| The objective of this thesis was to evaluate the compound use of vegetable oil and rumen adjusting agent on improving CLA content in vitro and in vivo. The in vitro experiment was conducted to determine the fatty acid content in vegetable oils using gas chromatograpgy, and select the best vegetable oil for the synthesis of fatty acid and the suitable addition of monensin. The in vivo experiment was conducted to evaluate the effect of soybean oil and monensin which were applied as two testing factors on rumen fermentation, fatty acid composition, diet digestibility, and blood parameters. Four healthy sheep (BW=38±1kg) fitted with permanent ruminal cannulas were assigned to 4 dietary treatments in a 4×4 Latin square over four consecutive periods of 12d each. 4 sheep received either a control diet or one of 3 treatment diets. The control diet (CK) consisted of 60% forage and 40% concentrate on a air-dry matter basis. The treatments diets were formulated with supplemental 4% of soybean oil (S), 4% of soybean oil plus 25mg/kg of monensin (S+M), or 25mg/kg monensin (M).Experiment 1, The objective of this study was to determine the fatty acid composition in vegetable oils using capillary gas chromatograpgy. Vegetable oils were analyzed for FA on a Shimadzu GC-2010 gas chromatograph equipped with a flame-ionization detector and 100-m SP-2560 fused silica capillary column (100m×0.25mm×0.2μm). The injector and detector temperatures were set at 240℃, and the split ratio in the injector port was 50:1. Purified nitrogen was used as the carrier gas with a head pressure of 266.9 kPa, a flow rate of 1.04mL/min, and linear velocity of 20cm/s. The initial column temperature was set at 165℃and held for 30min, increased to 200℃at 1.5℃/min and held for 20min, further increased to 230℃at 5℃/min, and finally held at 230℃for 5min. The result showed that the fatty acid in vegetable oils could be separated by capillary gas chromatograpgy very well. The ratio of oleic acid to linoleic acid was 28:55, 27:61, or 22:54 in soybean oil, sunflower oil, or corn oil respectively. There was 4% of linolenic acid in corn oil. The ratio of oleic acid to linoleic acid was 46:33 in peanut oil. Olive oil was rich in oleic acid with the percentage of 78%, 5.75% of linoleic acid. Linseed oil was rich in linolenic acid, and the ratio of oleic acid to linoleic acid to linolenic acid was 21:14:54.Experiment 2, The objective of this study was to determine the addition of vegetable oil in vitro. Avicel was used as substrates, and vegetable oil was supplemented at the level of 0, 5, 10, 15 and 20mg respectively of 0.5g avicel. The incubation time was 4, 8, 16, 24, 36 and 48h for each level, and set 4 repetition for each incubation at each time. Results showed that the pH showed an increasing tendency with the increasing addition of vegetable oil,, but the NH3-N concentrations, the TVFA concentrations, and the cellulose disappearance rate at 48h decreased gradually. Under this culture condition, the best addition of vegetable oil was 5mg to ensure the normal rumen fermentation, that is the fat supplementation accounts for equal to 1% of the substrate.Experiment 3, The objective of this study was to determine the ruminal fermentation of different vegetable oils and the synthesis regularity of PUFA (polyunsaturated fatty acids). The addition of vegetable oils was determined by experiment 2, and soybean oil, corn oil, sunflower oil, and peanut oil were used as fat sources. The incubation time was 2, 4, 8, 16, and 24h respectively, and culture fluid was used to determine the concentrations of PUFA and t11-C18:1. With the increasing of incubation time, the C18:0 content increased , the c9,c12-C18:2 content decreased gradually in culture fluid, and the content of t11-C18:1increased at first and decreased subsequently and then increased again with the maximum value at 24h. Contents of C18 fatty acids were increased (P<0.05) significantly in culture fluid with vegetable oils. The soybean oil treatment had the maximum content of t11-C18:1 (P<0.05), then sunflower oil treatment (P<0.05), and peanut oil treatment was lowest. The maximum content of c9,c12-C18:2 appeared in corn oil treatment (P<0.05), then soybean oil treatment (P<0.05), the lowest content appeared in peanut oil treatment. Comprehensive comparison the 4 vegetable oils, soybean oil as fat source had the best effect on the biohydrogenation of PUFA and the accumulation of t11-C18:1.Experiment 4, The objective of this study was to determine the effect of monensin at different levels on ruminal fermentation of linoleic acid (LA)and synthesis regularity of PUFA in vitro. LA was used as fat source and avicel was used as substrates. Monensin was supplemented at the level of 0, 10, 20, 30, and 40mg/kg substrates. After 2h, 4h, 8h, 16h, and 24h of incubation respectively, ruminal fermentation parameters and the biohydrogenation of PUFA in the culture fluid were determined. Results showed that monensin could decrease rumen pH and increase concentrations of NH3-N and TVFA in culture fluid, and there was a