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Research Article
 

Enrichment of Broiler Meat with n-3 Polyunsaturated Fatty Acids



R. Salamatdoustnobar, H. Aghdamshahriar and A. Gorbani
 
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ABSTRACT

One hundred twenty male broiler chickens were randomly distributed into three experimental treatments to determine of the amount Canola Oil (CO) fatty acids deposited in raw chicken tissues. These diets were isonitrogenous and isoenergetic were given to broiler chickens throughout a 42 day growth period. This trial was conducted in 3x3 factorial experiment. Birds were slaughtered at 56 days of age. After weighing the eviscerated carcass was apportioned into commercial cuts (back, two leg-thigh, two wings and breast). Breast and thigh meat samples were separated and frozen at 20°C until to determine as fatty acid profile. Data was analyzed with one way ANOVA and means compared with Duncan test. Results show that using CO with high level of ω-3 fatty acids could influence fatty acid profile and improved meat quality. Means of fatty acids percent for meat samples showed the quality of fatty acid composition improved with increase CO. The increase in dietary canola oil (from 0 to 4 g kg-1 diet) resulted in levels of ω-3 that approximately were 2 times higher in thigh and breast meat. Total n-3 content of breast and thigh meat significantly (p<0.05) was affected by canola oil in the diet and that contents were 1.70 and 1.12% for control group reached to 3.66 and 3.56% in T3 (4% CO) in breast and thigh, respectively.

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R. Salamatdoustnobar, H. Aghdamshahriar and A. Gorbani, 2008. Enrichment of Broiler Meat with n-3 Polyunsaturated Fatty Acids. Asian Journal of Animal and Veterinary Advances, 3: 70-77.

DOI: 10.3923/ajava.2008.70.77

URL: https://scialert.net/abstract/?doi=ajava.2008.70.77

INTRODUCTION

There are two reasons for the increasing level of polyunsaturation in chicken meat. First, human nutritionists recommend reducing the intake of Saturated Fatty Acids (SFA) because of its relationship with the development of cardiovascular diseases (Krauss et al., 2001). Secondly, the use of animal fats has been reduced approximately in world, in favor of vegetable oils that are more polyunsaturated. Many researchers have studied how the inclusion of different fat sources in the broiler`s diet affect) the proportion of Fatty Acids (FA), mainly Polyunsaturated Fatty Acids (PUFA), in meat (Scaife et al., 1994; Hrdinka et al., 1996; Lopez-Ferrer et al., 1999a, b) the amount of fat deposited by the birds (Sanz et al., 1999, 2000; Crespo and Esteve-Garcýa, 2001, 2002a, b). However, there are few reports on the effect of increasing levels of dietary PUFA on the amount and type of FA deposited in chicken tissues, especially in the edible portions. An increase in the degree of polyunsaturation of meat may enhance the development of organoleptic problems (Ajuyah et al., 1993; Gonza´lez-Esquerra and Leeson, 2000; Bou et al., 2001) and lead to an increased susceptibility to lipid oxidation (Klaus et al., 1995; Cortinas et al., 2001; Grau et al., 2001a, b). For a healthy diet, there should be a consumption of canola oil and some vegetable oils. For this reason, numerous research activities have been devoted to increasing the levels of these Fatty Acids (FA) in widely consumed products of animal origin whose lipid composition is easily modified (Hargis et al., 1991; Huyghebaert et al., 1995). Specifically, the use of vegetable oils in the diet of poultry makes it possible to increase the level of long-chain n-3 FA in meat (Chanmugam et al., 1992; Pinchasov et al., 1992).

Vegetable sources, such as canola oil and Linseed Oils (LO), may clearly increase the n-3 FA content in the form of Linolenic Acid (LNA), the precursor of the whole n-3 family. To enhance the conversion to longer-chain n-3 FA from their precursors and to increase the nutritional quality of poultry meat.

MATERIALS AND METHODS

Animals and Diets
The experiment was conducted of which Ross 208 strain were obtained from a commercial hatchery (270 one day old male broiler chicks) and were placed in 12 floor pens of 2x2 meters with 10 birds per pen. All chicks were fed a starter diet from 0 to 21 day and were ad libitum access to water and feed. The experimental design consisted in a completely randomized design with 3 treatments [T1 Control (Soybean +corn), T2 (2% CO) and T3 (4% CO)] with four replication. The treatments diets of were isonitrogenous and isoenergetic. Diets were formulated by adding 0, 2 and 4% canola oil to basal diet (corn and soybean meal) that met the requirements recommended by the National Research Council (1994). The control diet, which was not enriched with canola oil and was administered throughout the 21 days of experimental period (starter). The levels of canola oil were replaced with corn in diets during two different periods (grower and finisher). Ingredient composition and nutrient analysis for each treatment is described in Table 1-3.

