk laying period (Treatment 1; T1); this was the same oil source that was replaced in proportions of 25, 50, 75, or 100% with four different fat sources, resulting in 17 isocaloric dietary treatments: linseed oil (LO; T2 to T5), rapeseed oil (RO; T6 to T9), sunflower oil (SO; T10 to T13), and tallow (T; T14 to T17). Performance parameters were recorded weekly and analyzed on the basis of the replacing fat source. At the end of the 14-wk experimental period, eggs were collected, and their fatty acid (FA) profile was determined. Performance parameters were not significantly different among grouped treatments. Smaller proportions of FO in diets resulted in lower values of saturated and higher values of n-6 FA contents, regardless of the fat source used when replacing FO. The n-6 content increased mostly because of the rise in linoleic acid (LA), although the level of arachidonic acid (AA) was always higher when FO was completely suppressed. The amount of the different n-3 long-chain PUFA was lower (P < 0.001) when FO was present in lesser proportions in the diet. However, the slope of the decline of these FA changed according to the included fat. Replacing FO with LO resulted in the lowest decline of its derivatives by elongation and desaturation and an increase in the total n-3 FA in the form of linolenic acid (LNA).

To assess the effect of supplying linseed oil (LO) in the diet on performance, fatty acid (FA) composition, and quality objective parameters of broiler meat, diets enriched with 0, 2, or 4% LO plus tallow (T) up to 8% added fat (T1, T2, and T3, respectively) were given to broiler chickens throughout a 38-d growth period. T3 birds were slaughtered at 24 or at 52 d of age to study the effect of feeding time on FA accumulation in tissue. Objective and subjective evaluations of meat quality were performed on samples from 38-d-old birds, and the FA profiles of thigh and liver samples were determined. Performance parameters showed little difference between treatments. The differences in carcass yield values or in the objective quality parameters of the meat between treatments were not significant. Increased levels of LO clearly decreased the saturated (SAT) and monounsaturated FA (MUFA) contents. LO increased the amount of polyunsaturated FA (PUFA), mainly because of the linolenic (LNA) and linoleic (LA) acid content in the T3 samples, but they hardly reflected the wide range given in the experimental diets. The n-3 long-chain (LC) PUFA content of T3 thighs was slightly higher than in T1 thighs. Unexpectedly, longer feeding time of LO diets did not result in peripheral tissue accumulation of n-3 LC-PUFA, although chickens could convert LNA to longer-chain metabolites in liver at 24 d of age.

One hundred ninety-two female broiler chickens were randomly distributed into 16 experimental treatments as a result of the combination of 4 levels of dietary polyunsaturated fatty acids (PUFA) (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with alphatocopheryl acetate (alpha-TA) (0, 100, 200, and 400 mg/kg), to determine the modification of the amount and type of fatty acids (FA) deposited in raw and cooked chicken tissues. At 44 d, quantified FA of thighs and breasts were not affected by dietary supplementation with alpha-TA. Total FA content of breast was less than 15% of the total FA content of thigh. However, increasing the PUFA content of the diet by 46 g, from 15 to 61 g/kg, decreased total FA of thigh 17%, but did not affect FA content in breast meat. Monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) content of thigh (y) decreased linearly as the inclusion of dietary PUFA (x) increased (MUFA: y = 89.34 - 0.92x, R2 = 0.70; SFA: y = 53.81 - 0.43x, R2 = 0.57), whereas the relationship between PUFA content of feed (x) and thighs (y) was exponential (y = 92.03 92.03e(-00155x), R2 = 0.75). A similar response was observed in breast, with less variation and more incorporation of PUFA than thigh. Cooking of thigh meat led to a reduction in total FA content that affected SFA, MUFA, and PUFA in a similar proportion.

