| Conjugated linoleic acid(CLA),a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds,possesses many potentially beneficial effects to health. Supplementing ruminant animal diets with fat,especially vegetable oils rich in linoleic acid has been demonstrated to be an effective strategy to enrich ruminant products with CLA.Recent years, many experiments about supplementing ruminant animal diets with fat has been investigated as a means to influence a variety of ruminal environment parameters or to alter fatty acid profile of food products derived from ruminant animals.The objective of this study was to determine the effects of the addition of vegetable oils in equal-level of linoleic acid on ruminal fermentation,blood indexes, fatty acids profiles in rumen fluid and plasma.Four healthy crossbred of northeast semi-fine wool and dorset male sheep(BW=40±1kg) fitted with ruminal cannulas were used in a 4×4 Latin square design with 16d periods.Dies were 60%chinensis and 40%concentrate,and a control diet with no added fat.Peanut oil,corn oil,or soybean oil was added to high fiber diets at 4%,2.84%,or 2.86%of the dietary air-dry matter.After adding vegetable oil,linoleic acid was in the same level in each oil supplemented treatment diet,and the level of oleic acid in peanut oil treatment was 2 times than the corn oil treatment,the total content of oleic acid and linolenic acid in soybean oil treatment was equal to the content of oleic acid in corn oil treatment,the ratio of oleic acid to linolenic acid was 3:1 in soybean oil treatment.This experiment included the following 4 parts:Part 1:Effects of vegetable oils on ruminal environment.Ruminal samples were collected on the first day of each period and analyzed for ruminal pH,NH3-N concentration,protozoal counts, major VFA concentrations,acetate to propionate ratio,and the cell wall degrading enzymes activities.Results showed that vegetable oils had no effect(P＞0.05) on ruminal pH,and NH3-N, acetate,propionate,butyrate,TVFA concentrations,and acetate-to-propionate ratio,the proportion of each major VFA in rumen fluid,but the acetate to propionate ratio presented a decreasing tendency.Supplementing peanut oil in sheep diets decreased(P＜0.05) the protozoal counts in rumen fluid by 42.18%compared with sheep in the control diet.Corn oil or soybean oil also decreased the protozoal counts,but did not differ(P＞0.05).Supplementing peanut oil decreased (P＜0.05) the activities of FPase,CMCase,glucosidase,and pectase in rumen contents by 17.52%, 17.98%,17.95%,and 24.27%,respectively.Soybean oil treatment decreased the 4 cellulase activities in sheep rumen contents,but did not differ(P＞0.05).Corn oil treatment had a trend of increasing(P＞0.05) the 4 cellulase activities.However,supplementing vegetable oils did not affect the xylanase activity in sheep rumen contents,and there is a decreasing tendency in peanut and soybean oil treatments,and an increasing tendency in corn oil treatment.Part 2:Effects of vegetable oils on fatty acids profiles in plasma and rumen fluid.Blood samples were collected before morning feeding and rumen fluid samples were collected 4 times after morning feeding on the last day of each period and analyzed for fatty acids profile of plasma and rumen fluid.Sheep,diet supplemented with vegetable oil is helpful to the accumulation of precursor of CLA and CLA,and increased(P＜0.05) the concentration of t11C18:1 and CLA in rumen fluid compared with sheep in the control diet.Ruminal concentrations of PUFA and SFA were increased(P＜0.05) in oil supplementation treatments.The increasing contents of t11C18:1 and SFA were observed in plasma(P＜0.05),but vegetable oil supplementation did not influence the content of PUFA in plasma.Concentration of C18:0 in rumen fluid or plasma of peanut oil treatment was greater(P＜0.05) than the other treatments.Part 3:Effects of vegetable oils on serum indexes.Blood samples were collected before morning feeding on the last day of each period and analyzed for blood serum indexes.Compared with control diet,serum TG,CHOL,HDL,and LDL levels which is associated with lipid metabolism had an increasing trend in vegetable oil treatments,and both serum CHOL and LDL levels were greater(P＜0.05) in corn oil and soybean oil treatments.Supplementing vegetable oil had no evident regularity effect on T-AOC,but had a trend of decreasing MDA contents and increasing the activities of SOD.Oil treatments did not influence insulin concentration but had a trend to increased serum leptin,and supplementing peanut oil increased(P＜0.05) leptin level by 19.29%,and no significant increasing in corn and soybean oil treatments(P＞0.05).Supplementing vegetable oil did not influence the other biochemical indexes(P＞0.05).Part 4:In this part we studied the effects of the addition of vegetable oils to the concentrate portion of total mixed diets on ruminal and total tract digestibilities of nutrients.Rumen digestibilities of DM,CP,and NDF were measured by the nylon bag technique and nutrient total tract digestibilities by AIA on the 2,3,4,and 5 day of each period.Rumen digestibilities of DM,CP, and NDF did not differ(P＞0.05) among diets except for the negative associative effect on the disappearance of NDF in peanut oil treatment.Total tract digestibilities of EE was great(P＜0.05) for the diets containing vegetable oils than for the control diet because of trends for greater postruminal digestibilities.Apparent total tract of DM,CP,NDF,and ADF digestibilities were not different among treatments.Analysis indicated that,supplementing ruminant animal diets with 4%of peanut oil,2.84%of corn oil,or 2.86%of soybean oil could lead to the accumulation of t11C18:1(CLA precursor) and CLA in rumen fluid and plasma,and the influence had no differ when diets contained the same level of linoleic acid,and the influence of oleic acid or linolenic acid on the concentration of CLA and its precursor was not observed.It might conclude that,in the means of supplementing diets with different vegetable oils to enrich ruminant products with CLA,the amount could base on the content of linoleic acid in vegetable oil.But the amount and cost of peanut oil was greater than the other oils,and the peanut oil in this level had some inhibition on ruminal fermentation.The price of corn oil was greater than soybean oil.So considering from the two sides of action effect and economic benefit,corn oil and soybean oil are better than peanut oil in improving the CLA content in ruminant production,and soybean oil are more economical than corn oil.
|
PDF Full Text Request