At the age of 8 week, all the birds were weighed before being slaughtered and then eviscerated. Weights air-chilled carcasses after cutting off their heads and feet and after removing abdominal fat (considered as the fat extending within the ischium, surrounding the cloaca and adjacent to the abdominal muscle) to obtain ready-to-cook carcasses were recorded. In order to reduce variation in the cutting procedure, all dissections were carried out by one operator. After weighing the eviscerated carcass, it was apportioned into commercial cuts as back, two leg-thigh, two wings and breast (Hudspeth et al., 1973; Orr et al., 1984). Breast was obtained after removing wings by cutting through the shoulder joint at the proximal end of humerus and by cutting through the ribs, thereby separating the breast from the back (excluding skin).

Table 1: Percentage composition of experimental diet in starter period
1: Vitamin content of diets provided per kilogram of diet vitamin A,D, E and K.; 2: Composition of mineral premix provided as follows per kilogram of premix: Mn, 120,000mg; Zn, 80,000 mg; Fe, 90,000 mg; Cu, 15,000 mg; I, 1,600 mg; Se, 500 mg; Co, 600 mg

Table 2: Percentage composition of experimental diets in growth period
1: Vitamin content of diets provided per kilogram of diet: vitamin A, D, E and K; 2: Composition of mineral premix provided as follows per kilogram of premix: Mn, 120,000mg; Zn, 80,000 mg; Fe, 90,000 mg; Cu, 15,000 mg; I, 1,600 mg; Se, 500 mg; Co, 600 mg 3: T1 = 0% canola oil (CO); T2 = 2%CO; T3 = 4% CO

Table 3: Percentage composition of experimental diets in finisher period
1: Vitamin content of diets provided per kilogram of diet: vitamin A, D, E and K; 2: Composition of mineral premix provided as follows per kilogram of premix: Mn, 120,000mg; Zn, 80,000 mg; Fe, 90,000 mg; Cu, 15,000 mg; I, 1,600 mg; Se, 500 mg; Co, 600 mg 3: T1 = 0% canola oil (CO); T2 = 2%CO; T3 = 4% CO

The resulting cut pieces (breast meat, wings and thighs with drumsticks) were then weighed. After quartering, breasts and thighs were separated and frozen at 20°C until to determine as fatty acids profile. The lipid composition was determined by gas chromatography (Model 6890N American Technologies Agilent). The composition of meat samples fatty acid of supplemented lipids is shown in Table 4-7 data were statistically analyzed using one-way ANOVA and means with significant F ratio were compared by Duncan multiple range test.

Gas Chromatography of Fatty Acids Methyl Esters
Sample Preparation for Fatty Acids Determine
Breast and thigh weight was expressed as percentage of the carcass weight. Total lipid was extracted from breast and thigh according to the method of Folch et al. (1957). Approximately 0.5 g of meat weighed into a test tube with 20 mL of (chloroform: methanol = 2:1, vol/vol) and homogenized with a polytroon for 5 to 10 sec at high speed.

Table 4: Least square means for fatty acid profiles in broilers breast meat without skin fed canola oil1
1: Values given in this table are means of 3 dietary treatments with different levels of canola oil

Table 5: Least square means for fatty acid profiles in broilers thigh meat without skin fed canola oil1
1: Values given in this table are means of 3 dietary treatments with different levels of canola oil

Table 6: Least square means for different traits in broilers breast meat fed canola oil
Values in the same row with no common superscript are significantly different; Satur f.a; saturated fatty acids, MUFA; Monounsaturated fatty acid, PUFA; Polyunsaturated fatty acid

Table 7: Least square means for different traits in broilers thigh meat fed canola oil
Values in the same row with no common superscript are significantly different; Satur f.a; Saturated fatty acids, MUFA; Monounsaturated fatty acid, PUFA; Polyunsaturated fatty acid

The BHA dissolved in 98% ethanol added prior to homogenization. The homogenate filtered through a Whatman filter paper into a 100 mL graduated cylinder and 5 mL of 0.88% sodium chloride solution added, stopper and mixed. After phase separation, the volume of lipid layer recorded and the top layer completely siphoned off. The total lipids converted to Fatty Acid Methyl Esters (FAME) using a mixture of boron-trifluoride, hexane and methanol (35:20:45, vol/vol/vol). The FAME separated and quantified by an automated gas chromatography equipped with auto sampler and flame ionization detectors, using a 30 m´ 0.25 mm inside diameter fused silica capillary column, as described previously. A (Model 6890 N American Technologies Agilent) (USA) Gas chromatography used to integrate peak areas. The calibration and identification of fatty acid peak carried out by comparison with retention times of known authentic standards. The fatty acid results form gas chromatography with Chem Station software analyzed and expressed as weight percentages.

Statistical Analyses
Data were analyzed in a complete randomized design using the GLM procedure of SAS version 12 (SAS Inst. Inc., Cary, NC).

Yij = μ + ai + εij
Where,
Yij = All dependent variable
μ = Overall mean
ai = The fixed effect of oil levels (i = 1, 2, 3)
εij = The random effect of residual
Duncan multiple range test used to compare means.