We assessed the effect of a diet supplemented with fish oil (FO) on the performance, fatty acid (FA) composition, quality, and sensory traits of broiler meat. Diets enriched with 0, 2, or 4% FO plus tallow (T) up to 8% added fat (T1, T2, and T3, respectively) were given to the birds throughout a 38-d growth period. T3 was replaced by a mixture of FO, linseed oil (LO), and T (1, 3, and 4% respectively) for 1 wk (T4) or 2 wk (T5) before slaughter. Meat quality, taste, and FA profile were determined. Higher final weights were recorded for birds fed T3, although feed efficiency was not affected. Other performance or objective meat quality parameters did not show significant differences among treatments. High FO concentrations decreased the saturated and monoenoic FA contents in the thigh samples. The amount of polyunsaturated fatty acids (PUFA) increased when added to the diet (FO diets), mainly as long-chain n-3 FA [eicosapentaenoic fatty acid (EPA), docosapentaenoic fatty acid (DPA), and docosahexaenoic fatty acid (DHA)]. On the other hand, levels of total n-6 FA resulted in slight changes, mostly in linoleic acid (LA). By replacing the FO diet with the experimental mixture (T4, T5), the n-3 and n-6 FA contents increased, mainly in the form of linolenic acid and LA, respectively, only 1 wk later. After 1 wk of T4, the DHA levels in chicken decreased. Sensory panelists could not identify the meats from T4 and T5 as being different from the control diet (T1).

The present study was carried out to evaluate the influence of increasing amounts of dietary polyunsaturated fatty acids (PUFA) and alpha-tocopheryl acetate (alpha-TA) supplementation on lipid oxidation of raw and cooked thigh meat stored under refrigeration. One hundred ninety-two female, 1-d-old, broiler chickens were randomly distributed into 16 experimental treatments resuIting from the combination of 4 levels of dietary PUFA (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with alpha-TA (0, 100, 200, and 400 mg/kg). Thiobarbituric acid reactive substance (TBARS) values in cooked meat and cooked refrigerated meat were 12- and 24-fold higher, respectively, than in raw meat. Dietary polyunsaturation and alpha-TA supplementation affected lipid oxidation more markedly in cooked meat and cooked refrigerated meat than in raw meat and raw refrigerated meat. Lipid oxidation in cooked meat showed a significant linear increase as the concentration of PUFA in raw meat increased. The oxidative stability of meat was not affected by an increase in the dietary alpha-TA level from 200 to 400 mg/kg. Nonlinear relationship between TBARS values in cooked meat and alpha-tocopherol content of raw meat showed saturation in the antioxidant effect of alpha-Toc. The equation y = x (11.88 + 63.38e(-0.007z) was calculated to predict the minimum inclusion of alpha-tocopherol to diets (z) of chickens with certain dietary PUFA content (x) to assure a certain TBARS value (y).

The antioxidant effect of dietary supplementation with 500 or 1,000 mg/kg of a commercial rosemary extract vs. 200 mg/kg of alpha-tocopheryl acetate (alpha-TA) on the lipid oxidative stability of omega3-fatty acid (FA)-enriched eggs was compared. Lipid oxidation was measured in fresh eggs by the lipid hydroperoxide level and malonaldehyde content. Stability to iron-induced lipid oxidation was also measured. Results showed the clear antioxidant effect of dietary alpha-TA supplementation on omega3-FA enriched eggs. In contrast, dietary supplementation with rosemary extract showed no effect on any of the lipid oxidation parameters evaluated.

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A 2 x 2 x 2 factorial experiment was planned to study the influence of dietary fat source (linseed oil or sunflower oil) and dietary doses of alpha-tocopheryl acetate (alpha-TA) (0 or 200 mg/kg of feed) and canthaxanthin (CX) (0 or 5 mg/kg of feed) on fatty acid (FA) composition and lipid oxidation of fresh and spray-dried eggs. Dietary supplementation with alpha-TA and CX modified the levels of certain long-chain polyunsaturated FA (PUFA). Lipid oxidation in fresh eggs and spray-dried eggs at 0, 6, and 12 mo of storage was measured by the lipid hydroperoxide (LHP) and TBA values. The LHP and TBA values were up to 10 times higher in spray-dried eggs than in fresh eggs. The evolution of LHP and TBA values in spray-dried eggs showed that omega3 FA-enriched eggs were more susceptible to lipid oxidation than those enriched with omega6 FA. The omega-TA supplementation increased the lipid stability of enriched eggs and was very effective throughout the storage of spray-dried eggs. On the other hand, CX supplementation did not prevent lipid oxidation in PUFA-enriched eggs. Moreover, no synergistic effect between both compounds was detected.