Improvement of the quality of animal products by new scientific and practical methods is one of the important goals of animal nutritionists. Rearing systems based on low access to pasture decrease the useful fatty acids in animal products. Several studies have been shown that feeding strategies are known as the most effective factor on alteration of fatty acid composition of muscle and fatty tissues in ruminants. Therefore, this study aimed to assess the influence of Pomegranate seed oil (PSO) with higher ratio of unsaturated fatty acids, steroidal and polyphenolic compounds on blood metabolites and fatty acid profiles in bicepsfemoris muscles in the fattening lambs.

Twenty one male Sanjabi lambs (BW=27.5±2.6 kg, 3-4 months old) were used to evaluate the effects of PSO supplementation on blood parameters and fatty acid pattern of bicepsfemoris muscle. Lambs were randomly distributed between three treatments (control, and diets containing 2 and 4% of PSO) and were fed adlibitum for 90 days. The experimental diets were formulated (DM basis) to be isonitrogenous (CP=14.7%) and isocaloric (ME=2.6 Mcal/kgDM) and to meet NRC (2001) .Blood samples were taken from each lamb (10 ml) at the end of first, second, and third months and metabolite parameters concentration in blood were measured. Samples of Bicepsfemoris muscle were dissected and homogenized for determination of fatty acid composition to the procedure described by Folch et al. (1957). Fatty acid derivatives were prepared by methylation of the fatty acids (Metcalfe and Schmitz, 1961). The pattern of Fatty acids were determined by using gas chromatography apparatus (17, 37). This study was based on completely randomized design. Data were analyzed statistically by general linear model (GLM) procedure and means comparing were done by Duncan's multi-domain test with SAS (2004) software version 9.1 (51).

Results show that concentration of AST, ALT and ALP, insulin, uric acid and creatinine, were not affected by different levels of PSO in diet. No significant difference was observed in the amount of palmitic, stearic, myristic, linoleic acid (C18: 2) and linolenic acid (C18: 3) in bicepsfemoris muscle. Addition of PSO at level of 4% decreased (P <0.05) the MUFA level compared to control (47.69 vs. 39.08). Mean PUFA and PUFA to SFA ratio in bicepsfemoris muscle of lambs received PSO were higher than those in the control group (2.3 and 2.2 times, respectively). However, these differences were not significantly different. Total amount of omega-3 fatty acids (PUFA n-3) significantly increased due to feeding PSO.

Due to positive trend observed in MUFA, n-3 fatty acids and PUFA: SFA ratio, with increasing the levels of PSO, addition 4% of this oil in the diet of fattening lambs is recommended.