RESULTS

Fatty acids of thigh and breast meat with out skin were modified by dietary polyunsaturation level. Total ω-3 FA content in breast and thigh meat, were significantly (p>0.01) increased (from 1.70% for control group to 3.66% T3 and 1.12% for control group to 3.56% for T3, respectively) with usage canola oil in diets. (Table 6 and 7). Recent studies showed that fatty acids content of this tissues influence by usage canola oil in diets and C18:3n3, C20:5n3, C20:1n9 and C22:6n3 contents in T3 significantly (p<0.05) was higher(Table 4 and 5). As expected, when the dietary polyunsaturation level increased, PUFA content in the tissues also increased (Table 6 and 7). The increased dietary canola oil (from 0 to 4 g kg-1 diet) resulted in levels of ω-3 fatty acids that approximately were 2 times higher in thigh and breast meat and that was significant (p<0.05). However, the Saturated FA and MUFA contents of thigh and breast were reduced as the dietary degree of polyunsaturation increased and for thigh meat this condition for myristic acid (C14:0) and stearic acid not significant but for palmitic acid (C16:0), arachidic acid (C20:0) and behenic acid(C22:0) was significant (p<0.05) also for breast meat the contents C14:0, C16:0, C18:0, C20:0 and C22:0 all was significantly (p<0.05) reduce in T2 and T3. This reduction was more marked in saturated FA (1.92 and 5.61% in thigh and breast, respectively, between control group and T3). Increasing the level of dietary polyunsaturation caused an increase in the accumulation of PUFA in thigh and breast. Results showed approximately same content of PUFA in breast and thigh respectively 15.11 and 14.81% but not significant (Hulan et al., 1988; Lopez-Ferrer et al., 1999a; Gonza´lez-Esquerra and Leeson, 2000; Crespo and Esteve-Garcýa, 2001). The relationship between dietary PUFA content and the content of the different families of FA in chicken tissues supports the idea that the FA composition in chicken tissues is a combination of direct deposition from dietary FA and endogenous fat synthesis.

DISCUSSION

In the percent study, effects of different levels of canola oils for enrichment of breast and thigh meat were investigated. This study suggests that ω-3 FA content in breast and thigh meat increased and reached 1.70 and 1.12% to 3.66 and 3.56%, respectively. A similar difference in thigh and breast content was reported by Lopez-Ferrer et al. (1999b and 2001) who observed increases of 2.7 and 2.3% in thigh proportion when fish oil replaced rapeseed oil or tallow, respectively. Other authors did not find any differences in thigh proportion between chickens fed tallow or different vegetable oils with a lower content of very long chain ω-3 PUFA (Olomu and Baracos, 1991; Crespo and Esteve-Garcýa, 2001).These results agree with other studies showing that separable fat depots (Crespo and Esteve-Garcýa, 2002a) and specifically abdominal fat (Vila and Esteve-Garcýa, 1996; Sanz et al., 1999; Crespo and Esteve-Garcýa, 2001, 2002a, b; Villaverde et al., 2003a), are reduced with the addition of unsaturated oils to the diets. It seems that fat deposits may easily be influenced by the polyunsaturation level of the diet. The mechanism by which dietary polyunsaturation modifies body fat deposition is not completely understood. Some authors have suggested that the lower fat deposition in broilers fed polyunsaturated fats compared with those fed saturated fats was, in part, explained by an increased rate of lipid catabolism and by a decrease of FA synthesis (Sanz et al., 2000). Similarly, other authors reported significantly lower metabolic oxidation of lipids and consequently a lower thermogenesis in tissues of rats fed saturated fats than in rats fed unsaturated fats (Shimomura et al., 1990; Wilson et al., 1990). Some authors showed that the dietary polyunsaturation level of oils does not influence intramuscular fatty acids content of breast and thigh (Scaife et al., 1994; Crespo and Esteve-Garcýa, 2001), but Kirchgessner et al. (1993) and Ajuyah et al. (1991) found a higher lipid content in breast and thigh muscle with increasing levels of PUFA in the diet. However, other authors found lower lipid content of breast and thigh of chickens fed diets enriched with unsaturated oils (Sanz et al., 1999). Similar to the results of the percent study and such discrepant findings in intramuscular fat content of breast and thigh muscles may be attributed to several factors, such as the analytical procedure used to extract fat from samples. In general, modification of FA composition of intramuscular fat seems to be more limited (Pan and Storlien, 1993; Lopez-Bote et al., 1997). It may be due to the fact that FA in intramuscular fat are used mainly as components of cellular membranes and the cell has to maintain its physical characteristics to ensure fluidity and permeability of different compounds. Few differences in this tissues PUFA profile could be attributed to different roles of FA in these tissues or to their different phospholipid contents. The PUFA are preferentially incorporated into phospholipids (Hulan et al., 1988) and phospholipids are in a higher proportion in breast than in thigh muscles (Ratnayake et al., 1989). These results agree with other authors who observed that the PUFA content in chicken tissues depends more on the variation in dietary FA (Lopez-Ferrer et al., 2001). Results of the percent study conclude that a 4 percent canola oil an provide optimal performance according to ω-3 fatty acids in breast and thigh meat and could usage this oil in broiler chicks diets and could replace with energetic ingredients in diet with any problems.

ACKNOWLEDGMENTS

Financial support for this study (Islamic Azad University, Shabestar Branch) was provided. The authors are also grateful to them valuable support and to Oorumieh Jahad University for their skilled technical assistance throughout the experimental analyses

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