Effects of Various Dietary n-6:n-3 PUFA Ratios on Growth Performance, Carcass Traits, Blood Lipid Profiles and Meat Quality in Finishing Pigs

A total of 96 crossbred pigs [(Landrace × Yorkshire) × Duroc] with an average initial BW of 51.50 ± 1.56 kg were used in this 10-wk feeding trial to evaluate the effects of different dietary n-6:n-3 polyunsaturated fatty acids (PUFA) ratios in finishing pigs. Pigs were randomly allotted to 4 dietary treatments with 6 replications and 4 pigs per pen (2 barrows and 2 gilts). Pigs were fed a corn-soybean meal-based diet with various n-6:n-3 ratios (1:1, 5:1, 10:1 and 15:1). Pigs were weighed on initial and at the end of wk 5 and 10 while feed consumption was recorded to calculate ADG, ADFI, and G:F. At the end of the experiment, blood samples were taken from two pigs per pen via jugular venipuncture into vacuum tubes and serum recovered by centrifugation at 2,000 × g for 30 min at 4°C. The serum concentration of total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) and triglyceride were analyzed using an autoanalyzer (Automatic Biochemical Analyzer, RA-1000, Bayer Corp., Tarrytown, NY). After slaughter, backfat thickness and lean meat percentage were measured using a real time ultrasound instrument (Piglot 105, SFK Technology, Herlev, Denmark). Then a sample of the right loin was removed between the 10th and 11th ribs to determine meat quality, including meat color, sensory evaluation (color, marbling, and firmness scores), cooking loss, drip loss, pH, longissimus muscle area and water holding capacity. All data were analyzed using the GLM procedure of SAS. Differences among treatment means were determined using the Tukey’s range test. Growth performance, carcass traits and meat quality characteristics were not influenced (P > 0.10) by dietary n-6:n-3 ratios. The serum total cholesterol and LDL cholesterol contents of pigs fed the diet with an n-6:n-3 PUFA ratio of 1:1 (1.75 and 1.01 mmol/L) were lower (P < 0.05) than those fed the diet with ratios of 10:1 (2.11 and 1.39 mmol/L) and 15:1 (2.18 and 1.23 mmol/L). Furthermore, the serum triglyceride contents of pigs fed the diet with n-6:n-3 PUFA ratios of 1:1 (0.58 mmol/L) and 5:1 (0.60 mmol/L) were lower (P < 0.05) than those fed diet with ratios of 10:1 (0.96 mmol/L) and 15:1 (0.89 mmol/L). In conclusion, lowering the dietary n-6:n-3 to 1:1-5:1 is beneficial for lipid metabolism in finishing pigs and without adverse effects on growth performance, carcass traits and meat quality.