quadratic function relationship between the addition of monensin and the disappearance rate of cellulose. The relationship formula was y=-0.0261x2+1.0651x+7.6355, with R2=0.9918. It could be calculated by the derivative function that the disappearance rate of cellulose was inhibited while the addition of monensin was beyond 40.8mg/kg. The content of C18:0 in culture fluid increased with the increasing of incubation time, and decrease (P<0.05) with the supplementation of monensin. The quadratic function relationship between the addition of monensin and the content of t11-C18:1 was y=0.0014X2-0.0266X+0.3747, with R2=0.9894. It could be calculated by the derivative function that the content of t11-C18:1 in culture fluid increased with the increasing addition of monensin while the addition of monensin was beyond 9.5mg/kg. Monensin could decrease (P<0.05) the content of c9-C18:1, but there was no dose-effect between the addition of monensin and the synthesis of c9-C18:1. Monensin could inhibit the biohydrogenation of c9,c12-C18:2 and improve the content of c9,c12-C18:2 in culture fluid, furthermore the high dosage of monensin had the obvious inhibitory effect (P<0.05). The biohydrogenation rate of t11-C18:1 and c9,c12-C18:2 decreased with the increasing addition of monensin. It was concluded that the addition range of monensin was 9.5~40.8mg/kg in this experiment by ruminal fermentation and the synthesis of PUFA.Experimemt 5, The objective of this study was to determine the effect of monensin and soybean oil on fatty acid composition. Soybean oil increased (P<0.05) the contents of C16:0 and C18:0 in rumen fluid, but monensin decreased (P<0.05) the contents of C16:0 and C18:0 in rumen fluid. S+M treatment decreased (P<0.05) the contents of C16:0 and C18:0 in rumen fluid compared with S treatmeat. Soybean oil increased (P<0.05) the contents of t11-C18:1 and c9-C18:1 in rumen fluid and monensin increased (P<0.05) the contents of t11-C18:1, but decreased (P<0.05) the contents of c9-C18:1 in rumen fluid. S+M treatment increased (P<0.05) the content of t11-C18:1 in rumen fluid compared with S treatmeat. It was concluded that monensin could promote the synthesis of t11-C18:1 when diet was supplementel with soybean oil. Dietary supplementation with soybean oil and monensin increased (P<0.05) the the contents of c9,c12-C18:2 and c9,t11-CLA in rumen fluid, and the contents increased at first and decreased subsequently with feeding time and the maximum appeared at 4h after feeding. The biohydrogenation rate of t11-C18:1, c9,c12-C18:2,and c9,t11-CLA in the rumen fluid of dietary supplemented with monensin, but dietary supplemented with soybean oil decreased the biohydrogenation rate of c9,c12-C18:2. Results showed that dietary supplemented with soybean oil could increase the content of rumen fatty acid, and with monensin could decrease the content of saturated fatty acids and increase the content of PUFA especially t11-C18:1, furthermore, the compound use of soybean oil and monensin had a better effect.Ecperiment 6, Dietary supplementation with soybean oil and monensin increased (P>0.05) ruminal pH and the concentration of bacterial protein and decreased (P>0.05) the concentration of NH3-N. The concentration of TVFA in rumen fluid was decreased (P<0.05) in S treatment. Diet supplemented with monensin had a trend of increasing (P>0.05) the TVFA concentration, and decreased (P<0.05) the acetate concentration. The M treatment increased (P<0.05) the concentration of propionate. Dietary supplementation with soybean oil or monensin could decrease the activities of celulase and lipase.Experiment 7, Dietary supplementation with soybean oil could increase the concentration of TG, CHOL, HDL, and LDL in blood, and with monensin could increase (P<0.05) the level of leptin. Dietary supplementation with soybean oil and monensin had a trend of increasing the concentration of GLU and NEFA. Dietary supplementation with soybean oil increased (P<0.05) the concentration of T-AOC and SOD and decreased the concentration of MDA. The compound use of soybean oil and monensin could increase the antioxidation ability. Dietary supplementation with soybean oil and monensin decrease (P<0.05) the contents of C16 and C18 saturated fatty acid, and increased (P<0.05) the content of t11-C18:1 in blood. The compound use of soybean oil and monensin increaseed (P<0.05) the contents of t11-C18:1 and c9,c12-C18:2 in blood.Experiment 8, Dietary supplementation with soybean oil and monensin did not effect the passage rate and the degradation rate of DM and increased the degradability of neutral detergent fiber, but with soybean oil decreased (P<0.05) the effective degradability of crude protein, and with monensin decreased (P<0.05) the degradability of acid detergent fiber. Dietary supplementation with soybean oil and monensin had a trend of decreasing the whole tract apparent digestibility of dietary nutrients, but with monensin alone could increase (P<0.05) the apparent digestibility of crude protein. |
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