Abstract: During many years, the main objective of the poultry meat industry was to improve body weight and feed efficiency of the birds. However, in the modern poultry industry, there are other parameters that need to be taken into consideration such as low cholesterol, etc. deposition on the body. For this aim, an experiment was conducted to evaluation canola oil effects on the Iranian native Turkeys serum lipids and cholesterol. Ninety male Turkey chicks were randomly distributed into 3 experimental with three replicate for each groups. Diets were isonitrogenous and isoenergetic were given to Turkey chicks throughout four period of breeding (4th-8th, 8th-12th, 12th-16th and 16th-20th). The blood sample taken at the end of breeding period and serum values for triglycerides and total, High-Density-Lipoprotein (HDL) and LDL (calculated by Friedewald method). Data was analyzed with One Way (ANOVA) and means compared with Duncan test. For serum values were not found significantly different (p<0.05) in triglycerides and VLDL and in CHOL, LDL and HDL (p<0.05) were significantly different compared control group. Finally, our results shown that canola oil has a significant impact on lipid metabolism in native Turkey and could improve their serum lipid profile.

INTRODUCTION

Turkeys have been raised on the world to produce meat and their meat production currently developed in Iran. Oils have commonly been used as energy sources in the diets of Turkey. Thus, alter the biochemical parameter such as cholesterol, triglyceride and LDL and HDL very important to human health. Canola Oil (CO) has been recognized as rich plant source of Ω-3 fatty acids and medical research reported a diet abundant in Ω-3 fatty acids in beneficial for human health and has shown that some plant oil such as canola oil could alter some of serum biochemical parameters and transfer from animal feed into consumer products.

Cholesterol in the bloodstream is most important (Howard et al., 2006). Grundy (1980) found that dietary mono-unsaturated fatty acids (e.g., oleic) were very effective in lowering blood cholesterol concentration and may be important in preventing coronary heart disease. Poultry spices, age and breeding condition are known to affect cholesterol deposition (Hargis, 1988; Halle, 1996, 2001).

The objective of this research was to determine the effect of feeding canola oil on cholesterol and triglyceride, LDL and HDL content of male Iranian native Turkeys.

MATERIALS AND METHODS

Animal and diet: The investigation was performed on 90 male native Iranian Turkeys in their fattening period (from 4-20th week of age). The Turkey chicks with completely randomized design of 3 treatments, with 3 repetitions and 10 broiler chicks in each box were fed experimental diets containing 0% CO (T₁), 2.5% CO (T₂) and 5% CO (T₃) in fattening period. The experimental diets formulated isonitrogenouse and isoenergetic, accordance with the 1994 recommendations of the National Research Council (NRC).

The birds were given access to water and diets ad-libitum. The composition and calculated nutrient composition of the treatment diet is shown in Table 1. Four birds from each replicate were taken blood and after separate serum, translated to lab for analyses a cholesterol and triglyceride content.

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

Biochemical serum analysis: Total serum cholesterol, triglycerides and high density lipoprotein cholesterol were assayed using a commercial kit supplied by (Pars azmoon Co., Ltd.) and detected by (Alison, 300) autoanalyser system. Very low density lipoprotein cholesterol is estimated as (Triglycerides/5) (Friedewald et al., 1972). Low density lipoprotein cholesterol is estimated using the Friedewald equation (Low density lipoprotein cholesterol = Total cholesterol - (High density lipoprotein cholesterol-Trigylerides/5) (Friedewald et al., 1972).

Statistical analyses: Data were analyzed in a complete randomized design using the GLM procedure of SAS (2000) version 12 (SAS Inst. Inc., Cary, NC).

RESULTS AND DISCUSSION

The effect of canola oil on biochemical serum levels was shown in (Table 2). According to results were none significantly different on triglycerides and VLDL content in serum, while total cholesterol, HDL and LDL were significantly affected with dietary manipulation (p>0.05).

Table 2:	Least square means for serum biochemical parameter
1Triglycerides; 2Total cholesterol; 3Very low density lipoprotein cholesterol; 4High density lipoprotein cholesterol; 5Low density lipoprotein cholesterol. Values in the same row with no common superscript are significantly different

Cholesterol content has descending rate and affected canola oil and from 148.83 mg dL^-1 in control group (T₁) significantly reached to 114.0 mg dL^-1 in T₃ group, but compared with T₂ (126.67 mg dL^-1) hasn't significantly different. High density lipoprotein and very low density lipoprotein positively affected with CO and HDL content significantly increase in treatment contain with 5% CO (61.00 mg dL^-1) compared control group and for LDL results show that treatment with CO (T₂ and T₃) have lower content of LDL and significantly deferent compared with control group(p>0.05).

The present findings showed that substitution canola oil in dietary reduced the serum cholesterol concentration by 5%, whereas an addition of 2.5% decreased serum cholesterol, but not significant. Canola contains 65-75% monoenic fatty acids and 9-30% polyunsaturated fatty acids (Ackman, 1990). Monounsaturated fat has also been shown to lower cholesterol (Grundy, 1980; Mensink and Katan, 1989; Fouladi et al., 2008). Canola oil is an excellent source of monounsaturated fat, contains intermediate amounts of the precursor Ω-6 and Ω-3 polyunsaturated fatty acids Linoleic Acid (LA) and Alfa-Linoleic Acid (ALA), respectively and is very low saturated fat.

Canola oil as a source of phytosterols. Phytosterols (plant sterols) are structural analogs of the cholesterol found in animals and humans. The consumption of phytosterols has been shown in numerous studies to lower blood cholesterol levels and may therefore, help reduce the risk of cardiovascular disease (Ling and Jones, 1995). Unsaturated oil could decrease amount of harmful Low-Density Lipoprotein (LDL) cholesterol in the serum (Mensink and Katan, 1989; Judd et al., 1994; Katan et al., 1995; Ascherio and Willett, 1997). Studies have shown that consumption of monoenic fatty acids effectively lowers serum cholesterol concentrations (Mattson and Grundy, 1985; Sirtoni et al., 1986; Mensink and Katan, 1989; Dreon et al., 1990; Valsta et al., 1992; Grundy et al., 1988). The reduction of serum cholesterol by monoene-nich rapeseed oil agrees with earlier observations with monounsaturated fatty acids (Mattson and Grundy, 1985; Sirtoni et al., 1986; Mensink and Katan, 1989; Dreon et al., 1990; Valsta et al., 1992).

CONCLUSION

Finally, our results illustrated that canola oil has a significant impact on lipid metabolism in native Turkey and could improve there serum lipid profile.

ACKNOWLEDGEMENTS

Financial support for this study (Islamic Azad University, Shabestar Branch) and East Azerbaijan Research Center for Agriculture and natural Resources and Animal Science Research Department were provided. The authors are also grateful to them valuable support of Tabriz medical center for their skilled technical assistance.