Fatty Acid Deposition on Broiler Meat in Chickens Supplemented with Tuna Oil

The aim of the present study was to evaluate the effect of feeding four levels of tuna oil on performance and fatty acid (FA) profiles of broiler chicken meat. 240 Ross broiler chickens were randomly assigned to 20 pens and divided into four treatments: 0%, 0.75%, 1%, and 1.25% of tuna oil. At 49 days, breast and legs-thighs muscles were processed for FA analysis. Concentrations of FA in legs and thighs meat were significantly higher when compared with breast meat. In both types of meats (breast and legs-thighs), the inclusion of 1.0% or 1.25% of tuna oil in the diet significantly increased (P < 0.05) the concentration of n-3 FA (especially docosahexaenoic and eicosapentaenoic acids). Fat in broiler breast contained a proportion of 29% saturated FA (SFA): 36% monosaturated FA (MFA): 35% polyunsaturated FA (PUFA); while legs and thighs meat had a proportion of 28% SFA: 38% MFA: 33% PUFA. The addition of tuna oil in the broiler diet significantly reduced the deposition of SFA, MFA, and PUFA in breast meat, while in legs and thighs these reductions were less noticeable. The significant reduction in the concentration of n-6 PUFA and the increment of n-3 PUFA were more evident in breast than in legs and thighs, and with the addition of 1% and 1.25% of tuna oil. The results of the present study suggest a difference in FA deposition attributable to supplementation with tuna oil. The addition of tuna oil could be recommendable to increase n-3 PUFA in both broiler chicken breast and legs-thighs meats, providing a healthier and functional chicken meat to consumer.


Introduction
Dietary recommendations of n-3 polyunsaturated fatty acids (PUFA), including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) on health, immunomodulation and reduction of several chronic diseases due to an increase inflammatory response is well documented [1][2][3][4][5][6][7].Marine fish are important sources of n-3 PUFA [8][9][10].In many countries, the consumption of marine products is very low; hence the benefit that could be derived from a diet rich in n-3 PUFA does not reach the majority of the population.On the other hand, fat in broiler white meat contains 33.5% of saturated, 30.5% unsaturated and 32% polyunsaturated fatty acids [11], which encouraging human consumption when these are compared with the low levels of PUFA and high levels of saturated fatty acids (SFA) in red meats [12].Therefore, manipulating the ratio of these FA could make chicken meat even more attractive to consumers.Poultry diets greatly influence lipid profile of chicken meat, and so SFA, mono saturated fatty acids (MFA) or PUFA tends to resemble the profile of the feed [13,14].The aim of the present study was to evaluate the performance and fatty acid (FA) profiles in breast and legs-thighs meats of broiler chicken fed four levels of tuna oil.

Birds and Diets
A total of 240 day-old Ross x Ross broiler chickens were randomly assigned to 20 pens and divided into four treatments (0%, 0.75%, 1% and 1.25%).Treatments were assigned randomly and consisted of the incorporation tuna oil in commercial sorghum-soybean diets (Table 1).Starter or grower diets were calculated to meet the recommendations of the National Research Council (NRC) [15,16].The final concentration of n-6 and n-3 PUFA in the experimental diets are shown in Table 2. Feed and water were provided ad libitum until the end of the experiment (49 days of age).

Analytical Methods
At 49 days, 10 birds (one from each replicate) were humanely killed.Breast, legs and thighs were taken from these birds and the bones and skin removed.Meat sam-ples were macerated with a food processor and frozen at −20˚C until chemical analysis.Samples were processed according the methods described by Folch for total lipid analysis [17].Methyl esters of meat fatty acids were obtained and saponification was performed using boron trifluoride [18].Fatty acids were quantified by gas chromatography using a DB-23 column (JW 122-2332 of 30 m × 0.25 mm internal diameter) on a Varian 3400 CX gas-liquid chromatograph, equipped with an autosampler and a flame ionization detector (Varian Associates, Inc., Sugar Land, TX).Nitrogen was the carrier gas at a flow rate of 30 mL/min.Temperatures were: column, 230˚C; injector, 150˚C; detector, 300˚C.Myristic acid (Sigma Chemical Co., St. Louis, MO.) was used as an internal standard for fatty acids.Retention times were compared with fatty acid methyl ester standards.

Statistical Analysis
Data from the productive parameters and meat chemical analysis were analyzed by analysis of variance using the General Linear Models (GLM) procedure.Significant differences (P < 0.05) were further separated using Tukey's multiple range test and commercial statistical analysis software (SAS Institute, 2002), with sex and treatment replicate as main effects [19].

Production Parameters
Body weight, body weight gain, and feed conversion ratio were not influenced by dietary treatment (Table 3).These data are in agreement with previous studies which incorporated different PUFA into broilers' diets and did not find significant differences in these performance parameters [14,20].

Total Lipid and Fatty Acid Composition
The comparison of the content of total lipids and FA between meats in broiler diets with different concentrations of tuna oil is summarized in Table 4. Content FA were significantly altered in both types of meat, showing a progressive increase in n-3 PUFA when tuna oil was added, however, the concentrations of total lipids and FA in legs and thighs meat were significantly higher when compared with breast meat (Table 4).Interestingly, in both types of meat, the inclusion of 1.0 or 1.25% of tuna oil in the diet significantly increased the concentration of n-3 PUFA (especially EPA and DHA).The concentration of EPA in legs and thighs was 300% higher than in breast and 100% higher for DHA in the same tissues.
These results agree with previous reports [14,18,21].This profile is more beneficial for human consumption compared with the 40% SFA: 40% MFA: 20% PUFA presenting in beef meat [11].The addition of tuna oil in the broiler diet significantly reduced the deposition of SFA, MFA, and PUFA in breast meat, while in legs and thighs these reductions were less noticeable (Table 4).On the other hand, the significant reduction in the concentration of n-6 PUFA and the increment of n-3 PUFA were more evident in breast than in legs and thighs, and  with the addition of 1% and 1.25% than 0.75% of tuna oil (Table 4).Similar results have been reported by other researchers [13,15,22].The results of the present study suggest that tuna oil could be an attractive alternative to increase the concentrations of n-3 PUFA in broiler chicken meat.