Abstract
The effects of dietary sources of C18:2 n-6 or C18:3 n-3 fatty acids on the occurrence of conjugated linoleic acid (CLA) and time-dependent changes of free fatty acid fractions in rumen contents were investigated. Sheep (n=4) fitted with rumen fistula were used in a 44 Latin square design with each 14 d period. Sheep were fed one of four diets consisting of grass hay and concentrates in a ratio of 70:30. Dietary treatments were 100% concentrates (served as the control), and concentrates were replaced by safflower seed at 30% (SFS), safflower meal at 18% - safflower oil at 12% (SFO), and safflower meal at 18%-linseed oil at 12% (LNO). At the end of each experimental period, rumen contents from each sheep were collected before feeding and at 1, 3, 6 and 12 h after feeding. The levels of cis-9, trans-11 CLA in free fatty acid fraction were considerably increased in all treated groups relative to the control, but not significantly. The increase in cis-9, trans-11 CLA was slightly higher in SFS and SFO groups than group fed diet containing linseed oil. The level of cis-9, trans-11 CLA in free fatty acid fraction was reached to the maximum value at 1hr after feeding and, thereafter gradually decreased to near the value before feeding. The generation of trans-11 C18:1 was significantly higher in all treated groups than that of control. The level of trans-11 C18:1 was linearly increased after feeding of experimental diets, reaching the maximum value at 3 h. Feeding of diets containing polyunsaturated fats to sheep resulted in a marked increase in the levels of trans-11 C18:1 and a slight increase of CLA in free fatty acid fraction of rumen contents. Our results support that endogenous synthesis of CLA from trans-11 C18:1 may be involved the primary source of CLA in dairy product. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 2 : 222- 226)
Highlights
Conjugated linoleic acid (CLA) is an intermediary product in the ruminal biohydrogenation of polyunsaturated fats, such as C18:2 n-6 or C18:3 n-3 fatty acids, presented in concentrates and pasture
The total lipids the end of experimental period are slightly increased as compared to pre-experiment
To obtain free fatty acid fraction, the lipid animals fed treated diets containing full-fat seed or extracts were separated by thin layer chromatography on vegetable oils
Summary
Conjugated linoleic acid (CLA) is an intermediary product in the ruminal biohydrogenation of polyunsaturated fats, such as C18:2 n-6 or C18:3 n-3 fatty acids, presented in concentrates and pasture. The positive effects related to CLA have intensified the research efforts to increase the level of this fatty acid in milk and dairy products (Bauman et al, 2000). These studies have been focused on the development of dietary regimens to increase the level of CLA in milk and dairy products. At the end of each experimental period, rumen contents from each sheep were collected for determining the fatty acid composition.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
